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John Adjaye - One of the best experts on this subject based on the ideXlab platform.
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Selective removal of nitrogen compounds from Gas Oil using functionalized polymeric adsorbents: Efficient approach towards improving denitrogenation of petroleum feedstock
Chemical Engineering Journal, 2016Co-Authors: Prachee Misra, Ajay K. Dalai, Jackson M. Chitanda, John AdjayeAbstract:Abstract A major challenge in achieving deep hydrodesulfurization with the conventional hydrotreating technology is the inhibition and deactivation of the catalyst caused by heterocyclic nitrogen compounds. In this research, novel polymeric adsorbents were introduced for the selective removal of nitrogen compounds from bitumen-derived Light Gas Oil. Synthesis of polymers with high internal phase emulsion (polyHIPEs) was carried out using a monomeric mixture of unsaturated polyester resin, glycidyl methacrylate and divinylbenzene. To facilitate the selective removal of nitrogen compounds, reactive epoxy groups present in glycidyl methacrylate were used to functionalize the polyHIPEs with a fluorenone based π-acceptor, 2,4,5,7-tetranitro-9-fluorenone (TENF). Successful application of the synthesized polymers was found in the batch adsorption experiments at ambient temperature. Functionalized polyHIPEs were capable of selectively adsorbing nitrogen species from Light Gas Oil. The optimum ratio of monomers was found to be one of the key factors in determining the polymer performance. Particles with high glycidyl methacrylate content with toluene as the porogenic solvent were capable of removing 14.6% of nitrogen compounds. Reusability studies were performed successfully by regenerating the used polymers with toluene; which aids the separation of complexing agent and the adsorbed nitrogen species.
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Hydrotreating of Light Gas Oil using a NiMo catalyst supported on activated carbon produced from fluid petroleum coke
Frontiers of Chemical Science and Engineering, 2014Co-Authors: N Rambabu, Kapil K Soni, Sandeep Badoga, Ajay Kumar Dalai, John AdjayeAbstract:Nitric acid functionalized steam activated carbon (NAFSAC) was prepared from waste fluid petroleum coke (FPC) and used as a support material for the synthesis of a NiMo catalyst (2.5 wt-% Ni and 13 wt-% Mo). The catalyst was then used for the hydrotreatment of Light Gas Oil. The support and catalysts were characterized by Brunauer-Emmett-Teller (BET) Gas adsorption method, X-ray diffraction, H_2-temperature programmed reduction, NH3-temperature programmed desorption, CO-chemisorption, mass spetrography, scanning electron microscopy (SEM), Boehm titration, and Fourier transform infrared spectroscopy (FTIR). The SEM results showed that the carbon material retained a needle like structure after functionalization with HNO_3. The Boehm titration, FTIR, and BET results confirmed that the HNO_3 functionalized material had moderate acidity, surface functional groups, and mesoporosity respectively. The produced NAFSAC had an inert nature, exhibited the sink effect and few metal support interactions, and contained functional groups. All of which make it a suitable support material for the preparation of a NiMo hydrotreating catalyst. Hydrotreating activity studies of the NiMo/NAFSAC catalyst were carried out under industrial operating conditions in a laboratory trickle bed reactor using coker Light Gas Oil as the feedstock. A parallel study was performed on the hydrotreating activity of NiMo/ γ -Al_2O_3 as a reference catalyst. The hydrodesulfurization and hydrodenitrogenation activities of the NiMo/NAFSAC catalyst were 62% and 30%, respectively.
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Hydrotreating of coker Light Gas Oil on SBA-15 supported nickel phosphide catalysts
Catalysis Today, 2013Co-Authors: Kapil Soni, Philip E. Boahene, N Rambabu, Ajay K. Dalai, John AdjayeAbstract:Abstract SBA-15-supported nickel phosphides with a Ni/P atomic ratio of 2 and 0.5 were prepared by temperature programmed reduction method (TPR). The phase purity and structural/surface properties were studied by X-ray diffraction and N2 sorption measurements respectively. X-ray diffraction (XRD) analysis of the passivated catalysts confirmed the presence of Ni12P5 and Ni2P phases in catalysts prepared from oxidic precursors. Supports and catalysts were thoroughly characterized using other techniques such as SEM, EDAX, and TEM. Results from low angle XRD measurements confirmed the presence of hexagonally ordered mesoporous structure in SBA-15 material. Hydrotreating experiments were conducted under industrial conditions using coker Light Gas Oil (CLGO) as feed which contains 2439 ppm nitrogen 23,420 ppm sulfur respectively. The activity results show that SBA-15 supported NixPy catalysts show higher catalytic activities compared to reference NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts under similar reaction conditions. This higher catalytic activity of NixPy/SBA-15 is due to the structure and surface chemical properties of this phase which is resistant to sulfur poisoning. It was also found that the Ni/P ratio had a profound effect on the active structure and hydroprocessing behavior of the NixPy/SBA-15 catalysts. The HDS and HDN conversions was found in the following order NixPy/SBA-15 (0.5) > NixPy/SBA-15 (2.0) > NiMo/SBA-15 > NiMo/γ-Al2O3. The NixPy/SBA-15 (0.5) catalyst showed higher HDS and HDN activities compared with NixPy/SBA-15 (2.0) catalyst which has lower P content. The higher amount of P content in NixPy/SBA-15 (0.5) catalyst modifies the nature of the nickel in that catalyst and increased the amount of octahedral nickel species and causes higher hydrotreating activity.
