Supercritical Methanol Solvolysis and Catalysis for the Conversion of Delignified Woody Biomass into Light Alcohol Gasoline Bioblendstock

Supercritical methanol (SCM) solvolysis and catalysis has recently emerged as a promising pathway to produce gasoline-range light alcohols from woody biomass through staged depolymerization and hydro-deoxygenation (DHDO). Here, structure–property relationships of Cu“M”AlO_x catalysts (M = Mg, Zr, and Ce) are examined for upgrading delignified hybrid poplar via SCM-DHDO. CuCeAlO_x displays the highest activity, increasing the C₂-C₇ alcohol production rate and selectivity by twofold in batch reactions, and >50% in semicontinuous reactions relative to the current state-of-the-art CuMgAlO_x. The performance of CuCeAlO_x is correlated with its high reducibility and acidity. Cu sintering and biogenic impurity poisoning are identified as possible deactivation mechanisms over 60 h of continuous testing. The gasoline-range SCM-DHDO products are comprised of primarily aliphatic alcohols that result in improved energy density and favorably reduced vapor pressure, relative to ethanol, with the tradeoff of nonsynergistic octane blending with conventional gasoline and lower oxidation stability. Overall, this work highlights the potential to produce suitable light oxygenates by SCM-DHDO processing for gasoline bioblendstock applications.