Ordered mesoporous silica KIT-6 supported tin(II) oxides for the esterification synthesis of trimethylolpropane complex polyolester

Nowadays, heterogeneous catalytic esterification for synthetic esters production is believed more compatible with the postulates of green chemistry and sustainability goals. In this work, we developed hydrophobic stannous oxide supported on mesoporous silica KIT-6 materials (SnO/KIT-6) via a feasible synthesis and post-grafting modification approach, which served as solid heterogeneous catalysts and then tested in the synthesis of complex polyolester (CPE). The catalytic behaviour of as-prepared catalysts was also systematically investigated and the highest carboxyl conversion (ca.95.6 %) could be achieved under the optimal preparation conditions within the studied range. The obtained results revealed that Lewis acidity of the tin-based catalysts played a crucial role in esterification conversion efficiency, which varied depending upon the dispersion of different SnO loading. Furthermore, the reusability of the catalyst was evaluated and demonstrated relatively stable catalytic activity for up to five consecutive cycles. Additionally, the possible esterification reaction mechanism of CPE over the modified S-SnO/KIT-6 was also elucidated. The resultant catalysts leveraged full advantage of the unique textural properties and adequate surface hydrophobicity, intensively facilitating the diffusion of large polar molecules and resisting to deactivation from generated water. Collectively, the findings of present study may provide some valuable insights for adopting productive and environmentally benign catalytic processes to synthesize ester-based lubricants in the future.