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beneficial influence of edta on the structure and catalytic properties of sulfided nimo sba 15 catalysts for hydrotreating of Light Gas Oil
Applied Catalysis B-environmental, 2012Co-Authors: Sandeep Badoga, Kapil Soni, Ajay K. Dalai, Chandra K Mouli, John AdjayeAbstract:Abstract SBA-15 supported NiMo hydrotreating catalysts with different EDTA/Ni molar ratio were prepared by incipient wetness impregnation method. Hydrotreating activities of these catalysts were studied with Athabasca bitumen derived Light Gas Oil and comparison was done with NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts. A beneficial effect of chelating ligand was seen in hydrotreating activity and 28% increase in HDS of LGO was found as compared to NiMo/γ-Al2O3 in the case of EDTA/Ni molar ratio 4. Detailed mechanistic aspect of interaction between support – EDTA (ethylene diamine tetraacetic acid), EDTA-metallic species, support – metal, metallic species – metallic species at different reaction conditions is studied at different process parameters by using different characterization techniques such as X-ray absorption near-edge structure (XANES), Fourier transform infrared spectroscopy (FTIR), HRTEM, XRD, Raman, temperature programmed reduction (TPR), ICP-MS, CO chemisorption and N2 adsorption. A detailed scheme has been developed to explain the behavior of chelating agent in mesoporous SBA-15 supported catalysts. HRTEM results explain the high dispersion of Ni and MoS2 active phases in sulfided state even though big crystallite of MoO3 was seen in oxide state characterized by XRD and Raman spectra which explains role of EDTA in redistribution of active phases during sulfidation. XANES technique is used as predominant method for atomic level study of various structural changes in sulfided and oxide catalysts to find out the appropriate mechanism of the reaction. Characterization by XANES reveals that the presence of chelating agent delayed Ni2+ sulfidation which is main cause of improvement in HDS and HDN activity of the catalysts prepared in presence of organic chelates. Nickel sulfidation starts only when the EDTA–Ni complex decomposes and released nickel atoms move to the reactive edges of the MoS2 to form a finely dispersed sulfide Ni Mo S type II active phase.
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Beneficial influence of EDTA on the structure and catalytic properties of sulfided NiMo/SBA-15 catalysts for hydrotreating of Light Gas Oil
Applied Catalysis B: Environmental, 2012Co-Authors: Sandeep Badoga, Kapil Soni, Ajay K. Dalai, K. Chandra Mouli, John AdjayeAbstract:Abstract SBA-15 supported NiMo hydrotreating catalysts with different EDTA/Ni molar ratio were prepared by incipient wetness impregnation method. Hydrotreating activities of these catalysts were studied with Athabasca bitumen derived Light Gas Oil and comparison was done with NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts. A beneficial effect of chelating ligand was seen in hydrotreating activity and 28% increase in HDS of LGO was found as compared to NiMo/γ-Al2O3 in the case of EDTA/Ni molar ratio 4. Detailed mechanistic aspect of interaction between support – EDTA (ethylene diamine tetraacetic acid), EDTA-metallic species, support – metal, metallic species – metallic species at different reaction conditions is studied at different process parameters by using different characterization techniques such as X-ray absorption near-edge structure (XANES), Fourier transform infrared spectroscopy (FTIR), HRTEM, XRD, Raman, temperature programmed reduction (TPR), ICP-MS, CO chemisorption and N2 adsorption. A detailed scheme has been developed to explain the behavior of chelating agent in mesoporous SBA-15 supported catalysts. HRTEM results explain the high dispersion of Ni and MoS2 active phases in sulfided state even though big crystallite of MoO3 was seen in oxide state characterized by XRD and Raman spectra which explains role of EDTA in redistribution of active phases during sulfidation. XANES technique is used as predominant method for atomic level study of various structural changes in sulfided and oxide catalysts to find out the appropriate mechanism of the reaction. Characterization by XANES reveals that the presence of chelating agent delayed Ni2+ sulfidation which is main cause of improvement in HDS and HDN activity of the catalysts prepared in presence of organic chelates. Nickel sulfidation starts only when the EDTA–Ni complex decomposes and released nickel atoms move to the reactive edges of the MoS2 to form a finely dispersed sulfide Ni Mo S type II active phase.
Ajay K. Dalai - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Gasification of Light and heavy Gas Oils in supercritical water
Journal of the Energy Institute, 2020Co-Authors: Rachita Rana, Ajay K. Dalai, Sonil Nanda, Sivamohan N. Reddy, Janusz A. Kozinski, Iskender GökalpAbstract:Abstract Canada has the third-largest Oil sand reserves in the world as a result of which, it generates considerable amounts of Light Gas Oil and heavy Gas Oil through petroleum distillation. With the escalating energy demands, it has become essential to explore alternative fuel resources from biomass and petrochemical residues. This study explores the potential of supercritical water Gasification to transform Light and heavy Gas Oils to hydrogen-rich synGas through the optimization of process conditions such as temperature (375–675 °C), feed concentration (20–35 wt%) and reaction time (30–75 min). Nickel-supported functionalized carbon nanotubes (10%Ni/FCNT) were synthesized for application in catalytic supercritical water Gasification. The functionalization of carbon nanotubes resulted in an increase in their surface area from 108 m2/g (in pristine CNT) to 127 m2/g (in FCNT) and 122 m2/g (in 10%Ni/FCNT). The impregnation of catalytic nickel particles onto carbon nanotubes was confirmed through X-ray diffraction (XDR) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). Fourier-transform infrared (FTIR) spectroscopy of both Gas Oils revealed the presence of aliphatics, alkyl-aryl ethers and sulfur-containing compounds among several other aromatics. Light Gas Oil revealed higher hydrogen yields of 3.32 mol/kg compared to that of heavy Gas Oil (2.79 mol/kg) at optimal process conditions, i.e. 675 °C and 75 min, 20 wt% feed concentration. However, 10%Ni/FCNT enhanced hydrogen yields (4.46 mol/kg), total Gas yield (9.22 mol/kg), hydrogen selectivity (94%) and lower heating value (1685 MJ/kg) of product Gases obtained from Light Gas Oil in contrast to heavy Gas Oil. This study indicates a tremendous potential of Gas Oils for hydrogen generation via hydrothermal Gasification.
