Regulation of framework titanium siting in MWW-type titanosilicates by boron and aluminum incorporation and its effect on the catalytic performance

Abstract

Abstract The exploration of efficient catalysts with more accessible active titanium species based on the titanosilicate zeolites is in incremental demands for the construction of the high utilization active centers to the various reactions. Here, we report an active oxidation catalyst MWW-type titanosilicate (Al-Ti-MWW) with more “Ti” active species distributed on the zeolite surface obtained through the implantation of the heteroatom aluminum to the conventional Ti-MWW synthesis. Combined with the overall measurements, it was deduced that more “Ti” species were regulated to evenly distributed in the zeolite crystal, which was due to the competitive occupancy of the heteroatom Al, B and Ti over T locations. Consequently, the bulky-substrate reaction results such as the cyclohexene epoxidation reaction and cyclohexanone ammoximation reaction showed that the Al-Ti-MWW catalyst had a superior catalytic oxidation activity than that of conventional Ti-MWW. It is believed that the application of the convenient treatment method could provide an effective strategy for designing high-performance titanosilicate catalysts.