order to assess the promotional effects of La3+ on CO hydrogenation of Co/SiO2 catalyst, solvated metal atom impregnation (SMAI) method was used to prepare unpromoted 10% (mass fraction) Co/SiO2 and a series of La3+-p...order to assess the promotional effects of La3+ on CO hydrogenation of Co/SiO2 catalyst, solvated metal atom impregnation (SMAI) method was used to prepare unpromoted 10% (mass fraction) Co/SiO2 and a series of La3+-promoted 10% (mass fraction) Co/SiO2 catalyst with different La/Co atomic ratios (0.1, 0.3, 0.5). X-ray diffraction (XRD), and CO chemisorption measurements show that the cobalt particle size decreases as the La/Co ratios increase. X-ray photoelectron spectrescopy indicates that cobalt is in zero-valent state for all the samples. Catalytic test shows that the catalytic activity of La3+-promoted Co/SiO2 in CO hydrogenation is higher than that of unpromoted Co/SiO2, and enhances with the La/Co ratios increase. La3+ promotion also causes the enhanced selectivity of Co/SiO2 catalyst for higher hydrocarbon products.展开更多
NaY zeolite entrapped Ru3(CO)12 cluster has been synthesized from RuCl3 ion-exchanged NaY, which is well characterized by IR and Raman spectroscopies and CO chemisorp-tion. When the Ru3+/NaY sample is heated from 298 ...NaY zeolite entrapped Ru3(CO)12 cluster has been synthesized from RuCl3 ion-exchanged NaY, which is well characterized by IR and Raman spectroscopies and CO chemisorp-tion. When the Ru3+/NaY sample is heated from 298 K to 393 K for 25 h and for 10 h at 393 K, the sample colour changes from dark to brown-yellow. The in situ infrared spectrum exhibits absorption bands at 2130, 2064, 2040, 2017, 1990, 1953 and 1925 cm-1. The bands at 2130 cm-1 arises from the Runm+(CO)l m =1-3;n = 1 - 3; l = 1-12). The bands at 2064, 2040, 2017 and 1990 cm-1 are proposed to be associated with the Ru3(CO)12/NaY, which are close to Ru3(CO)12 crystalline. Furthermore, the Raman results provide bands at 150 and 185 cm-1, which can be attributed to Ru-Ru bonds of the sample as in the case of Ru3(CO)12 crystalline, for which the A1' Ru-Ru stretching mode is assigned to 185 cm-1 and E1' Ru-Ru stretching mode is assigned to a band at 150 cm-1, respectively. CO chemisorption of [Ru3]/NaY gives a CO/Ru ratio of 3.85, which is similar to the stoichiometry of Ru3(CO)12.展开更多
Interactions between metals and supports are of fundamental interest in heterogeneous catalysis, Noble metal particles supported on transition metal oxides (TMO) may undergo a so-called strong metal-support interactio...Interactions between metals and supports are of fundamental interest in heterogeneous catalysis, Noble metal particles supported on transition metal oxides (TMO) may undergo a so-called strong metal-support interaction via encapsulation. This perspective addresses catalytic properties of the metal catalysts in the SMSI state which can be explained on the basis of complementary studies. The electronic geometric and bifunctional effects originating from strong metal-support interactions (SMSI) that are responsible for the catalyst’s activity, selectivity, and stability are key factors that determine performance. A series of Pd-Sb supported on different metal oxide (<em>i.e.