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Selective removal of nitrogen compounds from Gas Oil using functionalized polymeric adsorbents: Efficient approach towards improving denitrogenation of petroleum feedstock
Chemical Engineering Journal, 2016Co-Authors: Prachee Misra, Ajay K. Dalai, Jackson M. Chitanda, John AdjayeAbstract:Abstract A major challenge in achieving deep hydrodesulfurization with the conventional hydrotreating technology is the inhibition and deactivation of the catalyst caused by heterocyclic nitrogen compounds. In this research, novel polymeric adsorbents were introduced for the selective removal of nitrogen compounds from bitumen-derived Light Gas Oil. Synthesis of polymers with high internal phase emulsion (polyHIPEs) was carried out using a monomeric mixture of unsaturated polyester resin, glycidyl methacrylate and divinylbenzene. To facilitate the selective removal of nitrogen compounds, reactive epoxy groups present in glycidyl methacrylate were used to functionalize the polyHIPEs with a fluorenone based π-acceptor, 2,4,5,7-tetranitro-9-fluorenone (TENF). Successful application of the synthesized polymers was found in the batch adsorption experiments at ambient temperature. Functionalized polyHIPEs were capable of selectively adsorbing nitrogen species from Light Gas Oil. The optimum ratio of monomers was found to be one of the key factors in determining the polymer performance. Particles with high glycidyl methacrylate content with toluene as the porogenic solvent were capable of removing 14.6% of nitrogen compounds. Reusability studies were performed successfully by regenerating the used polymers with toluene; which aids the separation of complexing agent and the adsorbed nitrogen species.
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Hydrotreating of coker Light Gas Oil on SBA-15 supported nickel phosphide catalysts
Catalysis Today, 2013Co-Authors: Kapil Soni, Philip E. Boahene, N Rambabu, Ajay K. Dalai, John AdjayeAbstract:Abstract SBA-15-supported nickel phosphides with a Ni/P atomic ratio of 2 and 0.5 were prepared by temperature programmed reduction method (TPR). The phase purity and structural/surface properties were studied by X-ray diffraction and N2 sorption measurements respectively. X-ray diffraction (XRD) analysis of the passivated catalysts confirmed the presence of Ni12P5 and Ni2P phases in catalysts prepared from oxidic precursors. Supports and catalysts were thoroughly characterized using other techniques such as SEM, EDAX, and TEM. Results from low angle XRD measurements confirmed the presence of hexagonally ordered mesoporous structure in SBA-15 material. Hydrotreating experiments were conducted under industrial conditions using coker Light Gas Oil (CLGO) as feed which contains 2439 ppm nitrogen 23,420 ppm sulfur respectively. The activity results show that SBA-15 supported NixPy catalysts show higher catalytic activities compared to reference NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts under similar reaction conditions. This higher catalytic activity of NixPy/SBA-15 is due to the structure and surface chemical properties of this phase which is resistant to sulfur poisoning. It was also found that the Ni/P ratio had a profound effect on the active structure and hydroprocessing behavior of the NixPy/SBA-15 catalysts. The HDS and HDN conversions was found in the following order NixPy/SBA-15 (0.5) > NixPy/SBA-15 (2.0) > NiMo/SBA-15 > NiMo/γ-Al2O3. The NixPy/SBA-15 (0.5) catalyst showed higher HDS and HDN activities compared with NixPy/SBA-15 (2.0) catalyst which has lower P content. The higher amount of P content in NixPy/SBA-15 (0.5) catalyst modifies the nature of the nickel in that catalyst and increased the amount of octahedral nickel species and causes higher hydrotreating activity.
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beneficial influence of edta on the structure and catalytic properties of sulfided nimo sba 15 catalysts for hydrotreating of Light Gas Oil
Applied Catalysis B-environmental, 2012Co-Authors: Sandeep Badoga, Kapil Soni, Ajay K. Dalai, Chandra K Mouli, John AdjayeAbstract:Abstract SBA-15 supported NiMo hydrotreating catalysts with different EDTA/Ni molar ratio were prepared by incipient wetness impregnation method. Hydrotreating activities of these catalysts were studied with Athabasca bitumen derived Light Gas Oil and comparison was done with NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts. A beneficial effect of chelating ligand was seen in hydrotreating activity and 28% increase in HDS of LGO was found as compared to NiMo/γ-Al2O3 in the case of EDTA/Ni molar ratio 4. Detailed mechanistic aspect of interaction between support – EDTA (ethylene diamine tetraacetic acid), EDTA-metallic species, support – metal, metallic species – metallic species at different reaction conditions is studied at different process parameters by using different characterization techniques such as X-ray absorption near-edge structure (XANES), Fourier transform infrared spectroscopy (FTIR), HRTEM, XRD, Raman, temperature programmed reduction (TPR), ICP-MS, CO chemisorption and N2 adsorption. A detailed scheme has been developed to explain the behavior of chelating agent in mesoporous SBA-15 supported catalysts. HRTEM results explain the high dispersion of Ni and MoS2 active phases in sulfided state even though big crystallite of MoO3 was seen in oxide state characterized by XRD and Raman spectra which explains role of EDTA in redistribution of active phases during sulfidation. XANES technique is used as predominant method for atomic level study of various structural changes in sulfided and oxide catalysts to find out the appropriate mechanism of the reaction. Characterization by XANES reveals that the presence of chelating agent delayed Ni2+ sulfidation which is main cause of improvement in HDS and HDN activity of the catalysts prepared in presence of organic chelates. Nickel sulfidation starts only when the EDTA–Ni complex decomposes and released nickel atoms move to the reactive edges of the MoS2 to form a finely dispersed sulfide Ni Mo S type II active phase.
