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 TiCl 4 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 SiCl 4 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 H 2 O 2 oxidant. The modified zeolite catalyst can decrease the adsorption of H 2 O molecules on the zeolite and increase the H 2 O 2 efficiency during the epoxidation of organic alkene and cycloalkene molecules, even in polar solvents. Graphical Abstract