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 °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.

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► Silver substituted octahedral molecular sieves as robust catalysts.
► Selective hydrogenation of acetophenone to 1-phenyl ethanol.
► 15%-Ag-OMS-2 was found to be the most active and selective.
► 10 atm H2 pressure, 160 °C, 60% conversion, 100% selectivity for 1-phenethyl alcohol.
► Reaction mechanism and kinetics.