| Summary: | 碩士 === 國立臺灣科技大學 === 化學工程系 === 107 === With fossil fuels, improving energy efficiency can lead to cut down of greenhouse gas emissions, Hydrogen becomes one of the important alternative energy carriers that can promote energy efficiency. To date, hydrogen is mainly product from steam reforming of methane (SRM). Dry reforming of methane (DRM) has also attracted attention because it can directly convert two major greenhouse gases, carbon dioxide and methane, into useful fuels. This study explores the use of defect fluorite mixed oxide of with La, Zr and Ce (LZC), to support Ni and Co for medium temperature methane reforming. Ni/LZC was prepared by different preparation methods, and that prepared by impregnation method (IP and IB) show better reactivity at Ni loading ≦13% than P(co-precipitation) and B(combustion) methods. On the other hand, Ni/LZC-P and Ni/LZC-B have better activity at ≧13%. The 16.7% Ni/LZC-P operated at near SRM equilibrium conversion at 500 oC can achieve a carbon balance close to 100%, demonstrated the advantage of the medium temperature reaction. Co/LZC catalysts from different preparation methods shows deactivation at mid temperature SRM owing to Co oxidation. Co/LZC-P can maintain good activity without deactivation and no carbon deposition at high temperature (650 oC) SRM for 15 hours. During 500 oC DRM, Ni/LZC-P has high activity, with high carbon deposit, while Co/LZC-P deactivates by Co oxidation but without coking. We demonstrate that NiCo(x)/LZC-P (Ni/Co=9 and 3) not only achieve good DRM activity at 500 oC but also successfully reduces the carbon deposition of Ni/LZC-P and Co oxidationof Co/LZC. The results of H2-TPR indicate a reduction characteristic as Ni/LZC-P with a slight shift to high temperature. This suggests that a small amount of Co leads to a stronger interaction between Ni and LZC supports.
|
|---|
