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Development of semi-synthetic catalyst based on clay and their use in catalytic cracking of petroleum residue

Development of semi-synthetic catalyst based on clay and their use in catalytic cracking of... Two semi-synthetic clay-based catalysts were prepared. These catalysts were obtained by incorporating lanthanum oxide (Cat1) and chromium oxide (Cat2). They were then tested for catalytic cracking of a heavy petroleum residue (fuel). The two formulations were carried out in the presence of silica to improve their acidity then underwent an acid activation. The catalysts obtained were characterized by various methods (XRD, FTIR, ICP-OES, SEM). The results showed that the incorporation of oxides and the addition of silica improves the structural characteristics of the final products. The support used was a kao- linite rich clay, having a specific surface area of 15.26  m /g and acidity of 14 meq/g. These values increase, respectively, to 2 2 456.14  m /g and 50 meq/g for Cat1 and to 475.12  m /g and 57 meq/g for Cat2. The influence of the type of oxide incorpo- rated, the specific surface area, the porosity and the acidity of the catalysts on their catalytic activity was studied. The nature of the oxide used proved to be decisive on the quality of the catalyst. Thus Cat1, prepared with lanthanum oxide, showed the best performance in cracking the petroleum residue achieving a conversion rate of 74.13% compared to 66.53% for cat2. Keywords Petroleum residue · Clay · Catalyst · Catalytic cracking Introduction be innovate to achieve performance [2, 25]. Therefore, new catalyst development need to be investigated to improve the Due to its impact on the environment, the use of heavy oil yield of FCC processes. residue (fuel) is strongly discouraged by government offi- A catalyst is a substance that increases the rate of a chem- cials. Thus, the demand of fuel will suffer a sharp drop in ical reaction, without being consumed or produced [8]. The coming years in favor of gasoline, diesel and other petro- activity and selectivity of the FCC catalyst are derived from leum products, which are lighter. To remain competitive the acidic sites and the pore structure, respectively. Catalytic and give added value to heavy oil residues, the refineries catalysts are therefore porous solids with acidic properties are stepping up their research to improve the fluid catalytic [4, 18, 23]. Commercial FCC catalysts generally consist of cracking (FCC) process [9, 19]. The FCC process consist to two main components: the zeolite and the matrix. The zeo- convert heavy oil feeds into light products. Although this lites used in FCC catalysts are mainly synthetic faujasite Y process has been used in refineries for decades, it needs to type zeolites and high silica Y zeolites, which are the main contributor to the catalytic activity and selectivity of the FCC catalyst [13]. The matrix is made of different constitu- * Soumahoro Gueu ents such as aluminosilicates and additives which are solid Soumahoro.gueu@inphb.ci compounds added to improve its properties [4, 9]. Neverthe- less, the high cost of these commercial catalysts could be a Laboratoire des Procédés Industriels, de Synthèse, de barrier to their use in development countries. It is urgent to L’Environnement et des Energies Nouvelles (LAPISEN), Institut National Polytechnique Félix Houphouët-Boigny, develop a novel FCC catalyst with local resource [20, 26]. Yamoussoukro BP 1093 Yamoussoukro, Côte d’Ivoire Recent research is directed towards the development Département Energies Fossiles, Université D’Agadez, of semi-synthetic clay-based catalysts. In this configura- BP 199 Agadez, Niger tion, the clay acts as a matrix in which metallic oxides Département de Chimie, Faculté Des Sciences Et are incorporated. Emam [8] has shown that clay catalysts Techniques, Université Abdou Moumouni de Niamey, are arousing much interest for catalytic application in the BP 10662 Niamey, Niger Vol.:(0123456789) 1 3 148 Applied Petrochemical Research (2021) 11:147–154 petroleum refining industry. According to Bouras [6 ], the Catalyst characterization interest given in recent years to the study of clays by labo- ratories around the world is explained by their abundance X-ray diffraction (XRD) patterns of all samples were in nature, the importance of their specific surface, their recorded at room temperature, using a Rigaku-Miniflex II porosity and especially their ability to exchange interfoliar diffractometer (Japan). The incident radiation is generated cations. Kaolin and montmorillonite are the most com- by the Kα line of copper (λ = 1.5406 Å) at 30 kV and 15 mA. monly used clays in the development of refining catalysts The analyzes were carried out in the angular interval [5–70°] [20]. Murray [21] estimates that more than 200,000 tonnes in 2θ with a step of 0.02° (2θ) and a counting time of 2 s. of kaolin are used annually to produce petroleum crack- The infrared spectroscopic analyzes were carried out in ing catalysts. This work deals with the development of ATR (Attenuated Total Reflectance) mode with a Fourier new semi-synthetic catalysts based on clay and oxides, Bruker Alpha Transform spectrometer equipped with a the characterization of these catalysts obtained and finally diamond crystal (refractive index of the diamond 2.451). their use in fuel cracking. To our knowledge, in the lit- The spectra were acquired with a nominal resolution of −1 −1 erature, it has not been reported cracking of fuel oil by 4  cm over a wavenumber range from 400 to 4000  cm . semi-synthetic catalysts or even by conventional catalytic Chemical analysis of the samples was performed using catalysts. This study therefore aims to fill this void. a Vista Pro Varian instrument equipped with an ICP-OES The objective of the current work was to prepare a FCC (Inductively Coupled Plasma-Optical Emission Spectros- catalyst, and to study the catalytic properties. Two cata- copy) plasma. lysts were prepared using a kaolinite rich clay as matrix. The BET isotherms were obtained using a Nova Station The influence of the type of oxide incorporated, the spe - B sorptiometer. The absorption gas used is nitrogen and cific surface area, the porosity and the acidity of the cata- the measurements are carried out at 77.350 K. The deter- lysts on their catalytic activity was studied. mination of the microporous volumes and the microporous surfaces are carried out by the t-plot method. A variable pressure scanning electron microscope (SEM) from the D.C.A.R. (SEM FEG Supra 40 VP Zeiss) Materials and methods of 2  nm resolution coupled to an X-ray microanalyzer (EDS) was used for the characterization of the microstruc- Materials ture and the surface chemical composition of the catalysts. The total acidity of the catalysts was determined using The catalysts prepared in this study were made from Niger the titration method of Boehm [5] which is used by many clay. This clay has been characterized in previous work researchers working on adsorbents [12]. This method con- [1]. It has a specific surface area of 15.26  m /g and a loss sists of assaying functional groups having various acidities on ignition of 16.1%. It is mainly composed of kaolin- with different bases. For the present study, the bases used ite (46.3%) and an interstratified smectite illite chlorite are sodium hydroxide (NaOH), sodium hydrogen carbonate (53.7%) [1]. The choice of this clay is explained because (NaHCO ) and sodium ethanolate (C H ONa). The proce- 3 2 5 the catalytic reactions taking place at high temperature dure is as follows: a mass of 500 mg of catalyst is placed in (≥ 500 °C), the catalyst must be a refractory material, able Erlenmeyer flasks. Then 25 mL of the different bases, all to withstand such temperature. prepared at 0.1 N, are transferred into each of the Erlen- meyer flasks containing the catalysts. The blank tests are carried out by proceeding in the same manner, with the dif- Catalyst preparation ference that Erlenmeyer flasks do not contain a catalyst. The samples and the blanks are stirred on magnetic stirrers at In a beaker containing 15 g of clay with a particle size 150 rpm for 72 hours at room temperature, then left to stand less than 2  µm, 0.55  g of lanthanum (La O ) or chro- for 6 hours. The supernatant is filtered through a Whatman 2 3 mium (Cr O ) oxide and 4  g of silica are added. After cellulose nitrate membrane (0.2 μm) then the excess basic 2 3 homogenization, acid activation is carried out by adding solution is dosed back with a 0.1 N HCl solution. 25 mL of 10% hydrochloric acid and then the whole is left under stirring for 6 hours. The resulting mixture is dried at 105 °C for 12 hours and then calcined at 800 °C for Catalytic cracking test thirty minutes. The catalyst containing lanthanum oxide is called Cat1 and the one obtained with chromium oxide The performance tests of the catalysts were carried out is called Cat2. in a stainless steel reactor (Fig. 1), manufactured in the 1 3 Applied Petrochemical Research (2021) 11:147–154 149 Fig. 1 Model of the cracking plant laboratory (LAPISEN). The methodology used here has Results and discussion been adapted to that of Houdry [14]. To carry out the cracking operation, a mass of 20 g of catalyst is placed XRD in a reactor. Then, the reactor is inserted into an electric furnace and the temperature is raised in steps of 100 °C The two catalysts developed (Cat1 and Cat2) were ana- until reaching 500 °C. After checking the seal of the instal- lyzed by the XRD method. The results obtained are given lation, a mass of 50  g of pre-heated petroleum residue in Fig.  2. The XRD pattern of the clay (support) shows is injected into the reactor. The reactor temperature is various clay minerals. The presence of smectite and illite constantly checked by a probe thermometer (TYPE K/J) is indicated by the peaks located at 6° and 9° respectively. and maintained at 500 °C. The cracked products leave the The intense peaks at 12.5° and 25°are relative to kaolinite reactor by passing through a refrigerating condenser and and the peak appearing around 26.78° is characteristic of are recovered in the form of droplets in recipe flasks. The quartz. It can also be seen that the XRD pattern of clay cracking operation is stopped when there is no more drop- exhibited the crystalline features. The XRD patterns of let drop in the receiving bottle. the catalysts show the disappearance of all kaolinite peaks The yield (Eq. 1) was calculated from the ratio between the initially present in clay. Indeed, from 580 °C, kaolinite mass of the product obtained after cracking (mo) and the initial (Al O, 2SiO, 2H O) loses the hydroxyl OH function and 2 3 2 2 mass introduced into the reactor (mi). it is transformed into metakaolinite (Al O, 2SiO ). This is 2 3 2 confirmed by the XRD patterns of the catalysts that show x = ∗ 100 i (1) a characteristic appearance of an amorphous material. The presence of metakaolinite, a refractory material, in these catalysts is an advantage for their use as cracking catalysts. Moreover, the presence of La SiO is identified at 2 5 27.84° (2θ) [7] and 34.9° (2θ) on the Cat1 spectrum [29]. This oxide (La SiO ) results from the reaction between 2 5 lanthanum oxide and silica, as predicted by Sun [29], in the following reaction (Eq. 2): 1 3 150 Applied Petrochemical Research (2021) 11:147–154 Fig. 2 XRD pattern of clay (support) and catalysts FTIR spectroscopy La O + SiO → La SiO (2) 2 3 2 2 5 The characteristic phases of chromium oxide (Cr O ) The Fig. 3 shows the IR spectra of the clay (support) and 2 3 have been identified on this spectrum. They correspond to the two catalysts produced. The spectrum of the support the peaks at 54.14°; and 64.04° (2θ) according to Karimi is characteristic of a clay. It shows the deformation vibra- [17]. tion modes of structural hydroxyl groups between 950 and Fig. 3 IR spectra a support, b Cat1, c Cat2 1 3 Applied Petrochemical Research (2021) 11:147–154 151 −1 800  cm . The absorption bands observed at wavenumbers Hussain et al. [15] for the catalytic cracking of vacuum gas −1 −1 1034, 1100  cm and 1159  cm are characteristic of the oil. antisymmetric modes of elongation of Si–O and Al–O bonds in aluminosilicates [10]. A comparative analysis of Textural analysis the spectrum of the support and those of the catalysts shows a remarkable change in structure. The difference observed Specific surface could be related on the one hand to the new elements that were added in the preparation and on the other hand to the The specific surfaces of the catalysts produced were eval- calcination that the catalysts underwent. The absorption uated by the method of Brunauer, Emmet and Teller (B. −1 2 2 band at 500  cm is attributed to the vibration mode of the E. T). They are 456.14 m /g and 475.12 m /g for the Cat1 La–O bond of lanthanum oxide according to Saravani and and Cat2 respectively. The results obtained show that the Khajehali [28]. This peak confirms the presence of La O surfaces have increased considerably compared to the spe- 2 3 phase in the Cat1 sample. The bands observed around 581 cific surface of the clay support (15.26  m /g). This is due −1 and 647  cm are characteristic absorption bands of Cr O to the acid activation performed during formulation. This 2 3 on the Cat2 spectrum according to Nguyen et al. [22]. considerable increase is also observed in the literature [3, 13] and reflects a significant development of microporosity. Catalyst acidity The values obtained in this study are better than 347  m /g and 177  m /g, representing the surface areas calculated by The acidity of the catalysts measured by Boehm method He et al. [13] and Al-Khattaf [3] respectively. In addition, indicates higher values of acidity for the catalysts compared Ribeiro et al. [27] found specific surface areas of 266, 276 to that of the support. Initially equal to 14 meq/g for the and 422  m /g for commercial FCC catalysts which are also support, the acidity was evaluated at 50 meq/g for Cat 1 lower than those of the catalysts developed here. These and 57 meq/g for Cat2. This significant increase could be results once again show the good characteristics developed justified by the presence of oxides which were added dur - by the catalysts prepared in this work. ing processing. These acidity values are lightly superiors to those of the FCC zeolite catalysts (30–50 meq/g) used by Porosity Ibarra et al. [16]. This suggests that the catalysts developed here would be efficient in cracking test as industrial catalysts The porosity of the catalyst is a very important factor. It from the point of view of surface acidity. is established that the diffusion of molecules from the residue to be cracked is easy when the dimensions of Chemical analysis the pore are 2–6 times larger than those of the molecules [30]. The data (Table 2) show that the diameters and the The chemical analysis of catalysts are given in Table 1. The pore volumes increased considerably after the prepara- SiO /Al O ratio of the support was equal to 2.08, similar tion of the catalysts. The type of oxide used does not 2 2 3 to that obtained by Gueu et al. [11]. The SiO content in influence the pore diameter which remained similar for Cat1 and Cat2 catalysts are 59.1% and 61.9% respectively. This content was initially equal to 49% in the support. The Table 2 Pore diameters and volumes of prepared catalysts observed increase is due to the addition of silica during the preparation of the catalysts. According to Otmani [24], silica Catalysts Average pore diam- Pore volume (cm /g) give good mechanical strength to catalysts and increase their eter (nm) acidic character [18] for the catalytic cracking operation. Support 0.75 0.18 Furthermore, the SiO contents of the catalysts are higher Cat1 2.12 0.49 than that of the commercial FCC catalyst (54.1%) used by Cat2 2.15 0.24 Table 1 Chemical analysis of Chemical composition (%) catalysts SiO Al O Fe O MgO TiO CaO Na O K O P O La Cr LOI 2 2 3 2 3 2 2 2 2 5 Sup-port 49 23.5 4.1 2.19 1.35 1.76 0.45 0.93 0.3 – – 16.1 Cat1 59.1 19.1 3.31 1.44 1.18 0.5 1.21 0.63 0.25 2.5 0.01 7.5 Cat2 61.9 19.4 4.52 1.76 1.13 2.05 0.37 0.77 0.24 0.01 0.01 5.3 Loss on ignition 1 3 152 Applied Petrochemical Research (2021) 11:147–154 the two catalysts. The pore volume developed by Cat1 is SEM significantly greater than that of Cat2. The images obtained by scanning electron microscopy (SEM) and X-ray microanalysis of the catalysts are pre- sented in Figs. 4 and 5. Fig. 4 SEM image and X-ray microanalysis of Cat1 Fig. 5 SEM image and X-ray microanalysis of Cat2 1 3 Applied Petrochemical Research (2021) 11:147–154 153 Figures 4 and 5 show that the catalysts mostly consist development of semi-synthetic catalysts would be