Effect of Surface Polarity of Titanium-Loaded ERB-1 Catalyst on Epoxidation and Ammoximation

The borosilicate zeolite ERB-1 with an MWW layer structure was deboronated and loaded with titanium by the atom planting method with TiCl4 vapor. The generated Ti-ERB-1 contains four-coordinate framework titanium species and shows higher activity for the reaction of large molecules in the zeolite for epoxidation in a nonpolar environment with cup-like hemi-cages and supercages containing 12-membered rings in the MWW structure. By comparing the cyclohexanone ammoximation and alkene epoxidation activities, the influence of the polarities of Ti-ERB-1, TS-1 and Ti-MWW on the catalytic activity in environments of differing polarities was explored. Then, the polarity of Ti-ERB-1 was modified by grafting silicon onto the surface via SiCl4 or trimethylchlorosilane and additional hydrothermal treatment with piperidine to decrease the hydrophilicity of the hydroxyl group in the deboronated ERB-1. The catalytic results of 1-hexene, cyclohexene, cyclooctene epoxidation and cyclohexanone ammoximation show that the successfully hydrophobically modified Ti-ERB-1 has significantly improved catalytic activity in aqueous solution and in the presence of H2O2 oxidant. The modified zeolite catalyst can decrease the adsorption of H2O molecules on the zeolite and increase the H2O2 efficiency during the epoxidation of organic alkene and cycloalkene molecules, even in polar solvents. [GRAPHICS] .

Automated summary

The borosilicate zeolite ERB-1 was modified by loading titanium and changing its polarity to improve its catalytic activity in aqueous solutions. The modified Ti-ERB-1 showed significantly improved catalytic activity in the presence of H2O2 oxidant.