A series of tungsten-substituted molybdophosphoric acids(H3PMo12-nWnO40·xH2O) were synthesized and characterized by inductive coupled plasma atomic emission spectroscopy(ICPAES),thermal gravimetry and differentia...A series of tungsten-substituted molybdophosphoric acids(H3PMo12-nWnO40·xH2O) were synthesized and characterized by inductive coupled plasma atomic emission spectroscopy(ICPAES),thermal gravimetry and differential scanning calorimetry(TG-DSC),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and FTIR pyridine adsorption.The as-prepared heteropoly acids have a Keggin type structure.The synthesis of tetrahydrofuran by reactive distillation and cyclodehydration of 1,4-butanediol was studied using the tungsten-substituted molybdophosphoric acids as catalysts.The results of catalytic test indicated that the catalytic activity increased with the increase in the substitution number(n) of tungsten atom in H3PMo12-nWnO40·xH2O and was constant as the substitution number(n) was more than 8.The catalytic activity increased with the increase in the catalyst loading and the selectivity of tetrahydrofuran was nearly 100%.展开更多
A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction...A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, in situ laser Raman spectroscopy, UV-Vis diffused reflectance spectroscopy, scanning electron microscopy, and temperature-programmed desorption of NH3 techniques. Their catalytic activities were evaluated for the vapor phase aerobic oxidation of benzyl alcohol. The catalysts exhibited high catalytic activity and the conversion of benzyl alcohol depended on the vanadia content while the catalyst with 15 wt% V2O5 content showed optimum activity. The characterization results suggest the presence of well-dispersed V2O5 and partially disintegrated Keggin ions of MPA on the support. In situ Raman studies showed a reduced Mo(IV) species when the catalysts were calcined at high temperatures. The high oxidation activity of the catalysts is related to the synergistic effect between MPA and V2O5.展开更多
基金Supported by Research Funds from Chinese Education Department (2003406)Bureau of Science and Technology of Jiangsu Province (BG2006025)
文摘A series of tungsten-substituted molybdophosphoric acids(H3PMo12-nWnO40·xH2O) were synthesized and characterized by inductive coupled plasma atomic emission spectroscopy(ICPAES),thermal gravimetry and differential scanning calorimetry(TG-DSC),Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD),and FTIR pyridine adsorption.The as-prepared heteropoly acids have a Keggin type structure.The synthesis of tetrahydrofuran by reactive distillation and cyclodehydration of 1,4-butanediol was studied using the tungsten-substituted molybdophosphoric acids as catalysts.The results of catalytic test indicated that the catalytic activity increased with the increase in the substitution number(n) of tungsten atom in H3PMo12-nWnO40·xH2O and was constant as the substitution number(n) was more than 8.The catalytic activity increased with the increase in the catalyst loading and the selectivity of tetrahydrofuran was nearly 100%.
基金supported by the Department of Science & Technology, New Delhi under SERC scheme, DST No. SR/S1/PC-40/2006
文摘A series of 12-molybdophosphoric acid (MPA) supported on V2O5 dispersed γ-Al2O3 catalysts with different vanadia loadings were prepared by impregnation and characterized by N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction, in situ laser Raman spectroscopy, UV-Vis diffused reflectance spectroscopy, scanning electron microscopy, and temperature-programmed desorption of NH3 techniques. Their catalytic activities were evaluated for the vapor phase aerobic oxidation of benzyl alcohol. The catalysts exhibited high catalytic activity and the conversion of benzyl alcohol depended on the vanadia content while the catalyst with 15 wt% V2O5 content showed optimum activity. The characterization results suggest the presence of well-dispersed V2O5 and partially disintegrated Keggin ions of MPA on the support. In situ Raman studies showed a reduced Mo(IV) species when the catalysts were calcined at high temperatures. The high oxidation activity of the catalysts is related to the synergistic effect between MPA and V2O5.
