The applicability of a commercial Pt-Sn/Al2O3 isobutane dehydrogenation catalyst in dehydrogenation of propane was studied. Catalyst performance tests were carded out in a fixed-bed quartz reactor under different oper...The applicability of a commercial Pt-Sn/Al2O3 isobutane dehydrogenation catalyst in dehydrogenation of propane was studied. Catalyst performance tests were carded out in a fixed-bed quartz reactor under different operating conditions. Generally, as the factors improving propane conversion decrease the propylene selectivity, the optimal operating condition to maximize propylene yield is expected. The optimal condition was obtamed by the experimental design method. The investigated parameters were temperature, hydrogen/hydrocarbon （HE/HC） ratio and space velocity, being changed in three levels. Constrains such as the susceptibility of the catalyst components to sintering or phase transformation were also taken into account. Activity, selectivity and stability of the catalyst were considered as the measured response factors, while the space-time-yield （STY） was considered as the variable to be optimized due to its commercial interest. A STY of 16 mol.kg^-1.h^-1 was achieved under the optimal conditions of T= 620 ℃, H2/HC = 0.6 and, weight hourly space velocity （WHSV） = 2.2 h^-1. Single carbon-carbon bond rupture was found to be the main route for the formation of lower hydrocarbon byproducts.展开更多
The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness ...The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness impregnation.The effects of different active metals forms(oxidation,reduction,sulfuration)and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD,XPS,BET,NH3-TPD and SEM.Especially,Ni-Mo/Al2O3 was first used in this reactive system.The results show that the oxidative4%Ni O-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin.The conversion of naphthalene and the selectivity of tetralin can reach 95.62%and 99.75%respectively at 200℃,8 h and 6 MPa.Compared with reduced and sulfureted 4%Ni O-20%MoO3/Al2O3 catalysts,oxidative 4%Ni O-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals,larger pore volume and size,and larger total acidity.NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity.展开更多
The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences ...The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.展开更多
A series of heteropoly acid (HPA) based Al2O3 catalysts with three-dimensional ordered (3DOM) structure were synthesized by colloidal crystal template method.Interconnected macropores (250 nm) could be clearly observe...A series of heteropoly acid (HPA) based Al2O3 catalysts with three-dimensional ordered (3DOM) structure were synthesized by colloidal crystal template method.Interconnected macropores (250 nm) could be clearly observed by scanning electron microscope (SEM) and transmission electron microscope (TEM).Mesopores could be detected by N2 adsorption-desorption isotherms which further confirmed the 3DOM structural characteristics of catalyst.Moreover,Keggin-type HPW was highly dispersed in the Al2O3 framework,which suggested by powder X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) results.The oxidation desulfurization (ODS) performance of 3DOM H3PW12O40/Al2O3 of refractory sulphur compounds was evaluated in the presence of hydrogen peroxide.It oxidized 98.5% of dibenzothiophene (DBT) into corresponding sulfone within 3 h,which exhibited superior ODS performance than corresponding mesoporous and microporous H3PW12O40/Al2O3 catalyst.The enhancement of ODS efficiency is related to the improvement of mass transfer of DBT in the pore channel resulting from the interconnected 3DOM structure.Furthermore,the as-prepared catalyst still demonstrates outstanding cycle performance after 6 runs,which could be easily recovered from the model fuel.展开更多
