CaO-Ca9Al6O18吸收剂的碳酸化反应动力学

以柠檬酸钙和硝酸铝为前体,采用湿法混合法制备了CaO质量分数为80%的CaO-Ca₉Al₆O₁₈吸收剂,并对其CO₂吸收性能进行了研究。结果表明,CaO-Ca₉Al₆O₁₈具有优异的CO₂吸收容量和长周期循环使用稳定性,经过50次循环使用后,其转化率仍保持在78%以上,远优于传统的CaO吸收剂。在500～700℃和CO₂分压为0.005～0.015 MPa条件下,研究了CaO-Ca₉Al₆O₁₈吸收剂的碳酸化反应动力学,分别采用离子反应模型和表观模型描述化学反应动力学控制阶段(快反应段)和产物层扩散阶段(慢反应段)。实验测得的吸收剂转化率与模型预测值吻合较好,快慢反应段的活化能分别为25.6、57.7 kJ·mol^-1。该动力学模型可准确模拟CaO-Ca₉Al₆O₁₈吸收剂在长周期循环使用条件下的碳酸化反应。

Carbonation kinetics of CO2 with CaO-Ca9Al6O18 sorbent

A CaO-Ca₉Al₆O₁₈ sorbent with a mass fraction of CaO of 80% was prepared by the wet mixing method.Calcium citrate and aluminum nitrate were used as calcium and aluminum precursors, respectively. The CO₂ capture performance of the sorbent was investigated by using thermogravimetry.The results showed that the CaO-Ca₉Al₆O₁₈ sorbent exhibited excellent CO₂ capture capacity and long-term cyclic stability, and its conversion remained above 77% after 50 consecutive cyclic operations, which was much better than that of conventional CaO sorbent.The carbonation kinetics between CO₂ and the CaO-Ca₉Al₆O₁₈ sorbent was then studied over a temperature range of 500—700℃ and CO₂ partial pressure of 0.005—0.015 MPa.The fast reaction regime (controlled by chemical reaction) and the slow reaction regime (controlled by diffusion) of the carbonation reaction were successfully described by an ion reaction model and an apparent model, respectively, and the corresponding activation energies were 25.6 kJ·mol^-1 and 57.7 kJ·mol^-1, respectively.The predicted conversions of the CaO-Ca₉Al₆O₁₈ sorbent agreed well with the experimental data.Finally, the kinetic model established was successfully used to predict the carbonation reaction of long-term cyclic operation.