Promotional effect of Y2O3 on the performance of Ag/α-Al2O3 catalyst for epoxidation of propylene with molecular oxygen
- 作者：Wei Yao ; Guanzhong Lu ; Yanglong Guo ; Yun Guo ; Yanqin Wang ; Zhigang Zhang
- 关键词：Silver/alumina catalyst ; Y2O3 promoter ; Epoxidation of propylene ; Molecular oxygen
- 刊名：Journal of Molecular Catalysis A ; Chemical
- 出版年：2007
- 期刊代码：57_13811169
- 类别：ch
- 出版时间：17 October 2007
- 卷：276
- 期：1-2
- 页码：162-167
- 文件大小：806 K
摘要
The Ag/α-Al2O3 catalysts modified with rare earth, alkali and alkaline earth metal oxides for the epoxidation of propylene by molecular oxygen were prepared and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), CO2-temperature programmed desorption (CO2-TPD), BET surface area and pore diameter distribution. The results show that the appropriate pore diameter and high surface area of α-Al2O3 support, and the suitable basic sites on the surface of catalyst are necessary to the highly effective Ag catalyst for the epoxidation of propylene. The presence of a small quantity of Y2O3 can restrain the sintering of Ag particles on the surface of α-Al2O3 and adjust the surface basicity of catalyst. The loadings of promoters and reaction temperature obviously affect the performance of Ag catalysts. Under the reaction condition of 0.1 MPa, 245 °C, space velocity 2000 h−1 and the feed of 20%C3H6/8%O2/N2, 4%conversion of propylene and 46.8%selectivity to propylene oxide were obtained over the 20 wt%Ag–0.1%Y2O3–0.1%K2O/α-Al2O3 catalyst.