Acceptorless Dehydrogenation of Alcohols and Polyols Over Cu‐Based Catalysts Prepared by NaBH₄ Reduction

Abstract

For the first time oxide (TiO2, CeO2, ZnO, Al2O3) supported Cu catalysts, prepared by the aqueous reduction method using sodium borohydride, were employed for the acceptorless dehydrogenation of 2‐octanol and various C4‐C8 polyols. The method used to prepare the catalysts enabled the formation of small Cu particles in the range of 14 to 36 nm, depending on the point of the zero charge of the support. We showed that conversion increased with Cu surface area where Cu/TiO2 led to the highest conversion of 2‐octanol (>99.9%). The selectivity depends on the support and conversion. Up to 80% conversion, the selectivity to 2‐octanone was between 83% and 90% when using Cu/TiO2. In this study, we also report for the first time the acceptor less dehydrogenation of 1,3‐butanediol, 2,3‐butanediol, 1,2‐pentanediol, and 1,5‐pentanediol in liquid phase. While metal active sites promoted the dehydrogenation reaction, the presence of acidic and basic sites favored the formation of by‐products, mainly resulting from dehydration reactions, pinacol rearrangements, and aldol and retro‐aldol condensations. In addition to value‐added chemicals, all the reactions also released molecular hydrogen.