There is a growing demand for propylene calls for effective carbon reduction methods. The methanol-to-propylene (MTP) process stands out as a promising solution for meeting global propylene demand sustainably. In this study, we identify the mechanistic factors responsible for enhanced reactivity, superior propylene selectivity, and durable catalyst lifespan in the MTP process catalyzed by both unmodified siliceous and Ca-modified ZSM-5 zeolites. By employing advanced characterization techniques like in situ UV-visible and solid-state NMR spectroscopy, along with well-designed control experiments, we highlight the importance of the alkene cycle within the zigzag channel of zeolite ZSM-5 for superior propylene selectivity. Furthermore, our work identifies oxymethylene species as a key intermediate that enhances the lifetime of the alkene cycle and governs MTP catalysis. We also explore the synergistic interaction between Lewis-Brønsted acids and their impact on hydrocarbon pool species to deepen our understanding of zeolite catalysis.

中文翻译：

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Ca改性和未改性沸石ZSM-5上甲醇制丙烯工艺的阐明选择性描述符


对丙烯的需求不断增长，需要有效的碳减排方法。甲醇制丙烯 （MTP） 工艺是可持续满足全球丙烯需求的有前途的解决方案。在这项研究中，我们确定了在未改性硅质和 Ca 改性的 ZSM-5 沸石催化的 MTP 工艺中负责增强反应性、优异丙烯选择性和持久催化剂寿命的机制因素。通过采用先进的表征技术，如原位紫外-可见光和固体 NMR 波谱，以及精心设计的控制实验，我们强调了沸石 ZSM-5 之字形通道内的烯循环对卓越丙烯选择性的重要性。此外，我们的工作将氧亚甲基物种确定为提高烯烃循环寿命并控制 MTP 催化的关键中间体。我们还探讨了 Lewis-Brønsted 酸之间的协同相互作用及其对碳氢化合物池物种的影响，以加深我们对沸石催化的理解。