Impact of lignin structure on oil production via hydroprocessing with a copper-doped porous metal oxide catalyst

- Lignins structure is linked to the oil composition obtained after hydroprocessing.
- Cu-PMO catalyst is effective on hydrogenolysis of low M.W. lignin fractions.
- Catalyzed hydroprocessing can provide aromatic monomers of commercial interest.

A copper-catalyzed depolymerization strategy was employed to investigate the impact of lignin structure on the distribution of hydroprocessing products. Specifically, lignin was extracted from beech wood and miscanthus grass. The extracted lignins, as well as a commercial lignin (P1000), were then fractionated using ethyl acetate to provide three different portions for each source of lignin [total of 9 fractions]. Each fraction was structurally characterized and treated with a copper-doped porous metal oxide (Cu-PMO) catalyst under 4 MPa H2 and at 180 °C for 12 h. The reaction conditions provided notable yields of oil for each fraction of lignin. Analysis of the oils indicated phenolic monomers of commercial interest. The structure of these monomers and the yield of monomer-containing oil was dependent on the origin of the lignin. Our results indicate that hydroprocessing with a Cu-PMO catalyst can selectively provide monomers of commercial interest by careful choice of lignin starting material.