Co-Zif Reinforced Kraft Lignin Biochar as an Efficient Catalyst for Highly Selective Hydrodeoxygenation of Lignin-Derived Chemicals

Abstract

Large amount of lignin was produced annually as a byproduct in papermaking and pulping processes, the challenges in disposal methods had posed serious obstacles for advanced carbon materials and value-added chemicals. This study involved the preparation of kraft lignin (KL) loaded metal-organic framework (ZIF-67) material derived Co nanoparticles carbon using various methods to produce kraft lignin biochar-based carbon materials (Co@NPC-KLB). The novel and advanced carbon materials was utilized for lignin derived bio-oil hydrodeoxygenation to generate high value fuels and chemicals. It could achieve nearly100% vanillin (VAN) conversion and 88.49% 2-methoxy-4-methylphenol (MMP) without the extra hydrogen at 240°C in ethanol. The results demonstrated that highly active and stable Co nanoparticles, large specific surface area, smaller nano Co nanoparticles, strong metal-support interaction and rich Lewis acid sites on the surface of biochar support exhibited a positive promoting effect on VAN hydrodeoxygenation to generate MMP. Furthermore, density functional theory (DFT) also confirmed that synergistic effect of Co nanoparticles and kraft lignin biochar promoted a high adsorption energy of VAN on the surface of kraft lignin biochar, enhanced the catalytic ability of the hydrodeoxygenation process. This study provided a novel approach for utilizing kraft lignin in preparation functional catalysts, opening up new opportunities for designing efficient biochar-based materials for advanced carbon materials and high-value chemicals.

Keywords: Co-ZIF, Kraft lignin, Biochar, Hydrodeoxygenation, lignin-derived chemicals