氨基改性吸附剂在低CO2分压下吸附CO2的热力学研究

为了减少温室效应,应采取有效措施减少温室气体CO2的排放。氨基改性吸附剂是捕获烟道气中CO2的重要吸附材料。建立了描述氨基改性MCM-41吸附剂在低CO2压力下吸附等温线的平衡模型,并计算了吸附热力学参数。该模型基于Dual-site Langmuir模型,同时假设CO2吸附具有两种独立的吸附机理,分别是氨基基团的化学吸附和吸附剂表面的物理吸附,提出了一种基于未改性介孔材料吸附容量和比表面积计算改性材料的物理吸附量方法。结果表明,该模型能较好地拟合吸附等温线,计算得到的物理化学吸附热分别为-25.4kJ/mol和-41.9kJ/mol,总吸附热为-67.3kJ/mol,与实验数据一致,且氨基改性MCM-41-TEPA饱和吸附容量可达到7.79mmol/g。

Thermodynamic study on amine-modified adsorbent of CO2 adsorption at low CO2 partial pressures

To reduce the greenhouse effect, effective measures should be taken to reduce the emissions of CO₂. Amine-modified adsorbents are considered as important adsorbent materials to capture CO₂. In this paper, a balance model was established to describe the adsorption isotherms of amine modified MCM-41 under low CO₂ partial pressure and the thermodynamic parameters was calculated. The model was based on Dual-site Langmuir model and assumed that there were two independent adsorption mechanisms:chemical adsorption on amine groups and physical adsorption via surface area. In order to distinguish the physical adsorption and chemical adsorption of amine modified adsorbents, a new method based on adsorption of non-modified adsorbents and surface area was proposed. The results showed that the model could fit well with the measured adsorption isotherms. The calculated physical and chemical adsorption heats are -25.4 kJ/mol and -41.9 kJ/mol respectively, the total adsorption heats is -67.3 kJ/mol, which were in accordance with the experimental data. The saturation adsorption capacity of MCM-41-TEPA could reach 7.79 mmol/g.