Silicalite-1 Stabilizes Zn-Hydride Species for Efficient Propane Dehydrogenation
Shaojia Song, Kun Yang, Peng Zhang, Wu Zhi, Jun Li, Hui Su, Sheng Dai, Chunming Xu, Zhenxing Li, Jian Liu, Weiyu Song
Abstract
Propane dehydrogenation (PDH) is promising for producing high value-added propylene. The discovery of a more efficient, economical, and nontoxic PDH catalyst is of great importance. Herein, we found zinc hydrides ([ZnH]+) as the highly reactive site for PDH. In situ spectroscopy and theoretical studies reveal that [ZnH]+ was transformed from zinc hydroxyl ([ZnOH]+) sites under reductive conditions. Accordingly, the formation of [ZnH]+ can be controlled by adjusting the amount of zinc hydroxyl ([ZnOH]+) species by various additives. The optimized Cu–ZnO@S-1 consists of exclusively isolated [ZnOH]+ sites, which help produce more [ZnH]+ toward optimal PDH activity. Specifically, the catalyst enables 43% propane conversion with >88% propylene selectivity, close to the thermodynamic equilibrium. This efficient PDH performance was attributed to the electron-deficient Zn in [ZnH]+ that can lower the dehydrogenation barrier, and the Cu-modified [ZnH]+ structure favors the direct PDH pathway to further promote the formation of propylene and H2.