Formation of HCO+ ion by protonation of carbon monoxide in zeolites: the origin of catalytic activity in methanol carbonylation

We show that CO can be protonated by Bronsted acid sites to form the super-electrophilic HCO+ cation in H-zeolites such as mordenite. This reactivity stems from the confining environment of small 8-ring side pockets of H-MOR. HCO+ is a catalytically active super-electrophile: it carbonylates dimethyl ether and hydrocarbons to methyl acetate and aldehydes.