| Abstract: | 本研究以改變離子交換法及化學還原法之條件製備鈷硼觸媒，探討負載量、表面結構、表面積、金屬比例、分散性以及結晶態與硼氫化鈉水解產氫動力學參數之關係，並將結果應用至硼氫化鈉產氫系統。在離子交換部分，以TP-207樹脂為載體，改變前驅物、pH值、溫度，結果顯示使用CoCl2在pH值3.93還原溫度25℃時，擁有最佳之鈷離子交換量；在觸媒還原階段中，改變還原劑種類、濃度、分散劑濃度、還原溫度、還原劑添加速率。藉由調整個還原變數，能夠改變金屬比例、表面積以及特地之結晶態。當Co/B接近2、表面積提升、能提升40℃及80℃下之活性。從結晶態結果得知，不同之晶型結果會影響水解產氫在40及80℃之活性。由還原階段之合成條件結果顯示: 以0.5 wt.% 之KBH4、10 wt.% 乙二醇、75℃的還原溫度、5 ml/min的還原劑添加速率，可以得到最佳之Co-B觸媒活性。經由L-H動力學模式進行實驗數據回歸，並與觸媒表面結構與組成做比較，選用KBH4還原劑並降低其還原劑濃度、還原溫度、添加速率可以提升觸媒活性。降低還原劑濃度、提升還原溫度、降低還原劑添加速率則能改善釋氫之拖尾現象。
In this work, the ion exchange and chemical reduction method were used to synthesize Co-B catalyst. Catalyst loading, surface structure, surface area, metal composition, and crystal structure of Co-B catalyst were investigated in order to understand the connection between surface morphology/composition and the kinetic parameters of NaBH4 hydrolysis reaction. In the ion exchange step, the maximum Co ion exchange amount over TP-207 resin was operated at the synthesis condition: CoCl2 precursor, 3.93 pH, 25 oC ion exchange temperature. In the reduction step, types and concentrations of reduction agents, the concentration of dispersion agent, the reduction temperatures, and injection rates were investigated. The metal composition, surface area, and crystal structure were adjusted by the synthesis variable. The 40 and 80oC activities of Co-B catalyst were improved by adjusting the ratio of Co and B to 2, increasing surface area, and synthesing the certain Co-B crystal type. The results show that the 40 and 80 oC activity of Co-B catalyst was improved while different crystal structure was formation. The optimal result shows the best Co-B catalyst activity was located on following synthesis condition: 0.5 wt.% KBH4, 10 wt.% Ethylene glycol, 75 oC reduction temperature and 5 ml/min injection rate. After regressing kinetic parameters by using L-H model, the catalyst activity can be improved by decreasing KBH4 concentration, reduction temperature and injection rate; the tail of hydrogen generation curve can be improved by decreasing KBH4 concentration and injection rate. |
