Solvent-mediated selective hydroconversion of benzyloxybenzene over a Ni/₄₀ catalyst

During biomass conversion, solvent types often play an important role in determining product selectivity and reaction mechanisms. Nevertheless, solvent function remains poorly understood. Herein, Ni/beta(40) was prepared by a slightly modified deposition-precipitation method and used for the catalytic hydroconversion (CHC) of benzyloxybenzene (BOB) to dicyclohexylmethane (DCHM) or toluene and phenol mediated by solvent types. The results show that solvent types, atmospheres, and Ni-20/beta(40) synergistically control product regulation. In n-hexane (H), DCHM was first produced with the selectivity of 94.5% under the optimum conditions (180 degrees C, 2 MPa H-2, and 4 h). In isopropanol (IP), toluene and phenol were unique products under the optimal conditions (180 degrees C, 0.5 MPa H-2, and 4 h). The characterizations of Ni-20/beta(40) and variation of product distributions from the CHC of BOB demonstrates that BOB conversion to DCHM in H via the >CH-O- bond cleavage induced by H+ addition, benzylium addition to ortho and para positions of phenol, (HH)-H-& mldr; transfer to the resulting 2-benzylphenol and 4-benzylphenol, dehydroxylation of 2-benzylcyclohexanol and 4-benzylcyclohexanol produced, together with benzene rings hydrogenation. By contrast, conversion of BOB to toluene and phenol in IP only depends on the cleavage of >CH-O- bond induced by H+ addition. Furthermore, Ni-20/beta(40) exhibites splendid reusability.