Synthesis, Characterisation and Catalytic Activity of Sol-Gel Derived Silica-Mineral Acids

Abstract:

Sol-gel silica-supported mineral acids (namely sol-gel perchloric acid (slg HClO₄), sulfuric acid (slg H₂SO₄) and phosphoric acid (slg H₃PO₄), prepared by incorporating mineral acids molecules into silica via sol-gel technique, were used as an efficient heterogeneous catalyst for the direct addition reaction of oleic acid (OA) to form estolides compound. The reactions were carried out under vacuum (2 mBar) for 10 hours at 70°C under solvent-less conditions. Liquid chromatography-mass spectrometry time of flight (LC-MS ToF) of reaction products results showed chromatographic peaks for the presence of two new estolide compounds, oleic-oleic monoestolide acid (m/z 563.51, as [M-^-), and oleic-oleic diestolide acid (m/z 845.77 [M-^-). The HClO sol-gel catalyst turned out to be the best catalyst, achieving a final conversion of 76.4% with 83.4% selectivity to oleic-oleic monoestolide acid (OOM) and 16.6% selectivity to oleic-oleic diestolide acid (OOD). The activity and selectivity of the mineral acid sol-gel catalysts have been investigated and compared with homogeneous HClO₄. The samples were characterised by XRD, TPD-NH₃ and XPS.

• Periodical: Advanced Materials Research (Volume 620)
• Pages: 278-283
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.620.278
• Online since: December 2012
• Authors: Nor Asikin Mohamad Nordin, Noraini Hamzah, Nadia Farhana Adnan, Wan Nor Roslam Wan Isahak, Mohd Zahid M. Yusof, Jumat Salimon, Mohd Ambar Yarmo
• Keywords: Estolide Synthesis, Mineral Acids, Oleic Acid, Sol-Gel (SG)

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