Add time:08/09/2019         Source:sciencedirect.com

A series of arenesulfonic acid-functionalized alkyl-bridged organosilica hollow nanospheres, Si(R)Si-ArSO3H-HNS, with different bridging alkyl groups such as ethyl, phenyl, or biphenyl in the silica/carbon framework were successfully fabricated by a P123-directed sol–gel co-condensation route and carefully adjusted the concentration of micelle-expanding agent and the acidity in the starting preparation system. The Si(R)Si-ArSO3H-HNS were applied in the synthesis of glycerol mono- and dilaurate from the esterification of glycerol with lauric acid, and the influence of glycerol-to-lauric acid molar ratio, structure of the bridging alkyl groups, and morphology of the nanohybrids on the catalytic activity were studied. The esterification activity of the Si(R)Si-ArSO3H-HNS outperformed commercial solid acid such as Amberlyst-15 or H-ZSM-5, regardless of the structure of the bridging alkyl groups; additionally, the biphenyl-bridged Si(Ph-Ph)Si-ArSO3H-HNS exhibited the highest esterification activity among various Si(R)Si-ArSO3H-HNS nanohybrids, attributing to the combination of advantages of strong Brønsted acidity, excellent porosity properties, hydrophobic surface, and unique hollow spherical nanostructure. Afterward, selective formation of glycerol mono- and dilaurate and possible esterification mechanism were studied. Finally, the reusability was studied and showed the Si(R)Si-ArSO3H-HNS can be reused three times without significant activity loss as well as structural and morphological changes.

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