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2017 Volume 45 Issue 2
2017, 45(2): 213-219
Abstract:
The yttrium (Y) modified unsupported Yx-Ni2P catalysts were prepared by one step method and stepwise method (x refers to mol ratio of Y to Ni), respectively.The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption specific surface area measurements (BET), CO uptake and X-ray photoelectron spectroscopy (XPS).The effects of preparation methods on thehydrodesulfurization (HDS) property of the catalysts were investigated by using dibenzothiophene (DBT) as the model compound.The results show that the addition of Y can suppress the formation of Ni5P4 phase and thus promote the formation of active Ni2P phase.The addition of Y can dramatically increase the surface area and pore volume, effectively improve the HDS activity of nickel phosphide catalyst.The Yx-Ni2P catalysts prepared by these two methods with Y/Ni mol ratio of 0.10 exhibited the highest HDS activity.As compared to the stepwise method, the one step method which obtained catalysts possessed a larger specific surface area with high pore volume, a lower surface P/Ni mol ratio, a larger CO uptake and more exposed active Ni sites as compared to stepwise method.As a result, it showed a higher HDS activity.At a temperature of 340℃, a pressure of 3.0 MPa, a H2/oil volume ratio of 700 and a weight hourly space velocity (WHSV) of 1.5 h-1, the conversion of DBT over Y0.10-Ni2P catalyst prepared by one step method reached 97.7%, which was an increase of 5.4% comparing with the Y0.10-Ni2P catalyst prepared by stepwise method (92.3%).
The yttrium (Y) modified unsupported Yx-Ni2P catalysts were prepared by one step method and stepwise method (x refers to mol ratio of Y to Ni), respectively.The catalysts were characterized by X-ray diffraction (XRD), N2 adsorption specific surface area measurements (BET), CO uptake and X-ray photoelectron spectroscopy (XPS).The effects of preparation methods on thehydrodesulfurization (HDS) property of the catalysts were investigated by using dibenzothiophene (DBT) as the model compound.The results show that the addition of Y can suppress the formation of Ni5P4 phase and thus promote the formation of active Ni2P phase.The addition of Y can dramatically increase the surface area and pore volume, effectively improve the HDS activity of nickel phosphide catalyst.The Yx-Ni2P catalysts prepared by these two methods with Y/Ni mol ratio of 0.10 exhibited the highest HDS activity.As compared to the stepwise method, the one step method which obtained catalysts possessed a larger specific surface area with high pore volume, a lower surface P/Ni mol ratio, a larger CO uptake and more exposed active Ni sites as compared to stepwise method.As a result, it showed a higher HDS activity.At a temperature of 340℃, a pressure of 3.0 MPa, a H2/oil volume ratio of 700 and a weight hourly space velocity (WHSV) of 1.5 h-1, the conversion of DBT over Y0.10-Ni2P catalyst prepared by one step method reached 97.7%, which was an increase of 5.4% comparing with the Y0.10-Ni2P catalyst prepared by stepwise method (92.3%).
2017, 45(2): 227-234
Abstract:
A series of MgAPO-5 molecular sieves with a wide range of Mg/P mol ratios in the gel was synthesized by a hydrothermal process.Using MgAPO-5 as acidic supports, the bifunctional NiW/MgAPO-5 catalysts were prepared by impregnation method, and applied to the hydrocracking of tetralin to produce BTEX.The synthesized MgAPO-5 molecular sieves and NiW/MgAPO-5 samples were characterized by XRD, N2 adsorption, SEM, NH3-TPD, Py-FTIR and H2-TPR.The results exhibit that the Mg/P mol ratio has a great influence on the unit cell parameters, morphology, the Mg content and the acidity of MgAPO-5 samples, and the ion of Mg2+ is incorporated into the framework.In the hydrocracking of tetralin, with the same amount of NiW, the activity of NiW/MgAPO-5 is primarily controlled by the acidic strength of MgAPO-5.The selectivity of BTEX was determined by the combined effect of the acidity of MgAPO-5 and the (de) hydrogenation function of NiW.The highest conversion is achieved with the Mg/P mol ratio of 0.05, and the best BTEX selectivity is obtained with the Mg/P mol ratio of 0.03.
A series of MgAPO-5 molecular sieves with a wide range of Mg/P mol ratios in the gel was synthesized by a hydrothermal process.Using MgAPO-5 as acidic supports, the bifunctional NiW/MgAPO-5 catalysts were prepared by impregnation method, and applied to the hydrocracking of tetralin to produce BTEX.The synthesized MgAPO-5 molecular sieves and NiW/MgAPO-5 samples were characterized by XRD, N2 adsorption, SEM, NH3-TPD, Py-FTIR and H2-TPR.The results exhibit that the Mg/P mol ratio has a great influence on the unit cell parameters, morphology, the Mg content and the acidity of MgAPO-5 samples, and the ion of Mg2+ is incorporated into the framework.In the hydrocracking of tetralin, with the same amount of NiW, the activity of NiW/MgAPO-5 is primarily controlled by the acidic strength of MgAPO-5.The selectivity of BTEX was determined by the combined effect of the acidity of MgAPO-5 and the (de) hydrogenation function of NiW.The highest conversion is achieved with the Mg/P mol ratio of 0.05, and the best BTEX selectivity is obtained with the Mg/P mol ratio of 0.03.
