Catalytic hydrogenolysis of diphenyl ether over Ni/AC catalyst: Effect of hydrophilicity modification of activated carbon

Directional depolymerization of lignin represents an essential process to produce value-added aromatic compounds. The catalyst obtained by adjusting the hydrophobicity of the support can regulate the reaction pathway and products selectivity for the cleavage of lignin-related compounds. Hydrophilic modification of activated carbon (AC) using trimethylchlorosilane (TMCS) was developed to decrease the hydrophilicity of carbon-based catalyst. The contact angle of the carrier dramatically increased from 43o to 130o after modified. AC was modified with an appropriate amount of TMCS and loaded with Ni to prepare Ni/10% TMCS-AC, which could effectively inhibit the hydrolysis of diphenyl ether (DPE) and the over‑hydrogenation of products. The selectivity of monocyclic aromatics (benzene and phenol) over Ni/10% TMCS-AC increased 30% compared with the unmodified Ni/AC. TMCS occupied part of the adsorption sites, which prevented the Ni from adsorbing more active hydrogen and inhibited the hydrogenation of benzene and phenol. Meanwhile, the hydrolysis of DPE was inhibited and the hydrogenolysis reaction pathway of DPE was over 90% than Ni/AC. The construction of the hydrophobic Ni/10% TMCS-AC highlighted a promising way to convert DPE to aromatic chemicals.