Catalytic Performance of Limonite in the Decomposition of Ammonia in the Coexistence of Typical Fuel Gas Components Produced in an Air-Blown Coal Gasification Process
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- 作者：Naoto Tsubouchi ; Hiroyuki Hashimoto ; Yasuo Ohtsuka
- 刊名：Energy & Fuels
- 出版年：2007
- 出版时间：November 2007
- 年：2007
- 卷：21
- 期：6
- 页码：3063 - 3069
- 全文大小：145K
- 年卷期：v.21,no.6(November 2007)
- ISSN：1520-5029
文摘
Catalytic decomposition of 2000 ppm NH3 in different atmospheres with an Australian α-FeOOH-rich limonite ore at 750–950 °C under a high space velocity of 45000 h−1 has been studied with a cylindrical quartz reactor to develop a novel hot gas cleanup method of removing NH3 from fuel gas produced in an air-blown coal gasification process for an integrated gasification combined cycle (IGCC) technology. The limonite shows very high catalytic activity for the decomposition of NH3 diluted with inert gas at 750 °C, regardless of whether the catalyst material is subjected to H2 reduction before the reaction or not. Conversion of NH3 to N2 over the reduced limonite reaches ≥99% at 750–950 °C, and the catalyst maintains the high performance for about 40 h at 750 °C. When the decomposition reaction is carried out in the presence of fuel gas components, the coexistence of syngas (20% CO/10% H2) causes not only the serious deactivation of the limonite catalyst but also the appreciable formation of deposited carbon and CO2. On the other hand, the addition of 10% CO2 or 3% H2O to the syngas improves the catalytic performance and concurrently suppresses the carbon deposition almost completely, and the NH3 conversion in the 3% H2O-containing syngas reaches about 90% and almost 100% at 750 and 850 °C, respectively. Influential factors controlling the catalytic activity of the limonite ore in the coexistence of fuel gas components are discussed on the basis of the results of the powder X-ray diffraction measurements, thermodynamic calculations, and some model experiments.