Catalytic gasification of pine-sawdust: Effect of primary and secondary catalysts

Abstract

Pine sawdust steam gasification in a fixed double bed reactor and continuous flow was investigated. K2CO3 as primary catalyst and cobalt supported on γ-Al2O3 and SiO2-Al2O3 as secondary catalyst was investigated. Thermal and catalytic steam gasification was compared. The effect of the support in tar yield and the H2/CO ratio was pursued. It is noteworthy to observe that the primary catalyst increases the biomass gasification. It is also marked the total consumption of CH4 species by the primary catalyst. The catalysts (K2CO3 and K2CO3-Co/γ-Al2O3) reduced tar formation from 11% in the thermal gasification to a value of 2.0% and 0.5% respectively. This tar yield reduction could be explained due to the action of potassium actives species of the primary catalyst combined with the lower acid strength of the support; high metal dispersion of cobalt species and the higher fraction of metallic cobalt species in Co/γ-Al2O3 catalyst. The catalysts decrease the formation of CO2 from 21% in the thermal gasification to values on the order of 3%. The highest H2/CO ratio with a value of 1.6 was obtained by K2CO3-γ-Al2O3 catalytic system. The presence of cobalt supported catalysts favored hydrogen consumption reactions such as reverse water gas shift reaction.