Catalytic steam gasification of pine sawdust.: Effect of catalyst weight/biomass flow rate and steam/biomass ratios on gas production and composition

Pine sawdust catalytic steam gasification has been studied in a fluidized bed at a relatively low temperature, 700 degrees C. The Ni-Al catalyst used was prepared by coprecipitation and calcined at 750 degrees C for 3 h. The influence of the catalyst weight/biomass flow rate (W/mb) and steam/ biomass (S/B) ratios on the product distribution and on the quality of the gas product obtained was analyzed. An increase of the W/mb ratio increases the total gas, H-2, CO, and CO2 yields, while CH4 and C-2 yields decrease. An increase of the S/B ratio increases H-2 and CO2 yields while CO and CH4 yields decrease. This fact can be explained by steam reforming and water-gas shift reactions. The increase of the S/B ratio also has a positive effect on the life of the catalyst. The gas composition and gas yields at initial time have also been studied. Far W/mb ratios > 0.5 h, the gas composition at initial time is similar to that for thermodynamic equilibrium for different S/B ratios. The influence of the S/B ratio on gas yield at initial time is more marked, up to a ratio of 1.5.