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Beneficial influence of EDTA on the structure and catalytic properties of sulfided NiMo/SBA-15 catalysts for hydrotreating of Light Gas Oil
Applied Catalysis B: Environmental, 2012Co-Authors: Sandeep Badoga, Kapil Soni, Ajay K. Dalai, K. Chandra Mouli, John AdjayeAbstract:Abstract SBA-15 supported NiMo hydrotreating catalysts with different EDTA/Ni molar ratio were prepared by incipient wetness impregnation method. Hydrotreating activities of these catalysts were studied with Athabasca bitumen derived Light Gas Oil and comparison was done with NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts. A beneficial effect of chelating ligand was seen in hydrotreating activity and 28% increase in HDS of LGO was found as compared to NiMo/γ-Al2O3 in the case of EDTA/Ni molar ratio 4. Detailed mechanistic aspect of interaction between support – EDTA (ethylene diamine tetraacetic acid), EDTA-metallic species, support – metal, metallic species – metallic species at different reaction conditions is studied at different process parameters by using different characterization techniques such as X-ray absorption near-edge structure (XANES), Fourier transform infrared spectroscopy (FTIR), HRTEM, XRD, Raman, temperature programmed reduction (TPR), ICP-MS, CO chemisorption and N2 adsorption. A detailed scheme has been developed to explain the behavior of chelating agent in mesoporous SBA-15 supported catalysts. HRTEM results explain the high dispersion of Ni and MoS2 active phases in sulfided state even though big crystallite of MoO3 was seen in oxide state characterized by XRD and Raman spectra which explains role of EDTA in redistribution of active phases during sulfidation. XANES technique is used as predominant method for atomic level study of various structural changes in sulfided and oxide catalysts to find out the appropriate mechanism of the reaction. Characterization by XANES reveals that the presence of chelating agent delayed Ni2+ sulfidation which is main cause of improvement in HDS and HDN activity of the catalysts prepared in presence of organic chelates. Nickel sulfidation starts only when the EDTA–Ni complex decomposes and released nickel atoms move to the reactive edges of the MoS2 to form a finely dispersed sulfide Ni Mo S type II active phase.
Kapil Soni - One of the best experts on this subject based on the ideXlab platform.
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Hydrotreating of coker Light Gas Oil on SBA-15 supported nickel phosphide catalysts
Catalysis Today, 2013Co-Authors: Kapil Soni, Philip E. Boahene, N Rambabu, Ajay K. Dalai, John AdjayeAbstract:Abstract SBA-15-supported nickel phosphides with a Ni/P atomic ratio of 2 and 0.5 were prepared by temperature programmed reduction method (TPR). The phase purity and structural/surface properties were studied by X-ray diffraction and N2 sorption measurements respectively. X-ray diffraction (XRD) analysis of the passivated catalysts confirmed the presence of Ni12P5 and Ni2P phases in catalysts prepared from oxidic precursors. Supports and catalysts were thoroughly characterized using other techniques such as SEM, EDAX, and TEM. Results from low angle XRD measurements confirmed the presence of hexagonally ordered mesoporous structure in SBA-15 material. Hydrotreating experiments were conducted under industrial conditions using coker Light Gas Oil (CLGO) as feed which contains 2439 ppm nitrogen 23,420 ppm sulfur respectively. The activity results show that SBA-15 supported NixPy catalysts show higher catalytic activities compared to reference NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts under similar reaction conditions. This higher catalytic activity of NixPy/SBA-15 is due to the structure and surface chemical properties of this phase which is resistant to sulfur poisoning. It was also found that the Ni/P ratio had a profound effect on the active structure and hydroprocessing behavior of the NixPy/SBA-15 catalysts. The HDS and HDN conversions was found in the following order NixPy/SBA-15 (0.5) > NixPy/SBA-15 (2.0) > NiMo/SBA-15 > NiMo/γ-Al2O3. The NixPy/SBA-15 (0.5) catalyst showed higher HDS and HDN activities compared with NixPy/SBA-15 (2.0) catalyst which has lower P content. The higher amount of P content in NixPy/SBA-15 (0.5) catalyst modifies the nature of the nickel in that catalyst and increased the amount of octahedral nickel species and causes higher hydrotreating activity.
