Establishment of correlation between reaction kinetics and carbon structures in the char gasification process

• Published in: Carbon resources conversion Vol. 6; no. 2; pp. 67 - 75
• Main Authors: Ge, Zefeng, Cao, Xi, Zha, Zhenting, Ma, Yuna, Zeng, Mingxun, Wu, Yuqing, Hou, Zenghui, Zhang, Huiyan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2023; KeAi Communications Co., Ltd
• Subjects: Activation energy; Carbon structure; Char gasification; Organic solid wastes; Sectionalized kinetic; Organic solid wastes; Carbon structure; Sectionalized kinetic; Char gasification; Activation energy
• ISSN: 2588-9133; 2588-9133
• DOI: 10.1016/j.crcon.2023.02.002

[Display omitted] •The char gasification of three representative solid wastes was investigated.•The sectionalized kinetic analysis was clarified based on temperature ranges.•Activation energy was highly related to the carbon microcrystalline structure.•Reaction rate was determined by carbon pore structures. For a gasification process, the char-CO2 gasification is the controlling step worthwhile to be deeply investigated. The article chosen corn stalk (CS), poplar sawdust (PS) and bagasse residue (BR) as the typical waste species derived from agricultural, forestal and industrial sources. The char-CO2 gasification behavior, reaction kinetics and carbon structure were studied to reveal the intrinsic factors determining the reaction kinetics. Generally, the carbon conversion and maximum conversion rate were influenced by the feedstocks species and char preparation temperatures, as influenced by ash proportion, potassium content in ash and carbon structure of char. The char-CO2 reaction for CS was subject more to the catalytic effect of alkali compositions, while pore structure affected more the gasification reaction for PS char. The isoconversional kinetic analysis indicated that the gasification reaction became stable at carbon conversion of 0.5. Subsequently, sectionalized kinetic parameters were calculated for the initial gasification temperature to the temperature reaching 50% conversion. The result showed that high initial gasification temperature increased the char-CO2 gasification barrier to hardly start the reaction but accelerate the reaction rate. The carbon structure analyses further clarified that the reaction activation energy was highly related to the microcrystalline structure of carbon, while the reaction rate was more determined by carbon pore structure.