Infrared studies of crotyl alcohol (but-2-en-1-ol), crotonaldehyde (but-2-enal) and crotonic acid (but-2-enoic acid) adsorption were carried out on ZrO2 - supported vanadium catalyst. The results were used to analyze the surface intermediates of crotonaldehyde dehydrogenation to maleic anhydride. Crotyl alcohol was adsorbed mainly in the alkoxide form, which is oxidized to crotonaldehyde and consecutively to crotonic acid. Final step in crotyl alcohol adsorption on V2O5-ZrO2 catalysis is the conversion of carboxylate species into maleic anhydride. The reaction of adsorbed crotonaldehyde and the oxygen atom of the catalyst resulted in the formation of carboxylate at higher temperature. The presence of two different surface carboxylate species (maleate and crotonate) was shown from IR spectra following crotonic acid adsorption. As distinct from the crotyl alcohol adsorption, the presence of surface maleic anhydride after adsorp-tion of crotonic acid and*or crotonaldehyde on V2O5-ZrO2 catalyst was not shown.
