On-purpose synthetic routes for propylene production have emerged in the last couple of decades in response to the increasing demand for plastics and a shift to shale gas feedstocks for ethylene production. Propane dehydrogenation (PDH), an efficient and selective route to produce propylene, saw booming investments to fill the so-called propylene gap. In the coming years, however, a fluctuating light olefins market will call for flexibility in end-product of PDH plants. This can be achieved by combining PDH with propylene metathesis in a single step, propane to olefins (PTO), which allows production of mixtures of propylene, ethylene and butenes, which are important chemical building blocks for a.o. thermoplastics. The metathesis technology introduced by Phillips in the 1960s and mostly operated in reverse to produce propylene, is thus undergoing a renaissance of scientific and technological interest in the context of the PTO reaction. In this review, we will describe the state-of-the-art of PDH, propylene metathesis and PTO reactions, highlighting the open challenges and opportunities in the field. While the separate PDH and metathesis reactions have been extensively studied in the literature, understanding the whole PTO tandem-catalysis system will require new efforts in theoretical modelling and operando spectroscopy experiments, to gain mechanistic insights into the combined reactions and finally improve catalytic selectivity and stability for on-purpose olefins production.

中文翻译：

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丙烷制烯烃串联催化：一种选择性生产轻质烯烃的途径

在过去的几十年中，为了应对塑料需求的增加以及乙烯生产向页岩气原料的转变，出现了用于丙烯生产的专用合成路线。丙烷脱氢 (PDH) 是一种高效且选择性的丙烯生产途径，为填补所谓的丙烯缺口而进行了大量投资。然而，在未来几年，波动的轻烯烃市场将要求 PDH 工厂的最终产品具有灵活性。这可以通过在一个步骤中将 PDH 与丙烯复分解结合，即丙烷转化为烯烃 (PTO) 来实现，这可以生产丙烯、乙烯和丁烯的混合物，它们是热塑性塑料的重要化学组成部分。Phillips 在 1960 年代引入的复分解技术，主要是反向操作生产丙烯，因此，在 PTO 反应的背景下，科学和技术兴趣正在复兴。在这篇综述中，我们将描述 PDH、丙烯复分解和 PTO 反应的最新技术，重点介绍该领域的开放挑战和机遇。虽然单独的 PDH 和复分解反应已在文献中得到广泛研究，但了解整个 PTO 串联催化系统需要在理论建模和原位光谱实验，以深入了解联合反应的机理，并最终提高用于目标烯烃生产的催化选择性和稳定性。