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beneficial influence of edta on the structure and catalytic properties of sulfided nimo sba 15 catalysts for hydrotreating of Light Gas Oil
Applied Catalysis B-environmental, 2012Co-Authors: Sandeep Badoga, Kapil Soni, Ajay K. Dalai, Chandra K Mouli, John AdjayeAbstract:Abstract SBA-15 supported NiMo hydrotreating catalysts with different EDTA/Ni molar ratio were prepared by incipient wetness impregnation method. Hydrotreating activities of these catalysts were studied with Athabasca bitumen derived Light Gas Oil and comparison was done with NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts. A beneficial effect of chelating ligand was seen in hydrotreating activity and 28% increase in HDS of LGO was found as compared to NiMo/γ-Al2O3 in the case of EDTA/Ni molar ratio 4. Detailed mechanistic aspect of interaction between support – EDTA (ethylene diamine tetraacetic acid), EDTA-metallic species, support – metal, metallic species – metallic species at different reaction conditions is studied at different process parameters by using different characterization techniques such as X-ray absorption near-edge structure (XANES), Fourier transform infrared spectroscopy (FTIR), HRTEM, XRD, Raman, temperature programmed reduction (TPR), ICP-MS, CO chemisorption and N2 adsorption. A detailed scheme has been developed to explain the behavior of chelating agent in mesoporous SBA-15 supported catalysts. HRTEM results explain the high dispersion of Ni and MoS2 active phases in sulfided state even though big crystallite of MoO3 was seen in oxide state characterized by XRD and Raman spectra which explains role of EDTA in redistribution of active phases during sulfidation. XANES technique is used as predominant method for atomic level study of various structural changes in sulfided and oxide catalysts to find out the appropriate mechanism of the reaction. Characterization by XANES reveals that the presence of chelating agent delayed Ni2+ sulfidation which is main cause of improvement in HDS and HDN activity of the catalysts prepared in presence of organic chelates. Nickel sulfidation starts only when the EDTA–Ni complex decomposes and released nickel atoms move to the reactive edges of the MoS2 to form a finely dispersed sulfide Ni Mo S type II active phase.
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Beneficial influence of EDTA on the structure and catalytic properties of sulfided NiMo/SBA-15 catalysts for hydrotreating of Light Gas Oil
Applied Catalysis B: Environmental, 2012Co-Authors: Sandeep Badoga, Kapil Soni, Ajay K. Dalai, K. Chandra Mouli, John AdjayeAbstract:Abstract SBA-15 supported NiMo hydrotreating catalysts with different EDTA/Ni molar ratio were prepared by incipient wetness impregnation method. Hydrotreating activities of these catalysts were studied with Athabasca bitumen derived Light Gas Oil and comparison was done with NiMo/SBA-15 and NiMo/γ-Al2O3 catalysts. A beneficial effect of chelating ligand was seen in hydrotreating activity and 28% increase in HDS of LGO was found as compared to NiMo/γ-Al2O3 in the case of EDTA/Ni molar ratio 4. Detailed mechanistic aspect of interaction between support – EDTA (ethylene diamine tetraacetic acid), EDTA-metallic species, support – metal, metallic species – metallic species at different reaction conditions is studied at different process parameters by using different characterization techniques such as X-ray absorption near-edge structure (XANES), Fourier transform infrared spectroscopy (FTIR), HRTEM, XRD, Raman, temperature programmed reduction (TPR), ICP-MS, CO chemisorption and N2 adsorption. A detailed scheme has been developed to explain the behavior of chelating agent in mesoporous SBA-15 supported catalysts. HRTEM results explain the high dispersion of Ni and MoS2 active phases in sulfided state even though big crystallite of MoO3 was seen in oxide state characterized by XRD and Raman spectra which explains role of EDTA in redistribution of active phases during sulfidation. XANES technique is used as predominant method for atomic level study of various structural changes in sulfided and oxide catalysts to find out the appropriate mechanism of the reaction. Characterization by XANES reveals that the presence of chelating agent delayed Ni2+ sulfidation which is main cause of improvement in HDS and HDN activity of the catalysts prepared in presence of organic chelates. Nickel sulfidation starts only when the EDTA–Ni complex decomposes and released nickel atoms move to the reactive edges of the MoS2 to form a finely dispersed sulfide Ni Mo S type II active phase.
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Catalytic hydrotreatment using NiMo/MAS catalysts synthesized from ZSM-5 nano-clusters
Applied Catalysis A-general, 2011Co-Authors: S. Mohanty, Kapil Soni, K. Chandra Mouli, John Adjaye, Ajay K. DalaiAbstract:Abstract Mesostructured alumino-silcate (MAS) materials were synthesized from ZSM-5 nano-clusters and used as catalysts supports for the hydrotreatment of a model compound and real feed stock. Supports and catalysts were thoroughly characterized by using XRD, N 2 adsorption analysis, FT-IR, 27 Al MAS NMR, Raman, EXAFS and HRTEM techniques. The alumino-silicate materials exhibited different acid strength and textural properties depending on the duration of hydrothermal treatment of the zeolite seeds. Materials synthesized with low seeding time of 4 h showed properties similar to Al-SBA-15 prepared using the direct synthesis route, whereas material with high seeding time ( t seed = 24 h) resembled ZSM-5. The EXAFS study of the sulfided catalysts revealed that sulfidation was highest in the NiMo catalyst supported on mesoporous alumino-silicate synthesized from ZSM-5 seeds with 16 h of hydrothermal treatment (MAS-16). Hydrotreating experiments were conducted using model compound (DBT) at 325 °C and 600 psi as well as real feed stock (Coker Light Gas Oil) at industrial conditions. Catalytic activity in the hydrodesulfurization (HDS) of dibenzothiophene (DBT) was found to be maximum for this particular catalyst (MAS-16). The same catalyst also gave higher hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) conversion than NiMo/γ Al 2 O 3 in the hydrotreating of Light Gas Oil.
