The alcohol synthesis with a good proportion of higher alcohols was studied over promoted Co/CuLaZr catalysts. the molybdenum addition improved greatly the performance. The results of probe molecule tests could be use...The alcohol synthesis with a good proportion of higher alcohols was studied over promoted Co/CuLaZr catalysts. the molybdenum addition improved greatly the performance. The results of probe molecule tests could be used to explain the effects.展开更多
A single component molybdenum catalyst was synthesized and its activity in the cycloaddition reaction of CO_(2)and epoxide was tested.The results show that the molybdenum catalysts exhibit high activity and a broad su...A single component molybdenum catalyst was synthesized and its activity in the cycloaddition reaction of CO_(2)and epoxide was tested.The results show that the molybdenum catalysts exhibit high activity and a broad substrate scope under the reaction conditions of 80℃and 0.5 MPa of CO_(2),solvent-free,and and no nucleophilic cocatalysts,affording a wide range of cyclic carbonates in yields of 42%~94%.The reaction mechanism was investigated using in situ infrared(in situ IR),high-resolution mass spectrometry(HRMS)and Fourier transform infrared spectroscopy(FT-IR).展开更多
Mo-modified Pd/Al2O3catalysts were prepared by an impregnation method and tested for the catalytic combustion of benzene. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction（XRD）, X-ray p...Mo-modified Pd/Al2O3catalysts were prepared by an impregnation method and tested for the catalytic combustion of benzene. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, temperatureprogrammed desorption of NH3（NH3-TPD）, H2temperature-programmed reduction（H2-TPR）, and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM）. The results showed that the addition of Mo effectively improved the activity and stability of the Pd/Al2O3catalyst by increasing the dispersion of Pd active components, changing the partial oxidation state of palladium and increasing the oxygen species concentration on the surface of catalyst. In the case of the Pd-Mo/Al2O3catalyst,benzene conversion of 90% was obtained at temperatures as low as 190°C, which was 45°C lower than that for similar performance with the Pd/Al2O3catalyst. Moreover, the 1.0% Pd-5% Mo/Al2O3catalyst was more active than the 2.0% Pd/Al2O3catalyst. It was concluded that Pd and Mo have a synergistic effect in benzene catalytic combustion.展开更多
Synthesis of cyclic carbonates from carbon dioxide(CO_(2))and epoxides is an effective pathway for the CO_(2) utilization.Although various metal catalysts have been reported,it is highly desirable to develop a method ...Synthesis of cyclic carbonates from carbon dioxide(CO_(2))and epoxides is an effective pathway for the CO_(2) utilization.Although various metal catalysts have been reported,it is highly desirable to develop a method for the reuse or recycling of catalysts.Herein,an N-heterocyclic carbene-pyridine molybdenum complex supported over SBA-15(Mo@SBA-15)was used as an efficient and recyclable catalyst for converting CO_(2) and epoxides into cyclic carbonates.Mo@SBA-15 in combination with tetra-butylammonium bromide(TBAB)shows high catalytic activity in the synthesis of cyclic carbonates under 100℃and 1 MPa CO_(2) pressure.In addition,Mo@SBA-15 was reused seven times without any significant activity loss.展开更多
A series of Mo-containing MFI zeolites with different Mo loadings(Mo-MFI-n,n represent the initial Si/Mo molar ratio)was hydrothermally synthesized by using tetrapropylammonium hydroxide as the template and Mo-EDTA co...A series of Mo-containing MFI zeolites with different Mo loadings(Mo-MFI-n,n represent the initial Si/Mo molar ratio)was hydrothermally synthesized by using tetrapropylammonium hydroxide as the template and Mo-EDTA complex as the Mo source.Various characterization results demonstrated that the use of the Mo-EDTA complex is beneficial for the incorporation of more Mo species into the MFI-type zeolites.The special complexing capability of EDTA^(2–)plays a critical role in adjusting the release rate of the Mo species to combine with the Si tetrahedron species during the zeolite growth process,thus leading to a uniform distribution of Mo in the MFI framework.In addition,a small portion of extra-framework Mo clusters may be distributed inside the channels or near the pore window of the zeolites.The catalytic properties of these Mo-containing MFI zeolites were evaluated for the epoxidation of cyclohexene with H_(2)O_(2)as the oxidant.The composition-optimized catalyst,Mo-MFI-50,efficiently converted cyclohexene to the corresponding epoxide with a relatively high conversion(93%)and epoxide selectivity(82%)at 75℃after 9 h of reaction.Moreover,the resultant Mo-containing MFI catalyst exhibited excellent structural stability and recoverability and was easily recycled by simple filtration without the need for calcination treatment.展开更多
The kinetics of epoxidation of methylbutene with structurally identical methylbutane hydroperoxide was studied in the presence of a molybdenum catalyst. The analysis of the rate curves suggested the most probable sche...The kinetics of epoxidation of methylbutene with structurally identical methylbutane hydroperoxide was studied in the presence of a molybdenum catalyst. The analysis of the rate curves suggested the most probable scheme of the process. The revealed features of the process and its mathematical description make it possible to more competently design a reactor unit for the commercial production of isoprene according to the developed scheme. The main kinetic constants were calculated.展开更多
文摘The alcohol synthesis with a good proportion of higher alcohols was studied over promoted Co/CuLaZr catalysts. the molybdenum addition improved greatly the performance. The results of probe molecule tests could be used to explain the effects.
