Formation and characterization of carbon-radical precursors in char steam gasification

Xiaolei Zhang, Weihong Yang, Wlodzimierz Blasiak

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

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 H2 and O2 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 > H2 > H > OH > O2. 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-O2, carbon-H2, 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 O2 and H2 molecules do not have a significant effect on adsorption.
LanguageEnglish
Pages6513-6521
Number of pages9
JournalEnergy and Fuels
Volume24
Issue number12
DOIs
Publication statusPublished - 8 Nov 2010

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Steam
Gasification
Carbon
Adsorption
Molecules
Quantum chemistry
Hydrogen bonds

Keywords

  • char steam
  • reactive radicals
  • gassification process

Cite this

Zhang, Xiaolei ; Yang, Weihong ; Blasiak, Wlodzimierz. / Formation and characterization of carbon-radical precursors in char steam gasification. In: Energy and Fuels. 2010 ; Vol. 24, No. 12. pp. 6513-6521.
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Formation and characterization of carbon-radical precursors in char steam gasification. / Zhang, Xiaolei; Yang, Weihong; Blasiak, Wlodzimierz.

In: Energy and Fuels, Vol. 24, No. 12, 08.11.2010, p. 6513-6521.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Formation and characterization of carbon-radical precursors in char steam gasification

AU - Zhang, Xiaolei

AU - Yang, Weihong

AU - Blasiak, Wlodzimierz

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N2 - 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 H2 and O2 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 > H2 > H > OH > O2. 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-O2, carbon-H2, 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 O2 and H2 molecules do not have a significant effect on adsorption.

AB - 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 H2 and O2 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 > H2 > H > OH > O2. 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-O2, carbon-H2, 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 O2 and H2 molecules do not have a significant effect on adsorption.

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