核壳型钙基CO2吸收剂制备及其活性再生研究

CO2 reduction have been accepted as an international consensus in recent years. To achieve the goal of CO2 reduction, the efficient and clean utilization of fossil fuels has been combined with the CO2 capture and storage technology in many countries. And the CO2 capture technology that based on CaO chemical looping is the most promising one. However, the decay of CO2 capture capacity of CaO-based sorbent, which was caused by the sintering of sorbent crystalline structure, is the major obstacle to the widely deploy of this technology. . To solve the major problems faced by Ca-baesd sorbent, which are the decline CO2 capture capacity and sorbent mechanical strength, this project intends to conduct studies on the synthesis and water/steam reactivation of novel core-shell CaO-based CO2 sorbent with low mass transfer resistance. Cyclic carbonation/calcination experiments of synthetic core-shell sorbent will be carried out to establish the relationship among sorbent compounds, sacrificial template additives, core-shell structure, mass transfer resistance and CO2 capture capacity, and to clarify the kinetic mechanism of core-shell sorbent carbonation/calcination. According to the experimental results, preparation process of core-shell structure sorbent with low mass transfer resistance will be developed. Over the core-shell sorbent, steam reactivation of deactivated sorbent will be performed to examine the effects of reactivation variables on the CO2 capture capacity and anti-corrosion performance. The reactivation mechanism as well as the modified core-shell sorbent preparation routing will be determined. Meantime, cold/hot state tests based on the dual fluidized bed reactor will also be conducted to evaluate the CO2 capture capacity and anti-corrosion performance. The preparation process will be improved according to the experiments that coupling steam hydration and cyclic carbonation calcination via the dual bed reactor. In general, carrying out this project will help to improve the preparation methods of core-shell sorbent, and will also help to solve the problem of sorbent deactivation and particle breakage.

基于CaO吸收剂的化学链CO2捕获技术备受关注，而钙基吸收剂高温烧结导致的活性衰退制约了该技术的进一步应用。本研究为解决钙基吸收剂在循环碳酸化-煅烧捕获CO2过程中活性衰退和颗粒破碎两大关键问题，拟对新型低传质阻力核壳结构钙基吸收剂制备及其水合活化再生开展研究，探索不同外壳及内核添加组分与改型吸收剂外壳气体传质阻力和碳酸化反应性的构效关系，获得低传质阻力外壳的核壳型吸收剂制备方法，建立吸收剂碳酸化和煅烧反应动力学模型；分析蒸汽活化过程变量对失活核壳吸收剂活性再生和颗粒机械强度的影响规律，揭示核壳型吸收剂水合活化过程的反应机理及其与非核壳型吸收剂活化机理差异，获得适合水合操作的低传质阻力吸收剂核壳构型；开展基于小型流化床反应器的核壳吸收剂冷态物料循环、磨损试验及高温CO2捕获试验研究，初步探索水合活化与碳酸化-煅烧流程的耦合特性，为后续研究提供参考。

在我国2030碳达峰和2060碳中和的战略背景下，基于钙基吸收剂的高温CO2捕获是目前极具应用前景的碳减排技术。但原生钙基吸收剂存在固碳性能随循环次数增加迅速衰退、颗粒力学强度低、抗磨损性能差的问题。本项目提出生物模板-惰性骨架掺杂及抗磨SiC球壳包覆制备高性能合成钙基吸收剂新方法，深入研究合成吸收剂的蒸汽活化再生反应特性、活化机理及活化策略。主要研究结果如下：.（1）钙基CO2吸收剂制备方面，获得了生物模板-水泥强化吸收剂和高抗磨性核壳型钙基吸收剂的优选制备策略。①协同高铝水泥作为骨架材料，淀粉作为可烧蚀成孔材料，优化水泥及成孔材料配比，通过挤出-滚圆法制备1-2mm粒径的生物模板-水泥强化钙基吸收剂，其固碳性能显著优于纯钙基吸收剂，初始破碎强度高达81N，远高于纯钙基吸收剂的5N；②基于上述生物模板法初步制备多孔钙基吸收剂球核，在其上包覆SiC/磷酸二氢铝球壳并经过干燥煅烧后形成CaO@SiC核壳钙基吸收剂，获得了优化的球核、球壳物料配比及制备流程，该吸收剂破碎强度高达120N，磨损试验结果表明其抗磨性能优异。.（2）钙基吸收剂的蒸汽活化机理方面，探明了蒸汽活化反应特性、活化机理及活化再生策略。逐层递进开展典型分析纯钙基吸收剂、天然钙基吸收剂、生物模板-水泥强化钙基吸收剂、CaO@SiC核壳钙基吸收剂蒸汽活化特性研究，厘清了蒸汽活化温度、蒸汽浓度、活化频率、活化策略对吸收剂碳捕获性能、力学强度、抗磨性的影响特性，通过孔隙、形貌分析阐明了蒸汽水合活化主要通过再生吸收剂孔隙结构形成新的反应界面，提升了后续的碳酸化反应深度，此外通过大量实验总结出低频（3-5次循环活化一次）、中温（250-300℃）、煅烧后水合的高效蒸汽活化再生策略。