CO2载体CaO循环煅烧/碳酸化反应的分形特征

捕捉煤燃烧释放出的CO₂时，作为CO₂载体的CaO微观结构特性对其循环碳酸化性能具有显著影响。采用分形维数作为表征CaO微观结构的特征参数，研究在循环煅烧/碳酸化反应过程中CaO的分形特征及其对CO₂捕捉性能的影响规律。结果表明，随着循环次数的增加CaO分形维数逐渐下降，CaO孔道也由粗糙和不规则变得越来越平滑和有规则性。煅烧温度升高则CaO分形维数下降。分形维数较大的CaO具有较高的碳酸化速率。在碳酸化过程的前10 min内CaO的分形维数迅速减小，此后随时间变化缓慢。在分形维数D≤2.61的实验范围内，CaO分形维数与其循环碳酸化转化率呈线性正相关;当D＞2.61时，可能存在临界分形维数D_cr，当D＞D_cr时随着分形维数的进一步增大CaO转化率反而减小。

Fractal characteristics of CaO as CO2 carrier during cyclic calcination/carbonation reactions

The microstructure of CaO as CO₂ carrier has significant effect on its cyclic calcination/carbonation performance during capturing CO₂ from coal combustion.The fractal dimension was proposed as a characteristic parameter for microstructure of CaO.The fractal characteristics of CaO as well as its effect on CO₂ capture performance were investigated during cyclic calcination/carbonation reactions.The results showed that the fractal dimension of CaO exhibited a decrease with increasing cycle number, and its pore channel changed from rough and irregular to smooth and regular.The fractal dimension of CaO showed a drop with increasing calcination temperature.The higher the fractal dimension of CaO, the greater the carbonation rate.CaO had a sharp reduction in the fractal dimension during the first 10 min of the carbonation period, and then the fractal dimension changed slowly with time.In the test range of CaO fractal dimension (D) less than 2.61, there was a linear proportional correlation between fractal dimension and cyclic carbonation conversion.And there probably was a critical D_cr, when D＞D_cr, CaO conversion likely declined with further increasing D.