生物质模板改性钙基吸附剂颗粒脱碳机理研究

CaO-based sorbent has received significant attention in high-temperature CO2 capture field due to its low cost and high CO2 sorption capacity. However, the spent and elutriated CaO-based sorbents are prone to be generated during CaO-based sorbent being continuously circulated to remove CO2 in the flue gas, which restricts the practical application of calcium looping process for CO2 capture. Therefore, the deactivation and elutration of CaO-based sorbent as the guide of this project, low-cost herbaceous plants are used as the pore-forming templatings to improve the cyclic CO2 capture performance of CaO-based pellets. Focusing on the co-modification effect of pore-forming of biomass template and doping of the residual biomass template ash, the modification effects of pore-forming and doping are separated via directional design experiments, aiming to reveal the co-modification mechanism of biomass templating through the single factor influence research. At the same time, draw lessons from traditional noncatalytic gas-solid reaction model of some reasonable assumptions, combining the CO2 capture characteristics of the biomass-templated CaO-based pellets, establishing the biomass-templated CaO-based pellets carbonation reaction grain model to comtribute deeply understand the carbonation mechanism of biomass-templated CaO-based pellets.

钙基吸附剂由于低成本及其高CO2吸附容量，在高温碳捕集领域受到了广泛关注。然而，钙基吸附剂循环流化脱除烟气中CO2时，容易出现失活和扬析的问题，制约了钙循环CO2捕集技术的实际应用。因此，本项目以钙基吸附剂失活和扬析的问题为导向，拟采用低成本的草本生物质作为造孔模板材料改性钙基吸附剂成型颗粒的循环脱碳性能。聚焦生物质模板造孔及其残余灰渣掺杂对钙基吸附剂颗粒的协同改性作用，定向设计实验，将生物质模板造孔和灰渣掺杂改性作用分离，通过单一因素影响研究来揭示其协同改性机理。同时，借鉴传统的非催化气固反应模型的部分合理假设，结合生物质模板改性钙基吸附剂颗粒脱碳反应过程特性，建立生物质模板改性钙基吸附剂颗粒碳酸化反应粒子模型，从微观机理层面认识生物质模板改性钙基吸附剂颗粒循环脱碳性能的作用机制。

钙基吸附剂由于低成本及其高CO2吸附容量，在高温碳捕集领域受到了广泛关注。然而，钙基吸附剂循环流化脱除烟气中CO2时，容易出现失活和扬析的问题，制约了钙循环CO2捕集技术的实际应用。本项目通过挤压-滚圆法制备生物质模板改性的钙基吸附剂颗粒，重点揭示不同预煅烧条件下（氮气热解、空气煅烧和煤粉掺燃）生物质模板改性钙基吸附剂颗粒的孔隙结构与其循环脱碳性能的构效关系。发现煤粉掺燃易导致颗粒纳米级孔隙的塌陷，但形成的微米级空穴强化CO2循环吸附的稳定性。进一步明析草本生物质造孔模板中碱金属杂质元素易与活性CaO形成低温共熔体，加速钙基吸附剂颗粒烧结的失活机制。并提出水洗、酸洗预处理去除生物质模板中水溶态和酸溶态的碱金属（钾和钠）杂质元素强化其对钙基吸附剂颗粒孔隙结构的重构作用，有效缓解生物质模板改性钙基吸附剂颗粒的烧结，并降低CO2扩散进入颗粒内部与其中活性CaO进行碳酸化反应的阻力，提升改性钙基吸附剂颗粒的循环脱碳性能。此外，开发了水化路径下TiO2负载强化钙基吸附剂颗粒循环脱碳性能的技术路径，在钙基吸附剂颗粒内部形成均匀分布的CaTiO3晶粒作为惰性骨架结构，并且水化产物的强键合作用有利于提升钙基吸附剂颗粒的机械性能。