The stability of supported metal particles is an important parameter in heterogenous catalysis. For silver catalysts supported on α-alumina, industrially used in ethylene epoxidation, the loss of silver surface area as result of particle growth is one of the most important deactivation mechanisms. In this work, the growth of silver particles was investigated by exposing catalysts to thermal treatments. The presence of oxygen during heating strongly enhanced particle growth, and the interparticle distance was a crucial parameter. However, restricting movement of complete silver particles using cage-like α–alumina did not limit particle growth. These findings indicate that Ostwald ripening was the dominant mechanism behind particle growth, with the diffusion of oxidized silver species being a rate limiting factor. Finally, higher surface area α–alumina provided better silver stability during ethylene epoxidation, with only limited decrease in selectivity. This makes silver supported on high surface area α–alumina promising candidates for ethylene epoxidation catalysis.

负载金属颗粒的稳定性是多相催化中的一个重要参数。对于负载在 α-氧化铝上的银催化剂，工业上用于乙烯环氧化，由于颗粒生长而导致的银表面积损失是最重要的失活机制之一。在这项工作中，通过将催化剂暴露于热处理来研究银颗粒的生长。加热过程中氧气的存在极大地促进了粒子的生长，粒子间距离是一个关键参数。然而，使用笼状 α-氧化铝限制完整银粒子的运动并没有限制粒子的生长。这些发现表明，奥斯特瓦尔德熟化是颗粒生长的主要机制，氧化银物质的扩散是一个速率限制因素。最后，较高的表面积α-氧化铝在乙烯环氧化过程中提供了更好的银稳定性，而选择性仅降低有限。这使得负载在高表面积α-氧化铝上的银成为乙烯环氧化催化的有希望的候选者。