Dynamics of silver particles during ethylene epoxidation

Dynamics of silver particles during ethylene epoxidation

[Display omitted] •Evolution Ag/α-Al2O3 catalyst for ethylene epoxidation investigated.•Catalyst deposited on Si3N4 wafers for identical location imaging by EM.•Size- and chlorine-dependent dynamic behaviour of silver particles.•Silver particles > 100 nm breakup under influence of chlorine.•Silve...

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Bibliographic Details
Published in:Applied catalysis. B, Environmental Vol. 272; p. 118983
Main Authors: van Hoof, A.J.F., van der Poll, R.C.J., Friedrich, H., Hensen, E.J.M.
Format: Journal Article
Language:English
Published: Amsterdam Elsevier B.V 05-09-2020
Elsevier BV
Subjects:
Aluminum oxide
Chlorine
dynamic evolution
Epoxidation
Ethylene
ethylene oxide
Oxidation
Particulates
silver
transmission electron microscopy
silver
transmission electron microscopy
ethylene oxide
dynamic evolution
chlorine
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Summary:[Display omitted] •Evolution Ag/α-Al2O3 catalyst for ethylene epoxidation investigated.•Catalyst deposited on Si3N4 wafers for identical location imaging by EM.•Size- and chlorine-dependent dynamic behaviour of silver particles.•Silver particles > 100 nm breakup under influence of chlorine.•Silver particles < 30 nm sinter under influence chlorine. Structural changes in α-Al2O3 supported silver particles during ethylene oxidation under industrially relevant conditions (20 bar and 225 °C, with and without chlorine) were investigated by quantitative TEM. Identical locations of two powder samples with average silver particle sizes of 41 nm and 127 nm were investigated in the fresh state and after 60 h of ethylene oxidation with and without chlorine. Without chlorine, silver particles were only slightly affected with a tendency for smaller (< 30 nm) particles to shrink. These silver particles even rapidly disappeared in the presence of chlorine. Particles larger than 100 nm tended to break up into smaller ones, indicative of a chlorine-induced re-dispersion process. These results confirm the dynamic nature of silver particles during the EO reaction and emphasize the role of chlorine on the observed substantial morphological changes of the active silver phase.
ISSN:0926-3373
1873-3883
DOI:10.1016/j.apcatb.2020.118983