particu- of very fine particle clusters. These images show a certain larly interesting to the refining industry. homogeneity in the composition of the samples. However, the Fig.  4 shows clusters in the form of aggregates. This Open Access This article is licensed under a Creative Commons Attri- particularity could be justified by an incomplete grinding bution 4.0 International License, which permits use, sharing, adapta- of the Cat1 sample during its SEM preparation. In addition, tion, distribution and reproduction in any medium or format, as long grains of quartz (SiO ) are also observed on these images. as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes This confirms the above analyses. were made. The images or other third party material in this article are The results of the X-ray microanalysis of the catalysts included in the article’s Creative Commons licence, unless indicated indicate the presence of several elements such as silicon (Si) otherwise in a credit line to the material. If material is not included in which is the most abundant element in all samples. It’s to the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will be note the appearance of lanthanum (La) in Fig. 4 and the need to obtain permission directly from the copyright holder. To view a appearance of the element chromium (Cr) in Fig.  5. The copy of this licence, visit http://creativ ecommons .or g/licenses/b y/4.0/. presence of these elements (La and Cr) confirms the incor - poration of the oxides. Catalytic cracking yield References 1. Abdoulaye ODM, Yao BK, Ahmed AM, Adouby K, Abro DMK, The catalysts developed here were used in the cracking of a Drogui P (2019) Mineralogical and morphological characteriza- petroleum residue. The cracking tests take place at 500 °C tion of a clay from Niger with a ratio fuel/catalyst (g/g) equal to 4.5. The results 2. Akah A (2017) Application of rare earths in fluid catalytic crack - recorded show a conversion rate of 74.13 and 66.53% for ing: a review. J Rare Earths 35:941–956 3. Al-Khattaf S (2003) The influence of alumina on the performance the Cat1 and Cat2 respectively. The acidity of the catalysts of FCC catalysts during hydrotreated VGO catalytic cracking. is very often considered to be the most important parameter. Energy Fuels 17:62–68 The greater the activity, the greater the catalytic efficiency. 4. Avidan AA (1993) Origin development and scope of FCC cataly- This assertion is not verified in this study. Indeed, despite its sis in: studies in surface science and catalysis. Elsevier 5. Boehm HP (1966) Chemical identification of surface groups in: low acidity, Cat1 has the best yield. This would be attribute advances in catalysis. Elsevier to its specific surface area and its pore volume which are 6. Bouras O (2003) Propriétés adsorbantes d’argiles pontées organo- high than those measured for Cat2. philes: synthèse et caractérisation (PhD Thesis). Limoges 7. Djoudi L (2016) Synthese et propriétés d’oxydes mixtes a base de lanthane, aluminium et Nickel (PhD Thesis). Université Mohamed Khider-Biskra Conclusion 8. Emam EA (2013) Clays as catalysts in petroleum refining industry. ARPN J Sci Technol 3:356–375 9. Feng R, Qiao K, Wang Y, Yan Z (2013) Perspective on FCC The objective of this work was to develop clay-based cata- catalyst in China. Appl Petrochem Res 3:63–70. https ://doi. lysts to crack a heavy oil residue. XRD and infrared ana- org/10.1007/s1320 3-013-0030-1 lyzes of the prepared catalysts confirmed the presence of 10. Goodman BA, Russell JD, Fraser AR, Woodhams FWD (1976) A Mössbauer and IR spectroscopic study of the structure of non- lanthanum oxide and chromium oxide. This indicates that tronite. Clays Clay Miner 24:53–59 the oxides have been well incorporated showing at the same 11. Gueu S, Finqueneisel G, Zimny T, Bartier D, Yao BK (2019) time that the method of preparation is suitable. Textural Physicochemical characterization of three natural clays used analysis showed that the incorporation of oxide, acid acti- as adsorbent for the humic acid removal from aqueous solu- tion. Adsorpt Sci Technol 37:77–94. https ://doi.or g/10.1180/ vation and calcination carried out during processing strongly clm.2020.26 influenced the composition and textural properties of the 12. Gueu S, Yao B, Adouby K, Ado G (2006) Heavy metals removal catalysts. The specific surfaces increase from 15.26 m /g for in aqueous solution by activated carbons prepared from coconut the support to 456.14 and 475.12  m /g for the Cat1 and Cat2 shell and seed shell of the palm tree. JApSc 6:2789–2793. https:// doi.org/10.3923/jas.2006.2789.2793 respectively. Pore volumes also increased from 0.18  cm /g 13. He L-J, Zheng S-Q, Dai Y-L (2017) Povećanje iskorištenja ben- 3 3 for the support to 0.49 cm /g and 0.24  cm /g for Cat1 and zina katalizatorom za krekiranje u fluidiziranom sloju (FCC). Cat2 respectively. Compared to the support, the acidities Kemija industriji 66:9–15 of the two catalysts are very higher. This was related to the 14. Houdry EJ (1953). Process for catalytically cracking hydrocarbons 15. Hussain AI, Aitani AM, Kub\uuČejkaAl-Khattaf MJS (2016) addition of silica and acidic activation made during catalysts Catalytic cracking of Arabian light VGO over novel zeolites as preparation. Finally, the catalytic cracking results indicated FCC catalyst additives for maximizing propylene yield. Fuel a conversion rate of 74.13 and 66.53% for Cat1 and Cat2 167:226–239 respectively. From this study, the use of this clay for the 1 3 154 Applied Petrochemical Research (2021) 11:147–154 16. Ibarra Á, Hita I, Azkoiti MJ, Arandes JM, Bilbao J (2019) Cata- using metallic composites. Appl Petrochem Res. https ://doi. lytic cracking of raw bio-oil under FCC unit conditions over dif-org/10.1007/s1320 3-021-00263 -1 ferent zeolite-based catalysts. J Ind Eng Chem 78:372–382. https 24. Otmani S (2006) Valorisation des charges lourdes compoundées ://doi.org/10.1016/j.jiec.2019.05.032 par le craquage catalytique (PhD Thesis) 17. Karimi N (2007) Etude par diffraction des rayons X in situ des 25. Pouwels C, Bruno K (2013) FCC catalyst design evolves to maxi- mécanismes d’oxydation de l’acier AISI 304 entre 800  °C et mize propylene. Hydrocarbon Process 1000 °C. Influence des dépôts sol-gel de lanthane et de cérium. 