Experimental study on potassium catalyzed gasification of large particle size biomass with CO2

Abstract

Candlenut wood with large particle size is selected to investigate the biomass gasification catalyzed by potassium. The sample pore structure, the spatial distribution of potassium, and the effects of potassium salt species on the biomass gasification with CO2 are examined. The results show that the large particle candlenut wood exhibits obvious spatial anisotropy and that the pore structure is mainly distributed along the axial direction. Large particle candlenut wood has a more uniform distribution of potassium salts along the axial direction. Part of the potassium salt releases outward during the gasification, which reduces the potassium salt content in the sample center. The average potassium contents of sample loaded with KCl and biochar of sample loaded with KCl are 9.273% and 7.745%, respectively. The synthesis of polycyclic aromatic hydrocarbons in tar could be inhibited by potassium, which could also catalyze the gasification and methane removal reactions of biochar and facilitate the formation of CO and H2. Compared to raw sample (28.99%), the syngas yields from the gasification of sample loaded with KCl, sample loaded with K2CO3, and sample loaded with K2SO4 are 40.22%, 52.16%, and 41.72%, separately. The catalysis of potassium is closely related to its occupation of the active sites on biochar. The chemical bonds formed by potassium and biochar are repeatedly broken and formed during the gasification, which promotes the decomposition of organic matter. Compared with KCl and K2SO4, K2CO3 has a better catalytic effect.