Efficient Production of Medium-Chain Structured Phospholipids over Mesoporous Organosulfonic Acid-Functionalized SBA-15 Catalysts

Abstract

It is highly desirable that efficient recoverable heterogeneous catalysts should be developed to replace the costly biocatalysts used in producing structured phospholipids (SPLs) with medium-chain fatty acids (MCFAs). Thus, mesoporous propyl and phenyl sulfonic acid-functionalized SBA-15 materials synthesized via surface modification methods were investigated for the soybean lecithin interesterification with methyl caprate or caprylate. The physicochemical properties of the synthesized solid acids were deeply studied by small-angle X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared and pyridine adsorption, etc. to build the possible structure-performance relationships. The results revealed that amounts of organosulfonic acid groups were successfully grafted onto the SBA-15 support, and most of the surface acid sites contained in the as-prepared organic-inorganic hybrid samples were assigned as strong Brönsted acid sites. Notably, the functionalized SBA-15 materials exhibited promising catalytic behaviors in producing MCFA-enriched SPLs under mild conditions (40 • C, 6 h) when compared with commercial Amberlyst-15 and typical phospholipases or lipases, mostly due to their high surface area, ordered structure and adequate Brönsted acid sites. Besides, the as-prepared materials could be easily recycled five times without obvious deactivation. This work might shed light on alternative catalysts for SPL production instead of the costly enzymes.

Acidolysis of phospholipids with medium‐chain fatty acids over M‐SBA‐15 (M = Zn, Al) silicas as efficient solid catalysts

“…Consequently, the M‐SBA‐15 (M = Zn, Al) catalysts with much higher quantities of strong Lewis acid sites are more effective for MCP production compared with the SBA‐15 parent, which is supported by the pyridine–FTIR results as illustrated in Fig. 1 and a recent publication 33 . Another fact is that the mesostructures of SBA‐15‐type catalysts could better facilitate the acidolysis processes than the homogeneous ones as discussed in Figs 2 and 3.…”

“…When the temperature was eventually raised to 70 °C, C10:0 and C8:0 incorporation reduced dramatically to ~27.57 ± 0.42% (or 21.38 ± 0.27%) and ~24.12 ± 0.29% (or 20.39 ± 0.09%), respectively. According to these results, it is indicated that parts of the MCP products are unstable at higher reaction temperature, resulting in their decomposition reaction and further formation of by‐products, as reported in the literature 33 . Therefore, the desired MCFA‐enriched SPLs should be synthesized at 50 °C for 6 h with 1:9 substrate mass ratio and 5 wt% catalyst loading.…”

“…On the other hand, the catalytic performance of M‐SBA‐15 (M = Zn, Al) silicas are assessed against other benchmarking results reported in the published literature. By contrast, it is obvious that Zn‐SBA‐15 and Al‐SBA‐15 silicas show superior activities in MCP production, with much higher FA incorporation, to most of the benchmark catalysts, such as lipase, 46 immobilized phospholipase A 1 6 and organosulfonic acid‐functionalized mesoporous silicon 33 . Moreover, notably, the catalytic reactions for SPL production performed in the present systems require significantly shorter reaction times and much lower catalyst loadings than in enzymatic systems 6,46‐48 .…”

“…Furthermore, it is noted that the intensity of the characteristic band corresponded to the acid site amount. The ratio of Lewis to Brönsted acid sites is calculated based on the method mentioned by Zhang et al 33 . As a result, it is revealed that a large majority of acid sites in Zn‐SBA‐15 (~100%) or Al‐SBA‐15 (~62%) catalyst belong to Lewis acid sites.…”

Efficient Synthesis of Structured Phospholipids Containing Short-Chain Fatty Acids over a Sulfonated Zn-SBA-15 Catalyst

“…Thereafter, the thus-synthesized Zn-SBA-15 material was functionalized with phenyl sulfonic acid groups according to the procedures reported in the literature. 29 Initially, trimethoxyphenylsilane (3.0 g) was added dropwise into a mixture of Zn-SBA-15 (1.0 g) and toluene (20 mL). The attained suspension was then refluxed for 24 h under a N 2 atmosphere.…”