Dual-template synthesis of hierarchically layered titanosilicate-1 zeolites for catalytic epoxidation of cyclooctene

A one-pot facile route for preparing hierarchically layered titanosilicate-1 (LTS-1) zeolites with stable interlayered mesopores was proposed by integrated using bolaform surfactant (BCph-12-6-6) and tetrapropyl ammonium hydroxide (TPAOH) as dual templates. By tuning the molar ratios of BCph-12-6-6/TPAOH from 5/0 to 5/9, the corresponding LTS-1 samples showed continuous transformations in morphology and intensified degrees of intergrowth by TS-1 nanosheets, resulting in an effective interlayer self-pillaring to avoid the excessive collapse after the removal of the occupied templates by calcination. Moreover, the LTS-1 samples by dual-template synthesis manifested enriched contents of mononuclear octahedrally coordinated Ti species (TiO6). Benefitted by the highly patulous structure and more accessible Ti active sites predominated with highperformance TiO6 species, the LTS-1 catalysts by dual-template synthesis exhibited a superior catalytic activity in the epoxidation of cyclooctene compared with the layered TS-1 directed by sole template of BCph-12-6-6 and the conventional bulk TS-1. It is reasonable to expect that the demonstrated work has important implications for the design and facile synthesis of layered titanosilicate zeolite catalysts with a stably hierarchical structure and tunable catalytic oxidation activities by an optimized distribution of titanium coordination states containing the coordinated TiO4 and TiO6 species.

Automated summary

The study presents a facile route for preparing stable hierarchically layered LTS-1 zeolites using dual templates and demonstrates their superior catalytic activity in the epoxidation of cyclooctene. By adjusting the dual-template ratios, effective interlayer self-pillaring was achieved with enriched TiO6 species.