Catalytic conversions in aqueous media: Part 3. Biphasic hydrogenation of polybutadiene catalyzed by Rh/TPPTS complexes in micellar systems

Vasilis Kotzabasakis, Nikolaos Hadjichristidis, Georgios Papadogianakis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

Water-soluble Rh/TPPTS complexes [TPPTS = P(C6H4-m-SO3Na)3] are active catalysts (TOF > 1200 h-1) for the biphasic hydrogenation of the completely water-insoluble heavy polybutadiene (PB) in single micelles formed by the cationic surfactant dodecyltrimethylammonium chloride (DTAC), or mixed micelles created by DTAC with either non-ionic or anionic surfactants. The reaction proceeds under mild conditions (T = 100 °C, PH2 = 20 bar) at a molar ratio of P/Rh = 3 and C{double bond, long}C units/Rh = 1000 within 20 min and at a rhodium concentration of only 10 ppm in water. The pH of the aqueous catalyst solution markedly influenced the activity. High catalytic activities were achieved under neutral conditions whereas at acidic or basic conditions the catalytic activity dramatically decreased. The hydrogenation rate depends critically on the microstructure of PB and the nature of micellar catalysis. The 1,4-units content of PB plays a major role for performing the catalytic hydrogenation reaction in single or mixed micellar systems for obtaining maximum reactivity. When the PB possesses a high 1,4-units content (98.0 wt% of 1,4-units and 2.0 wt% of 1,2-units) higher reaction rates were achieved in mixed micellar systems created by DTAC/Brij-35 surfactants compared to the rates observed in single DTAC micelles. In contrast, with PB starting material consisting of 61.0 wt% of 1,2-units and 39.0 wt% of 1,4-units higher reaction rates were obtained in single DTAC micelles compared to those rates achieved in mixed micellar systems.

Original languageEnglish (US)
Pages (from-to)95-100
Number of pages6
JournalJournal of Molecular Catalysis A: Chemical
Volume304
Issue number1-2
DOIs
StatePublished - May 1 2009

Keywords

  • Aqueous media
  • Hydrogenation
  • Micelles
  • Polybutadiene
  • TPPTS

ASJC Scopus subject areas

  • Catalysis
  • Process Chemistry and Technology
  • Physical and Theoretical Chemistry

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