Nitrogen catalytic combustion

Final purification of argon is readily accompHshed by several methods. Purification by passage over heated active metals or by selective adsorption (76) is practiced. More commonly argon is purified by the addition of a small excess of hydrogen, catalytic combustion to water, and finally redistiHation to remove both the excess hydrogen and any traces of nitrogen (see Fig. 5) (see Exhaust control, industrial). With careful control, argon purities exceed 99.999%. 

PGM catalyst technology can also be appHed to the control of emissions from stationary internal combustion engines and gas turbines. Catalysts have been designed to treat carbon monoxide, unbumed hydrocarbons, and nitrogen oxides in the exhaust, which arise as a result of incomplete combustion. To reduce or prevent the formation of NO in the first place, catalytic combustion technology based on platinum or palladium has been developed, which is particularly suitable for appHcation in gas turbines. Environmental legislation enacted in many parts of the world has promoted, and is expected to continue to promote, the use of PGMs in these appHcations. 

Catalytic combustion is a process in which a combustible compound and oxygen react on the surface of a catalyst, leading to complete oxidation of the compound. This process takes place without a flame and at much lower temperatures than those associated with conventional flame combustion. Due partly to the lower operating temperature, catalytic combustion produces lower emissions of nitrogen oxides (NOx) than conventional combustion. Catalytic combustion is now widely used to remove pollutants from... 

These two research areas share the common characteristic of involving inorganic solids in the combustion process. Catalytic combustion research focuses on using the solid to facilitate the oxidation of well-known fuels such as hydrogen and methane. Materials synthesis research focuses on using combustion as a means to react the solids either with each other or a gas, such as nitrogen (which in this case acts as an oxidizer), to make new solid materials. 

The nitrogen is constantly cleaned in a gas purification loop. All reaction products and contaminants are burnt in a catalytic combustion system. 

Unavoidable loss of gas is compensated via a feed valve for supplying virgin nitrogen into the circulation pipe. The exhaust gas of the process has to be bypassed for purification. After the separation of dust by a filter, the gas is heated to 400 °C for the catalytic combustion of the side products. The gas is then cooled down, and the excess oxygen is catalytically converted to water by using hydrogen. For economic reasons, the gas flow will recover the heat via a heat exchanger and then be cooled down by a gas cooler. 

An under-stoichiometric mixture of methane and oxygen (2 1) was diluted with 70% nitrogen, preheated and distributed within the distribution module and continuously delivered to the single wells. For the catalytic combustion of methane, a number of parallel and consecutive reactions occur [57]. During the tests mostly carbon dioxide was obtained according to the formula ... 

Most of the work on catalytic combustion applications has dealt with the use of natural gas, since this is a clean gaseous fuel with low nitrogen content. However, a number of other hydrocarbon fuels have been investigated as well [99-101], such as propane, gasoline, diesel fuel, and kerosenes. 

An LHV gas may contain up to a few thousand ppm of ammonia, produced from fuel-bound nitrogen during the gasification of a solid fuel. One of the major challenges in the catalytic combustion of LHV gases is to circumvent the formation of NO from this ammonia. The selectivity for this reaction is strongly dependent on the air-fuel ratio in the catalytic combustor and on the catalyst type [102,105], Clark et al. [102] and Tucci... 

Catalytic Combustion of Nitrogen Bearing Low Heat Value Gaseous Fuels for Power and Heat Generation, ETSU Project Profile 230, Dec 1998. 

Nitrogen(II) oxide in 80 to 90% yield is produced by the catalytic combustion of ammonia in oxygen in the presence of water vapor on a platinum-rhodium catalyst ... 

Catalytic combustion is an environmentally-driven, materials-limited technology with the potential to lower nitrogen oxide emissions from natural gas fired turbines consistently to levels well below 10 ppm. Catalytic combustion also has the potential to lower flammability at the lean limit and achieve stable combustion under conditions where lean premixed homogeneous combustion is not possible. Materials limitations [1,2] have impeded the development of commercially successful combustion catalysts, because no catalytic materials can tolerate for long the nearly adiabatic temperatures needed for gas turbine engines and most industrial heating applications. 

Total Nitrogen (TN) Combustion catalytic oxidation, combustion oxidation, photochemical oxidation... 

Although the process configuration varies widely there are three main steps common to each, they are oxidation of ammonia to nitric oxide (NO), oxidation of NO to nitrogen dioxide (N02), and then absorption of N02 in water to produce nitric acid (Figure 3.11). The first step of the catalytic combustion of ammonia takes place over a catalyst consisting of platinum/rhodium (90 10) or platinum/rhodium/palladium (90 5 5). The reaction is very rapid and goes almost to completion as shown in Reaction 3.11. The reaction is one of the most efficient catalytic processes in industrial chemistry, having an extremely... 

In conventional processes (Stamicarbon and Inventa), hydroxylamine sulfate is prepared by the Raschig technique. The first reaction is the catalytic combustion of ammonia in air at 850°C. in the presence of a platinum foam catalyst The heat generated by the reaction is recovered in a boiler which produces steam. Nitrogen oxides are formed by the following reaction mechanism ... 

Catalytic combustion is a preventive solution for the problem of NOx emissions [4]. To understand and appreciate this, the mechanisms of NOx formation have to be examined. The nitrogen oxides from combustion sources are collectively referred to as NOx they consist of 95% NO and 5% NO2. These oxides are formed from two sources first, by oxidation of atmospheric nitrogen during combustion second, by oxidation of the nitrogen compounds in the fuel. 

Response to Oxides of Nitrogen Other than Nitric Oxide. Although NO is normally the oxide of nitrogen in combustion products, exhaust aging at ambient temperature forms other products such as N02, N204, N205, and HN03. Catalytic muffler treatment of exhaust may produce... 

Application of SAPO-5 Ion-Exchanged with Pd for Combustion Catalyst. - There is a strong demand for the development of new combustor without the emission of air pollutants such as nitrogen oxide. Catalytic combustion of fuel is a new combustion... 

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