Biomass Hydropyrolysis in a Pressurized Fluidized Bed Reactor

Abstract

Biomass pyrolysis and hydropyrolysis have been studied in a high-temperature, high-pressure fluidized bed reactor system. The reactor system can be operated at reaction temperatures up to 982 °C (1800 °F) and pressures up to 4 MPa (600 psi). Baseline biomass pyrolysis experiments with an inert heat transfer material were conducted at various pressures and hydrogen partial pressures to determine the effect of these variables on product yields and quality, defined by the amount of oxygen in the hydrocarbon-rich liquid product. Biomass hydropyrolysis was performed at temperatures between 375 and 400 °C at 2 MPa (300 psi) with selected hydroprocessing catalysts. The most promising catalyst was exposed to 2.9 kg of woody biomass for a total of 21.7 h time on stream over a 10 day period. The cumulative mass balance during this period was 83%, and the overall C4+ yield was 16 wt %. This corresponds to 31% of the energy in the input biomass feedstock recovered in the hydrocarbon-rich liquid that contained an average of 4.2 wt % oxygen on a dry basis.