The deactivation of Ni/SiO2-Al2 O3 catalyst in hydrogenation of crude 1,4-butanediol was investigated.During the operation time of 2140 h,the catalyst showed slow activity decay.Characterization results,for four spent...The deactivation of Ni/SiO2-Al2 O3 catalyst in hydrogenation of crude 1,4-butanediol was investigated.During the operation time of 2140 h,the catalyst showed slow activity decay.Characterization results,for four spent catalysts used at different time,indicated that the main reason of the catalyst deactivation was the deposition of carbonaceous species that covered the active Ni and blocked mesopores of the catalyst.The TPO and SEM measurements revealed that the carbonaceous species included both oligomeric and polymeric species with high C/H ratio and showed sheet.Such carbonaceous species might be eliminated through either direct H2 reduction or the combined oxidation-reduction methodologies.展开更多
In this investigation, Pt–Ba–Ce/c-Al2O3 catalysts were prepared by incipient wetness impregnation and experiments were performed to evaluate the influence of H2 on the evolution mechanism of nitrogen oxides (NOx) st...In this investigation, Pt–Ba–Ce/c-Al2O3 catalysts were prepared by incipient wetness impregnation and experiments were performed to evaluate the influence of H2 on the evolution mechanism of nitrogen oxides (NOx) storage and reduction (NSR). The physical and chemical properties of the Pt–Ba–Ce/c- Al2O3 catalysts were studied using a combination of characterization techniques, which showed that PtOx, CeO2, and BaCO3, whose peaks were observed in X-ray diffraction (XRD) spectra, dispersed well on the c-Al2O3, as shown by transmission electron microscope (TEM), and that the difference between Ce3+ and Ce4+, as detected by X-ray photoelectron spectroscopy (XPS), facilitated the migration of active oxygen over the catalyst. In the process of a complete NSR experiment, the NOx storage capability was greatly enhanced in the temperature range of 250–350℃, and reached a maximum value of 315.3μmol·gcat^-1 at 350℃, which was ascribed to the increase in NO2 yield. In a lean and rich cycling experiment, the results showed that NOx storage efficiency and conversion were increased when the time of H2 exposure (i.e., 30, 45, and 60 s) was extended. The maximum NOx conversion of the catalyst reached 83.5% when the duration of the lean and rich phases was 240 and 60 s, respectively. The results revealed that increasing the content of H2 by an appropriate amount was favorable to the NSR mechanism due to increased decomposition of nitrate or nitrite, and the refreshing of trapping sites for the next cycle of NSR.展开更多
The effect of Zr on the catalytic performance of Pd/y-A1203 for the methane combustion was investigated. The results show that the addition of Zr can improve the activity and stability of Pd/γ-Al2O3 catalyst, which, ...The effect of Zr on the catalytic performance of Pd/y-A1203 for the methane combustion was investigated. The results show that the addition of Zr can improve the activity and stability of Pd/γ-Al2O3 catalyst, which, based on the catalyst characterization （N2 adsorption, XRD, CO- Chemisorption, XPS, CHa-TPR and O2-TPO）, is ascribed to the interaction between Pd and Zr. The active phase of methane combustion over supported palladium catalyst is the Pd^0/Pd^2＋ mixture. Zr addition inhibits Pd aggregation and enhances the redox properties of active phase Pd^0/ Pd^2＋. H2 reduction could effectively reduce the oxidation degree of Pd species and regenerate the active sites （Pd^0/ pd^2＋）.展开更多
The surface nature of fresh Mo2N/Al2O3, Mo2C/Al2O3 and/MoP/Al2O3 catalysts, which were synthesized directly in the IR cell to avoid passivation, were characterized by in situ IR spectroscopy with CO as a probe molecul...The surface nature of fresh Mo2N/Al2O3, Mo2C/Al2O3 and/MoP/Al2O3 catalysts, which were synthesized directly in the IR cell to avoid passivation, were characterized by in situ IR spectroscopy with CO as a probe molecule. CO adsorbed on fresh catalysts showed characteristic IR bands at 2045 cm-1 for Mo2N/Al2O3 catalyst, 2054 cm-1 for MozC/Al2O3 catalyst and 2037 cm-1 for MoP/Al2O3 catalyst, respectively. A strong band at 2200 cm-1 for Mo2N/Al2O3 catalyst, which could be ascribed to NCO species formed when CO reacted upon surface active nitrogen atoms, and a weak band at 2196 cm-1 for Mo2C/Al2O3 catalyst, which could be attributed to CCO species, were also detected. CO adsorbed on fresh Mo2N/Al2O3 catalyst, Mo2C/Al2O3 catalyst and MoP/Al2O3 catalyst, showed strong molecular adsorption, just like noble metals. Our experimental results are bolstered by direct IR evidence demonstrating the similarity in surface electronic property between the fresh Mo2N/Al2O3, Mo2C/Al2O3 and MoP/Al2O3 catalysts and noble metals.展开更多
