Temperature-regulated construction of hierarchical titanosilicate zeolites
Titanosilicate zeolites are an important class of heterogeneous catalysts widely used in several catalytic processes. The creation of hierarchical titanosilicate zeolites (e.g., TS-1 with MFI structure) is of great interest which can promote the mass transportation and molecular accessibility of the reactant molecules. Herein, we presented a temperature-regulated method to construct anatase-free hierarchical TS-1 zeolite catalysts by utilizing a two-step hydrothermal crystallization strategy with tetrabutylammonium hydroxide (TBAOH) as the sole organic structure directing agent. The two-step crystallization process, i.e., initial crystallization at lower temperature followed by secondary crystallization at higher temperature, afforded the incorporation of more active Ti species into TS-1 as well as the formation of hierarchical structures resultant from the layer-stacking growth manner. The prepared hierarchical TS-1 zeolite catalysts showed superior catalytic performance in the oxidative desulfurization of bulky organosulfur compound dibenzothiophene compared with the microporous counterpart, giving a higher turnover number (23.5 vs. 1.7). The temperature-based kinetic regulation approach offers an effective way to the construction of hierarchical titanosilicate zeolite catalysts with controllable active Ti atoms.