Promoter-Induced Morphological Changes of Ag Catalysts for Ethylene Epoxidation
Document Type
Article
Subject Area(s)
Engineering, Chemical Engineering, Catalysis and Reaction Engineering
Abstract
The combination of high-throughput reactor experiments and scanning electron microscopy analysis of promoted Ag catalysts provides critical insights into mechanistic and morphological changes. In particular, catalysts promoted with Cu, Cd, Au, Pt, and Re were analyzed to understand the morphological effects of these promoters on the Ag particles. Cu increases the sintering of Ag particles, while Cd and Re were found to alter the Ag particle sizes into a trimodal distribution. However, contrasting effects of Re and Cd were found on the catalyst activity. Cd−Ag catalysts exhibited a 5-fold increase in the ethylene conversion for a variety of Cd loadings, compared to unpromoted Ag. Moderate increases in conversion and selectivity were seen with the addition of 25 ppm Re, while further Re impregnation led to decreases in ethylene conversion and ethylene oxide selectivity. Au and Pt block surface Ag sites by nucleating as separate particles on the silver surface. In doing so, they reduce the activity of the catalyst, but also reduce the sintering of the Ag particles.
Digital Object Identifier (DOI)
Publication Info
Postprint version. Published in Industrial & Engineering Chemistry Research, Volume 48, Issue 13, 2009, pages 5943-5953.
Rights
© Industrial & Engineering Chemistry Research, 2009, American Chemical Society
APA Citation
Dellamorte, C.J., Lauterbach A.J., Barteau, A.M. (2009). Promoter-induced morphological changes of Ag Catalysts for Ethylene Epoxidation. Industrial & Engineering Chemistry Research, 48(13), 5943-5953.