A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-co...A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-containing catalysts were lower than those of the K-free ones, particularly for catalysts with high Pt contents （51.6 k）/mol for 0.42K-2.0Pt/Al2O3 and 6：3.6 kJ/mol for 2.0Pt/Al2O3 ）. The CO reaction orders were higher for the K-containing catalysts （about -0.2） than for the K-free ones （about -0.5）, with the former having much lower equilibrium constants for CO adsorption than the latter. In situ Fourier-transform infrared spectroscopy showed that surface CO desorption from the 0.42K-2.0Pt/Al2O3 catalyst was easier than from 2.0Pt/Al2O3. The promoting effect of K was therefore caused by weakening of the interactions between CO and surface Pt atoms. This decreased coverage of the catalyst with CO and facilitated competitive O2 chemisorption on the Pt surface, and significantly lowered the reaction barrier between chemisorbed CO and O2 species.展开更多
Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried ...Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2（molar ratio）=1：3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.展开更多
基金Supported by the Petrochemical Research&Technology Co. of National Petrochemical Co.
文摘The applicability of a commercial Pt-Sn/Al2O3 isobutane dehydrogenation catalyst in dehydrogenation of propane was studied. Catalyst performance tests were carded out in a fixed-bed quartz reactor under different operating conditions. Generally, as the factors improving propane conversion decrease the propylene selectivity, the optimal operating condition to maximize propylene yield is expected. The optimal condition was obtamed by the experimental design method. The investigated parameters were temperature, hydrogen/hydrocarbon （HE/HC） ratio and space velocity, being changed in three levels. Constrains such as the susceptibility of the catalyst components to sintering or phase transformation were also taken into account. Activity, selectivity and stability of the catalyst were considered as the measured response factors, while the space-time-yield （STY） was considered as the variable to be optimized due to its commercial interest. A STY of 16 mol.kg^-1.h^-1 was achieved under the optimal conditions of T= 620 ℃, H2/HC = 0.6 and, weight hourly space velocity （WHSV） = 2.2 h^-1. Single carbon-carbon bond rupture was found to be the main route for the formation of lower hydrocarbon byproducts.
基金supported by the Joint Funds of National Key R&D Program of China(2018YFB0604603)the National Natural Science Foundation of China(21536009,21776229)+2 种基金Science and Technology Plan Projects of Shaanxi Province(2017ZDCXL-GY-10-03,2018ZDXMGY-167)The Young Science and Technology Star Project of Shaanxi Province(2017KJXX-62)Science and Technology Program of Yulin(2018-2-22)。
文摘The selective catalytic hydrogenation of naphthalene to high-value tetralin was systematically investigated.A series of Al2O3 catalysts containing different active metals(Co,Mo,Ni,W)were prepared by incipient wetness impregnation.The effects of different active metals forms(oxidation,reduction,sulfuration)and reaction conditions on naphthalene hydrogenation were investigated and the catalysts were characterized by XRD,XPS,BET,NH3-TPD and SEM.Especially,Ni-Mo/Al2O3 was first used in this reactive system.The results show that the oxidative4%Ni O-20%MoO3/Al2O3 is the best catalyst for the preparation of tetralin.The conversion of naphthalene and the selectivity of tetralin can reach 95.62%and 99.75%respectively at 200℃,8 h and 6 MPa.Compared with reduced and sulfureted 4%Ni O-20%MoO3/Al2O3 catalysts,oxidative 4%Ni O-20%MoO3/Al2O3 has a well dispersed and uniform monolayer of the active metals,larger pore volume and size,and larger total acidity.NiO-MoO3/Al2O3 has a synergistic effect between NiO activity and MoO3 selectivity.
