摘要
等量吸附热是吸附过程中的一个重要的热力学参数。目前常用的Clausius-Clapeyron方程只适用于计算低压下的等量吸附热,而针对高压下页岩吸附CH过程中的等量吸附热的变化规律研究较少。首先开展了高压下CH气体在页岩中的等温吸附实验,构建了考虑温度相关性的Langmuir-Freundlich模型对吸附实验数据进行表征。然后从多元函数全微分的基本概念出发,基于多温度Langmuir-Freundlich模型提出了高压下考虑体相气体的非理想性和吸附相体积影响的等量吸附热计算新方法。研究结果表明:高压下页岩吸附CH过程中的等量吸附热随着绝对吸附量的增大而降低,页岩基质的非均质性对等量吸附热的影响占主导地位。如果忽略了体相气体非理想性或吸附相体积的影响将会高估等量吸附热。温度越高,气体的非理想性和吸附相体积对于等量吸附热计算结果的影响程度越低。
The isosteric heat of adsorption is an important thermodynamic parameter in the adsorption process. The commonly used Clausius-Clapeyron equation is only suitable for the calculation of the isosteric heat of adsorption under low pressure, while there are few studies on the variation of isothermal adsorption heat during CHadsorption on shale under high pressure. In this paper, isothermal adsorption experiments of CHon shale under high pressure were carried out, and a temperature-dependent Langmuir-Freundlich model was established to characterize the adsorption experimental data. Starting from the basic concept of multivariable differential calculus, a new method for calculating the isosteric heat of adsorption under high pressure considering the non-ideality of bulk phase and the influence of adsorbed phase volume was proposed based on the temperature-dependent Langmuir-Freundlich model.The results showed that the isosteric heat of adsorption decreased with the increase of absolute adsorption amount during CHadsorption on shale under high pressure, and the heterogeneity of shale matrix had a dominant effect on the isosteric heat of adsorption. If the non-ideality of the bulk phase or the influence of adsorbed phase volume was neglected, the calculated isosteric heat of adsorption was overestimated. The higher the temperature, the less the influence of gas nonideality and adsorbed phase volume on the calculation results of the isosteric heat of adsorption.
作者
田伟
刘慧卿
王庆
王敬
TIAN Wei;LIU Hui-qing;WANG Qing;WANG Jing(Key Laboratory of Petroleum Engineering of Ministry of Education,China University of Petroleum-Beijing,Beijing 102249,China)
出处
《当代化工》
CAS
2022年第8期1916-1922,1926,共8页
Contemporary Chemical Industry
基金
国家自然科学基金,页岩气多组分竞争吸附机理研究(项目编号:51774298)。
关键词
高压吸附
页岩气
等量吸附热
吸附相体积
Adsorption at high pressure
Shale gas
Isosteric heat of adsorption
Adsorbed phase volume
