Ambient Hydrogenolysis of α-O-4 Lignin Model Compounds over Perovskite-Supported Pd Catalysts

Abstract

Hydrogenolysis of lignin model compounds has attracted extensive research attention for lignin valorization. However, achieving such reactions under ambient conditions remains a major challenge. Herein, a series of ABO3-type perovskite-supported Pd catalysts (Pd/ABO3) were fabricated for the hydrogenolysis of α-O-4 lignin model compounds. Interestingly, both ABO3-type perovskite supports and reaction solvents significantly affected the catalytic performance of the constructed Pd/ABO3 catalysts, and Pd/MgTiO3, Pd/BaTiO3, and particularly Pd/CaTiO3 exhibited excellent catalytic activity toward the hydrogenolysis of benzyl phenyl ether in methanol under ambient conditions (room temperature and 1 atm H2), selectively producing toluene and phenol. Notably, Pd/CaTiO3 displayed good applicability for the hydrogenolysis of various α-O-4 lignin models under ambient conditions. Systematic discussion revealed that the high catalytic activity of Pd/CaTiO3 was attributed to the synergistic effect between negatively charged Pd0 sites, facilitating H2 activation to generate active hydrogen species, and oxygen defects/vacancies on the perovskite support, activating the C–O ether bond in α-O-4 lignin models. This work provides an efficient perovskite-supported Pd catalytic system for ambient hydrogenolysis of lignin model compounds via rational modulation of Pd0 electronic states and fabrication of appropriate structural defects.