Mesoscopic framework in hierarchical Pt/Silicate-1 zeolite catalyst enables stable low-temperature CO conversion

Hierarchical porous zeolites often exhibit improved diffusion and enhanced catalytic performance compared to conventional microporous zeolites. Meanwhile, metal encapsulation in a zeolite framework becomes an efficient way to achieve a highly dispersed and stable metal loading for heterogeneous catalysts. Herein, we synthesize a hierarchical Silicate-1 (S-1) zeolite catalyst with three-dimensional mesoscopic channels, which achieves both improved diffusion and uniform encapsulation of Pt species. We find that the optimized zeolite possesses atom-precise mesoscopic channels (2 and 4 nm) formed during the controlled crystallization process, which enables a better catalytic performance (100% CO conversion at a low temperature of ∼60 °C for over 250 h) compared with other mesoscopic S-1 catalysts with varied pore sizes and also superior to micropore-only S-1 with an even smaller Pt size. This unique channel structure enables a balance between maximizing the effective encapsulation of Pt and prohibiting aggregation of Pt species, further broadening the scope of hierarchical porous zeolite catalysts. [Display omitted] •The Pt-encapsulated mesoscopic S-1 zeolite catalysts are prepared by a two-step process through controlled crystallization.•The as-prepared catalysts achieve a 100% conversion of CO at as low as 60 °C with a stable operation for over 250 h.•The planar defects with a dimension of (2∼4) nm are identified as the major mesoscopic structure responsible for the improved catalytic performance.