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Selective cleavage of C−O bonds in diphenyl ether (DPE), a lignin-derived 4-O-5 linkage, is a challenging topic and of great significance to produce value-added aromatic products for sustainable future. Activated carbon (AC) with different pore structures has different catalytic effects on the reaction. Herein, Ni catalysts supported on AC-1, AC-2, and AC-3 with specific surface area (SSA) values of 829, 1731, and 2399 m 2 /g, respectively, were investigated in the hydrogenolysis and hydrolysis of DPE. The proper pore structure of AC facilitates the entry of reactants and promotes the reaction. AC with a larger SSA and stronger hydrophilicity was more conducive to metal dispersion and water adsorption to promote the hydrogenolysis/hydrolysis of DPE. The apparent activation energy (E a ) and the turnover frequency further demonstrated that Ni/AC-3 possessed the highest catalytic activity compared to Ni/AC-2 and Ni/AC-1. Catalytic hydrogenolysis/hydrolysis of DPE can be therefore achieved over Ni/AC-3 under mild conditions (180 °C and 1 MPa H 2 ), which is highly selective to afford cyclohexane and cyclohexanol as the major products with the selectivities of 35.5 and 63.9%, respectively. The application of a hydrophilic Ni/AC catalyst with a high SSA may provide a promising approach for the valorization of lignin-derived fragments.

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Catalytic hydrogenolysis of the aromatic ether C− O bond is a meaningful step in the appreciation of lignin-related compounds. Carbon supports in heterogeneous reactions are widely used due to low cost and high porosity. The waste sugar residue (WSR) obtained by drying the waste liquid from a productive process of vitamins is the dominant precursor to make porous activated carbon (PAC) due to abundant solid content and low ash content. Herein, a series of PACs were prepared by the WSR and then loaded with Ni for the conversion of diphenyl ether. PAC-600-700-2.5 obtained by adjusting the preparation conditions owned the highest surface area (3220 m 2 /g), and the prepared Ni/ PAC-600-700-2.5 catalyst possessed stronger hydrogen adsorption capacity. The resulting Ni/PAC-600-700-2.5 achieved the 100% conversion of diphenyl ether under extremely mild conditions (160 °C and 0.5 h). The remarkable catalytic activity of Ni/PAC-600-700-2.5 was owed to the rational pore structure of PAC-600-700-2.5, which enabled better dispersion of Ni on the support and produced more Ni 0 .

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