An evaluation of the performance and catalytic mechanism of high-temperature-induced Ni/Al2O3 in the hydrodeoxygenation of lignin

Abstract

Selectively converting lignin is advantageous for the advancement of renewable energy. Strong metal-support interaction (SMSI) in a catalyst significantly influences its catalytic activity during lignin conversion. Therefore, reasonable regulation of SMSI can effectively enhance the catalyst activity. Nickel layered double hydroxide (Ni-LDH) was prepared by in-situ method. An induced oxidation strategy, which involves regulating the surface reconstruction process of the catalyst by controlling the oxidation temperature during the oxidation stage, was also revealed. Consequently, Ni/Al₂O₃-600, featuring SMSI, was successfully prepared and demonstrated effective catalysis in the hydrodeoxygenation (HDO) of lignin into cyclanes. Ni/Al₂O₃-600, prepared at the optimal calcination temperature of 600 °C, exhibits on high activity for the HDO of lignin, achieving a soluble portion yield of 95.3 %. Furthermore, the lignin-related model compound phenoxyethylbenzene (PEB) was completely converted over Ni/Al₂O₃. The frontier molecular orbital structure of the intermediates of PEB was determined by calculation with density functional theory, and a mechanism for the HDO of PEB over Ni/Al₂O₃ was also proposed. This strategy offers a theoretical framework for the value-added utilization of lignin and the expansion of liquid fuel sources.