Abstract CO2 adsorption in activated carbon (AC) at ambient temperature was found to be mainly accomplished by filling of pores with diameter smaller than 1 nm. Kelvin equation correlates operating conditions with the critical (or maximum) diameter of pores where pore filling occurs, but it is not valid for the micropores due to deviation of the physical parameters of CO2 from their normal values. This work extends Kelvin equation to CO2 adsorption in AC by introducing a general dimensionless parameter (KCO2-AC, termed YL parameter) to account for the changes in physical parameters of CO2 in micropores. This approach is similar to the use of fugacity and activity coefficients to modify the ideal gas equation. The work includes measurements of CO2 adsorption capacity for 3 types of AC, fitting the capacity to the ACs' pores from the smallest one to the larger ones to determine the critical pore diameter at each condition, and fitting the critical pore diameter data to a modified Kelvin equation to obtain KCO2-AC. It is found that KCO2-AC varies slightly with the pore diameter but significantly with temperature and can be approximated by an empirical equation. The modified Kelvin equation excellently describes CO2 adsorption data for ACs reported in the literature and studied in this work.

中文翻译：

---

开尔文方程对活性炭中CO 2 吸附的扩展

摘要 发现常温下活性炭（AC）中的 CO2 吸附主要通过填充直径小于 1 nm 的孔隙来实现。开尔文方程将操作条件与发生孔隙填充的孔隙的临界（或最大）直径相关联，但由于 CO2 的物理参数与其正常值存在偏差，因此它不适用于微孔。这项工作通过引入一般无量纲参数（KCO2-AC，称为 YL 参数）来解释微孔中 CO2 物理参数的变化，将开尔文方程扩展到 AC 中的 CO2 吸附。这种方法类似于使用逸度和活度系数来修改理想气体方程。这项工作包括测量 3 种类型的 AC 的 CO2 吸附能力，将容量拟合到 AC 孔从最小到较大以确定每种条件下的临界孔径，并将临界孔径数据拟合到修正的开尔文方程以获得 KCO2-AC。发现 KCO2-AC 随孔径的变化而略有变化，但随温度的变化显着，并且可以通过经验方程来近似。修改后的开尔文方程很好地描述了文献中报道并在本工作中研究的活性炭的 CO2 吸附数据。