Reactive Catalytic Fast Pyrolysis of Biomass Over Molybdenum Oxide Catalysts: A Parametric Study

Reactive catalytic fast pyrolysis (RCFP) of biomass with atmospheric pressure hydrogen is a promising route for the deoxygenation of biomass pyrolysis vapors while retaining high carbon yields in the bio-crude. RCFP process development was accomplished in a bench-scale bubbling fluidized-bed reactor with in situ catalyst configuration. Results are presented that highlight the impact of temperature, biomass weight hourly space velocity (WHSV), reaction pressure, and time on stream on the hydrodeoxygenation of different oxygen-containing species produced during biomass reactive catalytic fast pyrolysis to improve the bio-crude product yield and quality. The highest bio-crude and C₄₊ hydrocarbons yield was 46.5 wt % on a carbon basis. The optimal temperature range for RCFP is 450–475 °C; the biomass WHSV should be kept low, around 0.6 h^–1 in this reactor system, to produce a low oxygen content bio-crude (7.2 wt %), and improvements in the bio-crude yield and quality based on increased pressure are less significant beyond 2.7 bar. The product composition varies by at most 10% for up to 3.5 h’ time on stream (biomass-to-catalyst ratio of 2.6 g g^–1), indicating a stable catalyst activity for hydrodeoxygenation.