Studies of Structured Catalytic Reactors

氨在铂或铂-铑催化剂上的催化氧化对硝酸的制造和稀燃发动机(例如柴油和天然气燃料)的催化废气处理系统中都是一个关键的反应。在第一个应用中，NH3氧化为NO通常在工业上使用网状催化剂进行，该催化剂由铂和铑的合金组成。一氧化二氮是氨氧化过程的副产品。尽管它不是有毒物质，特别是在这个过程中释放到大气中的水平，但它仍然是一种强烈的温室气体，其全球变暖潜力约为二氧化碳的310倍。目前，为了最大限度地减少氨氧化反应器的N2O排放，可以在纱布层5之后添加一个辅助催化剂。该催化剂的形状通常为颗粒或拉希环。目前人们对这一过程非常感兴趣，特别是在艾伯塔省，那里可以申请大量温室气体排放抵免来减少N2O。这项工作的目的是：(1)研究和阐明纱网反应器中催化剂周围边界层的传质和传热行为；(2)将氨氧化的微观动力学模型应用到CFD反应器模型中并进行验证；(3)利用CFD比较不同纱网设计的性能，并与实验性能进行比较；(4)研究氨氧化反应器中N2O的还原方法，

The catalytic oxidation of ammonia over platinum or platinum-rhodium catalysts is a crucial reaction for both the manufacture of nitric acid and in the catalytic exhaust gas after treatment systems for lean burn engines (e.g. with Diesel and natural gas fuels). In the first application, the oxidation of NH3 to NO is typically carried out industrially using a gauze type catalyst, which is composed of an alloy of platinum and rhodium. Nitrous oxide is a byproduct of the ammonia oxidation process. Although it is not a toxic substance, especially at the levels released to the atmosphere in this process, it is nonetheless a strong greenhouse gas, with a global warming potential about 310 times that of carbon dioxide. Currently, to minimize emissions of N2O from ammonia oxidation reactors, an auxiliary catalyst may be added after the gauze layers5. This catalyst is often in the form of pellets or Rashig ring in shape. There is currently great interest in this process, especially in Alberta, where significant greenhouse gas emission credits can be claimed for N2O abatement. The objectives of this work are:(1) Study and elucidate the mass and heat transfer behaviour in the boundary layers around the catalyst in gauze reactors;(2) Implement micro-kinetic models of ammonia oxidation into a CFD reactor model and validate same;(3) Compare the performance of different gauze designs using CFD and to compare with experimental performance;(4) Investigate methods for the reduction of N2O from ammonia oxidation reactors,