Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Preparation, characterization and evaluation of x-MoO3/Al-SBA-15 catalysts for biodiesel production

Preparation, characterization and evaluation of x-MoO3/Al-SBA-15 catalysts for biodiesel production Biodiesel is an alternative source of renewable energy that can be produced by a transesterification of vegetable oils. Mesoporous molecular sieves, such as SBA-15, due to high surface area and thermal stability are promising precursors for heterogeneous catalysts in the transesterification reaction. In this work, Al-SBA-15 precursor was obtained by direct hydrothermal synthesis, impregnated with different MoO contents (5, 10 and 15 wt%) by the pore saturation method, and evaluated as heterogeneous catalyst in the production of biodiesel from a transesterification of soybean oil with methanol. Al-SBA-15 precursor as well as MoO /Al-SBA-15 catalyst were characterized for its structural characteristic by X-ray diffrac- tion, textural characteristic by N adsorption analysis, and thermal stability by thermogravimetric analysis. An experimental planning 2 + 3 CtPt was used to evaluate the influence of MoO content and reaction time on biodiesel yield from soybean oil and methanol. The biodiesel content in the final product was obtained by gas chromatography. An average biodiesel yield of 96% was obtained with the catalyst 10%MoO /Al-SBA-15 under the following reaction conditions: 20:1 methanol/ soybean oil molar ratio, and 3 wt% of catalyst loading at 150 °C in 3 h. After five consecutive reaction cycles, the biodiesel yield decreased by about 34%. The density and acidity of the biodiesel produced are within the specified values for com- mercialization according to international standards. * Bianca V. S. Barbosa bianca.viana@eq.ufcg.edu.br Joyce S. B. Figueiredo joyce.barros24@hotmail.com Bruno T. S. Alves brunotdsa@gmail.com Vitória A. Freire vitoriaqil14@gmail.com José J. N. Alves jailson@eq.ufcg.edu.br Catalysis, Characterization and Biofuels Laboratory, Department of Chemical Engineering, Federal University of Campina Grande, UFCG/CCT/UAEQ, Aprígio Veloso Avenue. 882-Bodocongó, Campina Grande, Paraíba CEP 58109-970, Brazil Vol.:(0123456789) 1 3 18 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Graphical abstract Keywords Biodiesel · Transesterification · Al-SBA-15 precursor · MoO /Al-SBA-15 catalyst In the stoichiometric reaction of transesterification 1 mol Introduction of triglyceride reacts with 3 mols of alcohol producing 3 mols of alkyl esters and 1 mol of glycerol. Alcohol is mixed Currently, fossil fuels are the main energy source in the in excess to shift the reaction balance towards biodiesel, global energy system. However, the increase in global increasing its yield [8, 9]. A high methanol to oil molar ratio energy demand, uncertainties regarding the availability is usually used due to the lower contact between catalyst and of oil in the future, and the environmental impacts caused reactants in the heterogeneous process than in the homoge- by burning fossil fuels, are factors that justify the need to neous one. A methanol to oil molar ratio up to 30–150 to 1 search for alternative sources of renewable energy to avoid has been reported in the literature [9–12], to guarantee the an energy crisis [1–3]. In this scenario, fuels derived from highest FAMEs yield [3, 7, 13]. Transesterification consists vegetable biomass such as biodiesel and ethanol are alter- of a series of consecutive, reversible reactions, forming alkyl natives as renewable sources of energy. Biodiesel is free esters in each step as shown in Fig. 1. The triglyceride is of sulfur and aromatics, has a high flash point and a high converted stepwise to diglyceride, monoglyceride and finally number of cetane [4]. This biofuel can replace, totally or glycerol [14]. partially, diesel petroleum oil in automotive or stationary The main process variables in the transesterification reac- engines, as well as be used pure or blended with petroleum tion are temperature, alcohol/oil ratio, reaction time, type of diesel in different proportions [5 , 6]. catalyst, water content, and free fatty acid content in veg- Biodiesel is a mixture of mono alkyl esters produced in a etable oils. This study focused on catalyst preparation and transesterification reaction, in which triglycerides from dif- evaluation for biodiesel production, taking as input variables ferent sources of vegetable oils or animal fats react with a the catalyst composition and reaction time, and biodiesel short chain alcohol, usually methanol or ethanol in the pres- yield as response variable. ence of a homogeneous, heterogeneous or even enzymatic Industrially, homogeneous catalysts, such as potassium catalyst [7]. hydroxide (KOH), sodium hydroxide (NaOH) and sulfuric 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 19 Fig. 1 Consecutive steps in the H C-O-CO-R H C-OH 2 1 2 transesterification reaction Catalyst HC-O-CO-R CH OH HC-O-CO-R + CH -CO-R 2 + 3 2 3 1 MethanolMethyl ester H C-O-C-R H C-O-C-R 2 3 2 3 TriglyceridesDiglycerides H C-OH H C-OH 2 2 Catalyst HC-O-CO-R2 + CH3OH HC-OH + CH3-CO-R2 MethanolMethyl ester H C-O-C-R H C-O-C-R 2 3 2 3 Diglycerides Monoglycerides H C-OH H C-OH 2 2 Catalyst HC-OH CH OH HC-OH+ CH -CO-R + 3 3 3 Methanol Methyl ester H C-O-C-R H C-OH 2 3 2 MonoglycerideGlycerides acid (H SO ) have been used in the transesterification reac- catalysts is the use of amorphous silica with an ordered 2 4 tion, with sodium hydroxide being the most used due to mesoporous structure, such as SBA-15 as a support [18, 19]. its low cost and high product yield. As disadvantages, the The incorporation of metals in the structure of amorphous homogeneous catalysts are not recovered, but neutralized, silica, such as aluminum and molybdenum, define an acidic the process is susceptible to the formation of soap due to characteristic of the mesoporous material [20]. the presence of water and free fatty acids in the reaction The insertion of aluminum ions in the structure of the medium, which complicates the purification of the products, SBA-15 allows the creation of acidic sites that are essen- making the process expensive [15]. Thus, heterogeneous tial for reactions catalyzed by acid [20]. Al-SBA-15 with its catalysts are a promising alternative to replace homogene- unique structure, surface characteristics, good thermal sta- ous ones in industrial biodiesel production, having as main bility and mechanical resistance make this molecular sieve advantages the easy separation of the reaction mixture by have better catalytic performance than traditional alumina simple physical processes, the non-need for neutralization catalysts throughout the reaction [21]. The literature reports and disposal, which minimizes harmful effluents from the that the incorporation of molybdenum in supports promotes environmental point of view [16]; in addition, they can be its catalytic activity, motivating studies for its use in the regenerated and reused, are tolerant to water and organic transesterification reactions [22– 24]. Molybdenum based solvents, have high thermal stability, strong acidity, and high catalysts are viable alternatives for transesterification, but catalytic activity [5, 17]. As disadvantages, the use of het- typically suffer from poor recyclability or require high tem- erogeneous catalysts requires more severe reaction condi- peratures to achieve useful activity [22]. tions, such as high temperatures and pressure, as well as a Mohebbi et al. [25] investigated the effect of MoO on the longer reaction time, in addition to the leaching of the active esterification reaction of oleic acid by methyl route for bio- sites of the catalysts. diesel production, using different MoO contents (5, 15, 25 Among the different types, mesoporous materials are and 35 wt%) impregnated in the heterogeneous mesoporous widely used in the development of catalysts, including for nanocatalyst B-ZSM-5. The optimum MoO content was the production of biodiesel, due to important characteristics, 25  wt% incorporated in the B-ZSM-5 nanocatalyst, and such as regular pore structure, high specific surface area that the optimal operating conditions were reaction time of 6 h, 2 −1 can reach 1000  m  g , thickness pore wall of about 6 nm, temperature of 160  °C, catalyst concentration of 3  wt%, thermal stability, ease of separation and regeneration. An and methanol/oleic acid molar ratio of 20:1. The maximum interesting alternative for the production of heterogeneous conversion of free fatty acids was 98%, confirming the high 1 3 20 Materials for Renewable and Sustainable Energy (2022) 11:17–31 potential of the MoO -impregnated nanocatalyst for indus- characterized in terms of thermal, crystalline and textural trial applications. properties, as well as its activity in the transesterification Ding et al. [26] synthesized and evaluated three acidic reaction was proved. MoO content influenced more the imidazolium liquids as catalysts for production of biodiesel catalytic conversion than the reaction time, in the studied in a transesterification of palm oil under microwave irradia - range. The x_MoO /Al-SBA-15 catalyst performance was tion, and concluded that [HSO -BMIM]HSO catalyst was compared to that of others catalysts for biodiesel production 3 4 the most effective for the reaction. The effect of methanol to in the transesterification reaction reported in the literature. oil molar ratio, catalyst dosage, microwave power and reac- The manuscript is organized with an experimental sec- tion time on yield of biodiesel was evaluated using an exper- tion describing the catalyst preparation and characterization, imental planning. From the regression model, a maximum the reaction performed, and the biodiesel characterization. biodiesel yield of 99.64%, with the aid of [HSO -BMIM] Results are discussed in a second section, and finally the HSO under microwave irradiation, was predicted. The opti- main conclusions are presented in a final section. mal reaction conditions were: mole ratio of methanol to oil 11:1, ionic liquid dosage 9.17%, microwave power 168 W, and reaction time 6.43 h. The predicted value was verified Experimental with the average yield of 98.93% from three experiments. Pinto et al. [23] synthesized molybdenum trioxide cata- Catalyst preparation lysts calcined at different temperatures (200, 300, 400, 500, 600 and 700 °C), and evaluated the effect of the catalyst Direct synthesis of the Al‑SBA‑15 catalytic precursor calcination temperature on the catalyst performance for the production of biodiesel from different vegetable oils. Dif- The mesoporous molecular sieve Al-SBA-15 used as a cata- ferent temperature, oil/alcohol ratio, reaction time and cata- lytic precursor was synthesized from an adaptation of the lyst load were evaluated. The highest catalytic activity was methodology described by Li et al. [28] and Zhao et al. [29]. for the catalyst calcined at 600 °C. The optimal operational Initially, the Pluronic P123 triblock copolymer was dissolved −1 conditions were 0.5 wt% of catalyst in 5 g of oil, reaction in a stirred aqueous solution of HCl (1.6 mol  L ) at 35 °C. temperature of 150 °C, and a methanol/oil molar ratio of After complete homogenization of the mixture, tetraethyl- 45:1. In these conditions, the yield reached 90%, indicating orthosilicate (TEOS) was added to the reaction medium. In a that the molybdenum trioxide catalyst is effective for the backer, aluminum nitrate (Al(NO ) ·9H O) was dissolved in 3 3 2 −1 transesterification reaction for biodiesel production. a stirred solution of ethanol and HCl (1.6 mol  L ) at 35 °C. 2− Li et al. [27] synthesized SO –MoO –ZrO –ND O / The two solutions were mixed together and taken to a roto- 4 3 2 2 3 SiO catalysts with different calcination times, denominat - evaporator, remaining for 24 h at 40 °C. A gel was formed ing them SMZN/SiO -X, where X is the calcination time with molar composition 1 Si: 0.017 P123: 4.96 HCl: 0.054 (X = 2, 4, 6, 8 and 12 h). The catalysts were evaluated for Al: 35.42 EtOH, which was then crystallized in an oven at production of biodiesel by both esterification of lauric acid 100 °C for 48 h. The resulting material was cooled and then with methanol, and transesterification of triacetin and jat- washed with deionized water to remove excess of director ropha oil with methanol. A yield of 97.1% was achieved in until the filtrate reached pH = 7. The material was dried in an the esterification with SMZN/SiO -2 h and SMZN/SiO -4 h oven at 60 °C for 24 h. Finally, the catalytic precursor (Al- 2 2 catalysts. A methyl acetate yield around 92.1% was achieved SBA-15) was activated by calcination, under synthetic air with all catalysts in the transesterification of triacetin. In flow, from room temperature of 25 to 550 °C over 6 h, with −1 the transesterification of jatropha oil, yields of 75.4% and a flow rate of 150 mL  min and ramp heating temperature −1 71.2% in biodiesel were achieved with the catalysts SMZN/of 5 °C  min . SiO -2 h and SMZN/SiO -4 h, respectively, for a methanol/ 2 2 oil ratio of 9:1, 12 wt% of catalyst, temperature of 65 °C, and Impregnation of molybdenum trioxide in the catalytic reaction time of 10 h. precursor Al‑SBA‑15 In this work, heterogeneous catalysts with different MoO contents, impregnated in a modified SBA-15 catalytic pre- The incorporation of MoO to the catalytic precursor cursor by the incorporation of aluminum using direct was performed from ammonium heptamolybdate salt hydrothermal synthesis were synthesized, characterized [(NH )6Mo O ·4H O] using the pore volume saturation 4 7 24 2 and evaluated in the transesterification of vegetable oil with impregnation method. The desired MoO content in the final methanol. An experimental design 2 with 3 central points catalyst were 5, 10 and 15 wt%. In a typical synthesis, 1.0 g was used. The effect of MoO content in the catalytic sup- of calcined Al-SBA-15 catalytic precursor was impregnated port and reaction time on biodiesel yield was obtained. The