Infrared spectroscopic investigation of hydrocarbon oxidation over Co and Cu supported on nano-ZSM-5

Co-ZSM-51 has been reported to be active for methane activation at low temperatures. Conventional ZSM-5 are often micron size crystallites or aggregates and intrapore diffusion could be problematic when a reactive intermediate is the desired product. Thus, nano ZSM-5 was synthesized as the support for Co and the formation of adsorbed species from methane was monitored with infrared spectroscopy. As a test, methanol was activated at 35°C and adsorbed formaldehyde and its polymeric forms were observed immediately. Methane activation required higher temperatures (160-200°C) and a number of CH stretching bands were observed to develop around 3000 cm^-1 region. Between 1000 and 2000 cm^-1 region, the most prominent band detected could be assigned to adsorbed formate. Rates of formation of the surface species depended on the manner of Co introduction onto the ZSM-5 support.