Spherical NiCo-MOFs catalytic hydrogenolysis of lignin dimers and enzymatic lignin to value-added liquid fuels under nitrogen atmosphere

Abstract

Ni-based MOFs catalysts are promising candidates that can be used to achieve biomass valorization following the process of selective hydrogenolysis process. Here we report a spherical NiCo-based MOFs catalyst, which provides a larger BET surface to enhance 2-phenoxy-1-phenylethan-1-ol molecules enrichment and promote the hydrogenolysis on spherical NiCo-based MOFs catalyst surface. In addition, the synergistic interaction between Ni and Co species also shows great effect on catalytic hydrogenolysis of 2-phenoxy-1-phenylethan-1-ol molecules and enzymatic lignin. The yields of ethylcyclohexane and cyclohexanol are dramatically improved to more than 90 mol% over Ni3Co1-based MOFs catalyst under nitrogen atmosphere. Various lignin dimers derivatives are investigated over Ni3Co1-based MOFs catalyst, which indicates oxygen-containing functional groups played a critical role in the hydrogenolysis process. Isopropanol is used as solvent in the hydrogenolysis of 2-phenoxy-1-phenylethan-1-ol molecules and enzymatic lignin. 21% of H2 is observed in the GC/MS, suggesting that it is a catalytic transfer hydrogenolysis process. Catalytic hydrogenolysis of enzymatic lignin is also carried out under 280 ℃ over optimal Ni3Co1-based MOFs catalyst for 6 h, giving highest lignin oil yield (75.6 wt%) and lower O/C ratio (0.17). This work can be extended to different biomass valorizations to promote the catalytic behavior of spherical MOFs catalysts.