Abstract:
Renewable energy sources are receiving increasing attention in order to meet the energy needs of social development and mitigate the effects of greenhouse gases. Advances in hydrogen production technology from renewable energy sources have enabled the sustainable conversion of CO
2 into high-value aromatic hydrocarbons via hydrogenation, offering a promising a pathway for CO
2 emission and carbon recycling. Aromatics, as essential basic chemicals, are widely used in polymers, fuel additives, pharmaceutical intermediates, and other industries. However, due to its high thermodynamic stability and chemical inertness, the efficient activation and directional conversion of CO
2 molecules remain a significant challenge. CO
2 hydrogenation to aromatics primarily proceeds via two pathways: methanol intermediate route and modified Fischer-Tropsch synthesis route. Both routes rely on bifunctional catalysts, typically composed of metal oxides (or iron carbides) coupled with zeolites. The methanol-intermediate route first converts CO
2 into methanol or its derivatives through hydrogenation, followed by further aromatization on the acidic sites of the zeolite. This route exhibits high aromatics selectivity but suffers from limited CO
2 conversion The modified Fischer-Tropsch synthesis route, on the other hand, converts CO
2 into CO via the reverse water-gas shift (RWGS) reaction, followed by the Fischer-Tropsch step to produce olefin intermediates, which are finally aromatized on the zeolite to generate aromatic hydrocarbons. This route achieves higher CO
2 conversion activity but exhibits a broad product distribution, lower aromatics selectivity, and a tendency for excessive hydrogenation to produce alkanes. How to synergistically improve high CO
2 conversion, high aromatic selectivity and long-term catalyst stability remains a pivotal issue in this field. This article focuses on thermal catalytic CO
2 hydrogenation to aromatic hydrocarbons, systematically reviewing recent research progress in this area. Based on the two mainstream reaction systems mentioned above, the catalyst design and regulation strategies are first examined. These include the construction of composite oxides, the introduction of promoters in iron carbide-based catalysts, carrier optimization and innovative preparation methods, as well as modulation acidity, pore structure, and morphology of zeolites. These approaches aim to enhance the synergy among active sites and promote the transfer and transformation of reaction intermediates. Subsequently, the tandem catalysis, the hydrocarbon pool mechanism, hydrogen transfer mechanisms are elaborated upon. Strategies for optimizing reaction pathways through the directed enhancement of intermediates and synergistic catalysis to improve target product selectivity are also discussed, with the goal of improving selectivity toward target products. In parallel, catalyst deactivation behaviors are analyzed, including sintering and migration of metal oxides, phase transformation of iron carbides, and coke deposition on zeolites, providing a theoretical foundation for the development of long-term stable catalyst. Finally, opportunities and challenges are outlined, emphasizing that precise catalyst design, multi-scale investigation of reaction mechanisms, process integration and system optimization, and innovative reaction pathways are key research priorities. This review aims to offer forward-looking research directions and strategic references for the future development of this field.