Performance Study Of Hydrogen Production From Ammonia Decomposition In A Packed-bed Reactor

• Main Authors: Chen, Yen Ling, 陳彥伶
• Other Authors: Kuo, Wen Shiuh
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/63826168329916365069

碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 100 === The effect of the molar ratio of promoter-cesium(Cs)/catalyst-ruthenium (Ru), the flow rate of NH 3 and the temperature of reaction on the decomposition efficiency of ammonia in terms of the production efficiency of hydrogen was investigated in this study. In addition, the used Cs/Ru catalyst was sampled and characterized by a particle size analyzer, scanning electron microscopy (SEM)/energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) in order to realize the mechanism of NH3 decomposition reaction. The results showed that the decomposition efficiency of NH3 would increase with increasing the molar ratio of Cs/Ru, decreasing the flow rate of NH3 and increasing the temperature of reaction. The decomposition of NH3 would reach the highest efficiency, almost 100%, at the condition of a Cs/Ru molar ratio of 4.5, a NH3 flow rate of 3 mL/min and a reaction temperature exceeding 350 °C. The decomposition efficiency of NH3 was still higher than 80% at the condition of a NH 3 flow rate of 9 mL/min and a reaction temperature of 350 °C, indicating the effective promoting effect of Cs/Ru catalyst on the decomposition of NH 3 . However, as the Cs/Ru molar ratio was higher than 5.5, the production efficiency of H 2 was declined to a value which was lower than that of the condition with Ru only. In addition, the results of XRD analysis showed that the used Cs/Ru catalyst did not generate other defined crystals with the carrier – carbon in reaction channel. Also, it was found in the analysis of SEM/EDS that the Cs atoms were not bonded with Ru atoms, implying the uniform distribution of Cs atoms surrounding Ru atoms at the condition of a Cs/Ru molar ratio of 4.5. Nevertheless, at the condition of a higher Cs/Ru molar ratio, the surface of Ru atoms may be covered by Cs atoms, leading to less active sites of Ru catalyst for the decomposition of NH3. On the basis of the results obtained in this study, it was revealed that the decomposition efficiency of ammonia in terms of the production efficiency of hydrogen would be significantly promoted by adding an appropriate molar ratio of Cs/Ru in reactor, even at a lower reaction temperature and a higher flow rate of NH3.