Key Laboratory of Energy Thermal Conversion and Control, Ministry of Education, School of Energy and Environment , Southeast University , Nanjing 210096 , China.
Environ Sci Technol. 2019 Feb 19;53(4):2249-2259. doi: 10.1021/acs.est.8b06138. Epub 2019 Jan 30.
Herein we report the development of synthetic CaO-based sorbents for enhanced CO capture in calcium looping via a template-assisted synthesis approach, where carbonaceous spheres (CSs) derived from hydrothermal reaction of starch are used as the templates. Cage-like CaO hollow microspheres are successfully synthesized only using urea as the precipitant, and the formation mechanism of this unique hollow microsphere structure is discussed deeply. Moreover, cage-like CaO hollow microspheres possess an initial carbonation conversion of 98.2% and 82.5% under a mild and harsh conditions, respectively. After the 15 cycles, cage-like CaO hollow microspheres still possess a carbonation value of 49.2% and 39.7% under the corresponding conditions, exceeding the reference limestone by 85.7% and 148.1%, respectively. Two kinetic models are used to explore the mechanism of carbonation reaction for cage-like CaO hollow microspheres, which are subsequently proved to be feasible for analysis of chemical-controlled stage and diffusion-controlled stage in the carbonation process. It is found the unique hollow microsphere structure can significantly reduce the activation energy of carbonation reaction according to the kinetic calculation. Furthermore, the energy and raw material consumptions related to the synthesis of cage-like CaO hollow microspheres are analyzed by the life cycle assessment (LCA) method.
本文通过模板辅助合成方法，开发了用于增强钙循环中 CO 捕集的合成 CaO 基吸附剂，其中将源自淀粉水热反应的碳质球（CS）用作模板。仅使用尿素作为沉淀剂即可成功合成笼状 CaO 空心微球，并且深入讨论了这种独特的空心微球结构的形成机理。此外，笼状 CaO 空心微球在温和条件和苛刻条件下的初始碳酸化转化率分别为 98.2%和 82.5%。在 15 个循环后，笼状 CaO 空心微球在相应条件下的碳酸化值仍分别为 49.2%和 39.7%，分别超过参考石灰石的 85.7%和 148.1%。使用两个动力学模型来探索笼状 CaO 空心微球的碳酸化反应机理，随后证明它们适用于碳酸化过程中化学控制阶段和扩散控制阶段的分析。根据动力学计算发现，独特的空心微球结构可以显著降低碳酸化反应的活化能。此外，通过生命周期评估（LCA）方法分析了合成笼状 CaO 空心微球的能量和原材料消耗。