26. Qureshi MS, Nisar S, Shah R, Salman H (2020) Studies of liquid Apport de la spectroscopie infrarouge à l’identification des oxydes fuel formation from plastic waste by catalytic cracking over modi- mixtes (PhD Thesis) fied natural clay and nickel nanoparticles 10. Pakistan J Sci Ind 18. Leprince P (1998) Le raffinage du pétrole: procédés de transforma- Res 63(2):79 tion. Technip, Paris, p 550 27. Ribeiro AM, Machado Júnior HF, Costa DA (2013) Kaolin and 19. Liu Z, Zhang Z, Yang C, Gao X (2015) Domestic technology commercial fcc catalysts in the cracking of loads of polypropylene developments on high-efficiency heavy oil conversion FCC cata- under refinary conditions. Braz J Chem Eng 30:825–834 lysts’ industrialization. Appl Petrochem Res 5:269–275. https :// 28. Saravani H, Khajehali M (2016) Synthesis and characterization doi.org/10.1007/s1320 3-015-0133-y of lanthanum oxide and lanthanumoxid carbonate nanoparticles 20. Mamudu A, Emetere M, Okocha D, Taiwo S, Ishola F, Elehinafe from thermalizes of [La(acacen)(NO )(H O) complex. Orient J 3 2 F, Okoro E (2020) Parametric investigation of indigenous Nigeria Chem 32:491–498. https ://doi.org/10.13005 /ojc/32015 6 mineral clay (Kaolin and Bentonite) as a filler in the Fluid Cata- 29. Sun F (2010) Caractérisation de revêtements de silicate de lan- lytic Cracking Unit (FCCU) of a petroleum refinery. Alexandria thane de structure apatite dopé au magnésium réalisés par pro- Eng J 59:5207–5217. https ://doi.org/10.1016/j.aej.2020.09.050 jection plasma en vue d’application comme électrolyte de pile à 21. Murray HH (2006) Applied clay mineralogy: occurrences, pro- combustible de type IT-SOFC (PhD Thesis) cessing and applications of kaolins, bentonites, palygorskitesepio- 30. Zhang Z, Liu Z, Feng R, Liu P, Yan Z (2014) The development lite, and common clays. Elsevier of FCC catalysts for producing FCC gasoline with high octane 22. Nguyen TP, Jonnard P, Vergand F, Staub PF, Thirion J, Lap- numbers. Appl Petrochem Res 4:379–383 kowskiTran MVH (1995) Characterization of the poly (para- phenylene vinylene)-chromium interface by attenuated total Publisher’s Note Springer Nature remains neutral with regard to reflection infrared and X-ray emission spectroscopies. Synth Met jurisdictional claims in published maps and institutional affiliations. 75:175–179 23. Olaremu AG, Adedoyin WR, Ore OT, Adeola AO (2021) Sus- tainable development and enhancement of cracking processes 1 3 http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Petrochemical Research Springer Journals

Development of semi-synthetic catalyst based on clay and their use in catalytic cracking of petroleum residue

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10.1007/s13203-021-00268-w
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Abstract

Two semi-synthetic clay-based catalysts were prepared. These catalysts were obtained by incorporating lanthanum oxide (Cat1) and chromium oxide (Cat2). They were then tested for catalytic cracking of a heavy petroleum residue (fuel). The two formulations were carried out in the presence of silica to improve their acidity then underwent an acid activation. The catalysts obtained were characterized by various methods (XRD, FTIR, ICP-OES, SEM). The results showed that the incorporation of oxides and the addition of silica improves the structural characteristics of the final products. The support used was a kao- linite rich clay, having a specific surface area of 15.26  m /g and acidity of 14 meq/g. These values increase, respectively, to 2 2 456.14  m /g and 50 meq/g for Cat1 and to 475.12  m /g and 57 meq/g for Cat2. The influence of the type of oxide incorpo- rated, the specific surface area, the porosity and the acidity of the catalysts on their catalytic activity was studied. The nature of the oxide used proved to be decisive on the quality of the catalyst. Thus Cat1, prepared with lanthanum oxide, showed the best performance in cracking the petroleum residue achieving a conversion rate of 74.13% compared to 66.53% for cat2. Keywords Petroleum residue · Clay · Catalyst · Catalytic cracking Introduction be innovate to achieve performance [2, 25]. Therefore, new catalyst development need to be investigated to improve the Due to its impact on the environment, the use of heavy oil yield of FCC processes. residue (fuel) is strongly discouraged by government offi- A catalyst is a substance that increases the rate of a chem- cials. Thus, the demand of fuel will suffer a sharp drop in ical reaction, without being consumed or produced [8]. The coming years in favor of gasoline, diesel and other petro- activity and selectivity of the FCC catalyst are derived from leum products, which are lighter. To remain competitive the acidic sites and the pore structure, respectively. Catalytic and give added value to heavy oil residues, the refineries catalysts are therefore porous solids with acidic properties