- 學位論文
利用CuCrO2奈米粉末製備甲醇蒸氣重組產氫觸媒Cu/Cr2O3之特性研究
Preparation of methanol steam reforming catalyst Cu/Cr2O3 derived from CuCrO2 nanopowder
摘要
蒸氣重組產氫為目前運用於生產氫氣最重要的技術之一，對蒸氣重組產氫效率影響最大的因素則為轉化觸媒。在本研究中利用多孔性赤銅鐵礦化合物CuCrO2奈米粉做為前驅物，以還原法將Cu粒子還原於擔體表面，並將Cu粒子尺寸控制於一定尺寸下以增加觸媒的比表面積以及分散性。結果顯示還原溫度在200°C以上出現Cu繞射峰，超過500°C則轉變成為Cu/Cr2O3。SEM表面形貌觀察發現粉體仍然維持孔洞狀結構，700°C還原之粉末表面則觀察到明顯顆粒狀結構散布於表面上，顯示Cu開始聚集成較大顆粒。TEM觀察其微觀結構，發現500°C還原之粉體其表面Cu粒徑約為5 nm，並在擔體上具有良好分散性。觸媒粉體之比表面積BET測定結果高於以固態反應法製備之CuCrO2所還原的觸媒粉末。甲醇蒸氣重組測試結果發現產氫速率可達300 ml/min•g-cat以上，並且在320°C時可達1200 ml/min•g-cat。
並列摘要
Steam reforming is the key process in hydrogen generation. One of the most important factors in hydrogen production by steam reforming is the catalyst. In this study, the delafossite type CuCrO2 nanopowder was used as a precursor for preparing Cu/Cr2O3 catalyst. The size of Cu particles was controlled in the nano scale to obtain high surface area and better dispersion. In H2 reduction at higher than 200°C, diffraction peaks belonging to Cu metal were observed. Furthermore, the CuCrO2 powder was transformed into Cu/Cr2O3 by H2 treatment at higher than 500°C. The SEM images revealed that the powder retained a porous structure after reduction treatment. The TEM images showed that the Cu particles were about 5 nm in size and well dispersed on Cr2O3. The BET measurement showed that the surface area of nanopowder was higher than that of traditional CuCrO2 (by solid state method). The catalyst was evaluated by the generation rate with methanol steam reforming, and it yielded higher than 300 ml/ min. The highest hydrogen generation rate was as high as 1200 ml/ min•g-cat at 320°C.