Bimetallic transition metal phosphides are an interesting class of materials that have been reported as active catalysts for the direct deoxygenation (DDO) of lignin model compounds to aromatics at elevated temperatures. The catalytic selectivities, however, are strongly dependent on the bimetallic metals representing the catalyst structure, the metal to phosphorous ratios, and the materials’ synthesis method. From detailed bulk and surface characterization of FeMoP catalysts coupled with model compound reaction studies, we have attempted to correlate the structural features of these unique materials to the reaction products to determine why certain synthesis conditions affect the overall catalytic performance. One specific property these materials have is surface acidity, stemming from both Brønsted and Lewis acid sites, likely from surface POH groups and coordinatively unsaturated metal sites, respectively. In this work, a series of bimetallic FeMo phosphides were synthesized under varying conditions (i.e. reduction temperature and Fe:Mo molar ratio) to probe the effects of synthesis parameters on the resulting materials. Increasing the reduction temperature from 650 °C to 850 °C resulted in a loss of 63% of surface acid sites. The selectivity to deoxygenation of the bimetallic phosphides was determined using phenol and anisole as model compounds. The reduction in total acidity decreased the selectivity of phenol to aromatics by 25%. Yellow pine was also used as the source of whole biomass to show the FeMo phosphide catalysts were capable of depolymerization and direct deoxygenation. This presentation will focus on the synthesis methods to enhance aromatic production from whole lignocellulosic biomass and model compounds.

Hydrodeoxygenation of lignocellulosic biomass and lignin model compounds with bimetallic phosphide catalysts

249th National Meeting (2015)

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