制备温度对芒草热解焦CO2气化反应动力学的影响

利用热重分析仪进行了芒草热解焦与CO2气化反应实验研究,选取均相反应模型、颗粒反应模型和随机孔模型计算了芒草热解焦的CO2气化反应动力学参数,探讨了3种动力学模型的适用性.为进一步探讨制备温度对热解焦CO2气化反应的影响机理,利用扫描电镜(SEM)和Brunauer-Emmett-Teller(BET)分析了芒草热解焦的孔隙结构和表面形态.研究表明,随着制备温度的升高,热解焦表面结构被逐渐加深,表面粗糙度提高,比表面积相对增大,制备温度为600℃的热解焦具有最大的微孔容积与总孔容积之比,使得其更容易发生气化反应;制备温度为400℃时,芒草热解焦在3种模型下具有最小的平均活化能,随机孔模型对芒草热解焦实验数据拟合效果最好,其模拟的相关性系数R2均大于0.97.

Effect of Preparation Temperature on Gasification Reaction Kinetics of Miscanthus Pyrolysis Char with CO2

Gasification reaction experiments of Miscanthus pyrolysis char with CO2 were carried out by using a thermogravimetric analyzer.The corresponding gasification reaction kinetic parameters were calculated by the volumetric model,grain model and random pore model,and the applicability of these models was discussed.In order to further investigate the influencing mechanism of preparation temperature on the gasification reaction of pyrolysis char with CO2,the changes in the pore structure and surface morphology of Miscanthus pyrolysis char were analyzed by a scanning electron microscope(SEM)and the Brunauer-Emmett-Teller(BET)method.Results show that when the preparation temperature increased,the original surface structure was gradually deepened,the roughness was improved,and the specific surface area increased relatively.The pyrolysis char prepared at 600℃had the largest ratio of micropore volume to total pore volume,making it more prone to gasification reactions.When the preparation temperature was 400℃,the average activation energy of Miscanthus pyrolysis char was the smallest for all the three models.The random pore model provides the best fitting effect on the experimental data of Miscanthus pyrolysis char,and all its correlation coefficients are more than 0.97.