Catalytic effects observed during the co-gasification of coal and switchgrass

We are investigating catalytic gasification of coal char using biomass-derived potassium salts. Alkali metal salts, especially those containing potassium, are excellent promoters of gasification reactions but are generally considered too expensive for commercial use. Fast-growing biomass, which contains large quantities of potassium, may prove to be an excellent source of inexpensive gasification catalyst. A series of CO₂-char gasification tests were performed in a thermogravimetric analyzer (TGA) to evaluate the catalytic activity of alkali-rich biomass-derived materials. Both switchgrass char and switchgrass ash displayed catalytic activity in mixtures with coal char produced from Illinois No. 6 coal. The results obtained with switchgrass ash were especially impressive, with an almost eight-fold increase in coal char gasification rate at 895°C in a 10:90 mixture of coal char and switchgrass ash. These results give encouragement that biomass could be the source of inexpensive, coal gasification catalysts.