丙烯直接气相氧化过程中Ag/TS-1催化剂上活性银物种的分布

Distribution of active silver species of Ag/TS-1 catalyst on direct gas-phase epoxidation of propylene

在常压固定床、石英反应器中,以丙烯直接气相氧化反应为探针,考察了硅烷化处理及TS-1中模板剂对Ag/TS-1催化性能的影响.同时,采用UV-Vis、ICP和TEM等手段对其进行了表征.结果表明:在丙烯直接气相氧化过程中,载体TS-1硅烷化后所制备的Ag/TS-1的催化性能增强.通过硅烷化处理负载2%SiO2,制备的Ag/TS-1的丙烯转化率可达2.1%,环氧丙烷选择性98.4%.用TS-1原粉(含有模板剂)所制备的Ag/TS-1不具有环氧化性能.分子筛内外表面的银物种均具有环氧化性能,但内表面的银物种在丙烯气相氧化过程中起决定性的作用.

The effects of silylation treatment and the template of TS-1 on the catalytic properties of Ag/ TS-1 were investigated in a fixed bed, quartz reactor at ambient pressure, using the gas-phase epoxidation of propylene with hydrogen and oxygen as a probe, Moreover, the catalysts were characterized by UVVis, ICP and TEM, The results showed that, during the direct gas-phase epoxidation of propylene, the catalytic properties of Ag/TS-1 could be improved when TS-1 was silylanized, When 2%SiO2 was loaded on TS-1, 2, 1% propylene conversion with 98, 4% selectivity to propylene oxide （PO） was obtained over Ag/TS-1, The Ag/TS-1 did not show any catalytic selectivity to PO, when the TS-1 powder （with template） was used as the support, Both inner and outer silver species of Ag/TS-1 showed catalytic properties, however, the inner ones were the key active species in the gas-phase epoxidation of propylene,