CH_4/N_2在炭分子筛上的吸附平衡与扩散模型

Study on Adsorption Equilibrium and Diffusion Model of CH_4 and N_2 on a Carbon Molecular Sieve

使用高精密质量吸附仪(IGA-100,HIDEN)测定了CH4和N2纯组分在炭分子筛上于298、313和328 K温度下的吸附等温线及吸附动力学曲线,研究了CH4和N2在炭分子上的吸附热力学及动力学性质。选择Double Langmuir模型(DL)对吸附等温线数据进行了模拟;选择Fick扩散模型进行了吸附动力学的模拟。结果表明,DL模型可以准确地描述CH4和N2在炭分子筛上的吸附,拟合相关系数都非常接近1,N2在该炭分子筛上的吸附量大于CH4的吸附量;通过Fick扩算模型计算得:2 4N CHD/D=7.26,N2在该炭分子筛上的扩散速率大于CH4,所以该炭分子筛可以实现固定床出口直接富集CH4的目的。

Adsorption isotherms and kinetic curves of pure CH4 and N2 gases absorbing onto a carbon molecular sieve were measured by an intelligent gravimetric analyzer apparatus （IGA-100, HIDEN） at 298, 313 and 328 K, respectively. Thermodynamics and diffusion behaviors of CH4 and N2 on the carbon molecular sieve were also investigated. The Double Langmuir （DL） model and the Fick model were introduced to fit the adsorption isotherm and adsorption kinetic data, respectively. The fitting correction coefficients of the DL model for CH4 and N2 are close to 1 and the adsorption capacity of N2 is higher than that of CH4 on the carbon molecular sieve. The results of the Fick model indicate that the diffusion rate of N2 is much faster than that of CH4 on the carbon molecular sieve. Therefore, it is possible to enrich CH4 through a fixed bed using the carbon molecular sieve studied.