The transformation of formaldehyde on CoZSM-5 zeolites

The interaction of formaldehyde molecules with Co2+ ions in CoZSM-5 zeolites of various compositions containing various proportions between Co2+ in exchange positions and in oxide-like clusters, as well as the transformation of formaldehyde sorbed in zeolites was followed by IR spectroscopy. The interaction of formaldehyde with Co2+ resulted in a weakening of CO bond, what can be partially due to π-back donation of d electrons of Co2+ to π* antibonding orbitals of formaldehyde. Only Co2+ in exchange positions (contrary to Co2+ in oxide-like clusters) were able to interact with formaldehyde. IR studies illustrated also that formaldehyde molecules are oxidized to formate ions, by either Co3+ or Co2+ as oxidants. According to IR results Co3+ and Co2+ are reduced mostly to Co+ and metallic Co.