Ceria supported nickel nanoparticles for catalytic hydroconversion of lignin-related model compounds

Abstract

The combination method of impregnation, desiccation, and subsequent reduction with H2 was applied to prepare Nix/CeO2. Each catalyst was characterized with multiple tools and its catalytic performance for the catalytic hydroconversion (CHC) of lignin-related model compounds (LRMCs) containing oxybis(methylene)dibenzene (OBMDB) and guaiacol was evaluated. Over Ni14%/CeO2, OBMDB was completely converted into methylcyclohexane under initial hydrogen pressure (IHP) of 3 MPa at 200 °C for 2 h. The complete conversion of guaiacol to cyclohexanol (CHII) was realized under IHP of 4 MPa at 200 °C for 3 h. Additionally, H2 can be activated to H⋯H, H+, and H− over Ni14%/CeO2. H+ is attracted by oxygen atom in OBMDB, leading to the cleavage of >CH2-O- bond to produce phenylmethanol (PM) and benzylium, which is subsequently comminated with H− to produce toluene. Next, H⋯H transfers to toluene and PM resulting in the hydrogenation of benzene rings (BRs) to produce methylcyclohexane and cyclohexylmethanol followed by the dehydration to form methylcyclohexane. BR in guaiacol was hydrogenated by H⋯H transfer to produce 2-methoxycyclohexan-1-one (MCHI) and 2-methoxycyclohexan-1-ol (MCHII) in sequence and subsequent demethoxylation of them to generate cyclohexanone (CHI) and CHII, respectively. Finally, H⋯H transfers to CHI to produce CHII.