Molecular Design of Highly Active Methanol Synthesis Catalysts

Active catalysts for the synthesis of methanol from H 2 /CO 2 and H 2 /CO can be prepared by dispersing Cu on ZrO 2 . Mechanistic investigations demonstrate that these catalysts are bifunctional. ZrO 2 serves to adsorb CO x and retain all carbon-containing intermediates, whereas Cu adsorbs H 2 dissociatively and provides H atoms to the surface of ZrO 2 by spillover. Methanol is formed by the stepwise hydrogenation of carbon-containing species on ZrO 2 . The adsorption capacity of monoclinic ZrO 2 (m-ZrO 2 ) is significantly higher than that of tetragonal ZrO 2 (t-ZrO 2 ). Correspondingly, the methanol synthesis activity of Cu/m-ZrO 2 is higher than that of Cu/t-ZrO 2 . However, the observed increase in the rate of methanol synthesis is less than that anticipated on the basis of the relative CO x adsorption capacities of m-ZrO 2 and t-ZrO 2 . A possible explanation for this is discussed.