In situ Infrared Spectroscopic Study of CH4 Oxidation Over Co–ZSM-5

Surface species formed in CH 4 activation over Co–ZSM-5 were monitored by in situ DRIFT spectroscopy. IR absorption bands assigned to adsorbed methoxide, formate and polyoxymethylene were detected. The similarities in the IR bands and their evolution during He purge after reactions conducted under anaerobic and aerobic conditions suggested that Cannizzaro disproportionation of formaldehyde is a significant reaction pathway. This was verified when water was found to react with a surface species to form adsorbed formate. Continued formation of surface formate was observed during purging in He which indicated substantial surface storage of formaldehyde as polyoxymethylene.