商用沸石與其金屬改質吸附劑應用於二氧化碳溫室氣體捕獲之吸脫附效能比較研究

Abstract

二氧化碳溫室氣體之遽增為加速全球暖化現象的主因之一，而沸 石材料可依吸附質分子大小之不同而進行選擇性吸附，且具有成本低 廉及易於應用之優點，故經常用為吸附CO2 氣體的吸附劑。本研究藉 管柱吸附系統測試選出兼具最佳CO2 吸附容量與價格低廉的13X 沸 石，並以熱改質與金屬化改質分析比較此兩種改質方式對於CO2 吸附 容量提升之影響。研究結果顯示，當以0.5M 鉀離子濃度完成兩次離 子交換程序後之KX(0.5M)-Ⅱ金屬改質吸附劑有最佳的CO2吸附容量 68mg-CO2/gads，並相較改質前之原始材料提升近60%的吸附容量。

將吸附劑之前處理溫度由145℃提高至400℃後，13X 沸石之CO2 工作吸附容量則轉較金屬改質後之KX(0.5M)-Ⅱ吸附劑為高，並由 CO2-TPD 分析確認係因鹼性活性基濃度增加而造成此變化。此外，在 經過24 小時的水熱穩定性測試後，KX(0.5M)-Ⅱ吸附劑之CO2 吸附 容量衰退幅度則低於13X 沸石。最後本研究再以13X 沸石與 KX(0.5M)-Ⅱ吸附劑進行101 次之CO2 循環吸脫附操作，結果顯示兩 者均能有效維持80%以上的吸附指標，但KX(0.5M)-Ⅱ吸附劑則具有 較佳的材料穩定性。

Zeolitic materials are widely used in CO2 GHG removal due to its lower price and selective adsorption ability for target adsorbate according to their different pore sizes. This study aims to find the zeolitic adsorbent with high CO2 removal performance and lower price. The cation-exchanged method and thermal treatment were both employed to modify the zeolite support to enhance its CO2 adsorption performance. From the experimental results, it’s known that using 0.5M potassium solution and repeat the modified procedure to enhance the metal loading on the 13X zeolite could reach the best performance of CO2 capture, 68mg-CO2/gads, which increases 60% adsorption capacity as compared with the raw material. However, as the pretreatment temperature was changed from 145℃ to 400℃, the CO2 cpature performance of raw 13X zeolite became better than the metal modified adsorbent of KX(0.5M)-Ⅱ. Such change is due to the increase trend of basic active sites as measured by CO2-TPD. In this study the hydrothermal stability was also tested by boiling in 105℃ hot water for 24 hours, and the long-term stability was evaluated by l01 cyclic tests on CO2 adsorption/desorption. The results showed that the modified adsorbent KX(0.5M)-II was a relatively better material with better hydrothermal stability and long-term stability.