Characterizing rate inhibition in steam/hydrogen gasification via analysis of adsorbed hydrogen

M. G. Lussier, Z. Zhang, Dennis J. Miller

Research output: Contribution to journalArticle

  • 60 Citations

Abstract

Analysis of hydrogen adsorbed onto Saran and coal char is conducted via post-gasification temperature programmed desorption to 1770 K to characterize hydrogen inhibition in steam gasification. Exposure of annealed, outgassed chars to H2O/H2/Ar mixtures at 1120 K and pressures to 3.1 MPa results in rapid adsorption of hydrogen on the char over the initial 0.5% of char conversion. Steam gasification rate simultaneously declines as a result of adsorbing hydrogen blocking a portion of reactive surface sites. Between 0.5 and 40% char conversion, adsorbed hydrogen concentration is constant at ∼2 × 10-3 mmol H2 m-2 at all conditions; steam gasification rate is also constant with conversion but depends strongly on hydrogen partial pressure through the reverse oxygen exchange [C(O)+H2→Cf+H2O] pathway. Thus, dissociative adsorption is the observed mode of inhibition when quantities of hydrogen are limited, and reverse oxygen exchange dictates rate dependence on hydrogen at elevated pressures where the char surface is essentially saturated in hydrogen.

LanguageEnglish (US)
Pages1361-1369
Number of pages9
JournalCarbon
Volume36
Issue number9
StatePublished - Sep 1998

Profile

Steam
Gasification
Hydrogen
Oxygen
Adsorption
Coal
Temperature programmed desorption
Partial pressure

Keywords

  • Gasification
  • Hydrogen
  • Inhibition
  • Kinetics
  • Steam

ASJC Scopus subject areas

  • Materials Chemistry

Cite this

Characterizing rate inhibition in steam/hydrogen gasification via analysis of adsorbed hydrogen. / Lussier, M. G.; Zhang, Z.; Miller, Dennis J.

In: Carbon, Vol. 36, No. 9, 09.1998, p. 1361-1369.

Research output: Contribution to journalArticle

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