- 學位論文
使用Fe-Mo-Al催化劑以化學氣相沉積法成長奈米碳管
Synthesis of Carbon Nanotubes Using Fe-Mo-Al Catalysts by Chemical Vapor Deposition
摘要
Carbon nanotubes (CNTs) were synthesized by chemical vapor deposition using Fe/Mo-Al catalysts prepared by impregnation and co-precipitation. Two different metal salts, ferric nitrate and ferric sulfate, were used in impregnation. The XRD results indicated that when the Fe/Mo-Al catalyst was prepared using ferric nitrate with a higher Mo content, alumina phase will appear at a temperature as low as 900℃. In the catalytic growth of CNTs, it was found that adding Mo in the Fe-Al catalysts will enhance the yield of CNTs. On the other hand, CNTs can be grown in large scale at 800℃ when using Fe/Mo-Al catalyst prepared using ferric sulfate with a Fe/Mo ratio of 10. The diameter of CNTs increased when the temperature was raised above 850℃, but the yield will decrease. The co-precipitation was carried out using Fe2(SO3)4‧14H2O and Al(NO3)3‧9H2O. Three different precipitants, NaOH, NH4OH and Na2CO3, were used. The XRD results illustrated that the grain size of AlOOH is the smallest when using NH4OH as precipitant. The Mo content in the Fe/Mo-Al catalysts prepared by co-precipitation was found to affect both the morphology and yield of CNTs. For the lower Mo content, yield was low and carbon nanofibers could be observed in the product. The yield of CNTs was the largest for a Fe/Mo ratio of 1/1. As the Mo content was increased further, the yield of CNTs decreased.
並列摘要
本研究主要以含浸法和共析法製備Fe/Mo-Al催化劑，並利用化學氣相沉積法成長奈米碳管。在含浸法製備催化劑部份，分別使用硝酸鐵和硫酸鐵兩種過渡金屬塩類製備催化劑。XRD結果顯示，以硝酸鐵製備之催化劑於較高之鉬含量下，會於900℃時提早出現氧化鋁相之相變化；在奈米碳管的生長部份，以Fe-Al催化劑於900℃下成長奈米碳管之產率較低，但以Fe/Mo-Al催化劑則會使產量提升。另一方面，以硫酸鐵製備之Fe/Mo-Al催化劑會於Fe/Mo比為10:1時，在800℃大量生長奈米碳管，當成長溫度高於850℃以上時，奈米碳管的管徑有增大之趨勢但且碳產率也隨著減少。共析法主要使用硫酸鐵與硝酸鋁製備鐵/鋁催化劑，析出劑則分別使用氫氧化鈉、氨水和碳酸鈉等三種進行反應。XRD分析結果得知以氨水製備水鋁石前驅體的晶粒較小。在成長碳管部份，改變Fe/Mo-Al催化劑之鉬含量對奈米碳管的形態和產量有明顯影響。當鉬含量較少時，產物較少且包含少量的奈米碳纖維；Fe/Mo比為1/1時，產量為最大，而隨著鉬的含量增加，碳管的產量逐漸減少。