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

    • 58 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.

    Original languageEnglish (US)
    Pages (from-to)1361-1369
    Number of pages9
    JournalCarbon
    Volume36
    Issue number9
    StatePublished - Sep 1998

    Profile

    Hydrogen
    Gasification
    Deoxyglucose
    Steam
    Adsorption
    Oxygen
    Edema Disease of Swine
    Biogenic Amines
    Temperature programmed desorption
    Partial pressure
    Coal
    Bacillus megaterium
    Agglutination Tests
    Inhibins
    Liver Mitochondrion

    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

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

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

    Research output: Contribution to journalArticle

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    AB - 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.

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