Production of Structured Lipids Containing Medium-Chain Fatty Acids by Soybean Oil Acidolysis Using SBA-15-pr-NH2-HPW Catalyst in a Heterogeneous Manner

The Keggin-type H3PW12O40 (HPW) was successfully anchored onto the surface of amino-functionalized SBA-15 silica by means of protonating of amino-functionalized silica with the phosphotungstic acid. The as-prepared heterogeneous catalysts were fully characterized at the current research by using small-angle XRD, FT-IR, TEM, SEM, solid-state NMR, and nitrogen porosimetry measurement. The characterization results showed that the functionalized SBA-15 materials still retained the ordered mesoporous structure of SBA-15 silica with high surface area, and meanwhile the primary Keggin structure of heteropolyanions could be also remained intact upon the immobilization of the HPW. By using this solid catalyst, the acidolysis of soybean oil with caprylic or capric acid was carried out in a batch reactor to produce structured lipids containing medium chain fatty acids. The influence of reaction parameters, such as the substrate ratio, reaction temperature, catalyst loading, and reaction time, on the acidolysis reaction was investigated for the optimization of acidolysis processes. It was shown that the high incorporations of caprylic or capric acid of 58.7% or 61.9% was achieved, respectively, at 150 degrees C within 10 h when the medium chain fatty acids/oil molar ratio of 10:1 and catalyst loading of 9 wt % were employed. The solid catalyst could be recovered easily and reused for several cycles with little loss of activity due to the chemical interaction between the amino groups and the HPW anions.