Enantioselective hydrogenation of pyruvate esters in the mesoporous environment of Pt-MCM-41

T J Hall, J E Halder, G J Hutchings, R L Jenkins, P Johnston, P McMorn, P B Wells, R P K Wells

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Abstract

Pt-MCM-41 catalysts having loadings of up to 2% Pt have been synthesised using three strategies: (i) direct synthesis from a Pt2+-containing gel, (ii) exchange of Na+ in Al-MCM-41 (containing 8% aluminium) for Pt2+, (iii) exchange of H+ in H-MCM-41 (containing 1% aluminium) for Pt2+. HRTEM confirmed the retention of the mesoporous structure in the active catalysts and gave information on Pt particle size and location. Al-27 NMR provided information on the movement of aluminium within the structure during catalyst preparation. Enantioselective hydrogenation of methyl and ethyl pyruvate was catalysed by cinchonidine-modified Pt-MCM-41 at 293 K and elevated hydrogen pressures; performance was compared to that provided by the standard reference catalyst EUROPT-1. Catalysts prepared by strategies (i) and (ii) performed best, giving values of the enantiomeric excess comparable to those afforded by EUROPT-1 at rates moderated by an order of magnitude by mass transfer effects. Performance was impaired when Pt particle size in the mesopores was so small that conditions favoured racemic reaction.

Original languageEnglish
Pages (from-to)351-357
Number of pages7
JournalTopics in Catalysis
Volume11
Issue number1-4
DOIs
Publication statusPublished - Apr 2000

Keywords

  • enantioselective hydrogenation
  • platinum
  • cinchonidine
  • catalyst modifier
  • pyruvate hydrogenation
  • MCM-41
  • Pt-MCM-41 preparation
  • Pt-MCM-41 characterisation
  • modified platinum
  • molecular-sieves
  • catalysts
  • silica

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