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Hydrotreating of coker Light Gas Oil on Ti-HMS supported heteropolytungstic acid catalysts
Applied Catalysis A-general, 2011Co-Authors: Kapil Soni, Philip E. Boahene, Ajay K. Dalai, K. Chandra Mouli, John AdjayeAbstract:Abstract Ti-HMS substrates were synthesized by using dodecylamine as structure-directing agents. A series of HPW/Ti-HMS catalysts with different Si/Ti ratios, promoted by Ni was prepared using Keggin-type heteropolyacids (H 3 PW 12 O 40 ) as active phase precursors. These catalysts were compared with corresponding NiW/HMS catalysts prepared from the traditional precursors (ammonium metatungstate). Prepared supports and catalysts were characterized by small- and wide-angle XRD, N 2 physisorption, FT-IR, Raman, DRIFT, TEM, and SEM. Catalytic activity was assessed for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) of coker Light Gas Oil (CLGO) derived from Athabasca bitumen, in a trickle bed reactor at a temperature, pressure, and LHSV of 370 °C, 8.8 MPa, and 2.0 h −1 , respectively. The W catalysts prepared from heteropolyacids showed better performance for hydrotreating than their counterparts prepared from traditionally used W ammonium salts. The incorporation of Ti into HMS afforded catalysts that were more active than the Ti-free counterpart, due to the larger number of coordinately unsaturated sites (CUS) of the metal sulfide on Ti-loaded catalysts. Under steady-state conditions, the NiPW/Ti-HMS (20) catalyst with a Si/Ti ratio of 20 was the most active among the catalysts studied due to more uniform distribution of active species.
J. Adjaye - One of the best experts on this subject based on the ideXlab platform.
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Hydrodesulphurization and hydrodenitrogenation of Light Gas Oil using NiMo catalyst supported on functionalized mesoporous carbon
Applied Catalysis A-general, 2011Co-Authors: N. Prabhu, Ajay K. Dalai, J. AdjayeAbstract:Abstract The effect of functionalization on the hydrotreating activity of NiMo catalysts supported on mesoporous carbon supports (mC) was studied. mC support was prepared by volume templating of alkali modified SBA-15 using sucrose as carbon source. The mC supports were functionalized using nitric acid of various concentrations (upto 8 M HNO 3 ). The supports and catalysts were characterized by N 2 physisorption, SAXS, XRD, FTIR, TGA, Raman spectroscopy, SEM, TEM, and HRTEM. SAXS results showed the changes in structural orderliness of virgin and functionalized mC supports. Physisorption analysis indicated progressive reduction in surface area (SA) and pore volume with the increase in nitric acid concentration. Enhancement of surface functional groups after functionalization was observed through FTIR. SEM images showed that the carbon supports retain needle like morphology even after nitric acid etching. As seen by HRTEM, qualitatively Type-II like NiMoS phase (lower support metal interaction (SMI)) is generated on functionalized mC supported catalysts, which is active for hydrotreating. Hydrotreating activity study of these NiMo catalysts were carried out under industrial operating conditions in a laboratory trickle bed reactor using coker Light Gas Oil feed and it was found that NiMo supported on 6 M acid treated mC showed the highest activity. Based on equal catalyst mass, the hydrodesulphurization and hydrodenitrogenation activities of NiMo/mC catalyst were higher than that of NiMo/γ-Al 2 O 3 owing to lower SMI and higher SA. This study reveals that the functionalized mCs can become potential alternative catalyst support to conventional γ-Al 2 O 3 , for the hydrotreating of Gas Oil feedstocks.
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Hydrotreating of Light Gas Oil using carbon nanotube supported NiMoS catalysts: Kinetic modelling
The Canadian Journal of Chemical Engineering, 2010Co-Authors: S. Sigurdson, A. K. Dalai, J. AdjayeAbstract:Multi-walled carbon nanotubes (MWCNTs) were applied as supports for NiMo hydroprocessing catalysts. Rate expressions were developed for an optimum NiMo/MWCNT catalyst to help predict its hydrodesulfurisation (HDS) and hydrodenitrogenation (HDN) activities while varying the operation parameters for coker Light Gas Oil treatment. Power law models were best fit with reaction orders of 2.6 and 1.2, and activation energies of 161 and 82.3 kJ/mol, for the HDS and HDN reactions, respectively. Generalised Langmuir–Hinshelwood models were found to have reaction orders of 3.0 and 1.5, and activation energies of 155 and 42.3 kJ/mol, for the HDS and HDN reactions, respectively. Etude des nanotubes de carbone multiparois (MWCNT) lorsqu'ils servent de supports aux catalyseurs d'hydrotraitement NiMo. Des expressions de vitesse ont ete developpees pour un catalyseur NiMo/MWCNT optimal pour predire ses activites d'hydrodesulfurisation (HDS) et d'hydrodenitrogenation (HDN) tout en faisant varier les parametres d'exploitation pour le traitement du Gas-Oil leger de cokefaction. Les modeles de loi de puissance sont les mieux adaptes avec des ordres de reaction de 2,6 et 1,2 et des energies d'activation de 161 kJ/mol et 82,3 kJ/mol pour les reactions d'HDS et d'HDN respectivement. Les modeles generalises de Langmuir–Hinshelwood ont des ordres de reaction de 3,0 et 1,5 et des energies d'activation de 155 kJ/mol et 42,3 kJ/mol pour les reactions d'HDS et d'HDN respectivement. © 2010 Canadian Society for Chemical Engineering
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Hydrotreating of Gas Oil on SBA-15 supported NiMo catalysts