are stepping up their research to improve the fluid catalytic [4, 18, 23]. Commercial FCC catalysts generally consist of cracking (FCC) process [9, 19]. The FCC process consist to two main components: the zeolite and the matrix. The zeo- convert heavy oil feeds into light products. Although this lites used in FCC catalysts are mainly synthetic faujasite Y process has been used in refineries for decades, it needs to type zeolites and high silica Y zeolites, which are the main contributor to the catalytic activity and selectivity of the FCC catalyst [13]. The matrix is made of different constitu- * Soumahoro Gueu ents such as aluminosilicates and additives which are solid Soumahoro.gueu@inphb.ci compounds added to improve its properties [4, 9]. Neverthe- less, the high cost of these commercial catalysts could be a Laboratoire des Procédés Industriels, de Synthèse, de barrier to their use in development countries. It is urgent to L’Environnement et des Energies Nouvelles (LAPISEN), Institut National Polytechnique Félix Houphouët-Boigny, develop a novel FCC catalyst with local resource [20, 26]. Yamoussoukro BP 1093 Yamoussoukro, Côte d’Ivoire Recent research is directed towards the development Département Energies Fossiles, Université D’Agadez, of semi-synthetic clay-based catalysts. In this configura- BP 199 Agadez, Niger tion, the clay acts as a matrix in which metallic oxides Département de Chimie, Faculté Des Sciences Et are incorporated. Emam [8] has shown that clay catalysts Techniques, Université Abdou Moumouni de Niamey, are arousing much interest for catalytic application in the BP 10662 Niamey, Niger Vol.:(0123456789) 1 3 148 Applied Petrochemical Research (2021) 11:147–154 petroleum refining industry. According to Bouras [6 ], the Catalyst characterization interest given in recent years to the study of clays by labo- ratories around the world is explained by their abundance X-ray diffraction (XRD) patterns of all samples were in nature, the importance of their specific surface, their recorded at room temperature, using a Rigaku-Miniflex II porosity and especially their ability to exchange interfoliar diffractometer (Japan). The incident radiation is generated cations. Kaolin and montmorillonite are the most com- by the Kα line of copper (λ = 1.5406 Å) at 30 kV and 15 mA. monly used clays in the development of refining catalysts The analyzes were carried out in the angular interval [5–70°] [20]. Murray [21] estimates that more than 200,000 tonnes in 2θ with a step of 0.02° (2θ) and a counting time of 2 s. of kaolin are used annually to produce petroleum crack- The infrared spectroscopic analyzes were carried out in ing catalysts. This work deals with the development of ATR (Attenuated Total Reflectance) mode with a Fourier new semi-synthetic catalysts based on clay and oxides, Bruker Alpha Transform spectrometer equipped with a the characterization of these catalysts obtained and finally diamond crystal (refractive index of the diamond 2.451). their use in fuel cracking. To our knowledge, in the lit- The spectra were acquired with a nominal resolution of −1 −1 erature, it has not been reported cracking of fuel oil by 4  cm over a wavenumber range from 400 to 4000  cm . semi-synthetic catalysts or even by conventional catalytic Chemical analysis of the samples was performed using catalysts. This study therefore aims to fill this void. a Vista Pro Varian instrument equipped with an ICP-OES The objective of the current work was to prepare a FCC (Inductively Coupled Plasma-Optical Emission Spectros- catalyst, and to study the catalytic properties. Two cata- copy) plasma. lysts were prepared using a kaolinite rich clay as matrix. The BET isotherms were obtained using a Nova Station The influence of the type of oxide incorporated, the spe - B sorptiometer. The absorption gas used is nitrogen and cific surface area, the porosity and the acidity of the cata- the measurements are carried out at 77.350 K. The deter- lysts on their catalytic activity was studied. mination of the microporous volumes and the microporous surfaces are carried out by the t-plot method. A variable pressure scanning electron microscope (SEM) from the D.C.A.R. (SEM FEG Supra 40 VP Zeiss) Materials and methods of 2  nm resolution coupled to an X-ray microanalyzer (EDS) was used for the characterization of the microstruc- Materials ture and the surface chemical composition of the catalysts. The total acidity of the catalysts was determined using The catalysts prepared in this study were made from Niger the titration method of Boehm [5] which is used by many clay. This clay has been characterized in previous work researchers working on adsorbents [12]. This method con- [1]. It has a specific surface area of 15.26  m /g and a loss sists of assaying functional groups having various acidities on ignition of 16.1%. It is mainly composed of kaolin- with different bases. For the present study, the bases used ite (46.3%) and an interstratified smectite illite chlorite are sodium hydroxide (NaOH), sodium hydrogen carbonate (53.7%) [1]. The choice of this clay is explained because (NaHCO ) and sodium ethanolate (C H ONa). The proce- 3 2 5 the catalytic reactions taking place at high temperature dure is as follows: a mass of 500 mg of catalyst is placed in (≥ 500 °C), the catalyst must be a refractory material, able Erlenmeyer flasks. Then 25 mL of the different bases, all to withstand such temperature. prepared at 0.1 N, are transferred into each of the Erlen- meyer flasks containing the catalysts. The blank tests are carried out by proceeding in the same manner, with the dif- Catalyst preparation ference that Erlenmeyer flasks do not contain a catalyst. The samples and the blanks are stirred on magnetic stirrers at In a beaker containing 15 g of clay with a particle size 150 rpm for 72 hours at room temperature, then left to stand less than 2  µm, 0.55  g of lanthanum (La O ) or chro- for 6 hours. The supernatant is filtered through a Whatman 2 3 mium (Cr O ) oxide and 4  g of silica are added. After cellulose nitrate membrane (0.2 μm) then the excess basic 2 3 homogenization, acid activation is carried out by adding solution is dosed back with a 0.1 N HCl solution. 