</em> SiO<sub>2</sub>, <em>γ</em>-Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and ZrO<sub>2</sub>) were prepared by the impregnation method. The catalysts were characterized by N<sub>2</sub> adsorption (BET-SA and pore size distribution), TEM (transmission electron microscope), TPR (temperature-programmed reduction), CO-chemisorption, the structural characterization of Pd (dispersity, surface area), interaction between Pd and Sb<sub>2</sub>O<sub>3</sub> and also the influence of the nature of the support were investigated. SiO<sub>2</sub> supported Pd catalyst exhibited the highest surface area (192.6 m<sup>2</sup>/g) and pore volume (0.542 cm<sup>3</sup>/g) compared to the other supported oxides catalysts. The electron micrographs of these catalysts showed a narrow size particle distribution of Pd, but with varying sizes which in the range from 1 to 10 nm, depending on the type of support used. The results show almost completely suppressed of CO chemisorption when the catalysts were subjected to high temperature reduction (HTR), this suppression was overcome by oxidation of a reduced Pd/MeOx catalysts followed by re-reduction in hydrogen at 453 K low temperature reduction (LTR), almost completely restored the normal chemisorptive properties of the catalysts, this suppression was attributed by SbOx species by a typical SMSI effect as known f展开更多
Pentalithium aluminate（β-LiAlO） and the corresponding iron-containing solid solution(Li(AlFe)O)were synthetized by solid-state reaction. All the samples were characterized structural and microstructurally by X-ray ...Pentalithium aluminate（β-LiAlO） and the corresponding iron-containing solid solution(Li(AlFe)O)were synthetized by solid-state reaction. All the samples were characterized structural and microstructurally by X-ray diffraction, solid-state nuclear magnetic resonance, scanning electron microscopy, Nadsorption-desorption and temperature-programmed desorption of CO. Results showed that 30 mol% of iron can be incorporated into the β-LiAlOcrystalline structure at aluminum positions. Moreover, iron addition induced morphological and superficial reactivity variations. Li(AlFe)Osamples chemisorbed CObetween 200 and 700 °C, where the superficial chemisorption presented the highest enhancement,in comparison to β-LiAlO. Additionally, Li(AlFe)Osamples sintered at higher temperatures thanβ-LiAlO. Isothermal COchemisorption experiments of β-LiAlOand Li(AlFe)Owere fitted to a first order reaction model, corroborating that iron enhances the COchemisorption, kinetically. When oxygen was added to the gas flow, COchemisorption process was mainly enhanced between 400 and 600 °C for the Li(AlFe)Osample in comparison to β-LiAlO. Hence, Li(AlFe)Osolid solution presented an enhanced COchemisorption process, in the presence and absence of oxygen, in comparison to β-LiAlO.展开更多
文摘order to assess the promotional effects of La3+ on CO hydrogenation of Co/SiO2 catalyst, solvated metal atom impregnation (SMAI) method was used to prepare unpromoted 10% (mass fraction) Co/SiO2 and a series of La3+-promoted 10% (mass fraction) Co/SiO2 catalyst with different La/Co atomic ratios (0.1, 0.3, 0.5). X-ray diffraction (XRD), and CO chemisorption measurements show that the cobalt particle size decreases as the La/Co ratios increase. X-ray photoelectron spectrescopy indicates that cobalt is in zero-valent state for all the samples. Catalytic test shows that the catalytic activity of La3+-promoted Co/SiO2 in CO hydrogenation is higher than that of unpromoted Co/SiO2, and enhances with the La/Co ratios increase. La3+ promotion also causes the enhanced selectivity of Co/SiO2 catalyst for higher hydrocarbon products.
基金Project supported by the National Natural Science Foundation of China for Young Scientists and the Excellent Junior Faculty Foundation of the State Education Commission.
