Examination of the surface chemistry of activated carbon on enantio selective hydrogenation of methyl pyruvate over Pt/C catalysts

Pt/C catalysts were prepared on oxidized activated carbons. Different oxidation treatments were used both in liquid and gas phase using HNO3 and 5% O-2/N-2 as the respective oxidizing agents. Thus, different surface chemical properties were achieved. The enantioselective hydrogenation of methyl pyruvate with (-)-cinchonidine as modifier revealed that the catalytic activity is dependent on the concentration of the surface oxygen remaining after activation as measured by XPS. It is suggested that it is a result of the increase in the carbon hydrophilicity that would enable the reactants to go through the catalyst. It is also suggested that the active sites created by the decomposition of the functional groups would allow hydrogen chemisorption and, therefore, the C=O polarization via hydrogen bond interaction. The chemical nature of the surface functional groups did not seem to influence either the catalytic activity or enantioselectivity. (C) 2002 Elsevier Science B.V. All rights reserved.