奈米氧化鈰鋯固溶體之構形控制與乙醇轉氫效率研究

Abstract

本實驗以水熱法成功的利用硝酸鈰與含鋯之前驅物合成出奈米粒子、奈米柱、奈米方塊及奈米管等構型。 在CexZr1-xO2實驗中，當x = 0.1、0.2、0.25、0.8、0.9時，皆可得到單一相產物；當x = 0.8時，可得到沿〔110〕方向生長Ce0.8Zr0.2O2的奈米柱狀產物；當x = 0.9時，可得到由六個{100}晶面組成的Ce0.9Zr0.1O2奈米方塊，其中奈米方塊經由反應時間的縮短，可得到柱狀產物，時間拉長則變為奈米粒子；當反應改成加入微量之氧化鋯時，可成功合成出奈米管結構。由氫氣程溫還原實驗得知，氧化鈰奈米管氫氣消耗量為940μmol H2/g，而表面積大小為76.6 m2/g 。 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，實驗結果發現氧化鈰(奈米方塊)、氧化鈰(奈米管)、Ce0.9Zr0.1O2及Ce0.2Zr0.8O2固溶體，在適當條件下有110%以上之氫氣選擇率，對於乙醇轉氫實驗而言，為相當具有潛力之材料。

In the present study, we used Ce(NO3)3•6H2O and zirconium precursors to synthesize CexZr1-xO2 nanoparticles, nanorods, nanocubes, and nanotubes through a hydrothermal process. The PXRD results indicated that Ce0.1Zr0.9O2, Ce0.2Zr0.8O2, Ce0.25Zr0.75O2, Ce0.8Zr0.2O2, and Ce0.9Zr0.1O2 were single phase. According to TEM image and SAED pattern, Ce0.8Zr0.2O2 nanorods exhibited preferred growth in the 〔110〕 direction. TEM lattice image indicated that the CeO2 nanocubes were enclosed within {100} planes. Reducing or prolonging the reaction time can change the morphology of Ce0.9Zr0.1O2 nanocubes to nanorods and nanoparticles. Using a small amount of ZrO2 and Ce(NO3)3•6H2O as precursors, CeO2 nanotubes were synthesized successfully. A TPR result revealed that hydrogen consumed by ceria nanotubes is 940μmol H2/g(ceria). According to a BET analysis, the surface area is 76.6 m2/g(ceria). In our catalytic activity experiments for ethanol to hydrogen conversion, catalysts of 5% wt Ru/ CexZr1-xO2(x = 0.1, 0.2, 0.25, 0.5, 0.8, 0.9) and 5% wt Ru/CeO2 nanotubes demonstrated that the hydrogen selectivity of CeO2 nanocubes, CeO2 nanotubes, Ce0.9Zr0.1O2, and Ce0.2Zr0.8O2 were as high as 110% under appropriate conditions. The results revealed that these materials could be used as catalysts for ethanol reforming.