Mechanism of methanol synthesis on copper/zinc oxide/chromia catalyst

522-527The methanol synthesis catalyst Cu/ZnO/Cr2O3 is studied using IR and diffuse reflectance spectroscopy (DRS) and temperature programmed desorption (TPD) techniques. DRS shows copper to be present as Cuᵒ and Cu+. IR spectrum of adsorbed CO shows two bands. one due to linear adsorption on a single site and the other due to bridge-type adsorption. The TPD of adsorbed CO shows two desorption regions, one in the temperature range of 300 - 400K and another above 540K with readsorption taking place between 400 and 500K. The TPD of H2 also shows two desorption regions. CO is considered to be adsorbed on Cu and H2 on ZnO. The TPD of co-adsorbed CO and H2 indicates interaction between CO and H2. IR spectroscopic study of methanol decomposition suggests that the decomposition involves methoxide and formate intermediates. A mechanism is proposed for the synthesis reaction