Amide-assisted synthesis of TS-1 zeolites with active Ti(OH2)2(OH)2(OSi)2 sites toward efficient oxidative desulfurization

Abstract

Aiming to promote the activity of TS-1 zeolite in catalytic oxidative desulfurization (ODS), a general amide-assisted strategy was proposed to synthesize hierarchical TS-1 zeolite with rich and homogeneously distributed Ti(OH2)2(OH)2(OSi)2 species. Strong interactions between acrylamide (AM) and Si/Ti as well as self-polymerization of AM in synthetic gels change the zeolite formation process, thus to effectively construct Ti(OH2)2(OH)2(OSi)2, promote Ti evenly distribution and form micro-mesopore structure. The activity of Ti(OH2)2(OH)2(OSi)2 was evaluated by ODS of refractory sulfur-containing compounds. The advantages of Ti(OH2)2(OH)2(OSi)2 over TiO4 in substrate adsorption and reactive intermediate formation for ODS were further proved by theoretical calculations. By adjusting AM amount to optimize the Ti(OH2)2(OH)2(OSi)2 content and distribution, the obtained catalyst achieves 134.8 h-1 of turnover frequency and 100 % DBT removal at ten minutes, and maintains > 92 % removal after seven cycles at 333 K. This facile active-site construction strategy is promising to be extended to other heteroatom-containing zeolite catalysts.