Modeling of gas adsorption equilibrium over a wide range of pressure: a thermodynamic approach based on equation of state.
Modeling of gas adsorption equilibrium over a wide range of pressure: a thermodynamic approach based on equation of state.
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广泛压力范围内的气体吸附平衡建模：基于状态方程的热力学方法。
DOI：
10.1006/jcis.2002.8311
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发表时间：
2002
影响因子：
9.9
通讯作者：
P. Harting
中科院分区：
文献类型：
--
作者：
E. Ustinov;D. Do;A. Herbst;R. Staudt;P. Harting
提出了一种基于Bender状态方程的热力学方法，用于分析高压下超临界气体在活性碳上的吸附。该方法考虑了吸附相中的化学势与相应的体相中的化学势相等以及吸附体积(Eav)元素在气固相互作用势能上的分布。将该格式推广到亚临界流体吸附，并考虑了EAV中的相变。该方法适用于质量过剩吸附的重量测量，并已用于Ar、N、甲烷、乙烷、二氧化碳和氦在Norit R1上的吸附，温度范围为25-70℃。吸附体积元素在电位上的分布函数呈现重叠的峰，并对不同的气体一致地重现。结果表明，分布函数随温度的变化很小，并与用77K氮气吸附等温线得到的分布函数进行了比较，证实了分布函数随温度的变化很小。结果表明，用常规的室温氦膨胀方法可以直接测定孔体积和骨架密度等参数，但由于氦在活性碳小孔中的吸附，会导致错误的结果。该方法是分析和关联大范围压力和温度范围内过剩吸附等温线的一种方便的工具。这种方法可以很容易地推广到多组分吸附体系的分析。
A thermodynamic approach based on the Bender equation of state is suggested for the analysis of supercritical gas adsorption on activated carbons at high pressure. The approach accounts for the equality of the chemical potential in the adsorbed phase and that in the corresponding bulk phase and the distribution of elements of the adsorption volume (EAV) over the potential energy for gas-solid interaction. This scheme is extended to subcritical fluid adsorption and takes into account the phase transition in EAV. The method is adapted to gravimetric measurements of mass excess adsorption and has been applied to the adsorption of argon, nitrogen, methane, ethane, carbon dioxide, and helium on activated carbon Norit R1 in the temperature range from 25 to 70 degrees C. The distribution function of adsorption volume elements over potentials exhibits overlapping peaks and is consistently reproduced for different gases. It was found that the distribution function changes weakly with temperature, which was confirmed by its comparison with the distribution function obtained by the same method using nitrogen adsorption isotherm at 77 K. It was shown that parameters such as pore volume and skeleton density can be determined directly from adsorption measurements, while the conventional approach of helium expansion at room temperature can lead to erroneous results due to the adsorption of helium in small pores of activated carbon. The approach is a convenient tool for analysis and correlation of excess adsorption isotherms over a wide range of pressure and temperature. This approach can be readily extended to the analysis of multicomponent adsorption systems.