IMPROVED STEAM GASIFICATION OF LIGNOCELLULOSIC RESIDUES IN A FLUIDIZED-BED WITH COMMERCIAL STEAM REFORMING CATALYSTS

The improved/two-stage steam gasification of biomass or lignocellulosic residues in fluidized bed with steam reforming catalysts placed in a downstream secondary reactor has been studied. Two commercial catalysts, R-67 and RKS-1 from Topsoe, were used at their incipient fluidization conditions. At 720-760-degrees-C and space-times of only 0.10-0.20 s, with catalyst sizes under 1.0 mm and with steam/biomass ratios of 1.2-1.6, tar conversions of 99.95% were achieved in the catalytic reactor. In this process, tar and methane in the flue gas can be easily lowered below 5 mg/m3(NTP) and 0.5 vol %, respectively, without using oxygen. The catalyst deactivation by coke from the tar cracking is the main problem of this process.