Microporous and Mesoporous Materials, 2007Co-Authors: V. Sundaramurthy, Ajay K. Dalai, I. Eswaramoorthi, J. AdjayeAbstract:Abstract The siliceous and the metal substituted (B or Al)-SBA-15 molecular sieves were used as a support for NiMo hydrotreating catalysts (12 wt.% Mo and 2.4 wt.% Ni). The supports were characterized by X-ray diffraction (XRD), scanning electron microscopy and N 2 adsorption–desorption isotherms. The SBA-15 supported NiMo catalysts in oxide state were characterized by BET surface area analysis and XRD. The sulfided NiMo/SBA-15 catalysts were examined by DRIFT of CO adsorption and TPD of NH 3 . The HDN and HDS activities with bitumen derived Light Gas Oil at industrial conditions showed that Al substituted SBA-15 (Al-SBA-15) is the best among the supports studied for NiMo catalyst. A series of NiMo catalysts containing 7–22 wt.% Mo with Ni/Mo weight ratio of 0.2 was prepared using Al-SBA-15 support and characterized by BET surface area analysis, XRD and temperature programmed reduction and DRIFT spectroscopy of adsorbed CO. The DRIFT spectra of adsorbed CO showed the presence of both unpromoted and Ni promoted MoS 2 sites in all the catalysts, and maximum “NiMoS” sites concentration with 17 wt.% of Mo loading. The HDN and HDS activities of NiMo/Al-SBA-15 catalysts were studied using Light Gas Oil at temperature, pressure and WHSV of 370 °C, 1300 psig and 4.5 h −1 , respectively. The NiMo/Al-SBA-15 catalyst with 17 wt.% Mo and 3.4 wt.% of Ni is found to be the best catalyst. The HDN and HDS activities of this catalyst are comparable with the conventional Al 2 O 3 supported NiMo catalyst in real feed at industrial conditions.
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oxidative desulfurization and denitrogenation of a Light Gas Oil using an oxidation adsorption continuous flow process
Applied Catalysis A-general, 2005Co-Authors: Atsushi Ishihara, Danhong Wang, Franck Dumeignil, Hiroshi Amano, Eika W Qian, Toshiaki KabeAbstract:Abstract The oxidation of undesirable sulfur compounds present in a desulfurized Light Gas Oil (LGO; sulfur content: 39 ppm) was performed with tert-butyl hydroperoxide (t-BuOOH) as the oxidant in the presence of a 16 wt.% MoO3/Al2O3 catalyst. The oxidation activity of the sulfur compounds in the Light Gas Oil increased when the O/S molar ratio increased up to 15; the activity sLightly decreased for higher ratios. This optimal ratio was significantly higher that the stoichiometric one (=2) due to parallel oxidation reactions of olefins, etc., in the LGO. Further, we compared the oxidation reactivity of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), and trimethyldibenzothiophene (C3-DBT), which are refractory compounds present in the Light Gas Oil. The reactivity decreased in the order DBT ≫ 4,6-DMDBT > C3-DBT, irrespective of the WHSV and the temperature. Subsequent mathematical treatment revealed that the oxidative reaction of each sulfur compound follows a first-order kinetics. We found an activation energy of 32 ± 2 kJ mol−1, whatever the compound, suggesting that the oxidation mechanism was the same for these compounds. Then, according to the proposed global process, the previously oxidized molecules in the treated Light Gas Oil were further removed by adsorption over a silica gel at ambient temperature. As a result, the total sulfur content could be decreased after oxidation/adsorption to less than 5 ppm. Further, N-containing model compounds were also treated according to the same procedure and the denitrogenation performance decreased in the order indole > quinoline > acridine > carbazole. Subsequently, the same process allowed decreasing the N content in the LGO from an initial value of 13.5 ppm to a value of 0.8 ppm, which is a remarkable result.
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Hydrodesulfurization of sulfur-containing polyaromatic compounds in Light Gas Oil using noble metal catalysts
Applied Catalysis A: General, 2005Co-Authors: Atsushi Ishihara, Franck Dumeignil, Eika W Qian, Jeayoung Lee, Kouhei Mitsuhashi, Toshiaki KabeAbstract:We systematically monitored the hydrodesulfurization (HDS) activity of dibenzothiophene (DBT) and groups of substituted DBTs present in a SR-LGO over various noble metal catalysts (Ru, Rh, Ru-Rh, Pt, Pd and Pt-Pd) supported on alumina. The catalytic performances were compared to those obtained over a conventional CoMo catalyst. The Pd-based catalysts exhibited excellent HDS performances, especially for desulfurizing the refractory compounds. In particular, the 4,6-dimethyldibenzothiophene (4,6-DMDBT) HDS activity over the Pd or the Pd-Pt catalyst was equivalent to that over the CoMo catalyst. This was attributed to the exceptional hydrogenation (HYD) properties of the Pd-based catalysts, which enable desulfurization of the refractory compounds by considerably minimizing the effect of the steric hindrance due to their substituents. The synergetic effect observed on the bimetallic Pt-Pd system at low temperature for all the sulfur compounds was largely attenuated in the high temperature range, probably due to shifting of the HYD/dehydrogenation equilibrium to dehydrogenation. Despite a much lower metal loading (0.25 wt.%), the performances of the Rh catalyst were superior to those of the optimized 16 wt.% Ru catalyst. A synergetic effect was observed on the Ru-Rh catalyst, on which the DBT HDS activity was significantly enhanced compared to the activity of each corresponding monometallic catalyst. Further, we recently showed that the use of SiO2 or SiO2-Al2O3 as a support allows higher optimal Rh contents, making the Rh-based HDS catalysts even more promising. In brief, we obtained encouraging results, which showed for instance that the excellent properties of the noble metal catalysts in model HDS reactions are still observed during the HDS treatment of real feeds. # 2005 Elsevier B.V. All rights reserved.
