利用微波合成法製備摻雜鑭的奈米氧化鈰應用在乙醇轉氫效率研究

Abstract

本論文主要利用新穎的微波加熱法快速合成可以提升乙醇轉氫效率的CeO2奈米粒子和摻雜鑭的二氧化鈰固溶體。先以CeO2測試不同合成溫度、合成時間與鹼性濃度，我們發現乙醇轉氫測試下，最佳化條件是溫度180℃，合成時間30分鐘，鹼性濃度15M條件下，可得到113 ±3% 的氫氣選擇率。 運用上述最佳化條件以微波合成法成功合成出CexLa1-xO2奈米粒子、奈米粒子與奈米棒狀構型的混合。在CexLa1-xO2實驗中，當摻雜鑭的量太多時(x = 0.1~0.6)時，由XRD可知其有兩個相(立方晶體的二氧化鈰和六角晶體的氧化鑭)；但摻雜鑭的量減少至x =0.7、0.8 與0.9時，可得到單一相立方晶體二氧化鈰產物。利用上述所合成之固溶體，再添加重量百分比5%之釕金屬來做乙醇轉氫效率之實驗，結果發現Ce0.7La0.3O2固溶體，在適當條件下有117±4% 之氫氣選擇率，相較單純CeO2奈米粒子而言，有提升乙醇轉氫的催化活性。

In order to rapidly synthesize a catalyst to improve the hydrogen selectivity of ethanol steam reforming process, we employ a new microwave assisted method to prepare for the catalysts, CeO2 and La-doped CeO2 nanoparticles and nanorods. The catalytic activities for ethanol to hydrogen conversion have been studied extensively, with varying experimental conditions, including temperature、synthesis time and basic solution. We have found that the best hydrogen selectivity (113±3%) can be reached under the operational condition at 180℃、30min and 15M basic solution. Following the above-mentioned synthesis conditions, we can fabricate CexLa1-xO2 with the microwave assisted method. When x= 0.1~0.6, we have found two phase structures by XRD, the cubic crystal structure of CeO2 and the hexagonal crystal structure of La2O3 . But when we reduce the lanthanum molar ratio, Ce0.7La0.3O2, Ce0.8La0.2O2 and Ce0.9La0.1O2 appear to be single phase. In the catalytic activity study for ethanol to hydrogen conversion, the catalysts with 5% wt Ru/ Ce0.7La0.3O2 and 5% wt Ru/CeO2 nanoparticles have been investigated；the hydrogen selectivity of the former reaches 117±4% under appropriate conditions.