with an aqueous solution of the molybdenum precursor, catalysts x_MoO /Al-SBA-15 (x = 5, 10 and 15 wt%) were using the needed concentration to achieve the desired Mo 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 21 content assuming total incorporation [30, 31]. After impreg- evaluated. An experimental design with three levels for both nation, the material was dried in an oven at 60 °C for 24 h. variables was used, with the central point being the average The catalysts were calcined under the same conditions as the of the limits of the intervals. Al-SBA-15 catalytic precursor. Minitab 17.0 software was used to perform statistical analysis and regression of the data. Different models (linear Characterization of solids and quadratic) were tested and analyzed based on Analysis of Variance (ANOVA). Equation (1) describes the relation- The thermogravimetric analysis was performed using a ship between the dependent variable (Y) and the independent TGA-51 Shimadzu Thermogravimetric Analyzer coupled to (X and X ) uncoded variables, where a , a , a are the n m n nn nm a computer (for data storage) by the TA-60 WS collection linear regression coefficients. monitor software. The samples were analyzed on a range of 2 2 2 2 −1 30 to 1000 °C, a heating rate of 5 °C  min and a synthetic Y = a + a X + a X + a X X . (1) 0 n n nn nm n m −1 n air flow rate of 50 mL  min . The thermogravimetric analy- n=1 n=1 n=1 m=n+1 sis was used to investigate the thermal stability of catalysts and decomposition temperature of the molybdenum salt. Transesterification reaction The structural characteristics, identifications of phases and determination of crystallite size and crystallinity of the x_Al-SBA-15 catalysts with different MoO contents were catalyst was investigated by an X-ray diffraction method 3 used in the transesterification reaction of soybean oil and with a Shimadzu XRD-600 employing a Cu Kα radiation at methanol with different reaction time to evaluate the cata- 40 kV and 30 mA. The crystalline size was then calculated lytic potential. The reaction was carried out in a batch reac- from Scherrer's equation [32]. tor manufactured by Parr Instruments Inc.—Model 4848. Fourier-transformed infrared (FTIR) spectra for the cata- The reaction conditions were set up based on previous works lytic precursor and catalysts were obtained with a Spectrum and in accordance to the literature [9–12]. The reactor is an 400 Perkin Elmer spectrophotometer. The analysis was −1 autoclave made of stainless steel with a volume of 300 mL performed out in the region from 4000 to 400  cm wave −1 and was stirred at a speed of 500 rpm. The reactional system number with a resolution of 4  cm using a solid mixture containing an oil and alcohol mixture in the initial molar with KBr. ratio of 1:20 and 3 wt% catalyst concentration, was sealed Textural properties, pore volume and average pore size, and heated from room temperature to 150  °C. After the and specific surface area of x _MoO /Al-SBA-15 catalysts reaction time, the catalyst and glycerol were separated from were evaluated from N adsorption isotherms and BET the products by decantation. The transesterified oils were method [33], using a Quantachrome gas adsorption analyzer, transferred to a decanting funnel, remaining until the phases model 3200E YOUNG. were completely formed (glycerol + alcohol, oil, catalyst). The glycerol + alcohol and catalyst phases were removed and Biodiesel production the oil phase was washed in two steps: in the first, a solu- tion of hydrochloric acid (HCl—Vetec) [2 M] was added Experimental planning to remove the excess of alcohol and catalyst; in the second step, fixed volumes of 15 mL of deionized water were added A 2 + 3 CtPt factorial design was used to evaluate the influ- until pH ⁓ 7 was reached. The oil was dried with magnesium ence of reaction time and MoO content in the catalyst on sulfate heptahydrate (MgSO ·7H O—Vetec) and centrifuged the biodiesel yield in the transesterification reaction of soy - 4 2 for complete separation. The oil obtained was characterized bean oil. Table 1 shows the experimental levels of the inde- for density, acidity index and methyl esters. pendent variables used in this study. The effects of the reaction time in the range of 2 to 4 h Reusability of the catalyst and the MoO content in the range of 5 to 15 wt% were The most active catalyst was reused under the same reac- Table 1 Levels of independent variables in the experimental planning tion conditions as in the first cycle. The catalyst was dried 2 + 3CtPt for evaluation of the transesterification of soybean oil at 100 °C for 24 h and reused in four reaction cycle without Independent variable Symbol Levels regeneration. − 1 0 + 1 Time (h) A 2 3 4 MoO (wt%) B 5 10 15 1 3 DrTG (mg/min) DrTG (mg/min) 22 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Biodiesel characterization 100 (a) (I) (II) 0.00 The biodiesel or fatty acid methyl ester (FAME) content was analyzed following the standard method according TGA to EN 14103 [34] using a Shimadzu GC 2010 Plus gas -0.25 DrTG chromatograph with a split/splitless injector, a flame ioni- zation detector (FID), an AOC-20i auto-injector and a -0.50 100% dimethyl polysiloxane capillary column RTX-WAX 30 m × 0.32 mm × 0.25 μm (Restek Corporation). The oper- ating conditions were as follows: FID temperature, 250 °C; -0.75 the initial column temperature, 210 °C; final column temper - 40 −1 0 150 300 450 600 750 900 ature, 250 °C; H linear velocity, 50 cm  s ; and split mode Temperature (°C) injection in the ratio of 1:50. Methyl heptadecanoate was used as the standard for GC-FID. Equation (2) was used to determine the fatty acid methyl esters content, C (wt%). FAME (b) S − A C × V 0.000 A EI EI EI C = × × 100%, (2) FAME A m EI TGA -0.075 DrTG where, S represents sum of the peak areas, A is the peak A EI (I) area of methyl heptadecanoate (internal standard), C is the EI (II) -0.150 concentration (mg/mL) of methyl heptadecanoate solution (III) (10 mg/mL), V represents the volume (mL) of methyl hep- EI -0.225 tadecanoate and ‘m’ is the mass (mg) of the FAME sample. The chromatograms in Fig. 8 show that transesterification reaction was successful achieved and allows to calculate the 0150 300450 600 750 900 individual FAME content using Eq. (3). Temperature (°C) C × V FAME EI EI (3) C = × × 100%, FAME Fig. 2 Thermogravimetric (TG) analysis of the catalytic precursor Al- A m EI SBA-15 (a) and catalyst 10MoO /Al-SBA-15 (b) where, C is the F AME content (wt%); A is the FAME i FAME i i FAME area calculated by integration of the corresponding In Fig. 2a, there are two temperature ranges, correspond- peaks in the chromatogram. ing to two mass loss events. In the first event (I), in the The specific mass data were determined following the temperature range between 23.57 and 82.9 °C, there is a standard established by EN ISO 3675/12185 and ASTM mass loss of 2.89%, which corresponds to a physical loss of D1298 [35], using Density Master DMA 4100 M equipment. water and volatile materials in the material's porous; in the The acidity index was determined according to the norm second event (II) in the range of 82.95 to 383.43 °C there is a established by ASTM D664 and EN 14104 standards [36] mass loss of 46.63%, due to the elimination of molecules of by titration of the oil with a solution of ethyl ether and ethyl Pluronic P123 triblock copolymer director. The system prac- alcohol (2:1) using 0.1 M potassium hydroxide as the titrant. tically reaches the equilibrium at a temperature of 500 °C. In Fig. 2b, three mass loss events are observed. In the first event (I), in the temperature range of 23.44 to 351.69 °C, Results and discussion there is a mass loss of 24.28%, which corresponds to elimi- nation of hydration water, desorption of physically adsorbed Characterization of the catalyst water in the porous, and the decomposition of ammonium ions present in tetrahydrate ammonium molybdate salt. The Thermogravimetric analysis (TG/DTG) second event (II), in the temperature range of 351.69 to 756 °C, corresponds to a mass loss of 5.67% due to molyb- The decomposition temperature of the precursor salts of denum oxide fusion. In the third event (III), in the tempera- aluminum and molybdenum was determined from the ther- ture range of 756 to 871 °C, there is a mass loss of 5.9% mogravimetric curves shown in Fig. 2a, b. corresponding to the process of sublimation of molybdenum [37]. 1 3 Weight loss (%) Weight loss (%) Materials for Renewable and Sustainable Energy (2022) 11:17–31 23 (a) (b) 10 20 30 40 50 60 2θ 0246 810 2θ Fig. 3 XRD pattern of the Al-SBA-15 catalytic precursor X‑ray diffractometry (XRD) Figure 3 shows the diffractogram of the catalytic precursor Al-SBA-15. From the X-ray diffractogram in Fig.  3a, it is possible to observe the presence of peaks corresponding to the characteristic reflections of mesoporous materials with an ordered hexagonal structure of the type SBA-15. It is observed that the synthesized materials present the main reflection, corresponding to the Miller index (1 0 0), thus indicating that a material with a well-defined structure was obtained; the peaks of lower intensity are due to the reflec- Fig. 4 XRD pattern of the a 5MoO /Al-SBA-15, b 10MoO /Al- 3 3 tions of the planes (1 1 0) and (2 0 0), described by Zhao SBA-15 e c 15MoO /Al-SBA-15 catalysts et al. [29] as peaks characteristic of the hexagonal structure of the SBA-15 catalytic precursor. The ill-defined peak in may not be detected in the XRD due to the support having the region of 2θ = 23.71° shown in Fig. 3b is characteristic of amorphous silica materials, which is typical of SBA-15. multiple pores, which causes the species to disperse inside the pores. It is observed that as the MoO content increases, It is possible to notice the absence of characteristic peaks of aluminum trioxide on the surface of the mesoporous struc- there is an increase in the intensity of the peaks, indicat- ing the appearance of the crystalline phase corresponding ture, indicating an effective incorporation of aluminum in the structure of SBA-15 [38].to MoO on the surface of the SBA-15. Figure 4 shows the X-ray diffractograms of the x _MoO / Al-SBA-15 catalysts (x = 5, 10 and 15 wt%). Fourier transformed infrared spectroscopy In the diffractogram shown in Fig.  4b, c peaks corre- sponding to the species of molybdenum trioxide were iden- FTIR spectra of Al-SBA-15 catalyst precursor and x_MoO / Al-SBA-15 catalysts are shown in Fig. 5, in which the bands tified by comparison with the standard XRD (Nº. JCPDS −1 00-005-0508) from the library of the International Center at 3381 and 1633  cm correspond to the v(O–H) stretch- ing vibration of adsorbed water molecules. All samples for Diffractional Data (JCPDS). In Fig.  4a, there were no peaks related to the MoO species, due to the fact that these display four absorption peaks at about 1052, 967, 797 and −1 447  cm . These peaks in the catalytic precursor are attrib- active species are well dispersed in the channels of the SBA- 15 catalytic precursor. González et al. [39] investigated the uted to asymmetrical stretching of the Si–O–Si, Si–OH, T–O (T = Si or Al) groups and the bending vibration of the crystalline and chemical structure of MoO /SBA-15 cata- lysts with different MoO contents (5, 10, 15, 20 and 25% Si–O–T groups, respectively. For the catalysts, the peaks −1 in the 500–1000  cm region are attributed to different by mass) to evaluate their catalytic activity for the oxida- tion of 4.6-DMDBT; the study proved that the active species stretching vibrations of Mo–O. The peaks at about 970 (all 1 3 Intensity, u.a. (1 0 0) (1 1 0) (2 0 0) Intensity, u.a. 24 Materials for Renewable and Sustainable Energy (2022) 11:17–31 (d) 150 (c) (b) (a) 0.00.2 0.40.6 0.81.0 Fig. 5 FTIR spectra of a Al-SBA-15, b 5MoO /Al-SBA-15, c 10MoO /Al-SBA-15, d 15MoO /Al-SBA-15 3 3 P/P Fig. 6 N adsorption/desorption isotherm of a Al-SBA-15, b 5MoO / 2 3 −1 samples) and 913  cm (10 and 15% MoO catalysts) were 3 Al-SBA-15, c 10MoO /Al-SBA-15, d 15MoO /Al-SBA-15 3 3 assigned to Mo = O symmetric stretching mode, indi- terminal cating orthorhombic phase in MoO layers, and Mo–O–Si −1 bond, respectively. The peak at about 570  cm is assigned the second region, in the range P/P ≈ 0.45–0.8, occurs the typical capillary condensation in mesoporous materials, to the triply coordinated oxygen [Mo–O(3)] stretching mode, which results from the edge-shared oxygen in common with with a hysteresis loop. In the third region, for P/P > 0.8, multilayer adsorption occurs on the external surface of the three MoO octahedra. The FTIR spectra complemented the diffractograms, as it was possible to identify the MoO particles [42]. The pore diameter of Al-SBA-15 incorporated with 5, 10 bonds in the Al-SBA-15 structure [40, 41]. and 15 wt% of MoO is shown in Fig. 7. It can be seen from Fig. 7 that the support Al-SBA-15 Textural analysis by nitrogen adsorption (BET) as well as the catalysts 5MoO/Al-SBA-15, 10MoO /Al- 3 3 SBA-15 and 15MoO /Al-SBA-15 have a uniform distri- The adsorption and desorption isotherms of N of the cata- 2 3 lytic precursor Al-SBA-15 and the catalysts x_MoO /Al- bution of mesopores, with average diameters of 31.50 Å, 31.90 Å, 32.28 Å and 39.55 Å, respectively, in addition to SBA-15 (x = 5, 10 and 15 wt%) are shown in Fig. 6. Figure 6 shows type IV isotherms with a H1 type hys- unimodal pore size distribution. The textural properties of the Al-SBA-15 catalytic precur- teresis loop for the Al-SBA-15 support as well as for each catalyst. Leofanti et al. [33] noted that type IV isotherms are sor as well as the x_MoO /Al-SBA-15 catalysts (x = 5, 10 and 15 wt%) are shown in Table 2. typical in mesoporous materials. H1-type hysteresis results from capillary condensation that occurs within the material's From Table  2, it can be seen that the specific surface area and the total pore volume of the catalysts decrease mesopores and is characteristic of materials with a cylindri- cal pore system. Analyzing the adsorption isotherm, three with the increase in the MoO content incorporated in the catalytic precursor, being up to 70% smaller than that of distinct regions are observed: in the first, at low pressures, for P/P < 0.2, the N adsorption occurs in the monolayer; the Al-SBA-15 support. The pore diameter increased with 0 2 1 3 3 -1 Volume adsorbed (cm g ) Materials for Renewable and Sustainable Energy (2022) 11:17–31 25 Factors affecting the transesterification reaction 39.55° Table 3 shows fatty acid methyl ester (FAME) yield, density and acidity index of the biodiesel obtained. A high yield of FAME was observed for all conditions of reaction time and (d) MoO content used in the experimental planning. 