25 mL of 10% hydrochloric acid and then the whole is left under stirring for 6 hours. The resulting mixture is dried at 105 °C for 12 hours and then calcined at 800 °C for Catalytic cracking test thirty minutes. The catalyst containing lanthanum oxide is called Cat1 and the one obtained with chromium oxide The performance tests of the catalysts were carried out is called Cat2. in a stainless steel reactor (Fig. 1), manufactured in the 1 3 Applied Petrochemical Research (2021) 11:147–154 149 Fig. 1 Model of the cracking plant laboratory (LAPISEN). The methodology used here has Results and discussion been adapted to that of Houdry [14]. To carry out the cracking operation, a mass of 20 g of catalyst is placed XRD in a reactor. Then, the reactor is inserted into an electric furnace and the temperature is raised in steps of 100 °C The two catalysts developed (Cat1 and Cat2) were ana- until reaching 500 °C. After checking the seal of the instal- lyzed by the XRD method. The results obtained are given lation, a mass of 50  g of pre-heated petroleum residue in Fig.  2. The XRD pattern of the clay (support) shows is injected into the reactor. The reactor temperature is various clay minerals. The presence of smectite and illite constantly checked by a probe thermometer (TYPE K/J) is indicated by the peaks located at 6° and 9° respectively. and maintained at 500 °C. The cracked products leave the The intense peaks at 12.5° and 25°are relative to kaolinite reactor by passing through a refrigerating condenser and and the peak appearing around 26.78° is characteristic of are recovered in the form of droplets in recipe flasks. The quartz. It can also be seen that the XRD pattern of clay cracking operation is stopped when there is no more drop- exhibited the crystalline features. The XRD patterns of let drop in the receiving bottle. the catalysts show the disappearance of all kaolinite peaks The yield (Eq. 1) was calculated from the ratio between the initially present in clay. Indeed, from 580 °C, kaolinite mass of the product obtained after cracking (mo) and the initial (Al O, 2SiO, 2H O) loses the hydroxyl OH function and 2 3 2 2 mass introduced into the reactor (mi). it is transformed into metakaolinite (Al O, 2SiO ). This is 2 3 2 confirmed by the XRD patterns of the catalysts that show x = ∗ 100 i (1) a characteristic appearance of an amorphous material. The presence of metakaolinite, a refractory material, in these catalysts is an advantage for their use as cracking catalysts. Moreover, the presence of La SiO is identified at 2 5 27.84° (2θ) [7] and 34.9° (2θ) on the Cat1 spectrum [29]. This oxide (La SiO ) results from the reaction between 2 5 lanthanum oxide and silica, as predicted by Sun [29], in the following reaction (Eq. 2): 1 3 150 Applied Petrochemical Research (2021) 11:147–154 Fig. 2 XRD pattern of clay (support) and catalysts FTIR spectroscopy La O + SiO → La SiO (2) 2 3 2 2 5 The characteristic phases of chromium oxide (Cr O ) The Fig. 3 shows the IR spectra of the clay (support) and 2 3 have been identified on this spectrum. They correspond to the two catalysts produced. The spectrum of the support the peaks at 54.14°; and 64.04° (2θ) according to Karimi is characteristic of a clay. It shows the deformation vibra- [17]. tion modes of structural hydroxyl groups between 950 and Fig. 3 IR spectra a support, b Cat1, c Cat2 1 3 Applied Petrochemical Research (2021) 11:147–154 151 −1 800  cm . The absorption bands observed at wavenumbers Hussain et al. [15] for the catalytic cracking of vacuum gas −1 −1 1034, 1100  cm and 1159  cm are characteristic of the oil. antisymmetric modes of elongation of Si–O and Al–O bonds in aluminosilicates [10]. A comparative analysis of Textural analysis the spectrum of the support and those of the catalysts shows a remarkable change in structure. The difference observed Specific surface could be related on the one hand to the new elements that were added in the preparation and on the other hand to the The specific surfaces of the catalysts produced were eval- calcination that the catalysts underwent. The absorption uated by the method of Brunauer, Emmet and Teller (B. −1 2 2 band at 500  cm is attributed to the vibration mode of the E. T). They are 456.14 m /g and 475.12 m /g for the Cat1 La–O bond of lanthanum oxide according to Saravani and and Cat2 respectively. The results obtained show that the Khajehali [28]. This peak confirms the presence of La O surfaces have increased considerably compared to the spe- 2 3 phase in the Cat1 sample. The bands observed around 581 cific surface of the clay support (15.26  m /g). This is due −1 and 647  cm are characteristic absorption bands of Cr O to the acid activation performed during formulation. This 2 3 on the Cat2 spectrum according to Nguyen et al. [22]. considerable increase is also observed in the literature [3, 13] and reflects a significant development of microporosity. Catalyst acidity The values obtained in this study are