钙循环捕集CO2过程中CaO的孔隙演变规律与Ca-C-S竞争反应特性

Calcium looping cycle has been identified as one of the most promising post-combustion CO2 capture technologies to mitigate climate change. However, there is an important scientific question need further research: How the pore evolution during calcium looping affect the Ca-C-S competing reaction? To improve the cyclic carbonation conversion of calcium-based sorbents, the research will be focused on investigating the pore structure of the sorbents, and its effect on Ca-C-S competing reaction will be considered by different types of materials during reaction stages. Based on the evolution of mesopores and macropores, experimental and theoretical methods will be used to explore the scientific research: identify the law of pore structure changes of different calcium-based sorbents in the presence of SO2; describe the heterogeneous interface competing reaction characteristics of carbonation and sulfation; analyze the effect of pore evolution on the Ca-C and Ca-S competing diffusion; find out the pathway of controlling sulfation during cyclic CO2 capture. Above all, it is significant for the research to the development and optimization design of the novel high efficiency calcium looping cycle for CO2 capture.

钙循环捕集CO2技术是应对全球气候变暖而被重点发展的新型碳捕集技术之一。该技术有一个重要问题值得更深入的研究：在循环捕集CO2过程中，CaO的孔隙演变怎样影响Ca-C-S竞争反应？本项目以提高钙基吸收剂的循环碳酸化利用效率为目标，以CaO的孔隙结构为研究对象，分类型、分阶段地考虑孔隙结构演变对Ca-C-S竞争反应的影响机制。从介孔和大孔的演变规律入手将实验和理论方法相结合开展以下科学研究：掌握在SO2条件下不同类型钙基吸收剂的孔隙结构变化规律；深入研究碳酸化和硫酸化的非均相界面竞争反应机理；揭示孔隙变化对Ca-C和Ca-S竞争扩散的影响机制；寻求在钙循环捕集CO2过程中对硫酸化的调控机制。为钙循环捕集CO2技术的开发和优化设计提供理论依据。

CO2是造成气候变暖的主要原因之一，开发高效的大规模CO2减排技术迫在眉睫。基于钙基CO2吸附剂的化学链循环技术被认为是当前最有应用前景的CO2捕集技术之一，该技术至今仍然面临的技术瓶颈为：在高温循环反应中，钙基吸附剂的CO2捕集能力下降很快，而且吸附剂容易受到SO2的影响。项目以提高钙基吸附剂的循环碳酸化利用效率为目标，以CaO的孔隙结构为研究对象，分类型、分阶段地研究孔隙结构演变对Ca-C-S竞争反应的影响机制，掌握了不同类型钙基吸附剂的孔隙结构变化规，研究了不同孔隙结构对非均相界面反应的影响规律，探索孔隙变化对碳酸化和硫酸化竞争反应的调控机理。结果发现碱金属盐改性CaO的循环碳捕集能力是未改性CaO的3倍。钾离子改性的吸附剂在多循环反应中，100nm以上的大孔结构保持稳定。在SO2存在的条件下，改性吸附剂可以保持较高的多循环CO2捕集能力。