32.28° Effect of MoO content on biodiesel yield MoO was incorporated in the catalytic precursor Al- (c) SBA-15 with different contents (5, 10 and 15 wt%) and the catalyst obtained was evaluated in the biodiesel reaction. In the tested reaction conditions, the biodiesel yield increased 31.90° 16.8  wt% with the increase of MoO content from 5 to 15 wt%, for the shortest reaction time (2 h). For the long- est reaction time (4 h), the increase in MoO content from (b) 5 to 15 wt% increased 7.2% the FAME yield. The latter is because the initial reaction rate is as higher as the M oO content in the catalysts, and longer reaction time compen- 31.50° sates the lower reaction rate of the catalyst with lower MoO content. The highest biodiesel yield was obtained with the catalyst with 10 wt% of MoO and 3 h of reaction. Thus, (a) 10 wt% of MoO incorporated in the mesoporous structure is the optimum content to guarantee an active and well-dis- 050 100 150 200 persed phase in the channels and on the internal surface of Al-SBA-15. Pore Diameter (A) With the catalyst 5MoO /Al-SBA-15 the conversion was 89.2% in 4 h of reaction. From an economic point of view, Fig. 7 Pore size distribution of the a Al-SBA-15 catalytic precursor, even with the low MoO content, the reaction time is still and b 5MoO /Al-SBA-15, c 10MoO /Al-SBA-15, d 15MoO /Al- 3 3 3 SBA-15 catalysts compatible with those reported in the literature [24, 44, 45], which makes it also a candidate, since its lower produc- tion cost compensates the greater reaction time required to MoO content, due to the higher concentration of MoO on achieve a high conversion. 3 3 the external surface of the catalyst. Huang et al. [43], using Chen et al. [24] incorporated different Mo contents (1, different MoO contents in the mesoporous structure of Al- 3, 5, 7 and 10 wt%) in zeolite NaBeta, evaluating them for SBA-15, concluded that the decrease in both the specific the production of biodiesel from rice bran oil. The increase surface area and the pore volume is due to the migration in the Mo content from 1 to 7 wt% increased the conver- of MoO into the interior of the mesopores, as a result of sion from 44 to 74.8%, in the same reaction time (5  h). the strong interaction between molybdenum trioxide and the However, the activity of 10Mo/NaBeta catalyst decreases mesoporous structure. slightly because the active phase was not well dispersed in Table 2 Textural properties of the catalytic precursor Al-SBA-15 and x_MoO /Al-SBA-15 catalysts (x = 5, 10, 15 wt%) a 2 −1 2 −1 micro mes 3 −1 b 3 −1 c Catalyst S (m  g ) S (m  g ) V V (cm  g ) V (cm  g ) D (Å) BET ext P P P p BJH 3 −1 (cm  g ) Al-SBA-15 655.48 566.67 0.03 1.02 1.07 72.36 5MoO /Al-SBA-15 523.63 447.18 0.03 0.56 0.61 53.51 10MoO /Al-SBA-15 311.08 256.36 0.02 0.51 0.58 80.83 15MoO /Al-SBA-15 199.28 163.34 0.02 0.44 0.44 89.22 Specific surface area determined by Brunauer–Emmett–Teller (BET) method Total pore volume recorded at p/p = 0.99 Pore diameter calculated by Barrett–Joyner–Halenda (BJH) method 1 3 Pore Volume (cc/g) 26 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Table 3 Experimental and −3 Run Factors FAME yield (wt%)Density (kg  m ) Acidity Index predicted data of FAME yield, −1 (mg KOH  g ) a b c density and acidity index of the Time (h) MoO (wt%) Exp. Pred. Res. obtained oils 1 2 5 80.13 84.39 4.26 887.7 0.92 2 4 5 88.65 84.39 4.26 883.4 0.67 3 2 15 94.31 94.83 0.52 881.9 0.89 4 4 15 95.36 94.83 0.53 881.0 0.92 5 3 10 94.94 96.24 1.30 879.6 1.85 6 3 10 97.89 96.24 1.65 879.0 0.88 7 3 10 95.89 96.24 0.35 879.4 0.91 Soybean oil 920 0.00 Experimental values of response Predicted values of response Residual the channels resulting in smaller surface area. Yields above was 98% with the catalyst 10MoO /Al-SBA-15, in 3 h of 84% were obtained with the 7Mo/NaBeta catalyst and reac- reaction. tion time of 8 h. Thus, a kinetic study was performed by the Mohebbi et al. [25] using the catalyst MoO /B-ZSM-5 authors with the 7Mo/NaBeta catalyst. in the esterification of free fatty acids, found that the con- Sankaranarayanan et al. [38] synthesized MoO /γ-Al O version increased from 91 to 96% with an increase in the 3 2 3 catalysts with different MoO contents (8, 12 and 16 wt%), reaction time from 4 to 6 h. They also observed that for and calcined them at different temperatures (800, 950 and reaction times greater than 6 h there was no difference in the 1100 K). The catalysts were evaluated in the transesterifica- conversion, as the esterification reaction had already reached tion of sunflower oil with methanol. The effect of various the equilibrium. parameters, such as Mo content, calcination temperature, Mapossa et al. [45] studied the nanomagnetic catalyst reaction temperature and methanol to oil molar ratio on Ni0.5Zn0.5Fe O in the transesterification of soybean oil, 2 4 the oil conversion was obtained. The highest activity was in the range of 1 to 4 h. It was observed that increasing the with the catalyst calcined at 950 K containing 16 wt% of reaction time from 1 to 3 h, the biodiesel yield increased MoO , for which conversion higher than 90% was obtained reaching 92.1%. However, from 3 to 4 h, the biodiesel yield at 110 °C and 24 h in a batch reactor. The authors reported decreased to 87.0%. The authors attributed this decrease to that the catalytic activity decreased with reuse, however it the reversibility of the reaction as well as to parallel reac- can be regenerated by recalcination. tions, such as soap production, which contribute to reduced biodiesel yield. Reaction time effect Chemical composition of FAME The progress of the reaction was evaluated in the range of 2 to 4 h. For all catalysts, the conversion increased with the The produced biodiesel composition is given in Table 4. reaction time, confirming that the reaction is irreversible C wt% was calculated from Eq. (3) and the chroma- FAMEi without competing parallel reactions. The largest conversion tograms shown in Fig. 8. The most commonly found fatty Table 4 Concentrations of Biodiesel C (wt.%) FAMEi FAME in the biodiesel sample [C16:0] C[18:0] [C18:1] [C18:2] [C18:3] Others 1 10.31 2.27 20.69 49.55 5.93 11.25 2 11.03 2.43 22.13 52.99 6.33 5.08 3 10.99 2.66 22.97 53.27 6.12 3.98 4 13.04 2.89 22.20 52.63 6.19 3.05 5 11.48 2.55 23.41 55.50 6.53 0.52 6 11.22 2.49 22.87 54.22 6.38 2.81 7 9.23 2.51 23.06 54.65 6.43 4.12 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 27 predominant fatty acids were: polyunsaturated fatty acids, linoleic (C18:2; 49–54%) and linolenic (C18:3; 5–7%); Run 7 unsaturated fatty acids, oleic acid (C18:1; 20–23%) and satu- rated fatty acids, palmitic acid (C16:0; 9–13%) and stearic (18:0; 2–3%). Soybean oil for biodiesel production has the following typical composition [47]: oleic (20–30%), linoleic Run 6 (50–60%), palmitic (6–10%), stearic (2–5%) and linolenic (5–11%). Thus, the biodiesel produced in this work 'has a typical composition of biodiesel from soybean reported in Run 5 the literature. Density and acidity index Run 4 The acidity index and density are important properties for characterization of methyl or ethyl esters [47, 48]. The bio- −3 diesel should have a density between 850 and 900 kg  m −1 and an acid number below 0.50 mg KOH  g . The density Run 3 of each biodiesel obtained (Table 3) is within the standards established. Density values above the upper limit leads to the formation of a rich air/fuel mixture, increasing the emission Run 2 of pollutants, while values below the lower limit cause loss of engine power as well as increase in fuel consumption [49]. Lôbo et al. [50] stated that the density of biodiesel is directly related to the structure of its molecules. The longer Run 1 the length of the alkylester's carbon chain the greater the density. In relation to the acidity index, all results were outside the standard legal limits, which may be due to the leaching of MoO into the reaction medium, as this molecule has high acidity. Then, an acidity controlling unit may be designed as part of the process. Time (min) Statistical analysis of the data Fig. 8 Biodiesel samples chromatograms (Acronym: C16:0—methyl palmitate; C17:0—methyl heptadecanoate (internal standard); C18:0 – methyl stearate; C18:1—methyl oleate; C18:2—methyl linoleate; The effect of reaction time (A) and MoO content (B) on C18:3—methyl linoleneate) FAME yield were obtained with a significance level of 5% (α = 0.05) using the Minitab 17.0 software for statistical analysis. Table 5 shows the results of Analysis of Variance acids in biodiesel samples are: oleic (C18:1) followed by (ANOVA). stearic (C18:0), linoleic (C18:2), palmitic (C16:0) and lino- The F value calculated for factor B is greater than the lenic (C18:3) [46]. In all samples of biodiesel obtained, the tabulated value, therefore, the M oO content significantly Table 5 ANOVA for the Source Degree Sum of squares Mean square P-value F-value Tabulated Remarks experimental planning 2 + 3 of free- F-value CtPt dom A 1 22.90 22.90 0.07 10.10 18.51 Insignificant B 1 109.10 109.10 0.02 48.11 18.51 Significant A × B 1 13.95 13.950 0.13 6.15 18.51 Insignificant Curvature 1 75.30 75.298 0.03 33.21 18.51 Significant Error 2 4.53 4.53 – – – – Total 6 225.78 – – – – – R = 97.99% R = 99.00% 1 3 Heptano C16:0 C17:0 C18:0 C18:1 C18:2 C18:3 28 Materials for Renewable and Sustainable Energy (2022) 11:17–31 influences the FAME yield. The values of F calculated for Reusability of the catalyst factor A and interaction factor AxB are smaller than the tabulated ones, therefore, they are not significant. The cur - To verify the presence of the active phase of molybde- vature is significant, since the calculated F value is greater num in the used catalyst, XRDs were carried out after the than the tabulated F value, thus indicating that a quadratic first cycle of use. Figure  11 shows the X-ray diffracto- model should further be used to optimize the independent grams of the x_MoO /Al-SBA-15 catalysts (x = 5, 10 and variable values. The Pareto diagram depicted in Fig. 9 shows 15 wt%) after transesterification reaction. For 10_MoO / the significance of the factors with respect to the standard- Al-SBA-15 catalyst (Fig. 11b), it was observed that after ized effect. the first use in the reaction, there was a reduction in the As shown in Table 5, the coefficient of determination (R ) characteristic peaks of the MoO phase. The other cata- was 97.99%, which represents the percentage of data that lysts have the same profile as the diffractogram shown in the model can explain. The correlation coefficient (R ) was Fig. 4. The catalytic activity was studied over five cycles 99.00%, which indicates a strong correlation between the of catalyst use to assess its lifetime. The FAME yield data. obtained for each reuse cycle of the catalyst is shown in The response surface and isocurves of FAME yield as a Fig. 12. It was observed in Fig. 12 that the reused catalyst function of reaction time and MoO content are shown in reduced its activity after five consecutive reaction cycles Fig. 10. It can be seen a maximum FAME yield in a region and the yield decreased by about 34%. Malhotra et al. [16] close to the central point, as well as that the minimum and Thitsartarn et al. [51] have reported that leaching of FAME yield occurs for the lowest MoO content and the active species is a problem frequently encountered in het- shortest reaction time. erogeneous catalysts. The response surface shown in Fig. 10 corresponds to the model given in Eq. (4). Conclusion Y = 60.78 + 6.13A + 2.165B − 0.374A × B + 6.63CtPt (4) where Y is the FAME yield. The catalytic precursor Al-SBA-15 was obtained and veri- Equation (5) is the response surface keeping every terms fied from X-ray diffractograms. The catalyst x _MoO / in the model. However, it has been seen from ANOVA in Al-SBA-15 was obtained by incorporating MoO in Al- Table 5 that factor A and interaction factor A × B are not SBA-15. Characteristic peaks of MoO were identified significant on the FAME yield. Thus, disregarding the non- for catalysts with 10 and 15 wt% MoO contents. Ther- significant terms, and readjusting the model without them, mogravimetric analysis for the catalytic precursor Al- results in Eq. (4), with the coefficients of the coded model. SBA-15, as well as for salts decomposition and MoO formation indicates that the calcination temperature must Y = 89.613 + 5.223B + 6.63CtPt. (5) be up to 550 °C. The adsorption/desorption isotherms of N show a uniform cylindrical pore structure and unimodal As the curvature test was significant while the interaction pore size distribution. The density of all oils obtained term A × B was not, it is not possible to conclude about the from the transesterification reaction met the requirements significance of the second order term included in the model for biodiesel, however, the acidity index of none of the given in Eq. (4). In this case, the factorial design must be oils obtained was within the alloyed limits, probably due extended to an experimental planning 3 , with the inclusion to the leaching of MoO in the oil. MoO content in the of new experimental points, and thus adjust the model given 3 3 catalyst influences the biodiesel yield with a significance by Eq. (1), keeping all second order terms. Central com- level of α = 0.05, based on the F test and Pareto graph. posite planning is usually used to extend factorial planning. After the 5ht cycle of use, the biodiesel yield is dimin- Star planning is an example of central planning based on ished from ~ 96 to ~ 62% using the catalyst 10_MoO /Al- two initial factors. In this work, only experimental planning SBA-15. That catalyst is the recommended to be used in 2 was carried out with the addition of 1 central point with the transesterification of soybean for biodiesel production two repetitions. The addition of axial points would imply the in a competitive way with currently existing heterogene- production of new catalysts, which was not possible for now ous catalysts. due to the costs involved. 