better than 347  m /g and 177  m /g, representing the surface areas calculated by The acidity of the catalysts measured by Boehm method He et al. [13] and Al-Khattaf [3] respectively. In addition, indicates higher values of acidity for the catalysts compared Ribeiro et al. [27] found specific surface areas of 266, 276 to that of the support. Initially equal to 14 meq/g for the and 422  m /g for commercial FCC catalysts which are also support, the acidity was evaluated at 50 meq/g for Cat 1 lower than those of the catalysts developed here. These and 57 meq/g for Cat2. This significant increase could be results once again show the good characteristics developed justified by the presence of oxides which were added dur - by the catalysts prepared in this work. ing processing. These acidity values are lightly superiors to those of the FCC zeolite catalysts (30–50 meq/g) used by Porosity Ibarra et al. [16]. This suggests that the catalysts developed here would be efficient in cracking test as industrial catalysts The porosity of the catalyst is a very important factor. It from the point of view of surface acidity. is established that the diffusion of molecules from the residue to be cracked is easy when the dimensions of Chemical analysis the pore are 2–6 times larger than those of the molecules [30]. The data (Table 2) show that the diameters and the The chemical analysis of catalysts are given in Table 1. The pore volumes increased considerably after the prepara- SiO /Al O ratio of the support was equal to 2.08, similar tion of the catalysts. The type of oxide used does not 2 2 3 to that obtained by Gueu et al. [11]. The SiO content in influence the pore diameter which remained similar for Cat1 and Cat2 catalysts are 59.1% and 61.9% respectively. This content was initially equal to 49% in the support. The Table 2 Pore diameters and volumes of prepared catalysts observed increase is due to the addition of silica during the preparation of the catalysts. According to Otmani [24], silica Catalysts Average pore diam- Pore volume (cm /g) give good mechanical strength to catalysts and increase their eter (nm) acidic character [18] for the catalytic cracking operation. Support 0.75 0.18 Furthermore, the SiO contents of the catalysts are higher Cat1 2.12 0.49 than that of the commercial FCC catalyst (54.1%) used by Cat2 2.15 0.24 Table 1 Chemical analysis of Chemical composition (%) catalysts SiO Al O Fe O MgO TiO CaO Na O K O P O La Cr LOI 2 2 3 2 3 2 2 2 2 5 Sup-port 49 23.5 4.1 2.19 1.35 1.76 0.45 0.93 0.3 – – 16.1 Cat1 59.1 19.1 3.31 1.44 1.18 0.5 1.21 0.63 0.25 2.5 0.01 7.5 Cat2 61.9 19.4 4.52 1.76 1.13 2.05 0.37 0.77 0.24 0.01 0.01 5.3 Loss on ignition 1 3 152 Applied Petrochemical Research (2021) 11:147–154 the two catalysts. The pore volume developed by Cat1 is SEM significantly greater than that of Cat2. The images obtained by scanning electron microscopy (SEM) and X-ray microanalysis of the catalysts are pre- sented in Figs. 4 and 5. Fig. 4 SEM image and X-ray microanalysis of Cat1 Fig. 5 SEM image and X-ray microanalysis of Cat2 1 3 Applied Petrochemical Research (2021) 11:147–154 153 Figures 4 and 5 show that the catalysts mostly consist development of semi-synthetic catalysts would be particu- of very fine particle clusters. These images show a certain larly interesting to the refining industry. homogeneity in the composition of the samples. However, the Fig.  4 shows clusters in the form of aggregates. This Open Access This article is licensed under a Creative Commons Attri- particularity could be justified by an incomplete grinding bution 4.0 International License, which permits use, sharing, adapta- of the Cat1 sample during its SEM preparation. In addition, tion, distribution and reproduction in any medium or format, as long grains of quartz (SiO ) are also observed on these images. as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes This confirms the above analyses. were made. The images or other third party material in this article are The results of the X-ray microanalysis of the catalysts included in the article’s Creative Commons licence, unless indicated indicate the presence of several elements such as silicon (Si) otherwise in a credit line to the material. If material is not included in which is the most abundant element in all samples. It’s to the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will be note the appearance of lanthanum (La) in Fig. 4 and the need to obtain permission directly from the copyright holder. To view a appearance of the element chromium (Cr) in Fig.  5. The copy of this licence, visit http://creativ ecommons .or g/licenses/b y/4.0/. presence of these elements (La and Cr) confirms the incor - poration of the oxides. Catalytic cracking yield References 1. Abdoulaye ODM, Yao BK, Ahmed AM, Adouby K, Abro DMK, The catalysts developed here were used in the cracking of a Drogui P (2019) Mineralogical and morphological characteriza- petroleum residue. The cracking tests take place at 500 °C tion of a clay from Niger with a ratio fuel/catalyst (g/g) equal to 4.5. The results 2. Akah A (2017) Application of rare earths in fluid catalytic crack - recorded show a conversion rate of 74.13 and 66.53% for ing: a review. J Rare Earths 35:941–956 3. Al-Khattaf S (2003) The influence of alumina on the performance the Cat1 and Cat2 respectively. 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Journal

Applied Petrochemical ResearchSpringer Journals

Published: Mar 9, 2021

Keywords: Petroleum residue; Clay; Catalyst; Catalytic cracking

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