Currently, for the industrial ethylene epoxidation α-alumina supported silver catalysts are the only catalyst of choice. We demonstrate a novel method to produce these catalysts with different silver particle sizes, but without changing other key parameters that may affect the catalytic performance such as support specific surface area or metal precursor. α-Alumina was impregnated with a silver oxalate solution, and was subsequently dried and treated in different gas atmospheres and at different temperatures to tune the silver particle sizes in the range of 20–500 nm. Particles of 20 nm exhibited a lower turnover frequency than particles of 70 nm and larger, which exhibit a constant turnover frequency, in accordance with results in literature. However, the selectivity, when measured at constant conversion, was particle size independent. This is the first time that the effect of the particle size on the selectivity of ethylene epoxidation is reported at constant conversion. This was made possible by a new method of producing supported silver catalysts, which we expect that is also applicable for silver catalysts with other supports and for the preparation of other supported metal catalysts.

当前，对于工业乙烯环氧化，α-氧化铝负载的银催化剂是唯一选择的催化剂。我们展示了一种生产这些具有不同银粒径的催化剂的新颖方法，但没有改变可能影响催化性能的其他关键参数，例如载体比表面积或金属前体。α-氧化铝用草酸银溶液浸渍，然后干燥并在不同的气体气氛和不同的温度下进行处理，以调节银的粒径在20-500 nm范围内。根据文献结果，20nm的颗粒比70nm的颗粒具有更低的周转频率，而更大的颗粒具有恒定的周转频率。但是，当以恒定转化率测量时，选择性与粒度无关。这是第一次以恒定转化率报道了粒径对乙烯环氧化选择性的影响。这是通过一种生产负载型银催化剂的新方法使之成为可能的，我们希望该方法也适用于带有其他载体的银催化剂以及其他负载型金属催化剂的制备。