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 29 Term 4,303 AB 0 1 2 3 4 5 6 7 Standardized Effect Fig. 9 Pareto chart of the standardized effects (α = 0.05) Fig. 11 XRD pattern of the a 5MoO /Al-SBA-15, b 10MoO /Al- 3 3 SBA-15 e c 15MoO /Al-SBA-15 catalysts after transesterification reaction (a) 15.0 FAME Yield (wt. %) 12.5 < 81 81 – 84 10.0 84 – 87 87 – 90 90 – 93 7.5 40 93 – 96 > 96 5.0 2.0 2.5 3.0 3.5 4.0 Time (h) 1234 5 (b) Reaction Cycle (Rounds) Fig. 10 Effect of reaction time and % MoO on FAME yield: a 3D response surface and; b corresponding 2D Contour plot Fig. 12 Reusability of 10MoO /Al-SBA-15 catalyst (reaction condi- tions: MeOH:oil molar ratio = 20:1, 3 wt% catalyst, 150 °C, 3 h/cycle) 1 3 MoO3 (wt. %) % Fame Yield 30 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Acknowledgements This research was supported by the Department oil on Al-SBA-15 catalysts. Appl. Catal. B Environ. 184, 163–173 of Chemical Engineering—Federal University of Campina Grande. (2016) The scholarship was awarded by Coordination for the Improvement of 11. Sánchez Faba, E.M., Ferrero, G.O., Dias, J.M., Eimer, G.A.: Higher Level Education a Personnel (CAPES). Na-Ce-modified-SBA-15 as an effective and reusable bimetallic mesoporous catalyst for the sustainable production of biodiesel. Appl. Catal. A Gen. (2020). https://doi. or g/10. 1016/j. apcat a.2020. Declarations 12. Xie, W., Zhao, L.: Heterogeneous CaO–MoO -SBA-15 cata- Conflict of interest The authors declare that they have no conflict of lysts for biodiesel production from soybean oil. Energy Convers. interest. Manag. 79, 34–42 (2014) 13. Esan, A.O., Adeyemi, A.D., Ganesan, S.: A review on the recent Open Access This article is licensed under a Creative Commons Attri- application of dimethyl carbonate in sustainable biodiesel produc- bution 4.0 International License, which permits use, sharing, adapta- tion. J. Clean. Prod. 257, 120561 (2020) tion, distribution and reproduction in any medium or format, as long 14. Demirbas, A.: Biodiesel production from vegetable oils via cata- as you give appropriate credit to the original author(s) and the source, lytic and non-catalytic supercritical methanol transesterification provide a link to the Creative Commons licence, and indicate if changes methods. Prog. Energy Combust. Sci. 31, 466–487 (2005) were made. The images or other third party material in this article are 15. Mohamed, R.M., Kadry, G.A., Abdel-Samad, H.A., Awad, M.E.: included in the article’s Creative Commons licence, unless indicated High operative heterogeneous catalyst in biodiesel production otherwise in a credit line to the material. If material is not included in from waste cooking oil. Egypt. J. Pet. 29, 59–65 (2020) the article’s Creative Commons licence and your intended use is not 16. Malhotra, R., Ali, A.: Lithium-doped ceria supported SBA−15 permitted by statutory regulation or exceeds the permitted use, you will as mesoporous solid reusable and heterogeneous catalyst for bio- need to obtain permission directly from the copyright holder. To view a diesel production via simultaneous esterification and transesterifi- copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. cation of waste cottonseed oil. Renew. Energy 119, 32–44 (2018) 17. Rathore, V., Newalkar, B.L., Badoni, R.P.: Processing of vegetable oil for biofuel production through conventional and non-conven- tional routes. Energy Sustain. Dev. 31, 24–49 (2016) References 18. Li, L., Yan, B., Li, H., Yu, S., Ge, X.: Decreasing the acid value of pyrolysis oil via esterification using ZrO /SBA-15 as a solid 1. Manojkumar, N., Muthukumaran, C., Sharmila, G.: A compre- acid catalyst. Renew. Energy 146, 643–650 (2020) hensive review on the application of response surface methodol- 19. Kamaruzaman, M.F., Taufiq-Yap, Y.H., Derawi, D.: Green diesel ogy for optimization of biodiesel production using different oil production from palm fatty acid distillate over SBA-15-supported sources. J. King Saud. Univ. Eng. Sci. (2020). https:// doi. org/ 10. nickel, cobalt, and nickel/cobalt catalysts. Biomass Bioenergy 1016/j. jksues. 2020. 09. 012 134, 105476 (2020) 2. Lee, J.H., Jeon, H., Park, J.T., Kim, J.H.: Synthesis of hierarchi- 20. Li, X., Yin, H., Zhang, J., Liu, J., Chen, G.: Effect of organic cal flower-shaped hollow MgO microspheres via ethylene-glycol- template removal approaches on physiochemical characterization mediated process as a base heterogeneous catalyst for transesteri- of Ni/Al-SBA-15 and eugenol hydrodeoxygenation. J. Solid State fication for biodiesel production. Biomass Bioenergy 142, 105788 Chem. 282, 121063 (2020) (2020) 21. Socci, J., Osatiashtiani, A., Kyriakou, G., Bridgwater, T.: The 3. Gupta, J., Agarwal, M., Dalai, A.K.: An overview on the recent catalytic cracking of sterically challenging plastic feedstocks over advancements of sustainable heterogeneous catalysts and promi- high acid density Al-SBA-15 catalysts. Appl. Catal. A Gen. 570, nent continuous reactor for biodiesel production. J. Ind. Eng. 218–227 (2019) Chem. 88, 58–77 (2020) 22. Mouat, A.R., Lohr, T.L., Wegener, E.C., Miller, J.T., Delferro, 4. Kim, M., DiMaggio, C., Salley, S.O., Simon Ng, K.Y.: A new gen- M., Stair, P.C., Marks, T.J.: Reactivity of a carbon-supported sin- eration of zirconia supported metal oxide catalysts for converting gle-site molybdenum dioxo catalyst for biodiesel synthesis. ACS low grade renewable feedstocks to biodiesel. Bioresour. Technol. Catal. 6, 6762–6769 (2016) 118, 37–42 (2012) 23. Pinto, B.F., Garcia, M.A.S., Costa, J.C.S., de Moura, C.V.R., de 5. Chua, S.Y., Periasamy, L.A., Goh, C.M.H., Tan, Y.H., Mubarak, Abreu, W.C., de Moura, E.M.: Effect of calcination temperature N.M., Kansedo, J., Khalid, M., Walvekar, R., Abdullah, E.C.: Bio- on the application of molybdenum trioxide acid catalyst: screening diesel synthesis using natural solid catalyst derived from biomass of substrates for biodiesel production. Fuel 239, 290–296 (2019) waste—a review. J. Ind. Eng. Chem. 81, 41–60 (2020) 24. Chen, C., Cai, L., Zhang, L., Fu, W., Hong, Y., Gao, X., Jiang, 6. Chueluecha, N., Kaewchada, A., Jaree, A.: Enhancement of bio- Y., Li, L., Yan, X., Wu, G.: Transesterification of rice bran oil to diesel synthesis using co-solvent in a packed-microchannel. J. Ind. biodiesel using mesoporous NaBeta zeolite-supported molybde- Eng. Chem. 51, 162–171 (2017) num catalyst: experimental and kinetic studies. Chem. Eng. J. 382, 7. Chozhavendhan, S., Vijay Pradhap Singh, M., Fransila, B., 122839 (2020) Praveen Kumar, R., Karthiga Devi, G.: A review on influencing 25. Mohebbi, S., Rostamizadeh, M., Kahforoushan, D.: Effect parameters of biodiesel production and purification processes. of molybdenum promoter on performance of high silica Curr. Res. Green Sustain. Chem. 1–2, 1–6 (2020) MoO /B-ZSM-5 nanocatalyst in biodiesel production. Fuel 8. Huang, J., Zou, Y., Yaseen, M., Qu, H., He, R., Tong, Z.: Fabrica- (2020). https:// doi. org/ 10. 1016/j. fuel. 2020. 117063 tion of hollow cage-like CaO catalyst for the enhanced biodiesel 26. Ding, H., Ye, W., Wang, Y., Wang, X., Li, L., Liu, D., Gui, J., production via transesterification of soybean oil and methanol. Song, C., Ji, N.: Process intensification of transesterification for Fuel 290, 119799 (2021) biodiesel production from palm oil: microwave irradiation on 9. Malhotra, R., Ali, A.: 5-Na/ZnO doped mesoporous silica as reus- transesterification reaction catalyzed by acidic imidazolium ionic able solid catalyst for biodiesel production via transesterification liquids. Energy 144, 957–967 (2018) of virgin cottonseed oil. Renew. Energy 133, 606–619 (2019) 27. Li, B., Song, H.Y., Deng, Z.P., Huo, L.H., Gao, S.: Novel sensitive 10. Meloni, D., Perra, D., Monaci, R., Cutrufello, M.G., Rombi, E., amperometric hydrogen peroxide sensor using layered hierarchical Ferino, I.: Transesterification of Jatropha curcas oil and soybean 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 31 porous Α-MoO and GO modified glass carbon electrode. Sens. 41. Rakngam, I., Osakoo, N., Wittayakun, J., Chanlek, N., Peng- Actuators B Chem. 288, 641–648 (2019) sawang, A., Sosa, N., Butburee, T., Faungnawakij, K., Khem- 28. Li, M., Liu, N., Wu, Z., Li, Y., Li, S., Xu, W., Luo, Z., Liu, Y.: thong, P.: Properties of mesoporous Al-SBA-15 from one-pot A facile and novel route for dual-template method synthesis of hydrothermal synthesis with different aluminium precursors and mesoporous silica material Al-Ce-SBA-15. Mater. Lett. 185, catalytic performances in xylose conversion to furfural. Micropo- 85–88 (2016) rous Mesoporous Mater. 317, 110999 (2021) 29. Zhao, D., Feng, J., Huo, Q., Melosh, N., Fredrickson, G.H., 42. Zhou, C., Gao, Q., Luo, W., Zhou, Q., Wang, H., Yan, C.: Journal Chmelka, B.F., Stucky, G.D.: Triblock copolymer syntheses of of the Taiwan Institute of Chemical Engineers Preparation, char- mesoporous silica with periodic 50 to 300 angstrom pores. Sci- acterization and adsorption evaluation of spherical mesoporous ence (80-) 279, 548–552 (1998) Al-MCM-41 from coal fly ash. J. Taiwan Inst. Chem. Eng. 52, 30. Ciola, R.: Fundamentos da Catálise, 1st edn. Editora Moderna, 147–157 (2015) São Paulo (1981) 43. Peng, H., Min, L.I.U., Qiu-lian, C.: M oO /Al-SBA-15 modi- 31. Melero, J.A., Iglesias, J., Arsuaga, J.M., Sainz-Pardo, J., de Fru- fied catalyst and its application in coal tar hydrocracking. J. Fuel tos, P., Blazquez, S.: Synthesis, characterization and catalytic Chem. Technol. 48, 1079–1086 (2020) activity of highly dispersed Mo-SBA-15. Appl Catal A Gen 331, 44. Sankaranarayanan, T.M., Pandurangan, A., Banu, M., Sivasanker, 84–94 (2007) S.: Transesterification of sunflower oil over MoO supported on 32. Klug, H.P., Alexander, L.: No X-Ray Diffraction Procedures: For alumina. Appl. Catal. A Gen. 409–410, 239–247 (2011) Polycrystalline and Amorphous Materials, 2nd edn. New York 45. Mapossa, A.B., Dantas, J., Costa, A.C.F.M.: Transesterifica- (1974) tion reaction for biodiesel production from soybean oil using 33. Leofanti, G., Padovan, M., Tozzola, G., Venturelli, B.: Surface Ni Zn Fe O nanomagnetic catalyst: kinetic study. Int. J. 0.5 0.5 2 4 area and pore texture of catalysts. Catal. Today 41, 207–219 Energy Res. 44, 6674–6684 (2020) (1998) 46. Wan Ghazali, W.N.M., Mamat, R., Masjuki, H.H., Najafi, G.: 34. Thoai, D.N., Photaworn, S., Kumar, A., Prasertsit, K., Tongurai, Effects of biodiesel from different feedstocks on engine perfor - C.: A novel chemical method for determining ester content in mance and emissions: a review. Renew. Sustain. Energy Rev. 51, biodiesel. Energy Proc. 138, 536–543 (2017) 585–602 (2015) 35. Atabani, A.E., Silitonga, A.S., Anjum, I., Mahlia, T.M.I., Masjuki, 47. Singh, D., Sharma, D., Soni, S.L., Sharma, S., Kumari, D.: Chem- H.H., Mekhilef, S.: A comprehensive review on biodiesel as an ical compositions, properties, and standards for different genera- alternative energy resource and its characteristics. Renew. Sustain. tion biodiesels: a review. Fuel 253, 60–71 (2019) Energy Rev. 16, 2070–2093 (2012) 48. Atabani, A.E., Silitonga, A.S., Ong, H.C., Mahlia, T.M.I., Mas- 36. Sakthivel, R., Ramesh, K., Purnachandran, R., Shameer, P.M.: A juki, H.H., Badruddin, I.A., Fayaz, H.: Non-edible vegetable oils: review on the properties, performance and emission aspects of a critical evaluation of oil extraction, fatty acid compositions, the third generation biodiesels. Renew. Sustain. Energy Rev. 82, biodiesel production, characteristics, engine performance and 2970–2992 (2018) emissions production. Renew. Sustain. Energy Rev. 18, 211–245 37. Veríssimo, T., Brainer, S., Beatriz, D., Pryston, D.A.: Study of (2013) neat and mixed Sn(IV) and Mo(VI) oxides for transesterification 49. Hosseinzadeh-Bandbafha, H., Tabatabaei, M., Aghbashlo, M., and esterification: influence of the substrate on leaching. Catal. Khanali, M., Demirbas, A.: A comprehensive review on the envi- Lett. 149, 3132–3137 (2019) ronmental impacts of diesel/biodiesel additives. Energy Convers. 38. Cabrera-munguia, D.A., González, H., Gutiérrez-alejandre, A., Manag. 174, 579–614 (2018) Rico, J.L., Maya-yescas, R., Rosa, E., Huirache-acu, R.: Hetero- 50. Lobo, I.P., Ferreira, S.L.C., Da, C.R.S.: Biodiesel: Parâmetros de geneous acid conversion of a tricaprylin-palmitic acid mixture qualidade e métodos analíticos. Quim Nova 32, 1596–1608 (2009) over Al-SBA-15 catalysts: reaction study for biodiesel synthesis. 51. Thitsartarn, W., Maneerung, T., Kawi, S.: Highly active and Catal. Today 282, 195–203 (2017) durable Ca-doped Ce-SBA-15 catalyst for biodiesel production. 39. González, J., An, J., Chen, L., Manríquez, M., Salmones, J., Energy 89, 946–956 (2015) Limas, R., Arellano, U.: Quantitative determination of oxy- gen defects, surface lewis acidity, and catalytic properties of Publisher's Note Springer Nature remains neutral with regard to mesoporous MoO /SBA-15 catalysts. J. Solid State Chem. 263, jurisdictional claims in published maps and institutional affiliations. 100–114 (2018) 40. Chen, D., Liu, M., Yin, L., et al.: Single-crystalline MoO nano- plates: topochemical synthesis and enhanced ethanol-sensing performance. J. Mater. Chem. 21, 9332–9342 (2011) 1 3 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Materials for Renewable and Sustainable Energy Springer Journals

Preparation, characterization and evaluation of x-MoO3/Al-SBA-15 catalysts for biodiesel production

Loading next page...
