Ftir study of crotyl alcohol, crotonaldehyde and crotonic acid adsorption on the surface of the V/Zr oxide catalyst

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 ZrO 2 - 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 V 2 O 5 -ZrO 2 catalyst is the conversion ofcarboxylate 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 V 2 O 5 -ZrO 2 catalyst was not shown.