Catalytic Cleavage of the C–O Bond in Lignin and Lignin-Derived Aryl Ethers over Ni/AlP<i>_y</i>O<i>_x</i> Catalysts

Abstract

The conversion of lignin into value-added chemicals is one of the important ways for sustainable development. Herein, phytic acid, a biomass-derived chemical, was used as the phosphorus source and pore former to synthesize the AlPyOx support. After loading Ni, the Ni/AlPyOx catalysts were found to be highly active in the catalytic conversion of lignin model compounds to high-value-added chemicals under mild conditions. The benzyl phenyl ether (α-O-4 lignin model compound) could be completely converted into toluene and phenol with near-equivalent selectivity at 30 °C and 3 MPa H2. Diphenyl ether and 2-phenoxy-1-phenylethanol were also used as 4-O-5 and β-O-4 model compounds of lignin, respectively. The unique activity of Ni/AlP0.5Ox could be attributed to metallic Ni that interacts with AlP0.5Ox and the unique adsorption of substrates on the carrier. Lignin can also be degraded over Ni/AlP0.5Ox via selective cleavage of the C–O bond, and 26.60 wt % yield of identified monomers was obtained.