Breaking the Trade-Off Between Activity and Stability in Reverse Water-Gas Shift Reaction by Forming Highly Active...

The reverse water gas shift (RWGS) reaction holds significant industrial importance. While directly incorporating alkali metals can enhance the catalytic activity, its contribution to enhancing stability remains rather limited. Encapsulating metal centers within zeolites offers a solution to increase stability, however the fine structure of inner active units is hard to control, bringing negative impact on activity. In this work, a dual ligand-protected strategy to control the hybridization of Pt and Na species within silicalite-1 (S1) frameworks is reported, which possesses simultaneously-improved activity and stability compared with conventional RWGS catalysts. Specifically, the catalyst achieves an impressive turnover frequency (TOF) of 207,156.4 h^-1 with 100% CO selectivity at 350 °C. Moreover, it retains high activity even after undergoing accelerated aging tests at 800 °C. Further mechanistic investigations uncover the formation of a novel Pt─O─Na─Si unit within the confined space of S1, where a skeletal oxygen atom simultaneously coordinates with one Na⁺ ion and one Pt atom. In this hybrid structure, the Pt centers exhibit a significantly-raised oxidation state, which was identified as the key factor for the enhancement in RWGS activity: the positive oxidation state facilitates CO desorption, thereby promoting the forward progression of the reaction.