钙基吸收剂吸收CO_2的动力学分析

Kinetics of removal of CO_2 by calcium-based sorbents

利用热天平在非等温条件下研究了在N2/CO2气氛下,升温速率、样品粒径及CO2浓度等因素对钙基吸收剂与CO2反应特性的影响,并利用活化能和频率因子进行表征。结果表明:在5种不同前体制备的吸收剂中,草酸钙和乙酸钙制备的钙基吸收剂的活化能最低,更容易与CO2发生反应;在其他条件相同的情况下,分析纯CaCO3制备的钙基吸收剂的活化能,随循环次数增加而逐渐变大,并且在第5次循环到第10次循环之间,活化能增加幅度较大;随着分析纯CaCO3颗粒粒径的增大,其活化能也随之增大;随着升温速率的增大和反应气氛中CO2质量分数的增大,分析纯CaCO3制备的钙基吸收剂的活化能逐渐减小,而频率因子逐渐增大;掺杂有MgO的碳酸钙制备的钙基吸收剂的活化能小于分析纯CaCO3,且MgO掺杂比例为0.05的钙基吸收剂的活化能小于MgO掺杂比例为0.1的钙基吸收剂。

Under N2/CO2 atmosphere, non-isothermal thermo-balance experiment on different calcium-based sorbents was investigated to research the effect of the heating rate, particle size and CO2 concentration on the characteristics of calcium-based sorbent reacting with CO2. The results show that the activation energy of calcium- based sorbent prepared by calcium oxalate and calcium acetate is less than that of other five calcium-based sorbents, which are easier to react with CO2. The activation energy of calcium-based sorbent prepared by pure CaCO3 becomes higher as the number of cycles increasing, and particularly higher between the fifth and the tenth cycles. The activation energy also increases with the increasing of the particle size of pure CaCO3. When the heating rate and the volume ratio of CO2 in the reaction atmosphere increase, the activation energy of calcium-based sorbent prepared by pure CaCO3 decreases, while the frequency factor increases gradually. The activation energy of the calcium-based sorbent mixed with MgO is less than that of pure CaCO3 , and the activation energy of the sorbent contained 5% MgO （mass fraction） is less than that of the sorbent contained 10% MgO （ mass fraction ）.