Millisecond autothermal steam reforming of cellulose for synthetic biofuels by reactive flash volatilization

Three biomass-to-liquid process steps (volatilization of cellulose, tar-cleaning of organic products, and water-gas-shift of the gaseous effluent) have been integrated into a single autothermal catalytic reactor for the production of high quality synthesis gas at millisecond residence times (similar to 30 ms). Particles of cellulose (similar to 300 mu m) were directly impinged upon the hot, catalytic bed of Rh-Ce/gamma-Al2O3 catalyst on 1.3 mm alpha-Al2O3 spheres in the presence of O-2, N-2, and steam in a continuous flow fixed-bed reactor at 500-1100 degrees C. Complete conversion to gases was observed for all experimental parameters including N-2/O-2, S/C, the total flow rate of cellulose, and the fuel-to-oxygen ratio (C/O). The addition of steam increased the selectivity to H-2 and decreased the selectivity to CO in agreement with water-gas-shift equilibrium. Optimal conditions produced a clean gaseous effluent which exhibited similar to 80% selectivity to H-2 at a synthesis gas ratio of H-2/CO = 2.3 with no dilution from N-2 at a fuel efficiency of similar to 75%. Carbon-free processing was explained by relating the domain of experimental parameters to the thermodynamic prediction for the formation of solid carbon, CS.