文摘A single component molybdenum catalyst was synthesized and its activity in the cycloaddition reaction of CO_(2)and epoxide was tested.The results show that the molybdenum catalysts exhibit high activity and a broad substrate scope under the reaction conditions of 80℃and 0.5 MPa of CO_(2),solvent-free,and and no nucleophilic cocatalysts,affording a wide range of cyclic carbonates in yields of 42%~94%.The reaction mechanism was investigated using in situ infrared(in situ IR),high-resolution mass spectrometry(HRMS)and Fourier transform infrared spectroscopy(FT-IR).
基金supported by the National High-Tech Research and Development Program (863) of China (No. 2008AA06XK1480855)
文摘Mo-modified Pd/Al2O3catalysts were prepared by an impregnation method and tested for the catalytic combustion of benzene. The catalysts were characterized by N2 isothermal adsorption, X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, temperatureprogrammed desorption of NH3（NH3-TPD）, H2temperature-programmed reduction（H2-TPR）, and high-angle annular dark-field scanning transmission electron microscopy（HAADF-STEM）. The results showed that the addition of Mo effectively improved the activity and stability of the Pd/Al2O3catalyst by increasing the dispersion of Pd active components, changing the partial oxidation state of palladium and increasing the oxygen species concentration on the surface of catalyst. In the case of the Pd-Mo/Al2O3catalyst,benzene conversion of 90% was obtained at temperatures as low as 190°C, which was 45°C lower than that for similar performance with the Pd/Al2O3catalyst. Moreover, the 1.0% Pd-5% Mo/Al2O3catalyst was more active than the 2.0% Pd/Al2O3catalyst. It was concluded that Pd and Mo have a synergistic effect in benzene catalytic combustion.
文摘Synthesis of cyclic carbonates from carbon dioxide(CO_(2))and epoxides is an effective pathway for the CO_(2) utilization.Although various metal catalysts have been reported,it is highly desirable to develop a method for the reuse or recycling of catalysts.Herein,an N-heterocyclic carbene-pyridine molybdenum complex supported over SBA-15(Mo@SBA-15)was used as an efficient and recyclable catalyst for converting CO_(2) and epoxides into cyclic carbonates.Mo@SBA-15 in combination with tetra-butylammonium bromide(TBAB)shows high catalytic activity in the synthesis of cyclic carbonates under 100℃and 1 MPa CO_(2) pressure.In addition,Mo@SBA-15 was reused seven times without any significant activity loss.
文摘A series of Mo-containing MFI zeolites with different Mo loadings(Mo-MFI-n,n represent the initial Si/Mo molar ratio)was hydrothermally synthesized by using tetrapropylammonium hydroxide as the template and Mo-EDTA complex as the Mo source.Various characterization results demonstrated that the use of the Mo-EDTA complex is beneficial for the incorporation of more Mo species into the MFI-type zeolites.The special complexing capability of EDTA^(2–)plays a critical role in adjusting the release rate of the Mo species to combine with the Si tetrahedron species during the zeolite growth process,thus leading to a uniform distribution of Mo in the MFI framework.In addition,a small portion of extra-framework Mo clusters may be distributed inside the channels or near the pore window of the zeolites.The catalytic properties of these Mo-containing MFI zeolites were evaluated for the epoxidation of cyclohexene with H_(2)O_(2)as the oxidant.The composition-optimized catalyst,Mo-MFI-50,efficiently converted cyclohexene to the corresponding epoxide with a relatively high conversion(93%)and epoxide selectivity(82%)at 75℃after 9 h of reaction.Moreover,the resultant Mo-containing MFI catalyst exhibited excellent structural stability and recoverability and was easily recycled by simple filtration without the need for calcination treatment.
文摘The kinetics of epoxidation of methylbutene with structurally identical methylbutane hydroperoxide was studied in the presence of a molybdenum catalyst. The analysis of the rate curves suggested the most probable scheme of the process. The revealed features of the process and its mathematical description make it possible to more competently design a reactor unit for the commercial production of isoprene according to the developed scheme. The main kinetic constants were calculated.