 
/lp/springer-journals/preparation-characterization-and-evaluation-of-x-moo3-al-sba-15-8vfLCsQ0up
Publisher
Springer Journals
Copyright
Copyright © The Author(s) 2021
ISSN
2194-1459
eISSN
2194-1467
DOI
10.1007/s40243-021-00204-x
Publisher site
See Article on Publisher Site

Abstract

Biodiesel is an alternative source of renewable energy that can be produced by a transesterification of vegetable oils. Mesoporous molecular sieves, such as SBA-15, due to high surface area and thermal stability are promising precursors for heterogeneous catalysts in the transesterification reaction. In this work, Al-SBA-15 precursor was obtained by direct hydrothermal synthesis, impregnated with different MoO contents (5, 10 and 15 wt%) by the pore saturation method, and evaluated as heterogeneous catalyst in the production of biodiesel from a transesterification of soybean oil with methanol. Al-SBA-15 precursor as well as MoO /Al-SBA-15 catalyst were characterized for its structural characteristic by X-ray diffrac- tion, textural characteristic by N adsorption analysis, and thermal stability by thermogravimetric analysis. An experimental planning 2 + 3 CtPt was used to evaluate the influence of MoO content and reaction time on biodiesel yield from soybean oil and methanol. The biodiesel content in the final product was obtained by gas chromatography. An average biodiesel yield of 96% was obtained with the catalyst 10%MoO /Al-SBA-15 under the following reaction conditions: 20:1 methanol/ soybean oil molar ratio, and 3 wt% of catalyst loading at 150 °C in 3 h. After five consecutive reaction cycles, the biodiesel yield decreased by about 34%. The density and acidity of the biodiesel produced are within the specified values for com- mercialization according to international standards. * Bianca V. S. Barbosa bianca.viana@eq.ufcg.edu.br Joyce S. B. Figueiredo joyce.barros24@hotmail.com Bruno T. S. Alves brunotdsa@gmail.com Vitória A. Freire vitoriaqil14@gmail.com José J. N. Alves jailson@eq.ufcg.edu.br Catalysis, Characterization and Biofuels Laboratory, Department of Chemical Engineering, Federal University of Campina Grande, UFCG/CCT/UAEQ, Aprígio Veloso Avenue. 882-Bodocongó, Campina Grande, Paraíba CEP 58109-970, Brazil Vol.:(0123456789) 1 3 18 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Graphical abstract Keywords Biodiesel · Transesterification · Al-SBA-15 precursor · MoO /Al-SBA-15 catalyst In the stoichiometric reaction of transesterification 1 mol Introduction of triglyceride reacts with 3 mols of alcohol producing 3 mols of alkyl esters and 1 mol of glycerol. Alcohol is mixed Currently, fossil fuels are the main energy source in the in excess to shift the reaction balance towards biodiesel, global energy system. However, the increase in global increasing its yield [8, 9]. A high methanol to oil molar ratio energy demand, uncertainties regarding the availability is usually used due to the lower contact between catalyst and of oil in the future, and the environmental impacts caused reactants in the heterogeneous process than in the homoge- by burning fossil fuels, are factors that justify the need to neous one. A methanol to oil molar ratio up to 30–150 to 1 search for alternative sources of renewable energy to avoid has been reported in the literature [9–12], to guarantee the an energy crisis [1–3]. In this scenario, fuels derived from highest FAMEs yield [3, 7, 13]. Transesterification consists vegetable biomass such as biodiesel and ethanol are alter- of a series of consecutive, reversible reactions, forming alkyl natives as renewable sources of energy. Biodiesel is free esters in each step as shown in Fig. 1. The triglyceride is of sulfur and aromatics, has a high flash point and a high converted stepwise to diglyceride, monoglyceride and finally number of cetane [4]. This biofuel can replace, totally or glycerol [14]. partially, diesel petroleum oil in automotive or stationary The main process variables in the transesterification reac- engines, as well as be used pure or blended with petroleum tion are temperature, alcohol/oil ratio, reaction time, type of diesel in different proportions [5 , 6]. catalyst, water content, and free fatty acid content in veg- Biodiesel is a mixture of mono alkyl esters produced in a etable oils. This study focused on catalyst preparation and transesterification reaction, in which triglycerides from dif- evaluation for biodiesel production, taking as input variables ferent sources of vegetable oils or animal fats react with a the catalyst composition and reaction time, and biodiesel short chain alcohol, usually methanol or ethanol in the pres- yield as response variable. ence of a homogeneous, heterogeneous or even enzymatic Industrially, homogeneous catalysts, such as potassium catalyst [7]. hydroxide (KOH), sodium hydroxide (NaOH) and sulfuric 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 19 Fig. 1 Consecutive steps in the H C-O-CO-R H C-OH 2 1 2 transesterification reaction Catalyst HC-O-CO-R CH OH HC-O-CO-R + CH -CO-R 2 + 3 2 3 1 MethanolMethyl ester H C-O-C-R H C-O-C-R 2 3 2 3 TriglyceridesDiglycerides H C-OH H C-OH 2 2 Catalyst HC-O-CO-R2 + CH3OH HC-OH + CH3-CO-R2 MethanolMethyl ester H C-O-C-R H C-O-C-R 2 3 2 3 Diglycerides Monoglycerides H C-OH H C-OH 2 2 Catalyst HC-OH CH OH HC-OH+ CH -CO-R + 3 3 3 Methanol Methyl ester H C-O-C-R H C-OH 2 3 2 MonoglycerideGlycerides acid (H SO ) have been used in the transesterification reac- catalysts is the use of amorphous silica with an ordered 2 4 tion, with sodium hydroxide being the most used due to mesoporous structure, such as SBA-15 as a support [18, 19]. its low cost and high product yield. As disadvantages, the The incorporation of metals in the structure of amorphous homogeneous catalysts are not recovered, but neutralized, silica, such as aluminum and molybdenum, define an acidic the process is susceptible to the formation of soap due to characteristic of the mesoporous material [20]. the presence of water and free fatty acids in the reaction The insertion of aluminum ions in the structure of the medium, which complicates the purification of the products, SBA-15 allows the creation of acidic sites that are essen- making the process expensive [15]. Thus, heterogeneous tial for reactions catalyzed by acid [20]. Al-SBA-15 with its catalysts are a promising alternative to replace homogene- unique structure, surface characteristics, good thermal sta- ous ones in industrial biodiesel production, having as main bility and mechanical resistance make this molecular sieve advantages the easy separation of the reaction mixture by have better catalytic performance than traditional alumina simple physical processes, the non-need for neutralization catalysts throughout the reaction [21]. The literature reports and disposal, which minimizes harmful effluents from the that the incorporation of molybdenum in supports promotes environmental point of view [16]; in addition, they can be its catalytic activity, motivating studies for its use in the regenerated and reused, are tolerant to water and organic transesterification reactions [22– 24]. Molybdenum based solvents, have high thermal stability, strong acidity, and high catalysts are viable alternatives for transesterification, but catalytic activity [5, 17]. As disadvantages, the use of het- typically suffer from poor recyclability or require high tem- erogeneous catalysts requires more severe reaction condi- peratures to achieve useful activity [22]. tions, such as high temperatures and pressure, as well as a Mohebbi et al. [25] investigated the effect of MoO on the longer reaction time, in addition to the leaching of the active esterification reaction of oleic acid by methyl route for bio- sites of the catalysts. diesel production, using different MoO contents (5, 15, 25 Among the different types, mesoporous materials are and 35 wt%) impregnated in the heterogeneous mesoporous widely used in the development of catalysts, including for nanocatalyst B-ZSM-5. The optimum MoO content was the production of biodiesel, due to important characteristics, 25  wt% incorporated in the B-ZSM-5 nanocatalyst, and such as regular pore structure, high specific surface area that the optimal operating conditions were reaction time of 6 h, 2 −1 can reach 1000  m  g , thickness pore wall of about 6 nm, temperature of 160  °C, catalyst concentration of 3  wt%, thermal stability, ease of separation and regeneration. An and methanol/oleic acid molar ratio of 20:1. The maximum interesting alternative for the production of heterogeneous conversion of free fatty acids was 98%, confirming the high 1 3 20 Materials for Renewable and Sustainable Energy (2022) 11:17–31 potential of the MoO -impregnated nanocatalyst for indus- characterized in terms of thermal, crystalline and textural trial applications. properties, as well as its activity in the transesterification Ding et al. [26] synthesized and evaluated three acidic reaction was proved. MoO content influenced more the imidazolium liquids as catalysts for production of biodiesel catalytic conversion than the reaction time, in the studied in a transesterification of palm oil under microwave irradia - range. The x_MoO /Al-SBA-15 catalyst performance was tion, and concluded that [HSO -BMIM]HSO catalyst was compared to that of others catalysts for biodiesel production 3 4 the most effective for the reaction. The effect of methanol to in the transesterification reaction reported in the literature. oil molar ratio, catalyst dosage, microwave power and reac- The manuscript is organized with an experimental sec- tion time on yield of biodiesel was evaluated using an exper- tion describing the catalyst preparation and characterization, imental planning. From the regression model, a maximum the reaction performed, and the biodiesel characterization. biodiesel yield of 99.64%, with the aid of [HSO -BMIM] Results are discussed in a second section, and finally the HSO under microwave irradiation, was predicted. The opti- main conclusions are presented in a final section. mal reaction conditions were: mole ratio of methanol to oil 11:1, ionic liquid dosage 9.17%, microwave power 168 W, and reaction time 6.43 h. The predicted value was verified Experimental with the average yield of 98.93% from three experiments. Pinto et al. [23] synthesized molybdenum trioxide cata- Catalyst preparation lysts calcined at different temperatures (200, 300, 400, 500, 600 and 700 °C), and evaluated the effect of the catalyst Direct synthesis of the Al‑SBA‑15 catalytic precursor calcination temperature on the catalyst performance for the production of biodiesel from different vegetable oils. Dif- The mesoporous molecular sieve Al-SBA-15 used as a cata- ferent temperature, oil/alcohol ratio, reaction time and cata- lytic precursor was synthesized from an adaptation of the lyst load were evaluated. The highest catalytic activity was methodology described by Li et al. [28] and Zhao et al. [29]. for the catalyst calcined at 600 °C. The optimal operational Initially, the Pluronic P123 triblock copolymer was dissolved −1 conditions were 0.5 wt% of catalyst in 5 g of oil, reaction in a stirred aqueous solution of HCl (1.6 mol  L ) at 35 °C. temperature of 150 °C, and a methanol/oil molar ratio of After complete homogenization of the mixture, tetraethyl- 45:1. In these conditions, the yield reached 90%, indicating orthosilicate (TEOS) was added to the reaction medium. In a that the molybdenum trioxide catalyst is effective for the backer, aluminum nitrate (Al(NO ) ·9H O) was dissolved in 3 3 2 −1 transesterification reaction for biodiesel production. a stirred solution of ethanol and HCl (1.6 mol  L ) at 35 °C. 2− Li et al. [27] synthesized SO –MoO –ZrO –ND O / The two solutions were mixed together and taken to a roto- 4 3 2 2 3 SiO catalysts with different calcination times, denominat - evaporator, remaining for 24 h at 40 °C. A gel was formed ing them SMZN/SiO -X, where X is the calcination time with molar composition 1 Si: 0.017 P123: 4.96 HCl: 0.054 (X = 2, 4, 6, 8 and 12 h). The catalysts were evaluated for Al: 35.42 EtOH, which was then crystallized in an oven at production of biodiesel by both esterification of lauric acid 100 °C for 48 h. The resulting material was cooled and then with methanol, and transesterification of triacetin and jat- washed with deionized water to remove excess of director ropha oil with methanol. A yield of 97.1% was achieved in until the filtrate reached pH = 7. The material was dried in an the esterification with SMZN/SiO -2 h and SMZN/SiO -4 h oven at 60 °C for 24 h. Finally, the catalytic precursor (Al- 2 2 catalysts. A methyl acetate yield around 92.1% was achieved SBA-15) was activated by calcination, under synthetic air with all catalysts in the transesterification of triacetin. In flow, from room temperature of 25 to 550 °C over 6 h, with −1 the transesterification of jatropha oil, yields of 75.4% and a flow rate of 150 mL  min and ramp heating temperature −1 71.2% in biodiesel were achieved with the catalysts SMZN/of 5 °C  min . SiO -2 h and SMZN/SiO -4 h, respectively, for a methanol/ 2 2 oil ratio of 9:1, 12 wt% of catalyst, temperature of 65 °C, and Impregnation of molybdenum trioxide in the catalytic reaction time of 10 h. precursor Al‑SBA‑15 In this work, heterogeneous catalysts with different MoO contents, impregnated in a modified SBA-15 catalytic pre- The incorporation of MoO to the catalytic precursor cursor by the incorporation of aluminum using direct was performed from ammonium heptamolybdate salt hydrothermal synthesis were synthesized, characterized [(NH )6Mo O ·4H O] using the pore volume saturation 4 7 24 2 and evaluated in the transesterification of vegetable oil with impregnation method. The desired MoO content in the final methanol. An experimental design 2 with 3 central points catalyst were 5, 10 and 15 wt%. In a typical synthesis, 1.0 g was used. The effect of MoO content in the catalytic sup- of calcined Al-SBA-15 catalytic precursor was impregnated port and reaction time on