Cesium promotion in styrene epoxidation on silver catalysts.
The adsorption of a small amount of cesium on Ag(110) redirects the partial oxidation products of styrene from phenylacetaldehyde and phenylketene to styrene oxide. The cesium stabilizes the oxametallacycle intermediate and hinders its transformation to the intermediate that leads to the other products. Cesium does not appear to create any electronic effects on the bonding of the intermediates. Low coverages of cesium induce a (1 x 2) missing-row reconstruction of the entire clean Ag(110) surface and a (3 x 5) surface oxide structure on the cesium-reconstructed Ag(110) surface. This (3 x 5)-ordered surface oxide is superimposed on the Ag(111) microfacets produced by the cesium-induced reconstruction, which leads to selectivity and reactivity very similar to those of the extended (111) surface. These studies provide insight into the microscopic origins of the structural effects of cesium in styrene epoxidation on silver catalysts.
Zhou
Ling
L
School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, Massachusetts 02138, USA.
Gorin
Craig F
CF
Madix
Robert J
RJ
D002384:Catalysis; D002586:Cesium / Q000737:chemistry*; D004852:Epoxy Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010316:Particle Size; D012834:Silver / Q000737:chemistry*; D020058:Styrene / Q000737:chemistry*; D013499:Surface Properties
D004852:Epoxy Compounds; D002586:Cesium; D012834:Silver; D020058:Styrene