Novel Ti and Mn Mesoporous Molecular Sieves: Synthesis, Characterization and Catalytic Activity in the Epoxidation of Vegetable Oil

Abstract

The novel mesoporous materials containing titanium and manganese, Ti-HMS (50) and Mn-HMS (50) (the number 50 denoting the Si/metal of molar ratio), were synthesized using laurylamine as template at room temperature. They were characterized by a series of techniques including powder XRD, FT-IR, UV–Vis spectroscopy, TEM, TG and Nitrogen physisorption. The results indicated that titanium and manganese had been incorporated into the HMS and both them had a wormhole mesopore structure. It also suggested that Mn²⁺ and Mn³⁺ coexisted in the Mn-HMS, Ti⁴⁺ in Ti-HMS. Besides, epoxidation of soybean oil over these synthesized catalysts was performed using tert-butyl hydroperoxide (TBHP) as oxidant. An increase in the activity was observed when surface area, pore diameter and hydrophobic nature were increased, which meant more active center reacting with soybean oil (SBO), also could reduce the energy barrier and avoid the oxirane ring opening. Furthermore, the result indicated that Mn-HMS showed a higher selectivity (up to 82.9% for Mn and 51.1% for Ti), but Ti-HMS exhibited a better conversion.

Graphical Abstract

The novel mesoporous materials containing titanium and manganese, Ti-HMS (50) and Mn-HMS (50), were synthesized. All catalysts was characterized by XRD, which suggested a single low-angle (100) peak at 2.3° < 2θ < 2.8°, characteristic of HMS materials. It also suggested a decrease in uniformity and crystallinity of the porous structure because of the metal incorporation. Besides, for the epoxidation of soybean oil over these catalysts, Mn-HMS showed a higher selectivity (up to 82.9% for Mn and 51.1% for Ti), but Ti-HMS exhibited a better conversion.