biodiesel yield was obtained. The with an aqueous solution of the molybdenum precursor, catalysts x_MoO /Al-SBA-15 (x = 5, 10 and 15 wt%) were using the needed concentration to achieve the desired Mo 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 21 content assuming total incorporation [30, 31]. After impreg- evaluated. An experimental design with three levels for both nation, the material was dried in an oven at 60 °C for 24 h. variables was used, with the central point being the average The catalysts were calcined under the same conditions as the of the limits of the intervals. Al-SBA-15 catalytic precursor. Minitab 17.0 software was used to perform statistical analysis and regression of the data. Different models (linear Characterization of solids and quadratic) were tested and analyzed based on Analysis of Variance (ANOVA). Equation (1) describes the relation- The thermogravimetric analysis was performed using a ship between the dependent variable (Y) and the independent TGA-51 Shimadzu Thermogravimetric Analyzer coupled to (X and X ) uncoded variables, where a , a , a are the n m n nn nm a computer (for data storage) by the TA-60 WS collection linear regression coefficients. monitor software. The samples were analyzed on a range of 2 2 2 2 −1 30 to 1000 °C, a heating rate of 5 °C  min and a synthetic Y = a + a X + a X + a X X . (1) 0 n n nn nm n m −1 n air flow rate of 50 mL  min . The thermogravimetric analy- n=1 n=1 n=1 m=n+1 sis was used to investigate the thermal stability of catalysts and decomposition temperature of the molybdenum salt. Transesterification reaction The structural characteristics, identifications of phases and determination of crystallite size and crystallinity of the x_Al-SBA-15 catalysts with different MoO contents were catalyst was investigated by an X-ray diffraction method 3 used in the transesterification reaction of soybean oil and with a Shimadzu XRD-600 employing a Cu Kα radiation at methanol with different reaction time to evaluate the cata- 40 kV and 30 mA. The crystalline size was then calculated lytic potential. The reaction was carried out in a batch reac- from Scherrer's equation [32]. tor manufactured by Parr Instruments Inc.—Model 4848. Fourier-transformed infrared (FTIR) spectra for the cata- The reaction conditions were set up based on previous works lytic precursor and catalysts were obtained with a Spectrum and in accordance to the literature [9–12]. The reactor is an 400 Perkin Elmer spectrophotometer. The analysis was −1 autoclave made of stainless steel with a volume of 300 mL performed out in the region from 4000 to 400  cm wave −1 and was stirred at a speed of 500 rpm. The reactional system number with a resolution of 4  cm using a solid mixture containing an oil and alcohol mixture in the initial molar with KBr. ratio of 1:20 and 3 wt% catalyst concentration, was sealed Textural properties, pore volume and average pore size, and heated from room temperature to 150  °C. After the and specific surface area of x _MoO /Al-SBA-15 catalysts reaction time, the catalyst and glycerol were separated from were evaluated from N adsorption isotherms and BET the products by decantation. The transesterified oils were method [33], using a Quantachrome gas adsorption analyzer, transferred to a decanting funnel, remaining until the phases model 3200E YOUNG. were completely formed (glycerol + alcohol, oil, catalyst). The glycerol + alcohol and catalyst phases were removed and Biodiesel production the oil phase was washed in two steps: in the first, a solu- tion of hydrochloric acid (HCl—Vetec) [2 M] was added Experimental planning to remove the excess of alcohol and catalyst; in the second step, fixed volumes of 15 mL of deionized water were added A 2 + 3 CtPt factorial design was used to evaluate the influ- until pH ⁓ 7 was reached. The oil was dried with magnesium ence of reaction time and MoO content in the catalyst on sulfate heptahydrate (MgSO ·7H O—Vetec) and centrifuged the biodiesel yield in the transesterification reaction of soy - 4 2 for complete separation. The oil obtained was characterized bean oil. Table 1 shows the experimental levels of the inde- for density, acidity index and methyl esters. pendent variables used in this study. The effects of the reaction time in the range of 2 to 4 h Reusability of the catalyst and the MoO content in the range of 5 to 15 wt% were The most active catalyst was reused under the same reac- Table 1 Levels of independent variables in the experimental planning tion conditions as in the first cycle. The catalyst was dried 2 + 3CtPt for evaluation of the transesterification of soybean oil at 100 °C for 24 h and reused in four reaction cycle without Independent variable Symbol Levels regeneration. − 1 0 + 1 Time (h) A 2 3 4 MoO (wt%) B 5 10 15 1 3 DrTG (mg/min) DrTG (mg/min) 22 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Biodiesel characterization 100 (a) (I) (II) 0.00 The biodiesel or fatty acid methyl ester (FAME) content was analyzed following the standard method according TGA to EN 14103 [34] using a Shimadzu GC 2010 Plus gas -0.25 DrTG chromatograph with a split/splitless injector, a flame ioni- zation detector (FID), an AOC-20i auto-injector and a -0.50 100% dimethyl polysiloxane capillary column RTX-WAX 30 m × 0.32 mm × 0.25 μm (Restek Corporation). The oper- ating conditions were as follows: FID temperature, 250 °C; -0.75 the initial column temperature, 210 °C; final column temper - 40 −1 0 150 300 450 600 750 900 ature, 250 °C; H linear velocity, 50 cm  s ; and split mode Temperature (°C) injection in the ratio of 1:50. Methyl heptadecanoate was used as the standard for GC-FID. Equation (2) was used to determine the fatty acid methyl esters content, C (wt%). FAME (b) S − A C × V 0.000 A EI EI EI C = × × 100%, (2) FAME A m EI TGA -0.075 DrTG where, S represents sum of the peak areas, A is the peak A EI (I) area of methyl heptadecanoate (internal standard), C is the EI (II) -0.150 concentration (mg/mL) of methyl heptadecanoate solution (III) (10 mg/mL), V represents the volume (mL) of methyl hep- EI -0.225 tadecanoate and ‘m’ is the mass (mg) of the FAME sample. The chromatograms in Fig. 8 show that transesterification reaction was successful achieved and allows to calculate the 0150 300450 600 750 900 individual FAME content using Eq. (3). Temperature (°C) C × V FAME EI EI (3) C = × × 100%, FAME Fig. 2 Thermogravimetric (TG) analysis of the catalytic precursor Al- A m EI SBA-15 (a) and catalyst 10MoO /Al-SBA-15 (b) where, C is the F AME content (wt%); A is the FAME i FAME i i FAME area calculated by integration of the corresponding In Fig. 2a, there are two temperature ranges, correspond- peaks in the chromatogram. ing to two mass loss events. In the first event (I), in the The specific mass data were determined following the temperature range between 23.57 and 82.9 °C, there is a standard established by EN ISO 3675/12185 and ASTM mass loss of 2.89%, which corresponds to a physical loss of D1298 [35], using Density Master DMA 4100 M equipment. water and volatile materials in the material's porous; in the The acidity index was determined according to the norm second event (II) in the range of 82.95 to 383.43 °C there is a established by ASTM D664 and EN 14104 standards [36] mass loss of 46.63%, due to the elimination of molecules of by titration of the oil with a solution of ethyl ether and ethyl Pluronic P123 triblock copolymer director. The system prac- alcohol (2:1) using 0.1 M potassium hydroxide as the titrant. tically reaches the equilibrium at a temperature of 500 °C. In Fig. 2b, three mass loss events are observed. In the first event (I), in the temperature range of 23.44 to 351.69 °C, Results and discussion there is a mass loss of 24.28%, which corresponds to elimi- nation of hydration water, desorption of physically adsorbed Characterization of the catalyst water in the porous, and the decomposition of ammonium ions present in tetrahydrate ammonium molybdate salt. The Thermogravimetric analysis (TG/DTG) second event (II), in the temperature range of 351.69 to 756 °C, corresponds to a mass loss of 5.67% due to molyb- The decomposition temperature of the precursor salts of denum oxide fusion. In the third event (III), in the tempera- aluminum and molybdenum was determined from the ther- ture range of 756 to 871 °C, there is a mass loss of 5.9% mogravimetric curves shown in Fig. 2a, b. corresponding to the process of sublimation of molybdenum [37]. 1 3 Weight loss (%) Weight loss (%) Materials for Renewable and Sustainable Energy (2022) 11:17–31 23 (a) (b) 10 20 30 40 50 60 2θ 0246 810 2θ Fig. 3 XRD pattern of the Al-SBA-15 catalytic precursor X‑ray diffractometry (XRD) Figure 3 shows the diffractogram of the catalytic precursor Al-SBA-15. From the X-ray diffractogram in Fig.  3a, it is possible to observe the presence of peaks corresponding to the characteristic reflections of mesoporous materials with an ordered hexagonal structure of the type SBA-15. It is observed that the synthesized materials present the main reflection, corresponding to the Miller index (1 0 0), thus indicating that a material with a well-defined structure was obtained; the peaks of lower intensity are due to the reflec- Fig. 4 XRD pattern of the a 5MoO /Al-SBA-15, b 10MoO /Al- 3 3 tions of the planes (1 1 0) and (2 0 0), described by Zhao SBA-15 e c 15MoO /Al-SBA-15 catalysts et al. [29] as peaks characteristic of the hexagonal structure of the SBA-15 catalytic precursor. The ill-defined peak in may not be detected in the XRD due to the support having the region of 2θ = 23.71° shown in Fig. 3b is characteristic of amorphous silica materials, which is typical of SBA-15. multiple pores, which causes the species to disperse inside the pores. It is observed that as the MoO content increases, It is possible to notice the absence of characteristic peaks of aluminum trioxide on the surface of the mesoporous struc- there is an increase in the intensity of the peaks, indicat- ing the appearance of the crystalline phase corresponding ture, indicating an effective incorporation of aluminum in the structure of SBA-15 [38].to MoO on the surface of the SBA-15. Figure 4 shows the X-ray diffractograms of the x _MoO / Al-SBA-15 catalysts (x = 5, 10 and 15 wt%). Fourier transformed infrared spectroscopy In the diffractogram shown in Fig.  4b, c peaks corre- sponding to the species of molybdenum trioxide were iden- FTIR spectra of Al-SBA-15 catalyst precursor and x_MoO / Al-SBA-15 catalysts are shown in Fig. 5, in which the bands tified by comparison with the standard XRD (Nº. JCPDS −1 00-005-0508) from the library of the International Center at 3381 and 1633  cm correspond to the v(O–H) stretch- ing vibration of adsorbed water molecules. All samples for Diffractional Data (JCPDS). In Fig.  4a, there were no peaks related to the MoO species, due to the fact that these display four absorption peaks at about 1052, 967, 797 and −1 447  cm . These peaks in the catalytic precursor are attrib- active species are well dispersed in the channels of the SBA- 15 catalytic precursor. González et al. [39] investigated the uted to asymmetrical stretching of the Si–O–Si, Si–OH, T–O (T = Si or Al) groups and the bending vibration of the crystalline and chemical structure of MoO /SBA-15 cata- lysts with different MoO contents (5, 10, 15, 20 and 25% Si–O–T groups, respectively. For the catalysts, the peaks −1 in the 500–1000  cm region are attributed to different by mass) to evaluate their catalytic activity for the oxida- tion of 4.6-DMDBT; the study proved that the active species stretching vibrations of Mo–O. The peaks at about 970 (all 1 3 Intensity, u.a. (1 0 0) (1 1 0) (2 0 0) Intensity, u.a. 24 Materials for Renewable and Sustainable Energy (2022) 11:17–31 (d) 150 (c) (b) (a) 0.00.2 0.40.6 0.81.0 Fig. 5 FTIR spectra of a Al-SBA-15, b 5MoO /Al-SBA-15, c 10MoO /Al-SBA-15, d 15MoO /Al-SBA-15 3 3 P/P Fig. 6 N adsorption/desorption isotherm of a Al-SBA-15, b 5MoO / 2 3 −1 samples) and 913  cm (10 and 15% MoO catalysts) were 3 Al-SBA-15, c 10MoO /Al-SBA-15, d 15MoO /Al-SBA-15 3 3 assigned to Mo = O symmetric stretching mode, indi- terminal cating orthorhombic phase in MoO layers, and Mo–O–Si −1 bond, respectively. The peak at about 570  cm is assigned the second region, in the range P/P ≈ 0.45–0.8, occurs the typical capillary condensation in mesoporous materials, to the triply coordinated oxygen [Mo–O(3)] stretching mode, which results from the edge-shared oxygen in common with with a hysteresis loop. In the third region, for P/P > 0.8, multilayer adsorption occurs on the external surface of the three MoO octahedra. The FTIR spectra complemented the diffractograms, as it was possible to identify the MoO particles [42]. The pore diameter of Al-SBA-15 incorporated with 5, 10 bonds in the Al-SBA-15 structure [40, 41]. and 15 wt% of MoO is shown in Fig. 7. It can be seen from Fig. 7 that the support Al-SBA-15 Textural analysis by nitrogen adsorption (BET) as well as the catalysts 5MoO/Al-SBA-15, 10MoO /Al- 3 3 SBA-15 and 15MoO /Al-SBA-15 have a uniform distri- The adsorption and desorption isotherms of N of the cata- 2 3 lytic precursor Al-SBA-15 and the catalysts x_MoO /Al- bution of mesopores, with average diameters of 31.50 Å, 31.90 Å, 32.28 Å and 39.55 Å, respectively, in addition to SBA-15 (x = 5, 10 and 15 wt%) are shown in Fig. 6. Figure 6 shows type IV isotherms with a H1 type hys- unimodal pore size distribution. The textural properties of the Al-SBA-15 catalytic precur- teresis loop for the Al-SBA-15 support as well as for each catalyst. Leofanti et al. [33] noted that type IV isotherms are sor as well as the x_MoO /Al-SBA-15 catalysts (x = 5, 10 and 15 wt%) are shown in Table 2. typical in mesoporous materials. H1-type hysteresis results from capillary condensation that occurs within the material's From Table  2, it can be seen that the specific surface area and the total pore volume of the catalysts decrease mesopores and is characteristic of materials with a cylindri- cal pore system. Analyzing the adsorption isotherm, three with the increase in the MoO content incorporated in the catalytic precursor, being up to 70% smaller than that of distinct regions are observed: in the first, at low pressures, for P/P < 0.2, the N adsorption occurs in the monolayer; the Al-SBA-15 support. The pore diameter increased with 0 2 1 3 3 -1 Volume adsorbed (cm g ) Materials for Renewable and Sustainable Energy (2022) 11:17–31 25 Factors affecting the transesterification reaction 39.55° Table 3 shows fatty acid methyl ester (FAME) yield, density and acidity index of the biodiesel obtained. A high yield of FAME was observed for all conditions of reaction time and (d) MoO content used in the experimental planning. 