Pollen-templated bio-TS-1: a sustainable catalyst with hierarchical porosity for propylene epoxidation†

Abstract

Titanium silicalite (TS-1) emerges as a pivotal catalyst, finding widespread application across the domains of petrochemical and specialty chemical industries. However, its singular microporous structure limits its application in numerous reactions, such as propylene epoxidation. Here, we introduce a N self-doped bio-TS-1 catalyst with a stratified porous structure synthesized using an environmentally friendly pollen templating method. The unique hierarchical porous structure of the bio-TS-1 catalyst optimizes mass transfer efficiency, accelerates product resolution, and prevents the occurrence of carbon deposition. Concurrently, biomass self-doping of nitrogen effectively modulates the electronic structure of the catalyst, with Ti sites being more relaxed and the α-O in Ti-OOH being more aggressive towards CC bonds of propylene. The synergistic effect breaks the trade-off between performance and stability, with not only the PO yield reaching up to 305 g_PO h⁻¹ kg_cat⁻¹ but also the catalyst exhibiting stability for over 120 h. This simplified synthesis strategy provides a feasible solution for the preparation of highly efficient and stable hierarchical porous TS-1-based catalysts.