Catalytic upgrading of biomass pyrolysis vapors for selective production of phenolic monomers over metal oxide modified alumina catalysts

Abstract

This study investigates the catalytic vapor phase upgrading of sawdust to produce improved biocrude enriched in phenolic monomers. Various mixed metal oxide catalysts (MgO, CuO, Bi2O3, NiO, ZnO supported on Al2O3) were screened to determine the product composition. Further, the effect of different process parameters such as temperature (350 – 600 °C), metal oxide loadings (0 – 20 wt%), catalyst to biomass ratios (1:1–1:6), sweeping gas flow rates (0 – 15 LPH) were studied in terms of biocrude composition. Under non-catalytic conditions, maximum biocrude yields (∼39%) were obtained at an optimum temperature of 550 °C. The biocrude composition varied significantly with the type of metal oxide in which MgO and CuO produced higher amounts of phenolics (∼58%). Increasing MgO loading (5–20 wt%) and higher catalyst to biomass ratios (1:1) resulted in enhanced hydrocarbon yields to ∼15%. Premixing of biomass and catalyst in a fixed bed arrangement resulted in enhanced hydrocarbons/aromatics with simultaneous reduction in the phenolic content.