Formation and Characterization of Carbon-Radical Precursors in Char Steam Gasification
2010 (English)In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 24, 6513-6521 p.Article in journal (Refereed) Published
Highly reactive radicals play an important role in high-temperature gasification processes. However, the effect of radicals on gasification has not been systematically investigated. In the present study, the formation of carbon-radical precursors using atomic radicals such as OH, O, and H and molecules such as H-2 and O-2 was characterized, and the effect of the precursors on the adsorption step of steam char gasification was studied using quantum chemistry methods. The results revealed that the radicals can be chemisorbed exothermically on char active sites, and the following order of reactivity was observed: O > H-2 > H > OH > O-2. Moreover, hydrogen bonds are formed between steam molecules and carbon-radical complexes. Steam molecule adsorption onto carbon-O and carbon-OH complexes is easier than adsorption onto clean carbon surfaces. Alternatively, adsorption on carbon-O-2, carbon-H-2, and carbon-H complexes is at the same level with that of clean carbon surfaces; thus, OH and O radicals accelerate the physical adsorption of steam onto the char surface, H radical and O-2 and H-2 molecules do not have a significant effect on adsorption.
Place, publisher, year, edition, pages
2010. Vol. 24, 6513-6521 p.
Materials Engineering Mechanical Engineering
IdentifiersURN: urn:nbn:se:kth:diva-28601DOI: 10.1021/ef101144fISI: 000285266000038ScopusID: 2-s2.0-78650343292OAI: oai:DiVA.org:kth-28601DiVA: diva2:388079
QC 201101172011-01-172011-01-172013-03-27Bibliographically approved