Effects of Ca-Based Catalysts on Biomass Gasification with Steam in a Circulating Spout-Fluid Bed Reactor

The catalytic performances of natural Ca-based catalysts (dolomite and limestone) and synthetic Ca-based catalysts, used for improving biomass steam gasification, were fully investigated in a circulating spout-fluid bed reactor. In comparison to the catalytic role in biomass gasification, the synthetic Ca-based catalyst, 20% CaO/Al2O3 (20CaAl), displayed a better catalytic effect on the biomass carbon conversion reaction and tar reforming reaction than natural Ca-based catalysts, but the latter played a better role in the reforming reaction of light hydrocarbon because it contained small quantities of iron oxides. For the two types of Ca-based catalysts, the optimal operating temperature was about 860 degrees C to upgrade the quality of gas product and increase H-2 yield. The catalytic activity of synthetic Ca-based catalysts was visibly improved with the increment of CaO loading, and the preferential range of CaO loading was 12.5-20%. In comparison to the lifetime, 20CaAl (the synthetic catalyst) displayed better stability in the catalytic role than natural Ca-based catalysts.