Why Copper Is Intrinsically More Selective than Silver in Alkene Epoxidation:Ethylene Oxidation on Cu(111)versus Ag(111)

摘要

The heterogeneously catalyzed epoxidation of terminal alkenes is experimentally challenging,theoretically interesting,and technologically important.The epoxide products are versatile intermediates in chemical synthesis,yet aspects of the reaction mechanism await clarification.In principle,studies carried out on well-defined surfaces under ultrahigh vacuum(UHV)conditions offer a means of examining mechanistic issues at a fundamental level.However,it is not possible to study the adsorption and subsequent oxidation of ethylene itself on metal single-crystal surfaces under UHV because its adsorption enthalpy is too low-the molecule desorbs before it can react.