One-pot synthesis of ethylbenzene/1-phenylethanol and gamma-butyrolactone from simultaneous acetophenone hydrogenation and 1,4-butanediol dehydrogenation over copper based catalysts: effects of the support

Abstract

The effect of the support in the simultaneous hydrogenation of acetophenone and dehydrogenation of 1,4-butanediol was studied using supported (MgO, gamma-Al2O3, MgO-Al2O3 and SiO2) copper (10 wt%) catalysts, prepared via impregnation. In this process, acetophenone was transformed to 1-phenylethanol/ethylbenzene and 1,4-butanediol converted to gamma-butyrolactone/tetrahydrofuran under a hydrogen-free environment, indicating the major role of the supports. The Cu/MgO catalyst was active and highly selective towards the production of 1-phenylethanol and gamma-butyrolactone. However, an adverse behaviour was observed over Cu/MgO-Al2O3. An extraordinary catalytic performance was obtained over Cu/SiO2 with high selectivity for ethylbenzene (99%) and gamma-butyrolactone (99%). Contrarily, no hydrogenation of acetophenone was observed over Cu/g-Al2O3 due to the dehydration of 1,4-butanediol, yielding tetrahydrofuran. The main advantage of this process is that no external hydrogen is required for the hydrogenation of acetophenone. Copper dispersion, the reduction behaviour of copper, copper particle size and the acidity and basicity of the catalysts play important roles in the activity. All four catalysts were characterized using BET surface area, N2O pulse chemisorption, XRD, XRF, H-2-TPR, XPS, and TPD of NH3/CO2 to understand our results.