A heterogeneous catalyst system, employing Au nanoparticles (NPs) and Li–Al (1 : 2) layered double hydroxide (LDH) as support, showed excellent activity in aerobic oxidation of the benzylic alcohol group in β-O-4 linked lignin model dimers to the corresponding carbonyl products using molecular oxygen under atmospheric pressure. The synergistic effect between Au NPs and the basic Li–Al LDH support induces further reaction of the oxidized model compounds, facilitating facile cleavage of the β-O-4 linkage. Extension to oxidation of γ-valerolactone (GVL) extracted lignin and kraft lignin using Au/Li–Al LDH under similar conditions produced a range of aromatic monomers in high yield. Hydrolysis of the Au/Li–Al LDH oxidized lignin was found to increase the degree of lignin depolymerization, with monomer yields reaching 40% for GVL extracted lignin. Based on these results, the Au/Li–Al LDH + O2 catalyst system shows potential to be an environmentally friendly means of depolymerizing lignin to low molecular weight aromatics under mild conditions.
Digital Object Identifier (DOI)
This research was funded by the National Science Foundation under Cooperative Agreement No. 1355438 and by the Global Bioenergy, Biofuels, and Biorefining network (GB3-Net) supported by the British Council and the Department for Business, Innovation and Skills (BIS). This work was also funded in part by the DOE Great Lakes Bioenergy Research Center (DOE Office of Science BER DE-FC02-07ER64494 and DE-SC0018409).
Electronic supplementary information (ESI) available. See DOI: 10.1039/c8sc03208d
Song, Yang; Mobley, Justin K.; Motagamwala, Ali Hussain; Isaacs, Mark; Dumesic, James E.; Ralph, John; Lee, Adam F.; Wilson, Karen; and Crocker, Mark, "Gold-Catalyzed Conversion of Lignin to Low Molecular Weight Aromatics" (2018). Chemistry Faculty Publications. 139.