Propane dehydrogenation (PDH) reaction has emerged as one of the most promising propylene production routes due to its high selectivity for propylene and good economic benefits. However, the commercial PDH processes usually rely on expensive platinum-based and poisonous chromium oxide based catalysts. The exploration of cost-effective and ecofriendly PDH catalysts with excellent catalytic activity, propylene selectivity, and stability is of great significance yet remains challenging. Here, we discovered a new active center, i.e., an unsaturated tricoordinated cobalt unit (≡Si–O)CoO(O–Mo) in a molybdenum-doped silicalite-1 zeolite, which afforded an unprecedentedly high propylene formation rate of 22.6 mol_C3H6 g_Co^–1 h^–1 and apparent rate coefficient of 130 mol_C3H6 g_Co^–1 h^–1 bar^–1 with >99% of propylene selectivity at 550 °C. Such activity is nearly one magnitude higher than that of previously reported Co-based catalysts in which cobalt atoms are commonly tetracoordinated, and even superior to that of most of Pt-based catalysts under similar operating conditions. Density functional theory calculations combined with the state-of-the-art characterizations unravel the role of the unsaturated tricoordinated Co unit in facilitating the C–H bond-breaking of propane and propylene desorption. The present work opens new opportunities for future large-scale industrial PDH production based on inexpensive non-noble metal catalysts.

中文翻译：

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沸石中的三配位单原子钴促进丙烷脱氢

丙烷脱氢(PDH)反应因其丙烯选择性高、经济效益好而成为最有前途的丙烯生产路线之一。然而，商业PDH工艺通常依赖于昂贵的铂基和有毒的氧化铬基催化剂。探索具有优异催化活性、丙烯选择性和稳定性的经济高效、环境友好的PDH催化剂具有重要意义，但仍然具有挑战性。在这里，我们发现了一个新的活性中心，即钼掺杂的silicalite-1沸石中的不饱和三配位钴单元(≡Si–O)CoO(O–Mo)，它提供了前所未有的高丙烯形成速率，达到22.6 mol _C3H6 g _Co ^–1 h ^{–1和 130 mol} _C3H6 g _Co ^–1 h ^–1 bar ^–1的表观速率系数，在 550 °C 时丙烯选择性 >99%。这种活性比之前报道的钴原子通常为四配位的钴基催化剂高出近一个数量级，甚至优于大多数铂基催化剂在相似操作条件下的活性。密度泛函理论计算与最先进的表征相结合，揭示了不饱和三配位Co单元在促进丙烷和丙烯解吸的C-H键断裂中的作用。目前的工作为未来基于廉价非贵金属催化剂的大规模工业PDH生产开辟了新的机遇。