2017, 45(2): 235-242
Abstract:
The calcination process of precipitated iron based Fisher-Tropsch synthesis catalysts was optimized by the design of experiment (DOE) tools.And the molecular simulation model and the particle growing model were proposed.The results showed that the catalyst pore volume decreased, the bulk and skeleton density of the catalyst increased, and the attrition resistance of the catalyst improved with the calcination temperature and time increasing.The smaller the BET surface of the catalyst, the smaller the attrition of the catalyst is.The attrition and density of the catalyst have a inverse linear relationship.The bonding strength of Cu, Si with Fe by O atom and the particle size can be adjusted by calcination optimization, thus got high F-T activity and good stability.In our experiments, the optimized calcination temperature is 560℃.
The calcination process of precipitated iron based Fisher-Tropsch synthesis catalysts was optimized by the design of experiment (DOE) tools.And the molecular simulation model and the particle growing model were proposed.The results showed that the catalyst pore volume decreased, the bulk and skeleton density of the catalyst increased, and the attrition resistance of the catalyst improved with the calcination temperature and time increasing.The smaller the BET surface of the catalyst, the smaller the attrition of the catalyst is.The attrition and density of the catalyst have a inverse linear relationship.The bonding strength of Cu, Si with Fe by O atom and the particle size can be adjusted by calcination optimization, thus got high F-T activity and good stability.In our experiments, the optimized calcination temperature is 560℃.
2017, 45(2): 243-248
Abstract:
CuMnCe/TiO2-Al2O3 catalysts with different TiO2 contents were prepared by the co-impregnation method and characterized by BET, XRD, XPS and H2-TPR techniques.The catalytic performance in methane deoxidation reaction were investigated using CGK-5A fixed bed reactor.Results showed that doping some TiO2 in the Al2O3 support has no effect on the crystalline structure of the active ingredient.But it can effectively improve Al2O3 support sintering resistance and thermal stability, furthermore, it increases content of Ce3+/(Ce3++Ce4+) in the CuMnCe/Al2O3 catalysts, which improves the mobility of oxygen.Besides, the content of adsorbed oxygen Osur/(Osur+Olatt) and reducible species in the catalyst surface are increased.Thus, effectively, doping some TiO2 into the Al2O3 support improved the catalytic activity of deoxygenation catalyst for methane combustion.CuMnCe/4% TiO2-Al2O3 exhibited optimum catalytic activity and oxygen conversion rate reached 100% at 387℃.
CuMnCe/TiO2-Al2O3 catalysts with different TiO2 contents were prepared by the co-impregnation method and characterized by BET, XRD, XPS and H2-TPR techniques.The catalytic performance in methane deoxidation reaction were investigated using CGK-5A fixed bed reactor.Results showed that doping some TiO2 in the Al2O3 support has no effect on the crystalline structure of the active ingredient.But it can effectively improve Al2O3 support sintering resistance and thermal stability, furthermore, it increases content of Ce3+/(Ce3++Ce4+) in the CuMnCe/Al2O3 catalysts, which improves the mobility of oxygen.Besides, the content of adsorbed oxygen Osur/(Osur+Olatt) and reducible species in the catalyst surface are increased.Thus, effectively, doping some TiO2 into the Al2O3 support improved the catalytic activity of deoxygenation catalyst for methane combustion.CuMnCe/4% TiO2-Al2O3 exhibited optimum catalytic activity and oxygen conversion rate reached 100% at 387℃.
2017, 45(2): 249-256
Abstract:
The kinetic and deactivation kinetic models of methane catalytic cracking were established based on the data of thermal gravimetric analyzer.The kinetic model of methane catalytic cracking was established by the data of initial hydrogen production rate under the condition of no carbon deposition.The deactivation kinetic model was established by the reduced rate of methane catalytic cracking.The experiment was carried out over Ni-Mg composite catalyst, at the temperature of 535, 585, 635℃ and the methane partial pressures were 104, 2×104, 3×104 Pa.The result shows that the reaction order and activation energy were 0.5 and 82 kJ/mol, the deactivation order and activation energy were 0.5 and 118 kJ/mol respectively.The multi-walled carbon nanotubes were all produced under the experimental conditions.
The kinetic and deactivation kinetic models of methane catalytic cracking were established based on the data of thermal gravimetric analyzer.The kinetic model of methane catalytic cracking was established by the data of initial hydrogen production rate under the condition of no carbon deposition.The deactivation kinetic model was established by the reduced rate of methane catalytic cracking.The experiment was carried out over Ni-Mg composite catalyst, at the temperature of 535, 585, 635℃ and the methane partial pressures were 104, 2×104, 3×104 Pa.The result shows that the reaction order and activation energy were 0.5 and 82 kJ/mol, the deactivation order and activation energy were 0.5 and 118 kJ/mol respectively.The multi-walled carbon nanotubes were all produced under the experimental conditions.
