Key Note: The role of solvent in heterogeneous catalysis: a compressive approach for hydrogenation reactions

CARLOS R. APESTEGU¨ªA; NICOL¨¢S M. BERTERO; ANDR¨¦S F. TRASARTI; ALBERTO J. MARCHI

Munich

Congreso; 15th ICC; 2012

The synthesis of fine chemicals over solid catalysts often involves the use of solvents that may strongly influence the catalyst performance. Thus, the choice of suitable solvents is frequently critical to obtain high catalytic activity and selectivity. However, the optimal solvent selection requires a detailed knowledge on the relationship between the chemical nature of the solvents and the interactions taking place in the gas-liquid-solid catalytic systems. In this work, the solvent effect on catalyst activity and selectivity for the liquid-phase hydrogenation of acetophenone (AP) to 1-phenylethanol was thoroughly investigated over Ni/SiO2. It was found that the AP hydrogenation activity followed the order: C2¨CC3 alcohols > cyclohexane > toluene > tetrahydrofuran > ¦Ã-butyrolactone > methanol >> benzene ¡Ö acetonitrile. The highest catalyst activity for AP hydrogenation in C2-C3 alcohols is explained on the basis of: (i) the dissociative chemisorption of alcohols over the metal nickel surface, which increases the amount of reactive chemisorbed hydrogen; (ii) the polarization and activation of the C=O bond of AP molecule due to its interaction with alcohol molecules through H-bond.