銅鹽含浸改質活性碳纖維氈去除燃煤煙道氣中氣相汞之可行性探討

Influences of Copper Impregnation on Activated Carbon Fiber Mat for Gaseous Mercury Removal from Coal Combustion Flue Gases

凃信祈(Hsin-Chi Tu)

指導教授 ： 席行正

國立臺北科技大學/工程學院/環境工程與管理研究所/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00290

摘要

本研究利用高微孔活性碳纖維氈（ACM）做為起始原料，輔以氯化銅（CuCl2）含浸改質，搭配模擬煙道氣產生裝置，以低濃度Hg0為去除之標的物。經由不同之含浸濃度與酸預處理操作參數下，進行吸附實驗，以評估吸附劑對於氣相汞之去除效益，再輔以SEM、BET、EA與XPS等分析，探討吸附劑在不同參數下之物化特性，對於氣相汞之吸附容量及吸附機制間相關性。
研究結果顯示，經銅鹽含浸後，ACM之比表面積及孔體積分別隨著含浸量增加而減少，顯示CuCl2分子阻礙活性碳之孔結構。在模擬煙道氣環境下，未經銅鹽含浸處理之活性碳（ACM-raw）其吸附量為211.9 ug g-1，經HCl預處理後之活性碳其吸附量（HACM-raw）為512.1 ug g-1，顯示經酸預處理具有增進活性碳汞吸附之效能，此外經銅鹽含浸改質後之活性碳較未經銅鹽含浸改質之活性碳，其吸附效果並無較於N2環境下顯著，這暗指Hg0與煙道氣體組成產生強烈之競爭吸附作用，並且可能受煙氣影響而產生毒化作用導致活性下降。在N2環境下，活性碳吸附量明顯隨銅鹽含浸量增加而提升，值得注意的是當銅鹽含浸達8 wt%時吸附量有顯著提升；Hg0吸附容量與活性碳比表面積與孔體積成相反關係。在N2條件及煙道氣環境下，活性碳改質前後幾乎皆以擬二階吸附動力模式較佳，相關係數皆可大於0.91以上，此結果顯示Hg0吸附傾向於雙分子反應（bimolecular reaction），意指吸附一個Hg0分子需要兩個活化位址。

關鍵字

汞 ； 銅含浸 ； 煙道氣 ； 活性碳纖維

並列摘要

A Highly porous activated carbon fiber mat (ACM) impregated with various amounts of copper chloride (CuCl2) was examined for its feasibility to remove low-concentration Hg0 from N2 and simulated coal-combustion flue gases. Effects of acid pretreatmenton on carbon’s properties and Hg adsorption capacities were also evaluated. Instrumental analyses including scanning electron microscopy (SEM), surface area analyzer (BET), elements analyzer (EA) and electron spectroscopy for chemical analysis (XPS) were used to explore the influences of surface treatments on physical and chemical characteristics and the Hg0 adsorption performance of the resulting adsorbents.
The experimental results showed that the decrease in surface area and pore volume of ACM was significantly influenced by the amount of impregnated copper, indicating CuCl2 molecules blocking or filling the pore structure of activated carbon. In a simulated flue gas environment, ACM without copper impregnation (designated ACM-raw) had aadsorption capacity of 211.9 ug g-1. HCl pretreatment increased the adsorption capacity of raw ACM (designated HACM-raw) to 512.1 ug g-1. These results suggested that acid pretreatment enhanced the Hg0 adsorption equilibrium of ACM. Furthermore, in N2 environment, the Hg0 adsorption of Cu-impregnated ACM was significantly improved, especially when the Cu impregnation ratio was > 8 wt%. The experimemtal results also showed that the Hg0 adsorption capacity was inversely proportional to the surface area and pore volume of resulting adsorbents. However, Cu impregnation had less effects on enhancing the Hg0 adsorption of ACM under simulated flue gas condition and the adsorption capacities were similar to those obtained from N2 adsorption tests, suggesting that flue gas components may strongly compete the active sites on ACM for Hg0 adsorption, or poison the carbon surface and lead to smaller adsorption capacity. Kinetics analysis results indicated that Hg0 adsorption onto the carbon surface was bimolecular, namely, two active sites were needed for capture of one Hg0 molecules.

並列關鍵字

Cu impregnation ； flue gase ； mercury ； activated carbon fiber

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