Interaction of ethylene glycol with clean and oxidized surfaces of an
Ag catalyst has been studied under pre-catalysis conditions. On a clea
n surface, ethylene glycol was reversibly adsorbed with the formation
of a multilayer coverage. Adsorbed ethylene glycol weakly bonded to th
e oxidized silver surface leads to the selective formation of glyoxal
via two parallel routes: dehydrogenation and oxidation. Dissociative i
nteraction of ethylene glycol with Ag led to the appearance of formald
ehyde and carbon dioxide by-products.