Is the observed hydrogenation of formate the rate-limiting step in methanol synthesis?

Abstract

The role of formate in the synthesis of methanol from CO₂–H₂ Ges mixtures over copper is examined: It has often been assumed that the hydrogenation of the formate intermediate is the rate-limiting step in the synthesis since it is the most stable intermediate observed. The hydrogenation rate was determined experimentally on a Cu(100) single crystal. The results were examined by a micro-kinetic model, and indicate that the experimentally measured hydrogenation cannot directly lead to methanol synthesis. Instead, the results suggest that the measured hydrogenation of formate most likely leads to formaldehyde and/or formic acid, which could be side products and/or intermediates of the synthesis process.