32.28° Effect of MoO content on biodiesel yield MoO was incorporated in the catalytic precursor Al- (c) SBA-15 with different contents (5, 10 and 15 wt%) and the catalyst obtained was evaluated in the biodiesel reaction. In the tested reaction conditions, the biodiesel yield increased 31.90° 16.8  wt% with the increase of MoO content from 5 to 15 wt%, for the shortest reaction time (2 h). For the long- est reaction time (4 h), the increase in MoO content from (b) 5 to 15 wt% increased 7.2% the FAME yield. The latter is because the initial reaction rate is as higher as the M oO content in the catalysts, and longer reaction time compen- 31.50° sates the lower reaction rate of the catalyst with lower MoO content. The highest biodiesel yield was obtained with the catalyst with 10 wt% of MoO and 3 h of reaction. Thus, (a) 10 wt% of MoO incorporated in the mesoporous structure is the optimum content to guarantee an active and well-dis- 050 100 150 200 persed phase in the channels and on the internal surface of Al-SBA-15. Pore Diameter (A) With the catalyst 5MoO /Al-SBA-15 the conversion was 89.2% in 4 h of reaction. From an economic point of view, Fig. 7 Pore size distribution of the a Al-SBA-15 catalytic precursor, even with the low MoO content, the reaction time is still and b 5MoO /Al-SBA-15, c 10MoO /Al-SBA-15, d 15MoO /Al- 3 3 3 SBA-15 catalysts compatible with those reported in the literature [24, 44, 45], which makes it also a candidate, since its lower produc- tion cost compensates the greater reaction time required to MoO content, due to the higher concentration of MoO on achieve a high conversion. 3 3 the external surface of the catalyst. Huang et al. [43], using Chen et al. [24] incorporated different Mo contents (1, different MoO contents in the mesoporous structure of Al- 3, 5, 7 and 10 wt%) in zeolite NaBeta, evaluating them for SBA-15, concluded that the decrease in both the specific the production of biodiesel from rice bran oil. The increase surface area and the pore volume is due to the migration in the Mo content from 1 to 7 wt% increased the conver- of MoO into the interior of the mesopores, as a result of sion from 44 to 74.8%, in the same reaction time (5  h). the strong interaction between molybdenum trioxide and the However, the activity of 10Mo/NaBeta catalyst decreases mesoporous structure. slightly because the active phase was not well dispersed in Table 2 Textural properties of the catalytic precursor Al-SBA-15 and x_MoO /Al-SBA-15 catalysts (x = 5, 10, 15 wt%) a 2 −1 2 −1 micro mes 3 −1 b 3 −1 c Catalyst S (m  g ) S (m  g ) V V (cm  g ) V (cm  g ) D (Å) BET ext P P P p BJH 3 −1 (cm  g ) Al-SBA-15 655.48 566.67 0.03 1.02 1.07 72.36 5MoO /Al-SBA-15 523.63 447.18 0.03 0.56 0.61 53.51 10MoO /Al-SBA-15 311.08 256.36 0.02 0.51 0.58 80.83 15MoO /Al-SBA-15 199.28 163.34 0.02 0.44 0.44 89.22 Specific surface area determined by Brunauer–Emmett–Teller (BET) method Total pore volume recorded at p/p = 0.99 Pore diameter calculated by Barrett–Joyner–Halenda (BJH) method 1 3 Pore Volume (cc/g) 26 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Table 3 Experimental and −3 Run Factors FAME yield (wt%)Density (kg  m ) Acidity Index predicted data of FAME yield, −1 (mg KOH  g ) a b c density and acidity index of the Time (h) MoO (wt%) Exp. Pred. Res. obtained oils 1 2 5 80.13 84.39 4.26 887.7 0.92 2 4 5 88.65 84.39 4.26 883.4 0.67 3 2 15 94.31 94.83 0.52 881.9 0.89 4 4 15 95.36 94.83 0.53 881.0 0.92 5 3 10 94.94 96.24 1.30 879.6 1.85 6 3 10 97.89 96.24 1.65 879.0 0.88 7 3 10 95.89 96.24 0.35 879.4 0.91 Soybean oil 920 0.00 Experimental values of response Predicted values of response Residual the channels resulting in smaller surface area. Yields above was 98% with the catalyst 10MoO /Al-SBA-15, in 3 h of 84% were obtained with the 7Mo/NaBeta catalyst and reac- reaction. tion time of 8 h. Thus, a kinetic study was performed by the Mohebbi et al. [25] using the catalyst MoO /B-ZSM-5 authors with the 7Mo/NaBeta catalyst. in the esterification of free fatty acids, found that the con- Sankaranarayanan et al. [38] synthesized MoO /γ-Al O version increased from 91 to 96% with an increase in the 3 2 3 catalysts with different MoO contents (8, 12 and 16 wt%), reaction time from 4 to 6 h. They also observed that for and calcined them at different temperatures (800, 950 and reaction times greater than 6 h there was no difference in the 1100 K). The catalysts were evaluated in the transesterifica- conversion, as the esterification reaction had already reached tion of sunflower oil with methanol. The effect of various the equilibrium. parameters, such as Mo content, calcination temperature, Mapossa et al. [45] studied the nanomagnetic catalyst reaction temperature and methanol to oil molar ratio on Ni0.5Zn0.5Fe O in the transesterification of soybean oil, 2 4 the oil conversion was obtained. The highest activity was in the range of 1 to 4 h. It was observed that increasing the with the catalyst calcined at 950 K containing 16 wt% of reaction time from 1 to 3 h, the biodiesel yield increased MoO , for which conversion higher than 90% was obtained reaching 92.1%. However, from 3 to 4 h, the biodiesel yield at 110 °C and 24 h in a batch reactor. The authors reported decreased to 87.0%. The authors attributed this decrease to that the catalytic activity decreased with reuse, however it the reversibility of the reaction as well as to parallel reac- can be regenerated by recalcination. tions, such as soap production, which contribute to reduced biodiesel yield. Reaction time effect Chemical composition of FAME The progress of the reaction was evaluated in the range of 2 to 4 h. For all catalysts, the conversion increased with the The produced biodiesel composition is given in Table 4. reaction time, confirming that the reaction is irreversible C wt% was calculated from Eq. (3) and the chroma- FAMEi without competing parallel reactions. The largest conversion tograms shown in Fig. 8. The most commonly found fatty Table 4 Concentrations of Biodiesel C (wt.%) FAMEi FAME in the biodiesel sample [C16:0] C[18:0] [C18:1] [C18:2] [C18:3] Others 1 10.31 2.27 20.69 49.55 5.93 11.25 2 11.03 2.43 22.13 52.99 6.33 5.08 3 10.99 2.66 22.97 53.27 6.12 3.98 4 13.04 2.89 22.20 52.63 6.19 3.05 5 11.48 2.55 23.41 55.50 6.53 0.52 6 11.22 2.49 22.87 54.22 6.38 2.81 7 9.23 2.51 23.06 54.65 6.43 4.12 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 27 predominant fatty acids were: polyunsaturated fatty acids, linoleic (C18:2; 49–54%) and linolenic (C18:3; 5–7%); Run 7 unsaturated fatty acids, oleic acid (C18:1; 20–23%) and satu- rated fatty acids, palmitic acid (C16:0; 9–13%) and stearic (18:0; 2–3%). Soybean oil for biodiesel production has the following typical composition [47]: oleic (20–30%), linoleic Run 6 (50–60%), palmitic (6–10%), stearic (2–5%) and linolenic (5–11%). Thus, the biodiesel produced in this work 'has a typical composition of biodiesel from soybean reported in Run 5 the literature. Density and acidity index Run 4 The acidity index and density are important properties for characterization of methyl or ethyl esters [47, 48]. The bio- −3 diesel should have a density between 850 and 900 kg  m −1 and an acid number below 0.50 mg KOH  g . The density Run 3 of each biodiesel obtained (Table 3) is within the standards established. Density values above the upper limit leads to the formation of a rich air/fuel mixture, increasing the emission Run 2 of pollutants, while values below the lower limit cause loss of engine power as well as increase in fuel consumption [49]. Lôbo et al. [50] stated that the density of biodiesel is directly related to the structure of its molecules. The longer Run 1 the length of the alkylester's carbon chain the greater the density. In relation to the acidity index, all results were outside the standard legal limits, which may be due to the leaching of MoO into the reaction medium, as this molecule has high acidity. Then, an acidity controlling unit may be designed as part of the process. Time (min) Statistical analysis of the data Fig. 8 Biodiesel samples chromatograms (Acronym: C16:0—methyl palmitate; C17:0—methyl heptadecanoate (internal standard); C18:0 – methyl stearate; C18:1—methyl oleate; C18:2—methyl linoleate; The effect of reaction time (A) and MoO content (B) on C18:3—methyl linoleneate) FAME yield were obtained with a significance level of 5% (α = 0.05) using the Minitab 17.0 software for statistical analysis. Table 5 shows the results of Analysis of Variance acids in biodiesel samples are: oleic (C18:1) followed by (ANOVA). stearic (C18:0), linoleic (C18:2), palmitic (C16:0) and lino- The F value calculated for factor B is greater than the lenic (C18:3) [46]. In all samples of biodiesel obtained, the tabulated value, therefore, the M oO content significantly Table 5 ANOVA for the Source Degree Sum of squares Mean square P-value F-value Tabulated Remarks experimental planning 2 + 3 of free- F-value CtPt dom A 1 22.90 22.90 0.07 10.10 18.51 Insignificant B 1 109.10 109.10 0.02 48.11 18.51 Significant A × B 1 13.95 13.950 0.13 6.15 18.51 Insignificant Curvature 1 75.30 75.298 0.03 33.21 18.51 Significant Error 2 4.53 4.53 – – – – Total 6 225.78 – – – – – R = 97.99% R = 99.00% 1 3 Heptano C16:0 C17:0 C18:0 C18:1 C18:2 C18:3 28 Materials for Renewable and Sustainable Energy (2022) 11:17–31 influences the FAME yield. The values of F calculated for Reusability of the catalyst factor A and interaction factor AxB are smaller than the tabulated ones, therefore, they are not significant. The cur - To verify the presence of the active phase of molybde- vature is significant, since the calculated F value is greater num in the used catalyst, XRDs were carried out after the than the tabulated F value, thus indicating that a quadratic first cycle of use. Figure  11 shows the X-ray diffracto- model should further be used to optimize the independent grams of the x_MoO /Al-SBA-15 catalysts (x = 5, 10 and variable values. The Pareto diagram depicted in Fig. 9 shows 15 wt%) after transesterification reaction. For 10_MoO / the significance of the factors with respect to the standard- Al-SBA-15 catalyst (Fig. 11b), it was observed that after ized effect. the first use in the reaction, there was a reduction in the As shown in Table 5, the coefficient of determination (R ) characteristic peaks of the MoO phase. The other cata- was 97.99%, which represents the percentage of data that lysts have the same profile as the diffractogram shown in the model can explain. The correlation coefficient (R ) was Fig. 4. The catalytic activity was studied over five cycles 99.00%, which indicates a strong correlation between the of catalyst use to assess its lifetime. The FAME yield data. obtained for each reuse cycle of the catalyst is shown in The response surface and isocurves of FAME yield as a Fig. 12. It was observed in Fig. 12 that the reused catalyst function of reaction time and MoO content are shown in reduced its activity after five consecutive reaction cycles Fig. 10. It can be seen a maximum FAME yield in a region and the yield decreased by about 34%. Malhotra et al. [16] close to the central point, as well as that the minimum and Thitsartarn et al. [51] have reported that leaching of FAME yield occurs for the lowest MoO content and the active species is a problem frequently encountered in het- shortest reaction time. erogeneous catalysts. The response surface shown in Fig. 10 corresponds to the model given in Eq. (4). Conclusion Y = 60.78 + 6.13A + 2.165B − 0.374A × B + 6.63CtPt (4) where Y is the FAME yield. The catalytic precursor Al-SBA-15 was obtained and veri- Equation (5) is the response surface keeping every terms fied from X-ray diffractograms. The catalyst x _MoO / in the model. However, it has been seen from ANOVA in Al-SBA-15 was obtained by incorporating MoO in Al- Table 5 that factor A and interaction factor A × B are not SBA-15. Characteristic peaks of MoO were identified significant on the FAME yield. Thus, disregarding the non- for catalysts with 10 and 15 wt% MoO contents. Ther- significant terms, and readjusting the model without them, mogravimetric analysis for the catalytic precursor Al- results in Eq. (4), with the coefficients of the coded model. SBA-15, as well as for salts decomposition and MoO formation indicates that the calcination temperature must Y = 89.613 + 5.223B + 6.63CtPt. (5) be up to 550 °C. The adsorption/desorption isotherms of N show a uniform cylindrical pore structure and unimodal As the curvature test was significant while the interaction pore size distribution. The density of all oils obtained term A × B was not, it is not possible to conclude about the from the transesterification reaction met the requirements significance of the second order term included in the model for biodiesel, however, the acidity index of none of the given in Eq. (4). In this case, the factorial design must be oils obtained was within the alloyed limits, probably due extended to an experimental planning 3 , with the inclusion to the leaching of MoO in the oil. MoO content in the of new experimental points, and thus adjust the model given 3 3 catalyst influences the biodiesel yield with a significance by Eq. (1), keeping all second order terms. Central com- level of α = 0.05, based on the F test and Pareto graph. posite planning is usually used to extend factorial planning. After the 5ht cycle of use, the biodiesel yield is dimin- Star planning is an example of central planning based on ished from ~ 96 to ~ 62% using the catalyst 10_MoO /Al- two initial factors. In this work, only experimental planning SBA-15. That catalyst is the recommended to be used in 2 was carried out with the addition of 1 central point with the transesterification of soybean for biodiesel production two repetitions. The addition of axial points would imply the in a competitive way with currently existing heterogene- production of new catalysts, which was not possible for now ous catalysts. due to the costs involved. 