Selective depolymerization of lignin is one of the weakest links in the biorefinery economic chain. We recently discovered that nickel-loaded hydrotalcites, a class of solid base catalysts, selectively cleave the �-O-4 linkage in a lignin model compound (2-phenoxy-1-phenylethanol, PE), and reduce the molecular weight of two types of lignin under moderate conditions without added H2.  In this study, we expand our catalyst library with a screening of metals, metal salt precursors, and solvents.  We also apply our best-performing catalysts to three types of lignin and a variety of other lignin model dimers with �-O-4, a-O-4, 4-O-5', �-1, and 5-5' linkages.  Solvent performance appears to be a function of solvent molar volume, although alcohol solvents (ethanol and isopropanol) give higher PE conversion than predicted by this trend, possibly due to metal-facilitated transfer hydrogenation from the solvent to the substrate.

Metal-hydrotalcite solid catalysts for base-catalyzed depolymerization of lignin

248th National Meeting (2014)

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