In silver catalyzed ethylene epoxidation relatively large particles are desired because small silver particles are less active to the desired products.[1] Larger particles have lower specific metal surface areas. Controlling the particle size of ethylene epoxidation catalysts is therefore critical. Different particle sizes can be obtained using different precursors, support materials or metal loadings, but changing several key parameters at once may obscure particle size effects. We investigated how heat treatment in different gas atmospheres [2], as well as at different temperatures, can be used to tune the final particle size without changing support (8 m2/g α-Al2O3) or silver loading (15 wt%). Starting from impregnating α-Al2O3 with Ag2C2O4 [3] and exposing the obtained material to different heat treatments, we tuned the particle size from 20 to 400 nm. The resulting catalysts revealed a strong particle size effect on activity and a particle size independent selectivity (Figure). [1] Goncharova, S.N., Paukshtis, E.A., Bal’zhinimaev, B.S., Appl. Catal. A, 126 (1995) 67-84. [2] Munnik, P., Krans, N.A., de Jongh, P.E., de Jong, K.P., ACS Catal., 4 (2014) 3219–3226. [3] Jiang, J., Xu, T., Li, Y., Lei, X., Zhang, H., Evans, D.G., Sun, X. Duan, X., Bull. Korean Chem. Soc. 35 (2014) 1832–1836.

Particle size effects of Ag/α-Al2O3 for ethylene epoxidation

251st National Meeting (2016)

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