Ammonia Production via a Two-Step Al2O3/AlN Thermochemical Cycle. 3. Influence of the Carbon Reducing Agent and Cyclability

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• 作者：M. E. G&aacute ; lvez ; I. Hischier ; A. Frei ; A. Steinfeld
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2008
• 出版时间：April 2, 2008
• 年：2008
• 卷：47
• 期：7
• 页码：2231 - 2237
• 全文大小：549K
• 年卷期：v.47,no.7(April 2, 2008)
• ISSN：1520-5045

文摘

The production of ammonia via a two-step cyclic process is considered, consisting of an endothermiccarbothermic reduction of Al₂O₃ in a N₂ atmosphere to form AlN, followed by an exothermic steam hydrolysisof AlN to produce NH₃ and re-form Al₂O₃. Four carbon sources, namely, wood charcoal, petroleum coke,carbon black, and activated carbon, were examined as reducing agents for the Al₂O₃-reduction step in therange 1500-1700 ges/entities/deg.gif">C by means of thermogravimetry and gas chromatography. Rate laws and Arrhenius kineticparameters were determined by applying solid-solid and gas-solid kinetic models. The cyclability of thetwo-step process was studied by carrying out four subsequent cycles, yielding an increase in the reaction rateof the Al₂O₃-reduction step and in the ammonia yield of the AlN-hydrolysis step, attributed to the increasingspecific surface area after each cycle.