- 學位論文
多壁奈米碳管對甲苯(Toluene)蒸氣之吸附貫穿特性之研究
Study on the Multi-walled Carbon Nanotubes for Adsorption Breakthrough of Toluene
摘要
新世紀奈米科技材料－奈米碳管，除了物理性質及化學穩定性良好以外，另具有奈米尺度的中空孔隙、大的比表面積和許多優異的特性，被視為是一種極具潛力的儲氣材料。若將奈米碳管有效地用以吸附氣體或有機蒸氣，將對能源儲存、氣體感測和污染防治有相當地貢獻。甲苯為產業界常用之有機溶劑，用途廣泛，揮發時可能危害人身之健康。因此，本研究係探討三種多壁奈米碳管吸附甲苯蒸氣之吸附貫穿行為，除了建立奈米碳管吸附甲苯之貫穿特性參數外，並據以評估本研究所合成之奈米碳管與商用樣本之優劣性。 本研究利用化學氣相沈積法合成二種多壁奈米碳管，其中CNT 1使用乙炔為碳源、Fe(CO)5為觸媒；CNT 2使用Benzene為碳源、Ferrocene為觸媒，此兩種多壁奈米碳管合成後均先經純化後再進行後續研究。另選用一種商用奈米碳管(CBT)，作為比較之用。奈米碳管在進行吸附實驗前，先利用許多表面檢測技術進行特性分析。以甲苯作為吸附質，利用直讀式儀器偵測不同時間時的出口濃度，探討在不同吸附溫度及相對濕度下多壁奈米碳管對甲苯蒸氣的吸附貫穿行為。再經由修正的Wheeler方程式計算得到吸附動力常數(kv)值、平衡吸附量(We)及時間指數(n)值，進而瞭解溫度與相對濕度對吸附貫穿之影響。 研究結果發現，由TEM/HRTEM可觀察到P-CNT 1管徑最小，但由氮氣等溫吸附/脫附曲線分析可見其平均孔徑最大。由XPS分析顯示奈米碳管經純化後O1s明顯增加，但O1s之含氧官能基的含量比例並未呈一定的趨勢改變。吸附溫度對於甲苯蒸氣吸附之影響以P-CNT 1影響最為顯著，在溫度5、25及45 ℃時 之kv值分別為80850、19243及4408 min-1、We值最高約為8及最低2 mg/g及n值平均為0.26。相對濕度對P-CNT2吸附甲苯蒸氣之影響最大，在相對濕度1、50及85 %時之kv值為11249、8245及5694 min-1、We值最高約為10及最低8 mg/g及n值平均為0.46。從實驗結果發現以溫度變化之影響最為顯著。
並列摘要
Carbon nanotubes (CNTs), a new material in nanotechnology, have good physical and chemical properties with nanoscale porosity, large surface area and several excellent characteristics. It has been considered as a potential material for gas storage. If CNTs can be an effective adsorbent to adsorb gas or organic vapor, it will make a good contribution to energy storage, gas sensing and pollution prevention. Toluene is used widely in industry, but it might damage the human health when it volatiles. Therefore, this study intends to investigate the adsorption breakthrough behaviors of toluene on three kinds of multi-walled carbon nanotubes (MWNTs). Aside from establishment of the characteristic parameters of adsorption breakthrough, the performances of as-prepared MWNTs and commercial one are discussed. The chemical vapor deposition method was used to synthesize two kinds of MWNTs, where CNT 1 used acetylene as the carbon source and Fe(CO)5 as the catalyst; CNT 2 employed benzene as the carbon source and ferrocene as the catalyst. Both MWNTs were carried out the following experiments after purification. In addition, one commercial MWNTs, denoted as CBT, was selected for comparison. Before conducting the adsorption experiments, CNTs were probed by several material analyses. Toluene was chosen as the adsorbate, and its exit concentrations were measured by a direct-reading instrument. The adsorption temperature and relative humidity were the varying parameters in this study. Finally, the modified Wheeler equation was used to obtain the adsorption kinetic coefficient (kv), the adsorption amount (We), and the exponent of the time (n) by curve fitting. Meanwhile, the roles of adsorption temperature and relative humidity were discussed. The results show that P-CNT 1 has the smallest diameter obtained by TEM/HRTEM images, while it has the largest mean pore size by N2 adsorption/desorption isotherms. The XPS profiles indicate that the percents of O1s on CNTs surface increase after purification, but the changes of the percents do not obey a certain trend. Toluene adsorption on P-CNT 1 is affected the most significantly by adsorption temperature; on the other hand, the toluene adsorption on P-CNT 2 is the most dependent on the relative humidity. To sum up, the effects of adsorption temperature are more significant than that of relative humidity.
參考文獻
延伸閱讀
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