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4173084 
Journal Article 
Preparation and particle size effects of Ag/alpha-Al2O3 catalysts for ethylene epoxidation 
van Den Reijen, JE; Kanungo, S; Welling, TAJ; Versluijs-Helder, M; Nijhuis, TA; de Jong, KP; de Jongh, PE 
2017 
Yes 
Journal of Catalysis
ISSN: 0021-9517
EISSN: 1090-2694 
356 
65-74 
WOS:000418223300007 
Currently, for the industrial ethylene epoxidation alpha-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. alpha-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. (C) 2017 Published by Elsevier Inc. 
Ethylene epoxidation; Silver; alpha-Alumina; Catalyst design; Ethylene oxide; Particle size effect