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Oxidative desulfurization and denitrogenation of a Light Gas Oil using an oxidation/adsorption continuous flow process
Applied Catalysis A-general, 2004Co-Authors: Atsushi Ishihara, Danhong Wang, Franck Dumeignil, Hiroshi Amano, Eika W Qian, Toshiaki KabeAbstract:Abstract The oxidation of undesirable sulfur compounds present in a desulfurized Light Gas Oil (LGO; sulfur content: 39 ppm) was performed with tert -butyl hydroperoxide ( t -BuOOH) as the oxidant in the presence of a 16 wt.% MoO 3 /Al 2 O 3 catalyst. The oxidation activity of the sulfur compounds in the Light Gas Oil increased when the O/S molar ratio increased up to 15; the activity sLightly decreased for higher ratios. This optimal ratio was significantly higher that the stoichiometric one (=2) due to parallel oxidation reactions of olefins, etc., in the LGO. Further, we compared the oxidation reactivity of dibenzothiophene (DBT), 4,6-dimethyldibenzothiophene (4,6-DMDBT), and trimethyldibenzothiophene (C 3 -DBT), which are refractory compounds present in the Light Gas Oil. The reactivity decreased in the order DBT ≫ 4,6-DMDBT > C 3 -DBT, irrespective of the WHSV and the temperature. Subsequent mathematical treatment revealed that the oxidative reaction of each sulfur compound follows a first-order kinetics. We found an activation energy of 32 ± 2 kJ mol −1 , whatever the compound, suggesting that the oxidation mechanism was the same for these compounds. Then, according to the proposed global process, the previously oxidized molecules in the treated Light Gas Oil were further removed by adsorption over a silica gel at ambient temperature. As a result, the total sulfur content could be decreased after oxidation/adsorption to less than 5 ppm. Further, N-containing model compounds were also treated according to the same procedure and the denitrogenation performance decreased in the order indole > quinoline > acridine > carbazole. Subsequently, the same process allowed decreasing the N content in the LGO from an initial value of 13.5 ppm to a value of 0.8 ppm, which is a remarkable result.
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Methods of Activating Catalysts for Hydrodesulfurization of Light Gas Oil (Part 2)
Journal of The Japan Petroleum Institute, 2001Co-Authors: Weihua Qian, Atsushi Ishihara, Shigeru Yamada, Meiko Ichinoseki, Toshiaki KabeAbstract:Hydrodesulfurization (HDS) of a straight run Light Gas Oil (SRLGO, Sulfur: 1.50wt%) and ultra-deep HDS of a hydrotreated Light Gas Oil (HDLGO, Sulfur: 0.045wt%) were carried out over a commercial Co-Mo/Al2O3 catalyst presulfided with a novel sulfiding agent, bis-(1, 1, 3, 3-tetramethylbutyl)-polysulfide (CS-40). The HDS reaction conditions were: Temperature 310-390°C, total pressure 3.0MPa, LHSV 2.0-4.0h-1, Gas/Oil ratio 125 Nm3/m3. The catalyst presulfided in situ with CS-40 showed comparable activity to the corresponding catalyst presulfided with dimethyldisulfide (DMDS), and higher activity than that presulfided with H2S in HDS of SRLGO. Catalyst presulfided ex situ with CS-40 plus sulfur showed significantly enhanced activity for HDS of alkyl-substituted dibenzothiophenes (DBTs). No significant changes in apparent activation energies for HDS of DBT were observed. In contrast, the catalyst ex situ sulfided with CS-40 plus sulfur had smaller activation energies for HDS of 4, 6-dimethyldibenzothiophene (4, 6-DMDBT). The ex situ sulfiding method using CS-40 plus sulfur may enhance the formation of active sites for hydrogenation and results in increased activity for indirect desulfurization of alkyl-substituted DBTs via hydrogenation of the aromatic ring of DBTs to form cyclohexylbenzenes.
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Methods of Activating Catalysts for Hydrodesulfurization of Light Gas Oil (Part 1)
Journal of The Japan Petroleum Institute, 2001Co-Authors: Shigeru Yamada, Weihua Qian, Atsushi Ishihara, Guangde Wang, Toshiaki KabeAbstract:The organic sulfur compound bis-(1, 1, 3, 3-tetramethylbutyl)-polysulfide was investigated as a novel sulfiding agent for hydrodesulfurization (HDS) catalyst by evaluating the conversion of dibenzothiophene (DBT) on a commercial Co-Mo/Al2O3 catalyst. The catalyst presulfided using the polysulfide in situ showed the same or higher activity than those using the conventional sulfiding agents dimethyldisulfide (DMDS) and CS2. The catalytic activity for HDS and hydrogenation depended remarkably on the presulfiding procedure such as type of sulfiding agent, temperature program in the presulfiding procedure, and in situ or ex situ method. The 35S radioisotope tracer method was used to elucidate the effect of various sulfiding operation parameters on sulfur behavior on the sulfided catalyst in the HDS reaction of DBT. The effects of sulfiding agent and temperature program on the catalytic activity mainly originate from differences in the amount of labile sulfur formed in the different sulfiding processes.