Unraveling the Synergistic Participation of Ni-Sn in Nanostructured NiO/SnO2for the Catalytic Transfer Hydrogenolysis of Benzyl Phenyl Ether

Abstract

Selective transfer hydrogenolysis of lignin-derived aromatic ethers by the utilization of hydrogen donor solvent without hydrogenation of aromatic rings is a crucial strategy for the selective production of mono-aromatics. The use of non-noble metal-based catalysts toward transfer hydrogenolysis of an aromatic ether bond with high activity and selectivity is still to be achieved. Herein, we report the synthesis of a non-noble metal-based nanostructured NiO(x%)/SnO2 catalyst for the catalytic transfer hydrogenolysis of benzyl phenyl ether and its homologues ether. The developed catalyst afforded >95% reactant conversion and 100% selectivity toward the aromatic compounds using 2-propanol as a hydrogen source at 250 C and 4 h in the N2 atmosphere. The catalyst was thoroughly characterized by several physicochemical analytical techniques. The oxygen vacancy was analyzed by Raman and FT-IR spectroscopies and XPS analysis, and acidity was analyzed by the temperature-programmed desorption and pyridine-adsorbed FT-IR spectroscopy. The synergistic participation of NiO and SnO2 nanoparticles in NiO/SnO2, reducing ability, and interface formation were confirmed using temperature-programmed reduction, several physicochemical characterization techniques, and control reactions. Based on the catalytic activity data, it is concluded that the appropriate NiO loading (10 wt %) was the dominant factor for controlling the aromatic selectivity. The catalyst was efficiently recycled after a simple calcination process with no substantial loss in the catalytic activity. An in-depth study on the change in the catalyst chemical composition and their regeneration using various characterization techniques was conducted. A simple, cost-effective non-noble catalyst and straightforward eco-friendly transfer-hydrogenolysis catalytic process involving 2-propanol to produce aromatic platform chemicals would attract significant attention from catalysis researchers and industrialists.