Tailored MgAl2O4 supported Ru catalyst for selective C–O bond cleavage in diphenyl ether hydrogenolysis
Yongjian Zeng, Suyu Zhang, Lu Lin, Nantao Wang, Zhiwei Jiang, Chen Zeng, Xin Tu, Kai Yan
Abstract
The direct cleavage of C−O bonds in lignin and its derivatives via hydrogenolysis is an essential reaction process for lignin conversion. Herein, we design a MgAl2O4 supported Ru catalyst using a facile and green method involving ball milling and microwave heating. The optimal catalyst, 0.5Ru/MgAl2O4, displayed enhanced catalytic performance for 4−O−5 linkage scission compared to 0.5Ru/Al2O3 and 0.5Ru/MgO, achieving a tuenover frequency of 352.9 h−1 for diphenyl ether (DPE) conversion. 0.5Ru/MgAl2O4 with low Ru loading achieved complete conversion of DPE, with 43.8% yield of cyclohexane (CHE) and 42.6% yield of cyclohexanol (CHL) after 2 h at 160 °C and 1.5 MPa H2. The promising catalytic activity can be attributed to the abundant electron-rich Ru0 species with high dispersion formed on MgAl2O4, derived from the strong electron transfer from the support to Ru. The reaction mechanism for the direct cleavage of the 4−O−5 bond, followed by phenyl ring hydrogenation, was confirmed by rigorous experiments. This work provides an inspiring idea for developing efficient heterogeneous catalysts for the utilization of lignin resources via hydrogenolysis.