The effects of Ce on reduction of non-chromium iron based CO shift catalyst were studied by XRD, TPR, SEM and XPS. The results show that Ce refines Fe2O3 grains and riches on the surface of catalyst in the process of ...The effects of Ce on reduction of non-chromium iron based CO shift catalyst were studied by XRD, TPR, SEM and XPS. The results show that Ce refines Fe2O3 grains and riches on the surface of catalyst in the process of reduction, which leads to decrease of the initial reductive temperature and increase of the final reductive temperature.展开更多
Co-Mo-based catalysts supported on mixed oxide supports MgO-Al2O3 with different Mg/Al atom ratios for water gas shift reaction were studied by means of TPR, Raman, XPS and ESR. It was found that the octahedral Mo spe...Co-Mo-based catalysts supported on mixed oxide supports MgO-Al2O3 with different Mg/Al atom ratios for water gas shift reaction were studied by means of TPR, Raman, XPS and ESR. It was found that the octahedral Mo species in oxidized Co-Mo/MgO（x）-Al2O3 catalyst and the contents of Mo^5＋, Mo^4＋, S^2- and S^2-2 species in the functioning catalysts increased with increasing the Mg/Al atom ratio of the support under the studied experimental conditions. This is favorable for the formation of the active Co-Mo-S phase of the catalysts. Catalytic performance testing results showed that the catalysts Co-Mo/MgO-Al2O3 with the Mg/Al atom ratio of the support in the range of 0.475-0.525 exhibited optimal catalytic activity for the reaction.展开更多
Co-Mo/MgO-Al2O3 catalyst was presulfided with ammonium sulfide in aqueous solution and activated with synthesis gas for water gas shift reaction. The assay results indicate that the presulfided Co-Mo/MgO-Al2O3 catalys...Co-Mo/MgO-Al2O3 catalyst was presulfided with ammonium sulfide in aqueous solution and activated with synthesis gas for water gas shift reaction. The assay results indicate that the presulfided Co-Mo/MgO-Al2O3 catalyst exhibits an excellent catalytic activity and stability. XRD and EPR characterization results show that the O-S exchange might occur during the impregnation, leading to the formation of （NH4）2MoS4 （or （NH4）zMoxSy） precursor, which was then thermally decomposed and reduced to MoS2. The higher catalytic performance is attributed to an optimization formation of active Co-Mo sulfides, consisting of well dispersed MoS2 and Co-Mo-S phase due to the redispersion of Co sulfide particles over the edges of newly formed MoS2 crystallites.展开更多
A modified co-precipitation method for the production of Cu/ZnO/Al2O3 complex was studied. The modification was that part of Al was introduced by adding Al^（3＋） into Cu^（2＋）/Zn^（2＋） solution, and the rest of ...A modified co-precipitation method for the production of Cu/ZnO/Al2O3 complex was studied. The modification was that part of Al was introduced by adding Al^（3＋） into Cu^（2＋）/Zn^（2＋） solution, and the rest of Al was added after co-precipitation step in the form of pseudo-boehmite. The prepared samples were characterized by different techniques such as X-ray diffraction, N2 adsorption, H2-N2O titration, temperature programmed reduction and scanning electron microscopy. X-ray diffraction characterizations revealed that Al^（3＋） can be doped in aurichalcite lattice, and the maximum doping amount of Al^（3＋） was 5.0% of total Cu and Zn atoms. The Cu/ZnO/Al2O3 sample produced by the modified method, in which co-precipitated Al^（3＋） was 2.5% of total Cu and Zn atoms showed much better activity and stability in water-gas shift reaction than commercial sample. The high Cu surface area（26.1 m^2/g） obtained by decompositon of doped aurichalcite is believed to be responsible for the activity enhancement. The stability was enhanced mainly because of the support effect of γ-Al2O3, which was decomposed from pseudo-boehmite in the calcination step.展开更多
The effect of potassium-decoration was studied on the activity of water-gas shift （WGS） reaction over the Co-Mo-based catalysts supported on active carbon （AC）, which was prepared by incipient wetness co-impregnat...The effect of potassium-decoration was studied on the activity of water-gas shift （WGS） reaction over the Co-Mo-based catalysts supported on active carbon （AC）, which was prepared by incipient wetness co-impregnation method. The decoration of potassium on active carbon in advance enhances the activities of the CoMo-K/AC catalysts for WGS reaction. Highest activity （about 92% conversion） was obtained at 250 ？ C for the catalyst with an optimum K 2 O/AC weight ratio in the range from 0.12 to 0.15. The catalysts were characterized by TPR and EPR, and the results show that activated carbon decorated with potassium makes Co-Mo species highly dispersed, and thus easily reduced and sulfurized. XRD results show that an appropriate content of potassium-decoration on active carbon supports may favors the formation of highly dispersed Co 9 S 8 -type structures which are situated on the edge or a site in contact with MoS 2 , K-Mo-O-S, Mo-S-K phase. Those active species are responsible for the high activity of CoMo-K/AC catalysts.展开更多
采用常压微反、程序升温还原(TPR)、程序升温硫化(TPS)及原位红外光谱(IR)等技术,对Co Mo Al2O3催化剂的表征研究发现:在Co Mo Al2O3催化剂中不仅存在着Co、Mo中心,而且存在由Co、Mo相互作用产生的中心,Co Mo Al2O3催化剂的催化性能是...采用常压微反、程序升温还原(TPR)、程序升温硫化(TPS)及原位红外光谱(IR)等技术,对Co Mo Al2O3催化剂的表征研究发现:在Co Mo Al2O3催化剂中不仅存在着Co、Mo中心,而且存在由Co、Mo相互作用产生的中心,Co Mo Al2O3催化剂的催化性能是由Co、Mo中心和Co、Mo相互作用产生的中心共同作用的结果。展开更多
文摘The effects of Ce on reduction of non-chromium iron based CO shift catalyst were studied by XRD, TPR, SEM and XPS. The results show that Ce refines Fe2O3 grains and riches on the surface of catalyst in the process of reduction, which leads to decrease of the initial reductive temperature and increase of the final reductive temperature.