文摘NaY zeolite entrapped Ru3(CO)12 cluster has been synthesized from RuCl3 ion-exchanged NaY, which is well characterized by IR and Raman spectroscopies and CO chemisorp-tion. When the Ru3+/NaY sample is heated from 298 K to 393 K for 25 h and for 10 h at 393 K, the sample colour changes from dark to brown-yellow. The in situ infrared spectrum exhibits absorption bands at 2130, 2064, 2040, 2017, 1990, 1953 and 1925 cm-1. The bands at 2130 cm-1 arises from the Runm+(CO)l m =1-3;n = 1 - 3; l = 1-12). The bands at 2064, 2040, 2017 and 1990 cm-1 are proposed to be associated with the Ru3(CO)12/NaY, which are close to Ru3(CO)12 crystalline. Furthermore, the Raman results provide bands at 150 and 185 cm-1, which can be attributed to Ru-Ru bonds of the sample as in the case of Ru3(CO)12 crystalline, for which the A1' Ru-Ru stretching mode is assigned to 185 cm-1 and E1' Ru-Ru stretching mode is assigned to a band at 150 cm-1, respectively. CO chemisorption of [Ru3]/NaY gives a CO/Ru ratio of 3.85, which is similar to the stoichiometry of Ru3(CO)12.
文摘Interactions between metals and supports are of fundamental interest in heterogeneous catalysis, Noble metal particles supported on transition metal oxides (TMO) may undergo a so-called strong metal-support interaction via encapsulation. This perspective addresses catalytic properties of the metal catalysts in the SMSI state which can be explained on the basis of complementary studies. The electronic geometric and bifunctional effects originating from strong metal-support interactions (SMSI) that are responsible for the catalyst’s activity, selectivity, and stability are key factors that determine performance. A series of Pd-Sb supported on different metal oxide (<em>i.e.</em> SiO<sub>2</sub>, <em>γ</em>-Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, and ZrO<sub>2</sub>) were prepared by the impregnation method. The catalysts were characterized by N<sub>2</sub> adsorption (BET-SA and pore size distribution), TEM (transmission electron microscope), TPR (temperature-programmed reduction), CO-chemisorption, the structural characterization of Pd (dispersity, surface area), interaction between Pd and Sb<sub>2</sub>O<sub>3</sub> and also the influence of the nature of the support were investigated. SiO<sub>2</sub> supported Pd catalyst exhibited the highest surface area (192.6 m<sup>2</sup>/g) and pore volume (0.542 cm<sup>3</sup>/g) compared to the other supported oxides catalysts. The electron micrographs of these catalysts showed a narrow size particle distribution of Pd, but with varying sizes which in the range from 1 to 10 nm, depending on the type of support used. The results show almost completely suppressed of CO chemisorption when the catalysts were subjected to high temperature reduction (HTR), this suppression was overcome by oxidation of a reduced Pd/MeOx catalysts followed by re-reduction in hydrogen at 453 K low temperature reduction (LTR), almost completely restored the normal chemisorptive properties of the catalysts, this suppression was attributed by SbOx species by a typical SMSI effect as known f
基金financially supported by the Project SENERCONACYT(251801)CONACYT for financial support through the CONACYT-SNI research assistant system and PNPC-CONACYT,respectively
文摘Pentalithium aluminate（β-LiAlO） and the corresponding iron-containing solid solution(Li(AlFe)O)were synthetized by solid-state reaction. All the samples were characterized structural and microstructurally by X-ray diffraction, solid-state nuclear magnetic resonance, scanning electron microscopy, Nadsorption-desorption and temperature-programmed desorption of CO. Results showed that 30 mol% of iron can be incorporated into the β-LiAlOcrystalline structure at aluminum positions. Moreover, iron addition induced morphological and superficial reactivity variations. Li(AlFe)Osamples chemisorbed CObetween 200 and 700 °C, where the superficial chemisorption presented the highest enhancement,in comparison to β-LiAlO. Additionally, Li(AlFe)Osamples sintered at higher temperatures thanβ-LiAlO. Isothermal COchemisorption experiments of β-LiAlOand Li(AlFe)Owere fitted to a first order reaction model, corroborating that iron enhances the COchemisorption, kinetically. When oxygen was added to the gas flow, COchemisorption process was mainly enhanced between 400 and 600 °C for the Li(AlFe)Osample in comparison to β-LiAlO. Hence, Li(AlFe)Osolid solution presented an enhanced COchemisorption process, in the presence and absence of oxygen, in comparison to β-LiAlO.
