逆水煤气变换反应新兴强化技术研究进展

Research progress on emerging enhancement technologies for reverse water–gas shift reaction

  • 摘要: CO2排放量的持续增长,导致全球环境恶化,严重危及人类生存环境. 钢铁行业作为排碳大户,碳减排责任重大. 利用逆水煤气变换(RWGS)反应可将CO2转化为合成气组分CO,并进一步制取其他工业化学品,是一条极具潜力和发展前景的燃料生产绿色路线. 目前,RWGS反应中热催化工艺作为主要的技术路线表现出最高的成熟度,但其存在CO2高热力学稳定性、CO2转化率和CO产量低以及能源效率等问题,热力学分析表明,若要保持较高CO2平衡转化率需提高温度,降低温度会导致副反应的发生. 因此. 探索各种新兴强化技术解决上述问题,对于推进RWGS反应实现大规模工业应用至关重要. 文章首先综述了RWGS反应新兴强化技术的研究进展,比较了不同RWGS反应新兴强化技术的优点和局限性,并介绍了膜、光热反应、等离子体辅助和电场促进技术在RWGS反应中的应用以及对反应性能的改善作用;其次从技术和经济角度对RWGS反应新兴强化技术的工业化应用进行了分析讨论;最后,对RWGS反应新兴强化技术的应用前景进行展望,并给出未来的发展方向.

     

    Abstract: The continuous growth of carbon dioxide (CO2) emissions has led to the deterioration of the global environment, creating a serious crisis for the human living environment. As a major carbon emitter, the steel industry accounted for 16.9% of the total industrial CO2 emissions in China. Thus, the steel industry shoulders significant responsibility for carbon reduction in the process of implementing the country’s dual carbon strategy. Converting CO2 into high-value-added chemicals is an important way to achieve carbon reduction and resource recycling, but it faces certain technical challenges. The reverse water–gas shift (RWGS) reaction can convert CO2 into syngas component carbon monoxide (CO), which has both thermodynamic feasibility and economic advantages. The produced CO can be used in the preparation of other industrial chemicals, which is a promising green route to fuel production. At present, the thermal catalytic process in the RWGS reaction is the main technical route. However, it has problems such as high thermodynamic stability of CO2 and low CO2 conversion rate, CO production, and energy efficiency. Thermodynamic analysis indicates that the temperature must be increased to maintain a high equilibrium CO2 conversion rate. Reducing the temperature will lead to side reactions. The water produced by the reaction can also cause catalyst deactivation. Therefore, exploring various emerging enhancement technologies to solve the above problems is crucial for promoting the large-scale industrial application of RWGS reactions. Researchers have conducted extensive studies on the traditional thermal catalytic RWGS reaction in terms of catalytic material preparation, reaction mechanism analysis, and reaction parameter optimization. However, there is a lack of systematic review and evaluation of emerging enhancement RWGS reaction technologies. In this review, we first introduce the research progress of RWGS emerging enhancement technologies. The advantages and limitations of different RWGS technologies are compared, and the applications of membrane-, photothermal-, plasma-assisted, and electric field-promoted RWGS reaction and the improvement of reaction performance are discussed. Membranes have been widely used in other industrial reactions. In the RWGS reaction, water can be removed through membranes to achieve higher CO yields, which solves the problems of product separation and catalyst deactivation caused by H2O. However, membranes are expensive and their performance degrades easily owing to contamination. The photothermal reaction harnesses the synergistic interplay between light and heat energies to initiate CO2 reduction. This dual-energy approach transforms light into heat, effectively lowering the activation energy and overcoming energy barriers inherent in the RWGS reaction. Although this is an economical reaction route, the intermittency of sunlight and availability of high-performance photocatalysts remain a challenge. The synergistic effect of plasma-assisted and electric field-promoted systems with catalysts is conducive to improving the CO2 conversion rate and suppressing side reactions. However, the above two technologies are still in the experimental research stage. Finally, the application prospects of RWGS emerging enhancement technologies and suggestions for further applications are discussed.

     

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