New insights in the deactivation of sulfonic modified SBA-15 catalysts for biodiesel production from low-grade oleaginous feedstock

Juan A. Melero*, L. Fernando Bautista, Jose Iglesias, Gabriel Morales, Rebeca Sánchez-Vázquez, Karen Wilson, Adam F. Lee

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

Arenesulfonic-acid functionalized SBA-15 materials have been used in the production of biodiesel from low grade oleaginous feedstock. These materials display an outstanding catalytic activity, being able to promote the transformation of crude palm oil with methanol into fatty acid methyl esters with high yield (85%) under mild reaction conditions. However, high sensitivity of the catalyst against poisoning by different substances has also been detected. Thus, alkaline metal cations, such as sodium or potassium exert a negative influence on the catalytic activity of these materials, being necessary amounts around 500 ppm of sodium in the reaction media to decrease the catalytic activity of these materials to a half of its initial value in just two reaction runs. The deactivation of arenesulfonic acid functionalized SBA-15 materials seems to occur in this case by ion exchange of the acid protons at the sulfonic groups. Organic unsaponifiable compounds like lecithin or retinol also induce a negative influence in the catalytic activity of these sulfonic acid-based materials, though not so intense as in the case of alkaline metals. The deactivating mechanism associated to the influence of the organic compounds seems to be linked to the adsorption of such substances onto the catalytic acid sites as well as on the silica surface. The accumulation of lecithin in the surface of catalyst, observed by means of thermogravimetric analysis, suggest the creation of a strong interaction, probably by ion pair, between this compound and the sulfonic acid group.

Original languageEnglish
Pages (from-to)111-118
Number of pages8
JournalApplied Catalysis A: General
Volume488
Early online date28 Sep 2014
DOIs
Publication statusPublished - Nov 2014

Keywords

  • biodiesel
  • heterogeneous acid catalysts
  • low-grade feedstock
  • SBA-15
  • second generation biodiesel
  • sulfonic acid catalysts

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