C_2H_4/CO_2混合体系在活性炭上吸附的实验与模型

Adsorption of Ethylene and Carbon Dioxide Binary Systems on Active Carbon:Experiment and Model

通过重量法测定吸附等温线,研究了C2H4/CO2混合体系在活性炭上的吸附分离。采用高精度的智能重量分析仪,测定了C2H4和CO2纯组分以及混合组分在活性炭上的吸附等温线,将测量值与DL-IAST模型计算值进行比较,并计算出了C2H4的吸附选择性。结果表明,DL-IAST模型可以准确地描述C2H4和CO2纯组分在活性炭上的吸附;不同摩尔分数下,C2H4/CO2混合体系的DL-IAST模型计算值与实验值吻合得较好,C2H4摩尔分数越大,模型的相对偏差就越小;随着压力的增加,C2H4的吸附选择性减小,C2H4摩尔分数越大,C2H4的吸附选择性也减小。DL-IAST可以准确地描述C2H4/CO2混合体系的吸附等温线以及推算出C2H4的吸附选择性。

The adsorption isotherms of ethylene and carbon dioxide binary system on active carbon were studied by using the gravimetric method, and the isotherms of ethylene, carbon dioxide and their binary mixture systems on active carbon were determined by intelligent gravimetric analyzer （IGA）. The double Langmuir （DL） model was applied to study the adsorption of the pure gas, and the DL model combined with the ideal adsorbed solution theory （IAST） was used to predict the adsorption isotherms of the binary system. It was found that the combined method （DL-IAST） can be applied to describe the adsorption isotherms of adsorbing the binary system of C2H4 and CO2 on active carbon perfectly. For the binary systems with higher molar fraction of C2H4, their adsorption isotherms predicted by IAST agree with the experimental data better than that predicted for the binary systems with lower molar fraction of C2H4. The calculated results indicate that the adsorption selectivity of C2I-h is higher when the molar fraction of C2I-h in the binary system or the used adsorption pressure is lower. It can be concluded that the DL-IAST can be used to describe the adsorption isotherms and to calculate the C2H4 adsorption selectivity for the adsorption of C2H4 and CO2 binary systems on active carbon.