Development of selective catalysts for lignin depolymerization is an important step in the production of high-value renewable aromatic chemicals from biomass.  Metal-loaded hydrotalcites (M-HTC), a class of solid base catalysts, are promising in this application.  However, several important parameters govern catalyst activity and selectivity, including preparation procedure, metal salt precursor, and solvent.  While HTC catalysts have been used for a number of base-catalyzed transformations over the years, the factors influencing behavior of M-HTC catalysts are not currently well understood.  We report here extensive characterization of some M-HTC catalysts to explore the effects of different preparation steps and reaction conditions for lignin model dimers and whole lignin. The results suggest that solvent choice plays a role in catalyst dehydration during reaction, which in turn has implications for catalyst regeneration and recyclability.  We also report on the implications of atmospheric exposure (i.e., poisoning of basic sites by ambient CO2), and show that homogeneous chemistry due to metal leaching is negligible

Active site dynamics in metal/hydrotalcite-catalyzed lignin depolymerization

248th National Meeting (2014)

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