基金supported by the National Key Research and Development Program of China(2020YFB0606404)National Natural Science Foundation of China(21991092,22272195,U2003123,U1910203).
文摘Co-Mo-based catalysts supported on mixed oxide supports MgO-Al2O3 with different Mg/Al atom ratios for water gas shift reaction were studied by means of TPR, Raman, XPS and ESR. It was found that the octahedral Mo species in oxidized Co-Mo/MgO（x）-Al2O3 catalyst and the contents of Mo^5＋, Mo^4＋, S^2- and S^2-2 species in the functioning catalysts increased with increasing the Mg/Al atom ratio of the support under the studied experimental conditions. This is favorable for the formation of the active Co-Mo-S phase of the catalysts. Catalytic performance testing results showed that the catalysts Co-Mo/MgO-Al2O3 with the Mg/Al atom ratio of the support in the range of 0.475-0.525 exhibited optimal catalytic activity for the reaction.
文摘Co-Mo/MgO-Al2O3 catalyst was presulfided with ammonium sulfide in aqueous solution and activated with synthesis gas for water gas shift reaction. The assay results indicate that the presulfided Co-Mo/MgO-Al2O3 catalyst exhibits an excellent catalytic activity and stability. XRD and EPR characterization results show that the O-S exchange might occur during the impregnation, leading to the formation of （NH4）2MoS4 （or （NH4）zMoxSy） precursor, which was then thermally decomposed and reduced to MoS2. The higher catalytic performance is attributed to an optimization formation of active Co-Mo sulfides, consisting of well dispersed MoS2 and Co-Mo-S phase due to the redispersion of Co sulfide particles over the edges of newly formed MoS2 crystallites.
基金the National Natural Science Foundation of China(51572201)
文摘A modified co-precipitation method for the production of Cu/ZnO/Al2O3 complex was studied. The modification was that part of Al was introduced by adding Al^（3＋） into Cu^（2＋）/Zn^（2＋） solution, and the rest of Al was added after co-precipitation step in the form of pseudo-boehmite. The prepared samples were characterized by different techniques such as X-ray diffraction, N2 adsorption, H2-N2O titration, temperature programmed reduction and scanning electron microscopy. X-ray diffraction characterizations revealed that Al^（3＋） can be doped in aurichalcite lattice, and the maximum doping amount of Al^（3＋） was 5.0% of total Cu and Zn atoms. The Cu/ZnO/Al2O3 sample produced by the modified method, in which co-precipitated Al^（3＋） was 2.5% of total Cu and Zn atoms showed much better activity and stability in water-gas shift reaction than commercial sample. The high Cu surface area（26.1 m^2/g） obtained by decompositon of doped aurichalcite is believed to be responsible for the activity enhancement. The stability was enhanced mainly because of the support effect of γ-Al2O3, which was decomposed from pseudo-boehmite in the calcination step.
文摘The effect of potassium-decoration was studied on the activity of water-gas shift （WGS） reaction over the Co-Mo-based catalysts supported on active carbon （AC）, which was prepared by incipient wetness co-impregnation method. The decoration of potassium on active carbon in advance enhances the activities of the CoMo-K/AC catalysts for WGS reaction. Highest activity （about 92% conversion） was obtained at 250 ？ C for the catalyst with an optimum K 2 O/AC weight ratio in the range from 0.12 to 0.15. The catalysts were characterized by TPR and EPR, and the results show that activated carbon decorated with potassium makes Co-Mo species highly dispersed, and thus easily reduced and sulfurized. XRD results show that an appropriate content of potassium-decoration on active carbon supports may favors the formation of highly dispersed Co 9 S 8 -type structures which are situated on the edge or a site in contact with MoS 2 , K-Mo-O-S, Mo-S-K phase. Those active species are responsible for the high activity of CoMo-K/AC catalysts.
文摘采用常压微反、程序升温还原(TPR)、程序升温硫化(TPS)及原位红外光谱(IR)等技术,对Co Mo Al2O3催化剂的表征研究发现:在Co Mo Al2O3催化剂中不仅存在着Co、Mo中心,而且存在由Co、Mo相互作用产生的中心,Co Mo Al2O3催化剂的催化性能是由Co、Mo中心和Co、Mo相互作用产生的中心共同作用的结果。
