An investigation of alumina supported catalysts for the selective catalytic oxidation of ammonia in biomass gasification

L.I. Darvell, Katja Heiskanen, J.M. Jones (Corresponding Author), A.B. Ross, Pekka Simell, A. Williams

    Research output: Contribution to journalArticleScientificpeer-review

    77 Citations (Scopus)

    Abstract

    Alumina-supported catalysts containing different transition metals (Ni, Cu, Cr, Mn, Fe and Co) were prepared and tested for their activity in the selective oxidation of ammonia reaction at high temperatures (between 700 and 900 °C) using a synthetic gasification gas mixture. The catalysts were also characterised for their acidic properties by infrared studies of pyridine and ammonia adsorption and reaction/desorption. The Ni/Al2O3 and Cr/Al2O3 catalyst displayed the highest selective catalytic oxidation (SCO) activity in that temperature range with excellent N2 selectivities. FT-IR studies of adsorbed pyridine and NH3 indicate that Lewis acid sites dominate and that NH3 adsorption on these sites is likely to be the first step in the SCO reaction. FT-IR studies on less active catalysts, particularly on Cu/Al2O3 allowed the detection of oxidation intermediates, amide (NH2), and possibly hydrazine and imido and nitroxyl species. The amide and hydrazine intermediate gives credence to a proposed SCO mechanism involving a hydrazine intermediate, while the proposed imide, N–H, and/or nitroxyl, HNO species could be intermediates in incomplete oxidation of NH3 to N2O.

    Original languageEnglish
    Pages (from-to)681-692
    Number of pages12
    JournalCatalysis Today
    Volume81
    Issue number4
    DOIs
    Publication statusPublished - 2003
    MoE publication typeA1 Journal article-refereed
    EventCatalyst Lifecycle Meeting - Bath, United Kingdom
    Duration: 16 Sep 200217 Sep 2002

    Keywords

    • gasification

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