奈米碳管/碳纖維複材對甲苯蒸氣之吸附效能研究

Study of Adsorption of Toluene Vapor on Carbon Nanotubes/Carbon Fibers Composites

林韋翔(Wei-Shiang Lin)

指導教授 ： 江右君

元智大學/工程學院/機械工程學系/碩士(2012年)

摘要

活性碳纖維為相當廣泛使用的多孔性吸附劑，而CNTs 也具有吸附上的應用，若能將二者結合形成奈微米複合材料，勢必會具有極大的開發價值。文獻中有關奈米碳管(CNTs)稼接至碳纖維的相關研究，大部分著重在機械性質的討論，在蒸氣吸附方面的研究仍然相當有限。因此，本研究利用化學氣相沈積法在PAN系列碳纖維表面稼接CNTs，分析合成產物的物化特性和抗拉強度，評估基材多孔性和CNTs合成方式對材料特性所造成的差異。量測不同溫度、濃度下複材對甲苯蒸氣之吸脫附曲線、貫穿曲線及TPD程溫脫附，並討論吸附動力學、脫附效率。
研究結果發現，未先加入醋酸鈷碳纖維表面稼接的CNTs約呈陣列狀生長、直徑約26 nm；而加入醋酸鈷後，CNTs直徑稍微上升至40 nm左右。CNTs 中所含的氮原子，主要是以取代碳管石墨烯中一個碳原子或形成缺陷形式存在。碳纖維基材是否具多孔性，會影響其表面稼接CNTs 的合成步驟，也會影響所合成產物之材料/結構特性、抗拉強度、和對甲苯蒸氣的吸附效能。隨著吸附溫度的提升，樣本對甲苯蒸氣之吸附量相對減少、貫穿曲線之貫穿點亦較早出現，表示吸附屬於放熱反應；當樣本稼接奈米碳管後，溫度的提升對其吸附量的影響較小。樣本浸泡醋酸鈷後，其抗拉強度明顯提升。

關鍵字

奈米碳管 ； 碳纖維 ； 蒸氣吸附 ； 特性分析 ； 貫穿曲線

並列摘要

Activated carbon fibers (ACFs) are widely used porous adsorbents, and carbon nanotubes (CNTs) are known to have potential applications on adsorption. It would be highly interested if CNTs could be incorporated into ACFs forming a nano-micron composite material. Most of the research papers related to this composite materials in literature focused on the study of mechanical properties, but limited on vapor adsorption. Therefore, in this study, the chemical vapor deposition method was used to graft CNTs onto PAN-based ACFs, and another nonporous carbon fibers were also used for comparison. In addition, the effect of pre-immersion of carbon fibers (CFs) in the solution of cobalt precursor was also discussed. The physical-chemical properties and tensile strength of the samples were characterized. The adsorption performance of toluene vapor on the composites at different temperatures and concentrations were determined according to the adsorption isotherms, the adsorption kinetics, the isosteric heats of adsorption, the breakthrough curves, and the temperature programmed desorption (TPD) patterns.
Results show that the CNTs grafted on CFs without cobalt pre-immersion were almost aligned with a diameter of 26 nm, while those on CFs pre-immersed with cobalt had a diameter of 40 nm and their morphology depended on the CFs. The nitrogen atoms on CNTs were bonded by replacing the carbon atoms on the graphene layers or by forming the defects on the surface. The porosity of CFs influenced the properties of CNTs on the CFs and the adsorption performance of toluene vapor. It was observed that the tensile strength of the composites was improved as the CFs were pre-immersed with cobalt solution. When the adsorption temperature was increased, the adsorption amount of toluene decreased and the breakthrough time occurred earlier, indicative of exothermic reactions. It should be noted that the temperature impact was insignificant when the CFs were grafted with CNTs.

並列關鍵字

Carbon Nanotubes ； Carbon Fibers ； Vapor adsorption ； Characterization ； Breakthrough curves

參考文獻

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