臺灣博碩士論文加值系統

本研究主要探討以Feitknecht 化合物為前軀體製備Co-Al複合催化劑，以不同煆燒條件之催化劑經由化學氣相沉積法進行生長奈米碳纖維。研究結果顯示，不同的煆燒溫度及時間會影響奈米碳纖維之產率，以400℃進行4小時煆燒之催化劑可獲得最高之奈米碳纖維產率。針對不同煆燒條件之催化劑生長奈米碳纖維進行微結構分析，其奈米碳纖維之微結構並無隨著不同煆燒條件有所改變。
以最佳煆燒條件(400℃進行4小時煆燒)之複合催化劑進行不同製程參數，分別為通入碳源氣氛前進行還原與不還原處理之製程條件。經由還原處理之製程條件，適合生長奈米碳纖維之溫度範圍為500-700℃，隨著不同製程溫度變化分別可製備具錐形空孔(conical interval)、管狀(tubular) 微結構之奈米碳纖維。不經由還原處理之製程條件，適合生長奈米碳纖維之溫度範圍為600-800℃，隨著不同製程溫度變化分別可製備具錐形空孔、管狀微結構之奈米碳纖維。由還原處理與不經還原處理兩種方式所生長之奈米碳纖維的比較，實驗結果顯示僅影響奈米碳纖維的產率，其奈米碳纖維之微結構並無隨著還原處理與否而有所改變。
在添加不同氣氛(氬氣、氮氣、氫氣)混合甲烷之條件下，以純甲烷不經還原處理於700℃可製備具管狀結構之奈米碳纖維，添加氮氣後顯示與使用純甲烷所生長之奈米碳纖維的微結構有所不同，所生長之奈米碳纖維的微結構從管狀結構轉變為類竹節狀(bamboo-like)結構。以純甲烷不經還原處理於600℃可製備具錐形空孔結構之奈米碳纖維，當添加氮氣後顯示所生長之奈米碳纖維的微結構與利用純甲烷所生長有所不同，其微結構從錐形空孔結構轉變趨向管狀結構。

In this study, carbon nanofibers (CNFs) were grown by chemical vapor deposition (CVD) using a Co-Al composite catalyst derived from Feitknecht compound precursor. The experimental results showed that the highest yield of CNFs were obtained when the starting catalysts were calcined at 400℃ for 4 hours. The yield of CNFs were affected by the Co-Al composite catalyst with different calcination conditions, but no obvious change in the microstructure of CNFs were observed when using the catalyst with different calcination conditions.
Different synthetic parameters of CNFs were carried out by CVD over catalyst with calcination at 400℃ for 4 hours in air. Before purging carbon source gas, the synthetic parameters were carried out with reduction and non-reduction process. With reduction process, the CNFs were performed in the range of 500-700℃, and the CNFs with conical interval and tubular microstructure can be synthesized with different temperatures. Without reduction process, the CNFs were carried out in the range of 600-800℃, and the microstructure of CNFs with conical interval and tubular microstructure can be synthesized with different temperatures. For comparison between reduction and non-reduction process, the experimental results showed that the yield of CNFs was affected by reduction or non-reduction process, but no obvious change in the microstructure of CNFs was observed by reduction and non-reduction process.
The tubular microstructure of CNFs was synthesized at 700℃ from pure methane by non-reduction process. When hydrogen was added to methane, the CNFs with bamboo-like microstructure was synthesized at the same temperature. The CNFs with conical interval microstructure was synthesized at 600℃ from pure methane by non-reduction process. When nitrogen was added to methane, the CNFs with conical interval was tend to transform into tubular –like structure of CNF.

TABLES OF CONTENTS

ENGLISH ABSTRACT………………………………………………………………I
CHINESE ABSTRACT………………………………………………………………II
TABLE OF CONTENTS……………………………………………………………III
LIST OF FIGURES……………………………………………………………… V
LIST OF TABLES……………………………………………………………………X
CHAPTER
I. Introduction………………………………………………………………………1
II. Literature review………………………………………………………………4
2.1. Introduction of Carbon nanotubes and nanofibers………………4
2.2 Growth mechanism of carbon nanofibers…………………………………6
2.3 The choice of catalysts………………………………………………………8
2.4 Hydrotalcite (Feitknecht compound) ……………………………………9
2.5 Effect of decomposition temperature and gas on growth CNFs………11
III. Experimental………………………………………………………………………14
3.1 Preparation of catalysts…………………………………………………………14
3.2 The synthesis of CNFs by thermal CVD………………………………………14
3.2.1.With reduction process…………………………………………………………14
3.2.1.1 Catalyst with different calcination conditions…………………14
3.2.1.2 Synthesis of CNFs with reduction………………………………………15
3.2.2 Without reduction process……………………………………………………15
3.2.2.1 Synthesis of CNFs without reduction…………………………………15
3.2.2.2 Synthesis of CNFs with mixing different gases……………………15
3.3 Analyzer……………………………………………………………………………………16
3.3.1 XRD………………………………………………………………………………………16
3.3.2 TGA………………………………………………………………………………………16
3.3.3 FEG-SEM…………………………………………………………………………………17
3.3.4 HRTEM……………………………………………………………………………………17
3.3.5 RAMAN……………………………………………………………………………………17
3.3.6 EA…………………………………………………………………………………………17
IV. Results and Discussion………………………………………………………………20
4.1 Preparation of catalysts…………………………………………………………20
4.2 Synthesis of CNFs by CVD…………………………………………………………22
4.2.1 With reduction process…………………………………………………………23
4.2.1.1 Synthesis of CNFs using catalyst with different
calcination conditions………………………………………………………23
4.2.1.2 Synthesis of CNFs with reduction………………………………………32
4.2.2 Without reduction process……………………………………………………42
4.2.2.1 Synthesis of CNFs without reduction…………………………………42
4.2.2.2 Synthesis of CNFs with mixing different gases……………………52
4.2.3 Comparison with reduction and non-reduction process………………65
V. Conclusion…………………………………………………………………………………69
References………………………………………………………………………………………71

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