基金Supported by the Special Funds for Major State Basic Research Program of China （No.2003CB615702）, the National Natural Science Foundation of China （No.20636020） and the Natural Science Foundation of Jiangsu Province （No.BK2006722）.
文摘The catalytic hydrogenation of p-nitrophenol to p-aminophenol was investigated over Ni/Al2O3 catalyst on alumina support with different particle size. It is found that support particle size has significant influences on physiochemical properties and catalytic activity of the resulting Ni/Al2O3 catalyst, but little influence on the selec-tivity. At a comparable amount of Ni loading, the catalytic activity of Ni/Al2O3 prepared with alumina support of smaller particle size is lower. The reduction behavior of the catalyst is a key factor in determining the catalytic activity of Ni/Al2O3 catalyst. The supported nickel catalyst 10.3Ni/Al2O3-3 improves the life span of the membrane by reducing fouling on the membrane surface compared to nano-sized nickel.
基金Funded by the National Natural Science Foundation of China(No.21476177)。
文摘A series of heteropoly acid (HPA) based Al2O3 catalysts with three-dimensional ordered (3DOM) structure were synthesized by colloidal crystal template method.Interconnected macropores (250 nm) could be clearly observed by scanning electron microscope (SEM) and transmission electron microscope (TEM).Mesopores could be detected by N2 adsorption-desorption isotherms which further confirmed the 3DOM structural characteristics of catalyst.Moreover,Keggin-type HPW was highly dispersed in the Al2O3 framework,which suggested by powder X-ray diffraction (XRD) and Fourier transform infrared spectra (FT-IR) results.The oxidation desulfurization (ODS) performance of 3DOM H3PW12O40/Al2O3 of refractory sulphur compounds was evaluated in the presence of hydrogen peroxide.It oxidized 98.5% of dibenzothiophene (DBT) into corresponding sulfone within 3 h,which exhibited superior ODS performance than corresponding mesoporous and microporous H3PW12O40/Al2O3 catalyst.The enhancement of ODS efficiency is related to the improvement of mass transfer of DBT in the pore channel resulting from the interconnected 3DOM structure.Furthermore,the as-prepared catalyst still demonstrates outstanding cycle performance after 6 runs,which could be easily recovered from the model fuel.
基金Supported by the National Natural Science Foundation of China(21673132).
文摘The deactivation of Ni/SiO2-Al2 O3 catalyst in hydrogenation of crude 1,4-butanediol was investigated.During the operation time of 2140 h,the catalyst showed slow activity decay.Characterization results,for four spent catalysts used at different time,indicated that the main reason of the catalyst deactivation was the deposition of carbonaceous species that covered the active Ni and blocked mesopores of the catalyst.The TPO and SEM measurements revealed that the carbonaceous species included both oligomeric and polymeric species with high C/H ratio and showed sheet.Such carbonaceous species might be eliminated through either direct H2 reduction or the combined oxidation-reduction methodologies.
基金the National Natural Science Foundation of China (51676090)the Natural Science Foundation of Jiangsu Province (BK20150513), and the Six Talent Peaks Project in Jiangsu Province.
文摘In this investigation, Pt–Ba–Ce/c-Al2O3 catalysts were prepared by incipient wetness impregnation and experiments were performed to evaluate the influence of H2 on the evolution mechanism of nitrogen oxides (NOx) storage and reduction (NSR). The physical and chemical properties of the Pt–Ba–Ce/c- Al2O3 catalysts were studied using a combination of characterization techniques, which showed that PtOx, CeO2, and BaCO3, whose peaks were observed in X-ray diffraction (XRD) spectra, dispersed well on the c-Al2O3, as shown by transmission electron microscope (TEM), and that the difference between Ce3+ and Ce4+, as detected by X-ray photoelectron spectroscopy (XPS), facilitated the migration of active oxygen over the catalyst. In the process of a complete NSR experiment, the NOx storage capability was greatly enhanced in the temperature range of 250–350℃, and reached a maximum value of 315.3μmol·gcat^-1 at 350℃, which was ascribed to the increase in NO2 yield. In a lean and rich cycling experiment, the results showed that NOx storage efficiency and conversion were increased when the time of H2 exposure (i.e., 30, 45, and 60 s) was extended. The maximum NOx conversion of the catalyst reached 83.5% when the duration of the lean and rich phases was 240 and 60 s, respectively. The results revealed that increasing the content of H2 by an appropriate amount was favorable to the NSR mechanism due to increased decomposition of nitrate or nitrite, and the refreshing of trapping sites for the next cycle of NSR.
