CO2-assisted oxidative dehydrogenation of propane (CO2-ODHP) is an attractive strategy to offset the demand gap of propylene due to its potentiality of reducing CO2 emissions, especially under the demands of peaking CO2 emissions and carbon neutrality. The introduction of CO2 as a soft oxidant into the reaction not only averts the over-oxidation of products, but also maintains the high oxidation state of the redox-active sites. Furthermore, the presence of CO2 increases the conversion of propane by coupling the dehydrogenation of propane (DHP) with the reverse water gas reaction (RWGS) and inhibits the coking formation to prolong the lifetime of catalysts via the reverse Boudouard reaction. An effective catalyst should selectively activate the C-H bond but suppress the C-C cleavage. However, to prepare such a catalyst remains challenging. Chromium-based catalysts are always applied in industrial application of DHP; however, their toxic properties are harmful to the environment. In this aspect, exploring environment-friendly and sustainable catalytic systems with Cr-free is an important issue. In this review, we outline the development of the CO2-ODHP especially in the last ten years, including the structural information, catalytic performances, and mechanisms of chromium-free metal-based catalyst systems, and the role of CO2 in the reaction. We also present perspectives for future progress in the CO2-ODHP.
CO2辅助氧化丙烷脱氢制丙烯(CO2-ODHP)是一种弥补丙烯需求缺口的具有吸引力的策略;同时,由于具有一定的CO2减排潜力,使其在“碳达峰”和“碳中和”背景下备受关注。研究发现,将CO2作为弱氧化剂引入反应中不仅可以避免产物的过度氧化,还可以保持氧化还原性活性金属的高氧化态。此外,在反应体系中,CO2可以通过将丙烷脱氢(DHP)与逆水煤气反应(RWGS)耦合促使反应向生成丙烯方向移动,从而提高丙烷转化率;并且还可以通过逆Boudouard反应来延缓催化剂表面积炭的生成以提高催化剂的使用寿命。一般而言,高效催化剂具备选择性活化C-H键,同时抑制C-C断裂的特性。然而,制备这类催化剂仍然充满挑战。迄今为止,高毒性的Cr基催化剂在丙烷脱氢制丙烯的工业应用中依然被广泛使用。因此,探索环境友好、可持续的非Cr基催化体系是解决丙烷脱氢弊端的重要手段。文章综述了过去十年中CO2-ODHP的研究进展,包括非Cr基金属催化剂体系的结构特性、催化性能和反应机理以及CO2在不同催化体系中的作用。同时,还展望了CO2-ODHP未来需要着重解决的主要问题。.
Keywords: CO2; Catalytic performance; Chromium-free metals; Dehydrogenation; Propane; Propylene.
© Youke Publishing Co.,Ltd 2022.