反应控制法可控合成多层级银颗粒及其催化性能

Controllable synthesis of multi-layer silver particles by reaction control and its catalytic properties

采用反应控制法(即调控硝酸银、羟氨与甘氨酸体系中银的还原反应速率)合成了枝状、花状及球状三种不同形貌的具有多层级结构的银颗粒,将这三种银颗粒负载到氧化铝载体表面制成银催化剂,并研究了银颗粒的多层级结构对乙烯环氧化反应中银催化剂性能的影响。实验结果表明,反应控制法可实现多种形貌、不同层级结构的银颗粒的可控合成;而具有更丰富层级结构的暴露更多Ag(111)晶面的枝状银颗粒更有利于乙烯环氧化反应;控制反应过程中银的迁移以及银晶面结构的变化是提高银催化剂性能的关键。

Multi-layer structured silver particles with three different morphologies,dendritic,flower-like and spherical,were synthesized by reaction control,by regulating the reduction rate of silver ion in silver nitrate,hydroxylamine and glycine solution. Silver catalysts were prepared by loading silver particles onto the surface of the alumina supports. The effect of the multi-layer structures of the silver particles on the performance of silver catalysts in the ethylene epoxidation was investigated. The experimental results show Controllable synthesis of silver particles with various morphologies and different multi-layer structures can be realized by reaction control. The dendritic silver particles are more favorable for ethylene epoxidation reaction due to richer multilevel structure and more Ag(111) facets exposure,regulating the migration and facet structures of silver is key to improve the performance of silver catalysts.