Synchronous Construction of Ni/CeO₂/C with Double Defects as a Dual Engine for Catalytic Refinement of Lignin Oil Under Hydrogen-Free Condition

Abstract

The ambiguous structural defect types and sites of catalysts impede the investigation of structure–activity relationships at the atomic scale for catalytic transfer of hydrodeoxygenation of lignin and its derivatives. In this work, oxygen vacancies (Ov) and carbon defects (Cd) in Ni/CeO2/C catalysts were constructed by an in situ calcination atmosphere-induced engraving strategy. The dual defect embodied the chemical characteristics of heterogeneous frustrated Lewis pairs, and the synergy between Ov and Cd could effectively promote the adsorption and activation of isopropanol and the oxygen-containing substrate, which stimulated the production of more reactive Hδ+ and Hδ−, anchored the methyl group. Efficient conversion of lignin oil was achieved without initial H2 pressure, yielding 56% liquid product and 62.9% C6+ cycloalkanol selectivity. The traditional hydrodeoxygenation was transformed into a solid–liquid two-phase catalytic transfer hydrodeoxygenation, which enhanced the mass transfer. This study developed a catalytic system for catalytic transfer hydrodeoxygenation and offered insights for the preparation of heterogeneous frustrated Lewis pairs.