热钾碱溶液脱除沼气中CO_2的反应动力学

Reaction Kinetics of CO_2 Removal from Biogas Using Hot Potassium Carbonate Solvent

根据CO_2吸收过程串并联反应机理,建立了本征动力学方程;基于双膜扩散理论,建立了CO_2吸收反应的宏观动力学方程,并结合溶液的非理想性,对速率方程中的浓度效应进行了修正,获得了8个修正模型。通过实验设计,测定并进行了模型参数估值,分别计算了各模型的残差。通过比较残差大小及其分布,对模型进行了筛选,选取模型4为理想模型。其动力学参数为:表观活化能19 383.94 J/mol,表观指前因子3.042 9×10^(-5)mol/(m^2·s·Pa)。在此基础上,通过理论推导获得了热钾碱吸收CO_2的本征动力学方程,其模型参数为:本征反应活化能54.47 kJ/mol,指前因子3.222 8×10~9m^3/(mol·s)。计算了膜内转化系数γ,该值大于2,表明CO_2吸收为快速反应过程,反应主要在膜内完成。

Following the mechanism of series-parallel reaction in CO2 absorption process, the intrinsic kinetic equation was established. A macroscopic kinetic equation of CO2 absorption reaction was established based on the theory of double membrane diffusion. Considering the none-ideal solution, the concentration effect in the rate equation was corrected differently to obtain eight correction models. Through the orthogonal experiment design, the experimental factors were reaction temperature, initial concentration of potassium carbonate, reaction time and mixture of methane and carbon dioxide, and the level of each factor was 3. The experimental data were measured in a double-drive reactor and the model parameters were estimated. The residual values of each model were calculated respectively. The models were contrasted by comparing the residual value sizes and distributions, and the model 4 was considered as the ideal with kinetic parameters as follows: apparent activation energy E ob was 19 383.94 J/mol, apparent anterior factor kob^(0) was 3.042 9×10^-5 mol/(m^2 ·s ·Pa). Through theoretical derivation based on these model parameters, the intrinsic kinetic equation of CO2 absorption by hot potash was obtained with following model parameters: the intrinsic reaction activation energy E was 54.47 kJ/mol, the anterior factor k 0 was 3.222 8×10^9 m^3 /(mol ·s). The conversion coefficient γ was calculated to be a value much greater than 2, which indicated that the CO2 absorption was a rapid reaction process that mainly happened in the membrane.