Creation of a Highly Active Small Cu‐Based Catalyst Derived from Copper Aluminium Layered Double Hydroxide Supported on α‐Al2O3 for Acceptorless Alcohol Dehydrogenation

Abstract

AbstractA highly dispersed carbonate‐intercalated Cu2+‐Al3+ layered double hydroxide (CuAl LDH) was created on an unreactive α‐Al2O3 surface (CuAl LDH@α‐Al2O3) via a simple coprecipitation method of Cu2+ and Al3+ under alkaline conditions in the presence of α‐Al2O3. A highly reducible CuO nanoparticles was generated, accompanied by the formation of CuAl2O4 on the surface of α‐Al2O3 (CuAlO@α‐Al2O3) after calcination at 1073 K in air, as confirmed by powder X‐ray diffraction (XRD) and Cu K‐edge X‐ray absorption near edge structure (XANES). The structural changes during the progressive heating process were monitored by using in‐situ temperature‐programmed synchrotron XRD (tp‐SXRD). The layered structure of CuAl LDH@α‐Al2O3 completely disappeared at 473 K, and CuO or CuAl2O4 phases began to appear at 823 K or 1023 K, respectively. Our synthesised CuAlO@α‐Al2O3 catalyst was highly active for the acceptorless dehydrogenation of benzylic, aliphatic, or cyclic aliphatic alcohols; the TON based on the amount of Cu increased to 163 from 3.3 of unsupported CuAlO catalyst in 1‐phenylethanol dehydrogenation. The results suggested that Cu0 was obtained from the reduction of CuO in the catalyst matrix during the reaction without separate reduction procedure and acted as a catalytically active species.