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: Contribution to journalArticle

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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
Sodium Lactate
Lactic acid
Lactic Acid
phosphates
Phosphates
Nuclear magnetic resonance
Sodium
sodium
nuclear magnetic resonance
lactates
Catalysts
Polyphosphates
catalysts
Proton transfer
Aluminum Oxide
Silicon
Silicon Dioxide
Protons
Infrared spectroscopy

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: Contribution to journalArticle

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