Development and Testing of a High Temperature N2O Decomposition Catalyst
Development and Testing of a High Temperature N2O Decomposition Catalyst
复制标题
高温N2O分解催化剂的开发与测试
DOI：
10.2514/6.2010-7128
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发表时间：
2010
影响因子：
5.6
通讯作者：
D. Wickham
中科院分区：
文献类型：
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作者：
D. Wickham
目前的超音速燃烧冲压发动机动力高超音速导弹的设计采用简单的火箭助推器，使它们达到最低的工作速度，在那里一个双模式冲压/急停发动机可以接管。然而，低气压和低温度以及很短的停留时间使得超燃冲压发动机在高空点火困难。已经使用了各种方法来改善点火和火焰稳定性，并取得了一定的成功。然而，所有方法都有局限性，因此仍然需要改进技术。改进超燃冲压发动机点火和性能的一种方法是利用由N2 O分解产生的33%O2和66%N2的混合物。N2 O分解为N2和O2是一个非常放热的反应，产生的热量足以产生1300°C（2400°F）的产品温度。不幸的是，N2 O是一种相对稳定的化合物，它需要加热到约800°C（1470°F）才能在气相中开始分解。此外，N2 O可以分解成NO和N2，这是一个吸热反应，因此该过程将不利于点火。然而，使用催化剂可以解决这两个问题。催化剂可以降低反应所需的温度，并且它们还可以沿着所需的途径引导反应。因此，在SBIR第一阶段项目中，Reaction Systems的目标是确定在代表性条件下对N2 O分解具有活性的催化剂配方，表征其活性和热稳定性，并生成可用于预测速率随N2 O分压和温度变化的动力学模型。该项目中获得的结果表明，我们的催化剂可以满足将该技术从实验室应用于车辆所需的严格标准。我们证明了我们的催化剂在低温下对反应非常活跃。与不使用催化剂获得的结果相比，它们将反应发生所需的温度降低了600°C以上。此外，我们发现我们的催化剂对N2和O2具有高度选择性。另一方面，没有催化剂，我们得到了N2，但很少O2的产品，这表明气相N2 O分解遵循吸热途径，产生N2和NO。最后，我们生成了一个动力学模型，准确预测N2 O分解率在很宽的温度和压力范围内。
Present designs for scramjet-powered hypersonic missiles employ simple rocket boosters to bring them up to minimum operating speeds where a dual-mode ram/scram engine can take over. However, the low air pressures and temperatures and the very short residence times make scramjet ignition at altitude difficult. Various methods to improve ignition and flame holding have been used with some success. However, all methods have limitations and therefore improved technologies are still needed. One way to improve scramjet ignition and performance would be to utilize the mixture of 33% O2 and 66% N2 produced from N2O decomposition. N2O decomposition to N2 and O2 is a very exothermic reaction, and the heat produced is sufficient to generate product temperatures of 1300°C (2400°F). Unfortunately, N2O is a relatively stable compound and it needs to be heated to about 800°C (1470°F) to begin decomposing in the gas phase. In addition, N2O can decompose into NO and N2, which is an endothermic reaction and therefore this process would not be beneficial for ignition. However, employing a catalyst could solve both of these problems. Catalysts can reduce the temperature required for reaction and they can also direct the reaction along the desired pathway. Therefore, in this SBIR Phase I project, Reaction Systems’ objectives were to identify catalyst formulations that are active for N2O decomposition under representative conditions, characterize their activity and thermal stability, and produce a kinetic model that can be used to predict rate as a function of N2O partial pressure and temperature. The results obtained in this project showed that our catalysts can meet the demanding criteria needed to take this technology from the laboratory to a vehicle. We demonstrated that our catalysts were extremely active for the reaction at low temperatures. They reduced the temperature required for reaction to occur by over 600°C compared to results obtained without catalyst. In addition we found that our catalysts were highly selective for N2 and O2. On the other hand without catalyst, we obtained N2 but very little O2 in the products, suggesting that gas phase N2O decomposition follows the endothermic pathway, producing N2 and NO. Finally, we generated a kinetic model, which accurately predicted N2O decomposition rates over a wide range of temperatures and pressures.