FTIR and 31P-NMR spectroscopic analyses of surface species in phosphate-catalyzed lactic acid conversion

Garry C. Gunter, Radu Craciun, Man S. Tam, James E. Jackson, Dennis J. Miller

    Research output: Research - peer-reviewArticle

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    Abstract

    The surface species present on silica/alumina-supported sodium phosphates, active catalysts for the conversion of lactic acid to acrylic acid and 2,3-pentanedione, are examined by pre- and postreaction MAS 31P-NMR and FTIR spectroscopies. Species present following lactic acid conversion are identified by transmission FTIR of phosphates supported on silicon disks (as a model catalyst system) and verified by 31P-NMR and diffuse reflectance IR spectroscopy of actual catalysts used in reaction. Monosodium phosphate (NaH2PO4) condenses to a mixture of sodium polyphosphate (NaPO3)n and sodium trimetaphosphate (Na3P3O9), which exhibit little catalytic activity for converting lactic acid to desired products. Disodium phosphate (Na2HPO4) condenses to tetrasodium pyrophosphate (Na4P2O7), and proton transfer from lactic acid to pyrophosphate results in the formation of sodium lactate. Trisodium phosphate (Na3PO4) accepts a proton from lactic acid to form sodium lactate and disodium phosphate, which condenses to pyrophosphate. The presence of pyrophosphate and sodium lactate on supported disodium and trisodium phosphates explains their similar catalytic properties; the larger quantity of sodium lactate present on trisodium phosphate leads to higher conversions at lower temperatures.

    LanguageEnglish (US)
    Pages207-219
    Number of pages13
    JournalJournal of Catalysis
    Volume164
    Issue number1
    StatePublished - 1996

    Profile

    Lactic Acid
    Phosphates
    Nuclear magnetic resonance
    lactic acid
    phosphates
    nuclear magnetic resonance
    Lactic acid
    sodium
    Sodium
    Sodium Lactate
    sodium phosphate
    Catalysts
    lactates
    diphosphoric acid
    catalysts
    protons
    spectroscopy
    Polyphosphates
    Proton transfer
    Aluminum Oxide

    ASJC Scopus subject areas

    • Catalysis
    • Process Chemistry and Technology

    Cite this

    FTIR and 31P-NMR spectroscopic analyses of surface species in phosphate-catalyzed lactic acid conversion. / Gunter, Garry C.; Craciun, Radu; Tam, Man S.; Jackson, James E.; Miller, Dennis J.

    In: Journal of Catalysis, Vol. 164, No. 1, 1996, p. 207-219.

    Research output: Research - peer-reviewArticle

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