基金Acknowledgements This research was supported by the National High Technology Research and Development Program of China （Nos. 2010AA064904 and 2012AA062702） and the National Natural Science Foundation of China （Grant No. 21177006）.
文摘The effect of Zr on the catalytic performance of Pd/y-A1203 for the methane combustion was investigated. The results show that the addition of Zr can improve the activity and stability of Pd/γ-Al2O3 catalyst, which, based on the catalyst characterization （N2 adsorption, XRD, CO- Chemisorption, XPS, CHa-TPR and O2-TPO）, is ascribed to the interaction between Pd and Zr. The active phase of methane combustion over supported palladium catalyst is the Pd^0/Pd^2＋ mixture. Zr addition inhibits Pd aggregation and enhances the redox properties of active phase Pd^0/ Pd^2＋. H2 reduction could effectively reduce the oxidation degree of Pd species and regenerate the active sites （Pd^0/ pd^2＋）.
基金supported by the National Nature Science Foundation of China(No.20903054).
文摘The surface nature of fresh Mo2N/Al2O3, Mo2C/Al2O3 and/MoP/Al2O3 catalysts, which were synthesized directly in the IR cell to avoid passivation, were characterized by in situ IR spectroscopy with CO as a probe molecule. CO adsorbed on fresh catalysts showed characteristic IR bands at 2045 cm-1 for Mo2N/Al2O3 catalyst, 2054 cm-1 for MozC/Al2O3 catalyst and 2037 cm-1 for MoP/Al2O3 catalyst, respectively. A strong band at 2200 cm-1 for Mo2N/Al2O3 catalyst, which could be ascribed to NCO species formed when CO reacted upon surface active nitrogen atoms, and a weak band at 2196 cm-1 for Mo2C/Al2O3 catalyst, which could be attributed to CCO species, were also detected. CO adsorbed on fresh Mo2N/Al2O3 catalyst, Mo2C/Al2O3 catalyst and MoP/Al2O3 catalyst, showed strong molecular adsorption, just like noble metals. Our experimental results are bolstered by direct IR evidence demonstrating the similarity in surface electronic property between the fresh Mo2N/Al2O3, Mo2C/Al2O3 and MoP/Al2O3 catalysts and noble metals.
基金financially supported by the National Natural Science Foundation of China(21173195)~~
文摘A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-containing catalysts were lower than those of the K-free ones, particularly for catalysts with high Pt contents （51.6 k）/mol for 0.42K-2.0Pt/Al2O3 and 6：3.6 kJ/mol for 2.0Pt/Al2O3 ）. The CO reaction orders were higher for the K-containing catalysts （about -0.2） than for the K-free ones （about -0.5）, with the former having much lower equilibrium constants for CO adsorption than the latter. In situ Fourier-transform infrared spectroscopy showed that surface CO desorption from the 0.42K-2.0Pt/Al2O3 catalyst was easier than from 2.0Pt/Al2O3. The promoting effect of K was therefore caused by weakening of the interactions between CO and surface Pt atoms. This decreased coverage of the catalyst with CO and facilitated competitive O2 chemisorption on the Pt surface, and significantly lowered the reaction barrier between chemisorbed CO and O2 species.
基金financially supported by Independent Research Subject from Ministry of Science and Technology of China(No.2008BWZ005)
文摘Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2（molar ratio）=1：3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.
