Preparation of Nanosized Catalysts for the Reaction of NO Reduction by the Sol-Gel Method

• Main Authors: Pao-Cheng Chen, 陳寶丞
• Other Authors: Hung-Shan Weng
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/90596648843414780287

碩士 === 國立成功大學 === 化學工程學系 === 89 === The nano-particle technology is appropriate for producing high performance catalysts. These catalyst possess a markedly higher activity and selectivity compared with the conventional ones. The catalysts can be also used for reaction at a relativity low temperature, thereby reducing energy consumption. In order to increase the specific surface area, the sol-gel method was employed to prepare the nanosized La1-xAxCoO3 (A=Sr,Ce) catalysts with PAA and nitrates as the reactants while the pH value was controlled at 2. The effects of promoters,(Sr and Ce), reaction time and temperature on the formation of La1-xAxCoO3 powders were investigated. In addition, the activities of catalysts for the reduction of nitric oxide with carbon monoxide as the reducung agent were evaluated by comparing the CO conversion-temperature curves. The causes for different activities were also closely examined basing on the results of catalyst characterization. This research consists of two parts. In the first part, the nanosized catalysts of La1-xAxCoO3 (A=Sr,Ce) was synthesized by the sol-gel method. The individual and combined effects of promoters on the microstructure and morphology of catalysts were investigated. The effects of promoters on the catalytic activity for the reduction of NO was studied in the second part. The best catalyst was also screened from those prepared. The experimental results show that the nanosized catalyst prerared by the sol-gel method has high specific surface areas and small particle sizes, hence possess markedly higher activities than those of the catalysts prepared by the co-precipitation mathod. The activity test results indicate that partially substituting La with Sr or Ce increases the activity to reduce NO with CO as a reducing agent. An optimal substitution fraction exists in each series of catalysts and the La0.3Ce0.7CoO3 catalyst has the highest activity. The activity of catalyst can be correlated to the specific surface area, Co atomic ratio on surface as well as the crystal phase. 英文摘要------------------------------------------------------Ⅲ 誌謝----------------------------------------------------------Ⅴ 目錄----------------------------------------------------------Ⅵ 表目錄--------------------------------------------------------Ⅹ 圖目錄------------------------------------------------------ⅩⅡ 第一章 緒論----------------------------------------------------1 1-1 前言---------------------------------------------------1 1-2 空氣污染處理簡介---------------------------------------2 1-2-1 空氣污染的類型及影響--------------------------------2 1-2-2 氮氧化物的特性與形成--------------------------------2 1-2-3 氮氧化物之處理技術----------------------------------6 1-2-3-1 燃燒控制技術-------------------------------------6 1-2-3-2 後燃燒控制技術-----------------------------------9 1-3 奈米材料在觸媒上的應用--------------------------------13 1-3-1 奈米粒子的基本性質---------------------------------13 1-3-2 奈米粒子之應用-------------------------------------15 1-4 研究動機及目的----------------------------------------20 第二章 奈米微粒溶膠技術---------------------------------------23 2-1 前言--------------------------------------------------23 2-2 結晶原理----------------------------------------------24 2-2-1 成核理論-------------------------------------------25 2-2-2 晶體成長-------------------------------------------27 2-2-3 成核成長之分隔-------------------------------------30 2-2-4 液相結晶理論---------------------------------------31 2-3 溶膠製備技術------------------------------------------36 2-3-1 奈米微粒溶膠理論-----------------------------------36 2-3-2 水溶膠製備技術-------------------------------------37 2-3-3 溶劑溶膠製備技術-----------------------------------37 2-3-4 有機-無機混成溶膠製備技術--------------------------38 2-3-5 凝膠乾燥-------------------------------------------39 2-3-6 溶膠凝膠技術之應用---------------------------------40 第三章 實驗設備及方法-----------------------------------------42 3-1 觸媒製備之流程----------------------------------------42 3-1-1 LaCoO3波洛斯凱特型觸媒之製備----------------------42 3-1-2 促進劑的添加及物性探討-----------------------------44 3-2 實驗儀器說明------------------------------------------49 3-3 觸媒反應設備說明--------------------------------------52 3-3-1 前言-----------------------------------------------52 3-3-2 設備說明-------------------------------------------52 3-3-3 實驗步驟-------------------------------------------54 第四章 觸媒結構鑑定與表面性質分析-----------------------------58 4-1 前言--------------------------------------------------58 4-2 PAA溶液之配置-----------------------------------------58 4-3 LaCoO3觸媒之製備及條件測試----------------------------59 4-4 La1-xAxCoO3觸媒(A=Sr,Ce)之製備及晶相鑑定--------------64 4-5 觸媒表面原子組成與化學態分析--------------------------66 4-5-1 表面原子組成分析-----------------------------------66 4-5-2 表面氧原子化學態分析-------------------------------72 4-6 結論--------------------------------------------------73 第五章 觸媒活性測試------------------------------------------113 5-1 前言-------------------------------------------------113 5-2 以LaCoO3觸媒用於一氧化氮反應之實驗結果---------------113 5-3 以La-Sr-Co系觸媒用於一氧化氮還原反應之實驗結果-------115 5-4 以La-Ce-Co系觸媒用於一氧化氮還原反應之實驗結果-------121 5-5 結論-------------------------------------------------124 第六章 結論與未來研究方向------------------------------------125 6-1 總結-------------------------------------------------125 6-2 未來研究方向-----------------------------------------125 參考文獻-----------------------------------------------------128