Abstract: In recent years, the saturated adsorption capacity of novel adsorbents has been continuously enhanced. However, due to limitations in process design, the actual adsorption capacity of adsorbents during cyclic operation remains significantly lower than their saturated value. To establish an accurate adsorption bed model and investigate the complex heat and mass transfer mechanisms involved in the adsorption process, 13X molecular sieves were employed to conduct adsorption experiments on CO2/N2 gas mixtures. Through static adsorption experiments and dynamic breakthrough experiments, the competitive adsorption isotherms as well as the mass and heat transfer coefficients of the adsorption process were determined. Based on these fundamental data, a temperature swing adsorption (TSA) system model was successfully constructed, which accurately reproduced the breakthrough curves and temperature distributions under three distinct operating conditions. This adsorption bed model exhibited excellent performance in reflecting real-world adsorption behavior, particularly in scenarios involving low gas concentrations. The analysis of the loading condition of the adsorption bed indicated that the adsorbent utilization ratio (AUR) of the conventional TSA process was only 58.13%, with a significant amount of adsorbent not being fully utilized. Therefore, a novel multi-bed series TSA adsorption process was designed in this study. By switching different adsorption beds between the upstream bed and the downstream bed, the AUR was increased to 85.50%. Concurrently, the product purity increased from 90.74% (conventional TSA process) to 94.21%, and the energy consumption decreased from 6.48 MJ/kg CO2 to 4.79 MJ/kg CO2. However, the series process had a small amount of CO2 leakage during the adsorption stage, resulting in a gas recovery rate of 87.92%. In addition, although the conventional TSA process can achieve the similar AUR as the series process by extending the adsorption time, its recovery was only 71.80%, which was 16.12 percentage points lower than that of the novel series process.

Key words: series adsorption, temperature swing adsorption, molecular sieve, carbon capture, numerical simulation

摘要： 近年来，新型吸附剂的饱和吸附量不断增加，但其在循环过程中的实际吸附量因工艺流程设计局限而显著低于饱和值。为构建精准的吸附床模型，深入探究吸附工艺中复杂的传热与传质机理，本研究选用13X分子筛对CO2/N2进行吸附实验。通过静态吸附与动态穿透实验，确定了竞争吸附等温线及吸附过程的传质传热系数，并基于该数据完成了变温吸附(Temperature Swing Adsorption, TSA)系统模型的搭建。对吸附床负载情况分析表明，常规TSA工艺的吸附剂利用率(AUR)仅为58.13%，大量吸附剂未实现充分利用，存在明显优化空间。为此，本研究设计了多床串联式新型TSA吸附工艺，通过使不同吸附床在上游床和下游床之间切换，使吸附剂利用率提升至85.50%，产品纯度从常规TSA工艺的90.74%提升至94.21%，能耗从6.48 MJ/kg CO2降至4.79 MJ/kg CO2。然而，串联工艺在吸附阶段存在少量CO2泄露问题，导致气体回收率降至87.92%。此外，常规TSA工艺虽可通过延长吸附时间达到与串联工艺相近的AUR，但此时气体回收率仅为71.80%，较串联工艺低16.12个百分点。

关键词: 串联吸附, 变温吸附, 分子筛, 碳捕集, 数值模拟