Ni-Foam-Structured Ni–Al₂O₃ Ensemble as an Efficient Catalyst for Gas-Phase Acetone Hydrogenation to Isopropanol

Abstract

The free-standing Ni-Al₂O₃ ensemble derived from NiAl-layered double hydroxides (NiAl-LDHs) grown onto a Ni-foam has been developed for the exothermic gas-phase acetone hydrogenation to isopropanol. This approach works effectively and efficiently to achieve a unique combination of high activity/selectivity and enhanced heat/mass transfer stemmed from the Ni-foam. The outstanding catalyst is obtained by direct reduction of the un-calcined NiAl-LDH/Ni-foam, with a high turnover frequency of 0.90 s^-1, being capable of converting 90.8% acetone into isopropanol with almost 100% selectivity under stoichiometric H₂/acetone molar ratio, atmospheric pressure at 80 °C, and a WHSV_acetone of 10 h^-1. The catalyst derivation using the un-calcined NiAl-LDH/Ni-foam enables the Ni nanoparticles to be intertwined with Al₂O₃ to form a large Ni-Al₂O₃ interface, without interruption of impurities such as irreducible NiO (in the case of calcined NiAl-LDH/Ni-foam samples), which markedly improves the strong acetone adsorption next to the Ni⁰ hydrogenation sites, thereby leading to a dramatic improvement of catalyst activity.