稼接奈米碳管之活性碳纖維作為氣相吸附劑之應用研究

Application of Carbon Nanotubes-grafted Activated Carbon Fibers as Gas-phase Adsorbents

江右君(Yu-Chun Chiang) ； 林韋翔(Wei-Shiang Lin)

《燃燒季刊》 78期 (2012/08) Pp. 31-42

https://doi.org/10.30041/CQ.201208.0003

摘要

本研究利用化學氣相沈積法在PAN系列活性碳纖維（ACFs）表面稼接奈米碳管（CNTs），ACFs已知為使用相當廣泛的多孔性吸附劑，而CNTs也具有吸附上的應用，若能將二者結合形成不同尺度之複合吸附材料，應具有極大的開發價值。分析合成產物的物化特性，並選擇甲苯（Toluene）為吸附質，量測複合吸附材對甲苯蒸氣之貫穿曲線、程溫脫附效能及等溫吸附曲線。研究結果發現，ACFs表面稼接的CNTs以類似義大利麵的形式生長、直徑約30-70 nm。原ACFs與稼接CNTs之ACFs的微孔體積／總孔體積的比值分別約為63%及65%，反應出二樣本皆具微孔特性。但CNTs的稼接可能阻塞ACFs表面的孔隙，導致比表面積僅為原ACFs的76%。隨著吸附溫度的提升，貫穿點亦較早出現，表示吸附屬於放熱反應；傳統的Wheeler eq.可用以描述稼接CNTs之ACFs對甲苯蒸氣的吸附貫穿數據。隨著溫度的增加，兩樣本之飽和吸附量均降低，但在溫度較高的環境下稼接CNTs之ACFs對甲苯的飽和吸附量卻較原ACFs好。稼接CNTs之ACFs之甲苯脫附效率約為90%，而ACF僅有75%。本研究也發現，Langmuir方程式可適當描述樣本的等溫吸附曲線。

關鍵字

奈米碳管 ； 活性碳纖維 ； 氣相吸附 ； 等溫吸附曲線 ； 貫穿曲線

並列摘要

The objective of this study was to graft carbon nanotubes (CNTs) onto activated carbon fibers (ACFs) using chemical vapor deposition method. The idea was based on the fact that the ACFs were widely used porous adsorbents and the CNTs were considered as promising adsorbents. It should be attracted much attention if both materials could be incorporated as a composite adsorbent with different dimensions. The properties of the samples were characterized using several techniques. Toluene was selected as the target adsorbate, and the adsorption breakthrough curves, the temperature programmed desorption profiles and the adsorption isotherms were measured. Results showed that the CNTs grown on ACFs were spaghetti-like with a diameter of 30-70 nm. The ratios of micropore volume to total pore volume for as- received ACFs and CNTs-grafted ACFs were 63 and 65%, implying the microporosity. However, introduction of CNTs on the surface of ACFs were believed to block part of the pores, resulting in the decrease of specific surface area to 76%. The break point occurred earlier as the adsorption temperature increased, indicative of exothermic reaction; moreover, the Wheeler equation can be successfully used to describe the breakthrough curves. The equilibrium adsorption amounts decreased with increasing temperature, and it is worthy of note that the greater adsorption amounts on CNTs-grafted ACFs were observed at 55℃ compared to as-received ACFs. In addition, the desorption efficiency was better for CNT-grafted ACFs. Langmuir equation worked well for data fitting of toluene adsorption isotherms.

並列關鍵字

Carbon nanotubes ； activated carbon fibers ； gas-phase adsorption ； adsorption isotherms ； breakthrough curves