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球形颗粒Li4SiO4吸附CO2反应动力学研究

Reaction kinetics study on CO2 adsorption of spherical Li4SiO4 particles

  • 摘要: Li4SiO4吸附CO2的动力学研究普遍以粉末样品为对象,忽略了流化床反应器对于吸附颗粒尺寸的基本要求,因而大幅削弱了其参考价值。为此,基于挤出滚圆法通过添加PE、C6H12O6、NH4HCO3造孔剂实现了Li4SiO4颗粒成型,分别得到了P颗粒、C颗粒和N颗粒,随后采用热重分析、抗压强度测试和孔结构测试研究了3种吸附颗粒的基础特性;进一步基于吸附性能最优的P颗粒进行了CO2吸附反应过程测试与动力学分析。结果表明:P颗粒的抗压强度最低、吸附性能最优,N颗粒的性能则与P颗粒相反,3种造孔后的颗粒吸附性能均强于未造孔颗粒。孔结构测试发现P颗粒具有最佳的比表面积和孔隙结构、C颗粒其次、N颗粒最差,因此造成了性能方面的差异。晶粒模型及Jander模型对P颗粒CO2吸附动力学的研究发现,反应速率常数随温度升高、CO2浓度升高以及粒径降低而增大,P颗粒吸附CO2过程在〖JP2〗动力学控制阶段的活化能和指前因子〖JP〗分别为41.61 kJ/mol和4.20 m0.133·mol-0.289·s-1,而在扩散控制阶段则分别为114.81 kJ/mol和131.92 s-1。

     

    Abstract: The kinetic study of CO2 adsorption by Li4SiO4 generally takes powder samples as the object, ignoring the basic requirements of the fluidized bed reactor for the adsorption particle size, which greatly weakens its reference value. To this end, Li4SiO4 particles were formed by adding PE, C6H12O6, NH4HCO3 pore-forming agents based on extrusion spheronization, and P particles, C particles and N particles were obtained respectively. Then, the basic characteristics of the three particles were studied by thermogravimetric analysis, compressive strength test and pore structure test. Furthermore, the CO2 adsorption reaction process test and kinetic analysis were carried out based on the P particle with the best adsorption performance. The results show that P particles have the lowest compressive strength and the best adsorption performance, while the performance of N particles is opposite to that of P particles. Pore structure testing found that P particles had the best specific surface area and pore structure, C particles second, and N particles the worst, thus causing the difference in performance. The study on the kinetics of CO2 adsorption of P particles by the grain model and Jander model found that the reaction rate constant increases with the increase of temperature, the increase of CO2 concentration and the decrease of particle size. and the activation energy of P particle adsorption process of CO2 in the kinetic control stage and pre-exponential factors are 41.61 kJ/mol and 4.20 m 0.133·mol-0.289·s-1, respectively, while they are 114.81 kJ/mol and 131.92 s-1 in the diffusion-controlled phase, respectively.

     

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