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 29 Term 4,303 AB 0 1 2 3 4 5 6 7 Standardized Effect Fig. 9 Pareto chart of the standardized effects (α = 0.05) Fig. 11 XRD pattern of the a 5MoO /Al-SBA-15, b 10MoO /Al- 3 3 SBA-15 e c 15MoO /Al-SBA-15 catalysts after transesterification reaction (a) 15.0 FAME Yield (wt. %) 12.5 < 81 81 – 84 10.0 84 – 87 87 – 90 90 – 93 7.5 40 93 – 96 > 96 5.0 2.0 2.5 3.0 3.5 4.0 Time (h) 1234 5 (b) Reaction Cycle (Rounds) Fig. 10 Effect of reaction time and % MoO on FAME yield: a 3D response surface and; b corresponding 2D Contour plot Fig. 12 Reusability of 10MoO /Al-SBA-15 catalyst (reaction condi- tions: MeOH:oil molar ratio = 20:1, 3 wt% catalyst, 150 °C, 3 h/cycle) 1 3 MoO3 (wt. %) % Fame Yield 30 Materials for Renewable and Sustainable Energy (2022) 11:17–31 Acknowledgements This research was supported by the Department oil on Al-SBA-15 catalysts. Appl. Catal. B Environ. 184, 163–173 of Chemical Engineering—Federal University of Campina Grande. (2016) The scholarship was awarded by Coordination for the Improvement of 11. Sánchez Faba, E.M., Ferrero, G.O., Dias, J.M., Eimer, G.A.: Higher Level Education a Personnel (CAPES). Na-Ce-modified-SBA-15 as an effective and reusable bimetallic mesoporous catalyst for the sustainable production of biodiesel. Appl. Catal. A Gen. (2020). https://doi. or g/10. 1016/j. apcat a.2020. Declarations 12. Xie, W., Zhao, L.: Heterogeneous CaO–MoO -SBA-15 cata- Conflict of interest The authors declare that they have no conflict of lysts for biodiesel production from soybean oil. Energy Convers. interest. Manag. 79, 34–42 (2014) 13. Esan, A.O., Adeyemi, A.D., Ganesan, S.: A review on the recent Open Access This article is licensed under a Creative Commons Attri- application of dimethyl carbonate in sustainable biodiesel produc- bution 4.0 International License, which permits use, sharing, adapta- tion. J. Clean. Prod. 257, 120561 (2020) tion, distribution and reproduction in any medium or format, as long 14. Demirbas, A.: Biodiesel production from vegetable oils via cata- as you give appropriate credit to the original author(s) and the source, lytic and non-catalytic supercritical methanol transesterification provide a link to the Creative Commons licence, and indicate if changes methods. Prog. Energy Combust. Sci. 31, 466–487 (2005) were made. The images or other third party material in this article are 15. Mohamed, R.M., Kadry, G.A., Abdel-Samad, H.A., Awad, M.E.: included in the article’s Creative Commons licence, unless indicated High operative heterogeneous catalyst in biodiesel production otherwise in a credit line to the material. If material is not included in from waste cooking oil. Egypt. J. Pet. 29, 59–65 (2020) the article’s Creative Commons licence and your intended use is not 16. Malhotra, R., Ali, A.: Lithium-doped ceria supported SBA−15 permitted by statutory regulation or exceeds the permitted use, you will as mesoporous solid reusable and heterogeneous catalyst for bio- need to obtain permission directly from the copyright holder. To view a diesel production via simultaneous esterification and transesterifi- copy of this licence, visit http://creativecommons.org/licenses/by/4.0/. cation of waste cottonseed oil. Renew. Energy 119, 32–44 (2018) 17. Rathore, V., Newalkar, B.L., Badoni, R.P.: Processing of vegetable oil for biofuel production through conventional and non-conven- tional routes. Energy Sustain. Dev. 31, 24–49 (2016) References 18. Li, L., Yan, B., Li, H., Yu, S., Ge, X.: Decreasing the acid value of pyrolysis oil via esterification using ZrO /SBA-15 as a solid 1. Manojkumar, N., Muthukumaran, C., Sharmila, G.: A compre- acid catalyst. Renew. Energy 146, 643–650 (2020) hensive review on the application of response surface methodol- 19. Kamaruzaman, M.F., Taufiq-Yap, Y.H., Derawi, D.: Green diesel ogy for optimization of biodiesel production using different oil production from palm fatty acid distillate over SBA-15-supported sources. J. King Saud. Univ. Eng. Sci. (2020). https:// doi. org/ 10. nickel, cobalt, and nickel/cobalt catalysts. Biomass Bioenergy 1016/j. jksues. 2020. 09. 012 134, 105476 (2020) 2. Lee, J.H., Jeon, H., Park, J.T., Kim, J.H.: Synthesis of hierarchi- 20. Li, X., Yin, H., Zhang, J., Liu, J., Chen, G.: Effect of organic cal flower-shaped hollow MgO microspheres via ethylene-glycol- template removal approaches on physiochemical characterization mediated process as a base heterogeneous catalyst for transesteri- of Ni/Al-SBA-15 and eugenol hydrodeoxygenation. J. Solid State fication for biodiesel production. Biomass Bioenergy 142, 105788 Chem. 282, 121063 (2020) (2020) 21. Socci, J., Osatiashtiani, A., Kyriakou, G., Bridgwater, T.: The 3. Gupta, J., Agarwal, M., Dalai, A.K.: An overview on the recent catalytic cracking of sterically challenging plastic feedstocks over advancements of sustainable heterogeneous catalysts and promi- high acid density Al-SBA-15 catalysts. Appl. Catal. A Gen. 570, nent continuous reactor for biodiesel production. J. Ind. Eng. 218–227 (2019) Chem. 88, 58–77 (2020) 22. Mouat, A.R., Lohr, T.L., Wegener, E.C., Miller, J.T., Delferro, 4. Kim, M., DiMaggio, C., Salley, S.O., Simon Ng, K.Y.: A new gen- M., Stair, P.C., Marks, T.J.: Reactivity of a carbon-supported sin- eration of zirconia supported metal oxide catalysts for converting gle-site molybdenum dioxo catalyst for biodiesel synthesis. ACS low grade renewable feedstocks to biodiesel. Bioresour. Technol. Catal. 6, 6762–6769 (2016) 118, 37–42 (2012) 23. Pinto, B.F., Garcia, M.A.S., Costa, J.C.S., de Moura, C.V.R., de 5. Chua, S.Y., Periasamy, L.A., Goh, C.M.H., Tan, Y.H., Mubarak, Abreu, W.C., de Moura, E.M.: Effect of calcination temperature N.M., Kansedo, J., Khalid, M., Walvekar, R., Abdullah, E.C.: Bio- on the application of molybdenum trioxide acid catalyst: screening diesel synthesis using natural solid catalyst derived from biomass of substrates for biodiesel production. Fuel 239, 290–296 (2019) waste—a review. J. Ind. Eng. Chem. 81, 41–60 (2020) 24. Chen, C., Cai, L., Zhang, L., Fu, W., Hong, Y., Gao, X., Jiang, 6. Chueluecha, N., Kaewchada, A., Jaree, A.: Enhancement of bio- Y., Li, L., Yan, X., Wu, G.: Transesterification of rice bran oil to diesel synthesis using co-solvent in a packed-microchannel. J. Ind. biodiesel using mesoporous NaBeta zeolite-supported molybde- Eng. Chem. 51, 162–171 (2017) num catalyst: experimental and kinetic studies. Chem. Eng. J. 382, 7. Chozhavendhan, S., Vijay Pradhap Singh, M., Fransila, B., 122839 (2020) Praveen Kumar, R., Karthiga Devi, G.: A review on influencing 25. Mohebbi, S., Rostamizadeh, M., Kahforoushan, D.: Effect parameters of biodiesel production and purification processes. of molybdenum promoter on performance of high silica Curr. Res. Green Sustain. Chem. 1–2, 1–6 (2020) MoO /B-ZSM-5 nanocatalyst in biodiesel production. Fuel 8. Huang, J., Zou, Y., Yaseen, M., Qu, H., He, R., Tong, Z.: Fabrica- (2020). https:// doi. org/ 10. 1016/j. fuel. 2020. 117063 tion of hollow cage-like CaO catalyst for the enhanced biodiesel 26. Ding, H., Ye, W., Wang, Y., Wang, X., Li, L., Liu, D., Gui, J., production via transesterification of soybean oil and methanol. Song, C., Ji, N.: Process intensification of transesterification for Fuel 290, 119799 (2021) biodiesel production from palm oil: microwave irradiation on 9. Malhotra, R., Ali, A.: 5-Na/ZnO doped mesoporous silica as reus- transesterification reaction catalyzed by acidic imidazolium ionic able solid catalyst for biodiesel production via transesterification liquids. Energy 144, 957–967 (2018) of virgin cottonseed oil. Renew. Energy 133, 606–619 (2019) 27. Li, B., Song, H.Y., Deng, Z.P., Huo, L.H., Gao, S.: Novel sensitive 10. Meloni, D., Perra, D., Monaci, R., Cutrufello, M.G., Rombi, E., amperometric hydrogen peroxide sensor using layered hierarchical Ferino, I.: Transesterification of Jatropha curcas oil and soybean 1 3 Materials for Renewable and Sustainable Energy (2022) 11:17–31 31 porous Α-MoO and GO modified glass carbon electrode. Sens. 41. Rakngam, I., Osakoo, N., Wittayakun, J., Chanlek, N., Peng- Actuators B Chem. 288, 641–648 (2019) sawang, A., Sosa, N., Butburee, T., Faungnawakij, K., Khem- 28. Li, M., Liu, N., Wu, Z., Li, Y., Li, S., Xu, W., Luo, Z., Liu, Y.: thong, P.: Properties of mesoporous Al-SBA-15 from one-pot A facile and novel route for dual-template method synthesis of hydrothermal synthesis with different aluminium precursors and mesoporous silica material Al-Ce-SBA-15. Mater. Lett. 185, catalytic performances in xylose conversion to furfural. Micropo- 85–88 (2016) rous Mesoporous Mater. 317, 110999 (2021) 29. Zhao, D., Feng, J., Huo, Q., Melosh, N., Fredrickson, G.H., 42. Zhou, C., Gao, Q., Luo, W., Zhou, Q., Wang, H., Yan, C.: Journal Chmelka, B.F., Stucky, G.D.: Triblock copolymer syntheses of of the Taiwan Institute of Chemical Engineers Preparation, char- mesoporous silica with periodic 50 to 300 angstrom pores. Sci- acterization and adsorption evaluation of spherical mesoporous ence (80-) 279, 548–552 (1998) Al-MCM-41 from coal fly ash. J. Taiwan Inst. Chem. Eng. 52, 30. Ciola, R.: Fundamentos da Catálise, 1st edn. Editora Moderna, 147–157 (2015) São Paulo (1981) 43. Peng, H., Min, L.I.U., Qiu-lian, C.: M oO /Al-SBA-15 modi- 31. Melero, J.A., Iglesias, J., Arsuaga, J.M., Sainz-Pardo, J., de Fru- fied catalyst and its application in coal tar hydrocracking. J. Fuel tos, P., Blazquez, S.: Synthesis, characterization and catalytic Chem. Technol. 48, 1079–1086 (2020) activity of highly dispersed Mo-SBA-15. Appl Catal A Gen 331, 44. Sankaranarayanan, T.M., Pandurangan, A., Banu, M., Sivasanker, 84–94 (2007) S.: Transesterification of sunflower oil over MoO supported on 32. Klug, H.P., Alexander, L.: No X-Ray Diffraction Procedures: For alumina. Appl. Catal. A Gen. 409–410, 239–247 (2011) Polycrystalline and Amorphous Materials, 2nd edn. New York 45. Mapossa, A.B., Dantas, J., Costa, A.C.F.M.: Transesterifica- (1974) tion reaction for biodiesel production from soybean oil using 33. Leofanti, G., Padovan, M., Tozzola, G., Venturelli, B.: Surface Ni Zn Fe O nanomagnetic catalyst: kinetic study. Int. J. 0.5 0.5 2 4 area and pore texture of catalysts. Catal. Today 41, 207–219 Energy Res. 44, 6674–6684 (2020) (1998) 46. Wan Ghazali, W.N.M., Mamat, R., Masjuki, H.H., Najafi, G.: 34. Thoai, D.N., Photaworn, S., Kumar, A., Prasertsit, K., Tongurai, Effects of biodiesel from different feedstocks on engine perfor - C.: A novel chemical method for determining ester content in mance and emissions: a review. Renew. Sustain. Energy Rev. 51, biodiesel. Energy Proc. 138, 536–543 (2017) 585–602 (2015) 35. Atabani, A.E., Silitonga, A.S., Anjum, I., Mahlia, T.M.I., Masjuki, 47. Singh, D., Sharma, D., Soni, S.L., Sharma, S., Kumari, D.: Chem- H.H., Mekhilef, S.: A comprehensive review on biodiesel as an ical compositions, properties, and standards for different genera- alternative energy resource and its characteristics. Renew. Sustain. tion biodiesels: a review. Fuel 253, 60–71 (2019) Energy Rev. 16, 2070–2093 (2012) 48. Atabani, A.E., Silitonga, A.S., Ong, H.C., Mahlia, T.M.I., Mas- 36. Sakthivel, R., Ramesh, K., Purnachandran, R., Shameer, P.M.: A juki, H.H., Badruddin, I.A., Fayaz, H.: Non-edible vegetable oils: review on the properties, performance and emission aspects of a critical evaluation of oil extraction, fatty acid compositions, the third generation biodiesels. Renew. Sustain. Energy Rev. 82, biodiesel production, characteristics, engine performance and 2970–2992 (2018) emissions production. Renew. Sustain. Energy Rev. 18, 211–245 37. Veríssimo, T., Brainer, S., Beatriz, D., Pryston, D.A.: Study of (2013) neat and mixed Sn(IV) and Mo(VI) oxides for transesterification 49. Hosseinzadeh-Bandbafha, H., Tabatabaei, M., Aghbashlo, M., and esterification: influence of the substrate on leaching. Catal. Khanali, M., Demirbas, A.: A comprehensive review on the envi- Lett. 149, 3132–3137 (2019) ronmental impacts of diesel/biodiesel additives. Energy Convers. 38. Cabrera-munguia, D.A., González, H., Gutiérrez-alejandre, A., Manag. 174, 579–614 (2018) Rico, J.L., Maya-yescas, R., Rosa, E., Huirache-acu, R.: Hetero- 50. Lobo, I.P., Ferreira, S.L.C., Da, C.R.S.: Biodiesel: Parâmetros de geneous acid conversion of a tricaprylin-palmitic acid mixture qualidade e métodos analíticos. Quim Nova 32, 1596–1608 (2009) over Al-SBA-15 catalysts: reaction study for biodiesel synthesis. 51. Thitsartarn, W., Maneerung, T., Kawi, S.: Highly active and Catal. Today 282, 195–203 (2017) durable Ca-doped Ce-SBA-15 catalyst for biodiesel production. 39. González, J., An, J., Chen, L., Manríquez, M., Salmones, J., Energy 89, 946–956 (2015) Limas, R., Arellano, U.: Quantitative determination of oxy- gen defects, surface lewis acidity, and catalytic properties of Publisher's Note Springer Nature remains neutral with regard to mesoporous MoO /SBA-15 catalysts. J. Solid State Chem. 263, jurisdictional claims in published maps and institutional affiliations. 100–114 (2018) 40. Chen, D., Liu, M., Yin, L., et al.: Single-crystalline MoO nano- plates: topochemical synthesis and enhanced ethanol-sensing performance. J. Mater. Chem. 21, 9332–9342 (2011) 1 3

Journal

Materials for Renewable and Sustainable EnergySpringer Journals

Published: Apr 1, 2022

Keywords: Biodiesel; Transesterification; Al-SBA-15 precursor; MoO3/Al-SBA-15 catalyst

References