Ru nanoparticles supported on various metal-modified (La, Zr, Cr, Ce and Ga) α-Al2O3 for the selective hydrogenolysis of lignin and its derived ethers.

Controlling the C-O bond hydrogenolysis while suppressing the direct hydrogenation of aromatic rings in lignin-derived ethers is critical and challenging for the utilization of lignin. Herein, a series of metal-modified (La, Zr, Cr, Ce and Ga) α-Al 2 O 3 -supported Ru-based catalysts were synthesized for the conversion of diphenyl ether (DPE). The catalyst characterizations demonstrate that the metal modification cannot change the chemical valence of Ru but promotes the dispersion of Ru nanoparticles and adjusts the adsorption state of DPE. The results indicate that the metal modification inhibits the arenes hydrogenation at low temperatures but facilitates the C-O bond cleavage during heating (at low H 2 pressures or an inert atmosphere). Ru-Cr/α-Al 2 O 3 shows the highest reaction rate for DPE conversion at 1 MPa Ar and 200 °C. Moreover, Ru-Cr/α-Al 2 O 3 not only efficiently converts different lignin model compounds by hydrogenolysis, but also achieves the controlled depolymerization of real lignin to generate guaiacols under mild conditions. [Display omitted] • Controlling DPE hydrogenolysis is achieved over metal-modified Ru-based catalyst. • Ru-Cr/α-Al 2 O 3 shows the highest activity for DPE conversion at 1 MPa Ar and 200 °C. • The metal modification cannot change the chemical valence of Ru. • The metal doping enhances the C-O bond cleavage of lignin and its derivatives. • The routes for the conversion of DPE under different conditions are presented. [ABSTRACT FROM AUTHOR]