One-pot synthesis of ethylbenzene/1-phenylethanol and γ-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, γ-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 γ-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 γ-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 γ-butyrolactone (99%). Contrarily, no hydrogenation of acetophenone was observed over Cu/γ-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, H₂-TPR, XPS, and TPD of NH₃/CO₂ to understand our results.