Selective hydrogenation of acetophenone to 1-phenyl ethanol over nanofibrous Ag-OMS-2 catalysts

Hydrogenation of acetophenone is interesting and poses a challenge in selective conversion to 1-phenyl ethanol which is a perfumery chemical. It is a complex network of series and parallel reactions. Silver incorporated octahedral molecular sieve catalysts (Ag-OMS-2) were synthesized by precipitation method and employed in the hydrogenation of acetophenone to 1-phenyl ethanol (1-PEA). The catalysts were fully characterized by TGA, XRD, SEM, EDX, TPD, TPR and nitrogen adsorption. They show a nano fibrous structure with very high activity toward hydrogenation. Acetophenone conversion increased with an increase in silver loading from 5 to 15% by wt. 15% Ag-OMS-2 showed the highest activity and 100% selectivity to 1-PEA at hydrogen pressure of 10 atm and 160 degrees C. Effects of various parameters such as speed of agitation, type of solvent, catalyst loading, acetophenone concentration, and temperature were studied. A kinetic model was built using Langmuir-Hinshelwood-Hougen-Watson mechanism with weak adsorption of all species leading to a power law model. The activation energy was found to be 12.38 kcal/mol. (C) 2012 Elsevier B.V. All rights reserved.