Abstract:

The sorption kinetics of nano Ca-based CO₂ sorbents was investigated by thermogravimetric analysis（TGA）at 500—650℃ and N₂ atmosphere with 0.015—0.025 MPa CO₂ partial pressure. According to the characteristics of CO₂ sorption kinetics of nano Ca-based CO₂ sorbents，the sorption time point corresponding to two times of maximum sorption rate was proposed as the criterion to divide the sorption curve into rapid reaction section and slow reaction section. Boltzmann equation and Avrami-Erofeev equation were selected to simulate the kinetics of both rapid reaction section and slow reaction section. The activation energies were 27.52 kJ·mol^-1 and 70.25 kJ·mol^-1 respectively for the rapid reaction section and slow reaction section，with the mean average relative deviation of sorption ratio 10.29％，4.17% respectively. The decomposition kinetics of nano Ca-based CO₂ sorbents was experimentally studied also by thermogravimetric analysis（TGA）at 650—800℃ and three cases of N₂ atmosphere，0.02 MPa,0.04 MPa CO₂ partial pressure N₂ atmosphere. The decomposition kinetics equations were correlated by the shrinking core model by ignoring the effects of mass and heat transfer. The activation energies were 141.9 kJ·mol^-1，34.7 kJ·mol^-1 and 113.2 kJ·mol^-1 in the above three cases respectively，with the average relative deviation of decomposition ratio less than 5.66%，7.82% and 5.01% respectively.

摘要：

采用TGA测定纳米钙基CO₂吸附剂在500～650℃温度范围内，CO₂分压0.015～0.025 MPa氮气气氛中的吸附反应动力学。针对纳米钙基CO₂吸附剂吸附CO₂反应特征，提出以两倍最大吸附速率对应的时间点前后分别为快速反应段与慢速反应段。分别采用Boltzmann方程与Avrami-Erofeev方程拟合快速反应段与慢速反应段吸附反应动力学方程，得到纳米钙基CO₂吸附剂在快速反应段与慢速反应段的活化能分别为27.52、70.25 kJ·mol^-1。吸附率拟合与实验值平均相对误差分别为10.29％、4. 17%。研究测试了纳米钙基CO₂吸附剂在650～800℃温度范围内，N₂，0.02、0.04 MPa CO₂分压氮气气氛中的分解反应动力学。忽略反应过程中传热、传质影响，采用收缩核模型，分别求得吸附剂在N₂，0.02、0.04 MPa CO₂分压氮气气氛中的活化能为141.9、34.7、113.2 kJ·mol^-1。碳酸钙分解率与实验值比较平均相对误差分别小于5.66% 、7.82%、5.01%。