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    二氧化碳加氢制低碳烯烃催化剂改性策略的研究进展

    Research progress in catalyst modification strategies for CO2 hydrogenation to light olefins

    • 摘要: 二氧化碳(CO2)排放量的持续增长引发全球生态环境的恶化,导致气候变化、海洋酸化等一系列环境问题,CO2减排已成为当前可持续发展所面临的巨大挑战。低碳烯烃作为化工行业重要的基础原料和平台分子,广泛用于制备多种增值化学品。不同于以往合成低碳烯烃的原料和工艺,以CO2为原料合成低碳烯烃不仅可以实现CO2的资源化利用,还可以缓解对石油资源的依赖,是实现环境、能源以及经济的共赢之举。目前,广泛报道的CO2加氢制低碳烯烃主要有2种路径:以CO为中间体的CO2-FTO路径和以甲醇为中间体的CO2-MTO路径。CO2-FTO路径具有高的CO2转化率,但C—C偶联不可控,产物服从安德森–舒尔茨–弗洛里(Anderson-Schulz-Flory,简称ASF)分布,导致低碳烯烃选择性受到限制;CO2-MTO路径突破了ASF分布的限制,可实现较高的低碳烯烃选择性,但存在CO2转化率较低、副产物CO选择性较高的问题。文章系统综述了2条路径的反应过程、反应机理以及提升催化性能所采用的催化剂改性策略,其中,CO2-FTO路径的改性策略主要围绕Fe基催化剂展开,包括助剂的掺杂(碱金属助剂、过渡金属助剂等)、载体的优化(氧化物、碳材料)等;CO2-MTO路径的改性策略从金属氧化物、分子筛以及二者的耦合方式等3个角度出发。另外,对近期报道的一种关于CO2加氢制低碳烯烃的新反应路径(即RWGS+CO加氢路径)做了简要概述。最后,总结不同路径改性策略的优势与不足,并对未来研究方向进行了展望。总体而言,CO2加氢制低碳烯烃是一条具有广阔发展前景的可持续化工生产路线。

       

      Abstract: The continuous growth of carbon dioxide (CO2) emissions exacerbates global ecological degradation, leading to a series of environmental issues such as climate change and ocean acidification. Reducing CO2 emissions has therefore become a critical challenge for sustainable development. Light olefins, serving as essential feedstocks and platform molecules in the chemical industry, are widely used to produce various value-added chemicals. Unlike conventional feedstocks and processes for olefin synthesis, the conversion of CO2 into light olefins not only enables resource utilization of CO2 but also reduces dependence on petroleum resources, representing a promising approach that benefits the environment, energy security, and the economy. Currently, two main pathways for CO2 hydrogenation to light olefins are widely reported: the CO2-Fischer-Tropsch to Olefins (CO2-FTO) pathway via CO as an intermediate, and the CO2-Methanol to Olefins (CO2-MTO) pathway via methanol. The CO2-FTO pathway achieves high CO2 conversion, but the C—C coupling is uncontrollable, resulting in a product distribution that follows the Anderson-Schulz-Flory (ASF) model, which limits the selectivity toward light olefins. In contrast, the CO2-MTO pathway breaks the ASF distribution constraint and enables higher light olefin selectivity; however, it suffers from low CO2 conversion and high CO byproduct selectivity. This review systematically summarizes the reaction processes, mechanisms, and catalyst modification strategies employed to enhance catalytic performance for both pathways. For the CO2-FTO route, modification strategies primarily focus on Fe-based catalysts, including the doping of promoters (e.g., alkali metals, transition metals) and the optimization of supports (e.g., oxides, carbon materials). For the CO2-MTO route, strategies are discussed from three perspectives: metal oxides, zeolites, and their coupling methods. Additionally, a recently reported alternative pathway (i.e., RWGS followed by CO hydrogenation) is briefly outlined. Finally, the advantages and limitations of different modification strategies across pathways are summarized, and future research directions are proposed. Overall, CO2 hydrogenation to light olefins represents a sustainable chemical production route with broad prospects for development.

       

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