Conversion nitric oxide

Fig. 3. Nitric Oxide conversion as a function of oxigen inlet concentration on Pt Co M reduced ( ) Co M oxidazed ( ) anfl COjjM reduced ( )samples. NO 1000 ppm, CH. 1000 ppm, balance to 1 atm He, Temperature 450 °C, GHSV 6500 h .

Ravi, V., Mok, Y.S., Rajanikanth, B.S. et al. (2003) Temperature effect on hydrocarbon-enhanced nitric oxide conversion using a dielectric barrier discharge reactor, Fuel Processing Technology 81, 187-99. 

Under diesel conditions, carbon monoxide and hydrocarbon oxidation is favoured. Under the highly oxidising conditions encountered in the diesel gas stream, reduction of nitric oxide is not expected. A nitric oxide conversion window is observed at temperatures between 493 and 623 with a T50 value of 523 K. However, large NO absorption bands are observed at temperatures above and below the conversion window.28... 

On Figure 34 we note a sharp drop from the interpolated NO-level between 0730 and 0740 hours. This reflects the previously noted failure of the data to approach quasi-equilibrium between NO, NO2, O3, and sunlight intensity under high-oxidant conditions. The NO-conversion seems to proceed at roughly the observed rate after the transient is absorbed in the system however, the level ends up closer to Azusa values than to El Monte values. If we were to use 0830 El Monte concentrations as initial values, we would have a lower HC/NO-ratio and could expect still slower nitric oxide conversion rates. Thus, nitric oxide and hydrocarbon decay more like the Azusa data than the El Monte data. 

The NO2 behavior on Figure 35 exhibits more nearly what one would expect than do either the reactive HC or the NO. Proceeding from the end of its transient adjustment to observed sunlight intensity, the air mass gradually undergoes NO2-transition from Azusa levels to El Monte levels as it meanders about in the northeastern area of the basin. Nitric oxide conversion supported by increasing sunlight intensities drives the NO2... 

For all 482°C runs, nitric oxide conversion decreased as the oxygen level was increased above 0.05%. Carbon monoxide and propylene conversions always increased with increasing oxygen concentrations. As would be expected, carbon monoxide, propylene, and nitric oxide conversions decreased as space velocity increased. 

Table VI. Propylene, Carbon Monoxide, and Nitric Oxide Conversions and Ammonia Formation within the Oxygen Window...

Table VII. Ammonia in Nitric Oxide Conversion with CuMn204 X as a Function of Oxygen Concentration and Space Velocity...

The Cu/ZSM-5 microreactor experiments were performed by heating a powdered sample (particle diameter <150mm) from 150 to 500°C at 10°C min under a simulated exhaust gas. The gas mixture comprised 300ppm NO, 300ppm CO, SOOppm C3H6, 5% O2,10% H20,13% CO2 in N2, and was flowed over the sample at 120 dm h g. Nitric oxide conversion was monitored by a chemiluminescent analyser (Analysis Automation), while propene conversion was measured using a gas... 

With the object of stressing the possibility of an oxygenated compound as intermediate of the selective NO reduction with methane, metlianol was used as reducing agent. Figure 3.b shows tlie results of metlianol and nitric oxide conversion at different temperatiues for reactions A and B over CoMordenite. It can be observed that the conversion of nitric oxide to nitrogen begins to occiu at temperatures similar to those for the selective reduction with methane. Tliis fact clearly supports the... 

It is necessary here to draw attention on the way in wliich tliese experiments were conducted in what concerns to the oxygen feed. As already stated in the Experimental section, oxygen was incorporated to the gas phase very close to the catalyst bed. Experiences perfonned mixing oxygen at the reactor inlet, showed lower nitric oxide conversions. Tliis is due to the fact tliat methanol oxidation takes place in the reactor void voliune before reacliing tlie catalyst bed, tlius obtaining NO conversions similar to those of tlie non-catalytic gas phase reaction. 

Hamada et al. [15] did not find nitric oxide conversion using metlianol as reducing agent and CuZSM5 as catalyst, thus differing from oin results. Probably tliis is due to the influence of tlie gas phase reactions mentioned above, or maybe these autliors did not reach temperatures Ingli enougli to bum tlie carbon deposit. 

Figure 5 shows nitric oxide conversions at different temperatures for the NO + CH3OH and NO + CH3OH + Oj reactions in the gas phase. 

In these experiments, the catalyst bed was replaced by a similar volume of quartz cliips. It is interesting to observe tliat tlie NO conversions for botli reactions are similar. DiflFerent from methanol, when metltane or etliylene are used as reducing agents in tlie HC + NO + O2 reaction in tlie gas phase, no nitric oxide conversion is observed [10]. Tliese results seem to support tlie existence of a mechanism with oxygenated intennediates, the production of tliese intennediates via catalytic oxidation of HC with O2 or with NO2, being a fiuidamental role of tlie catalyst. Once tlie intennediate has been fonned, its reaction with NOx could take place on tlie... 

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