Titanium silicalite-1(TS-1) was synthesized by a hydrothermal synthesis method with different amounts of tetrapropyl ammonium hydroxide(TPAOH) as template.The as-prepared TS-1 was characterized by scanning electron mi...Titanium silicalite-1(TS-1) was synthesized by a hydrothermal synthesis method with different amounts of tetrapropyl ammonium hydroxide(TPAOH) as template.The as-prepared TS-1 was characterized by scanning electron microscopy,X-ray powder diffraction,Fourier-transform infrared resonance spectroscopy,ultravioletvisible diffuse reflectance spectroscopy and nitrogen physical adsorption and desorption,and studied in the propylene epoxidation with hydrogen peroxide in a fixed bed reactor.The results showed that the amount of TPAOH had a strong influence on the grain morphology,the amount of framework Ti,and the average particle sizes of TS-1.With the increase of TPAOH amount in the synthesis(the molar ratio of TPAOH/SiO_2 increasing from 0.25 to 0.45),the morphology changed gradually from ellipsoids to cubes,the particle sizes of TS-1 decreased slightly,the amount of the framework Ti increased appreciably,and the catalytic stability in the propylene epoxidation increased markedly.Moreover,all the catalysts had the same selectivity to propylene epoxide.However,when the molar ratio of TPAOH/SiO_2 was further increased to 0.55,the particles became large hexagons with the size distribution in a wide range,and the catalytic stability decreased sharply although the amount of the framework Ti increased further,which can be attributed to the long diffusion paths of the reactants in the zeolite.展开更多
Mesoporous molecular sieves possessing high mesopore volumes and large specific surface areas were prepared and characterized by means of XRD, low temperature N_2 adsorption-desorption measurements, FT IR, Raman, UV...Mesoporous molecular sieves possessing high mesopore volumes and large specific surface areas were prepared and characterized by means of XRD, low temperature N_2 adsorption-desorption measurements, FT IR, Raman, UV-visible diffuse reflectance and XPS spectroscopy. The materials contain both framework and extra-framework Ti centers which exhibit selective oxidation catalytic activity and photocatalytic activity respectively. The catalysis of selective oxidation was studied with the hydroxylation of benzene with hydrogen peroxide and photochemical activity was studied by the yields of ·OH and H_2O_2, respectively.展开更多
基金Supported by the National Natural Science Foundation of China(No.21276183)
文摘Titanium silicalite-1(TS-1) was synthesized by a hydrothermal synthesis method with different amounts of tetrapropyl ammonium hydroxide(TPAOH) as template.The as-prepared TS-1 was characterized by scanning electron microscopy,X-ray powder diffraction,Fourier-transform infrared resonance spectroscopy,ultravioletvisible diffuse reflectance spectroscopy and nitrogen physical adsorption and desorption,and studied in the propylene epoxidation with hydrogen peroxide in a fixed bed reactor.The results showed that the amount of TPAOH had a strong influence on the grain morphology,the amount of framework Ti,and the average particle sizes of TS-1.With the increase of TPAOH amount in the synthesis(the molar ratio of TPAOH/SiO_2 increasing from 0.25 to 0.45),the morphology changed gradually from ellipsoids to cubes,the particle sizes of TS-1 decreased slightly,the amount of the framework Ti increased appreciably,and the catalytic stability in the propylene epoxidation increased markedly.Moreover,all the catalysts had the same selectivity to propylene epoxide.However,when the molar ratio of TPAOH/SiO_2 was further increased to 0.55,the particles became large hexagons with the size distribution in a wide range,and the catalytic stability decreased sharply although the amount of the framework Ti increased further,which can be attributed to the long diffusion paths of the reactants in the zeolite.
基金Supported by the State Major Basic Research Project of China(No. 2 0 0 0 0 4 80 0 9) and the National Natural ScienceFoundation of China(No. 2 0 1730 0 3)
文摘Mesoporous molecular sieves possessing high mesopore volumes and large specific surface areas were prepared and characterized by means of XRD, low temperature N_2 adsorption-desorption measurements, FT IR, Raman, UV-visible diffuse reflectance and XPS spectroscopy. The materials contain both framework and extra-framework Ti centers which exhibit selective oxidation catalytic activity and photocatalytic activity respectively. The catalysis of selective oxidation was studied with the hydroxylation of benzene with hydrogen peroxide and photochemical activity was studied by the yields of ·OH and H_2O_2, respectively.
