Abstract:

Direct air capture (DAC) is a highlight among carbon capture and storage technologies in recent years, and adsorption is the mainstream DAC technology. The performance of adsorbent is the key of adsorption DAC. The ideal adsorbent should satisfy the following advantages: high CO₂ capacity, low regeneration energy consumption, and high stability. Generally, the capacity of amine-impregnated adsorbent is higher, but the support materials decide the adsorbent performance. In this study, γ-Al₂O₃ and MCF was impregnated with PEI to discuss the effects of support materials on adsorbents. According to the results, the effects of support materials on the adsorbents are mainly reflected in CO₂ capacity and adsorption kinetics. In 0.4 mbar and 25℃, the capacity of PEI-MCF and PEI-Al₂O₃ are 1.76 mmol/g and 1.49 mmol/g respectively. As for adsorption kinetics, PEI-MCF is 62% faster than PEI-Al₂O₃ in the dry condition. In the humid condition, the capacity and kinetics of PEI-MCF is also better than PEI-Al₂O₃. However, the cycle stability of two materials has little difference, which indicates scarce influence of support materials.

Key words: direct air capture, carbon dioxide, adsorption, adsorbents, amine-impregnated, support

摘要：

直接空气碳捕集（direct air capture，DAC）是近年热门的碳捕集与封存（carbon capture and storage）技术，其中吸附法是目前主流的DAC技术。吸附剂的性能，是吸附法DAC的关键指标。理想的吸附剂应该满足：高CO₂吸附量、低再生能耗、高稳定性等优点。一般来说，胺浸渍吸附剂的吸附量较高，其使用的载体，也会对吸附剂的性能产生影响。使用聚乙烯亚胺（PEI）浸渍氧化铝（γ-Al₂O₃）和介孔硅泡沫（MCF）两种不同的载体，以比较载体对于吸附剂性能的影响。根据实验结果，载体对于吸附剂的影响主要体现在吸附量和吸附速率两个层面。在0.4 mbar（1 bar=0.1 MPa）、25℃条件下，PEI-MCF的吸附量为1.76 mmol/g；PEI-Al₂O₃为1.49 mmol/g。吸附速率方面，干燥环境下PEI-MCF与PEI-Al₂O₃相比大约快62%。在潮湿环境下，PEI-MCF的吸附量和吸附速率也优于PEI-Al₂O₃。但是，两种材料的循环稳定性差异较小，并未受到载体的影响。

关键词: 直接空气捕集, 二氧化碳, 吸附（作用）, 吸附剂, 胺浸渍, 载体