Flow rates ammonia oxidation

The situation is different in the case of ammonia oxidation. Both on platinum (156) and nonplatinum (157) catalysts under the conditions of a commercial process, the reaction occurs in the external diffusion region. Diffusion of ammonia rather than of oxygen is determining the rate since the reaction is conducted with oxygen in excess with respect to stoichiometry, as given by (397). Concentration of ammonia at the surface of the catalyst is so small as compared to its concentration in the gas flow that the difference of concentrations that determines the rate of diffusion virtually coincides with the ammonia content in the flow. 

A flow apparatus for detroying 98% of the w-dissolved RDX at flow rates of 2500fi/min is described in Ref 114. The photolysis products include nitrogen gas, nitrous oxide gas. nitrate and nitrite ions, formaldehyde and ammonia. One intermediate product has been identified as l-nitroso-3,5-dimtro-l,3,5-triazacyclohexane. The primary photochemical steps involved in the photolysis are postulated... 

The rate o oxidation o ammonia at atmospheric pressure on single wires and ribbons has been determined as a function of a gas flow rate and catalyst size. In agreement with boundary layer diffusion theory the function rx, where r is the average rate of reaction/unit area, and x is the length of the surface measured in the direction of gas flow, is directly proportional to gas velocity. 

P11-7b The oxidation of ammonia is to be carried out over platinum gauze. The molar flow rate of ammonia is 10 mol/min at a temperature of 500 K and a pressure of 202.6 kPa. Is one 250-mesh screen 10 cm in diameter sufficient to achieve 60% conversion The wire diameter is 0.044 mm. Assume 25% excess air, and ignore the effects of volume changes on the Reynolds number. 

In many cases, the external mass and heat transfer resistances are negligible because of the high gas flow rate that destroys the external resistances (see for example the ammonia converter, ch. 6, sec. 6.3.3, and the steam reformer, ch. 6, sec. 6.3.4). A counter example is the case of the partial oxidation of o-Xylene to phthalic anhydride, ch. 6, sec. 6.3.6, where external mass and heat transfer resistances must be taken into consideration for precise modelling of these reactors. 

Fig. 12.22 Ammonia oxidation reaction data versus temperature for microreactor ACT-G3-7 channel A with a feed gas flow rate of 4.0 mL min (Closed-loop temperature control was used for this experiment, and each heater was given the same set point temperature.)...

Process of selective catalytic reduction of nitrogen oxides by ammonia (SCR) involves injection of ammonia into a gas stream containing nitrogen oxides, then reduction of NOx by ammonia on the surface of a catalyst typically containing vanadium oxide on titania. The reactions involved are mildly exothermic (additional heat is required in most cases). Limits of the optimal process temperature, usually from 200 to 350°C, are dictated by catalyst activity at low temperatures and by the reaction selectivity at high temperatures. The NOj-containing gas flows often have low temperature and variable flow rates and concentrations. This combination of factors makes application of an RFR to NO reduction advantageous. One industrial unit for NO selective catalytic reduction was reported to operate in Russia [44], with ammonia water injection between two catalyst beds. 

The overall objective is to produce triethanolamine, which is featured in the third reaction. Which of the following alternatives is more desirable a stoichiometric (1 1) feed of ethylene oxide and ammonia enters the reactor or a 3 1 molar ratio of ethylene oxide to ammonia enters the reactor Provide support for your answer by calculating the reactor volume in liters and the outlet molar flow rate of triethanolamine that correspond to your design. 

Finally, the mole fraction of component i is written as its molar flow rate divided by the total molar flow rate. The differential mass balance is written for each component in the mixture A = ethylene oxide, B = ammonia, C = monoethanolamine, D = diethanolamine and E = triethanolamine. The matrix of stoichiometric coefficients is summarized as follows for five components that participate in three independent chemical reactions ... 

The feed stream contains a 3 1 molar flow rate ratio of ethylene oxide to ammonia. 

Oxidation with 10 mM periodic acid and 550 mM ammonia in water, flow rate 0.3 mL/min... 

The starting point in development of an ammonia flame mechanism was a mechanism previously used to model ammonia oxidation in a flow tube near 1300 K ( ). Additional reactions were added that were thought to be important at the higher flame temperatures. Calculations with this mechanism produced profiles in marked disagreement with our data. The predictions were slower than observed decay of NH species was much too slow, and OH peaked too late by about 2.5 mm. To make matters worse, far too much NO was formed. The NO problem was especially troublesome in that attempts to increase the rate of NH decay only served to produce even more NO, since NO was the primary decay channel for the NHi species. A possible resolution of this dilemma involves reactions of the NHi species with each other to form N-N bonds. These complexes could then split off H atoms to ultimately form N2. 

In a continuous flow reactor, these quantities will, of course, again depend on the external parameters pi and T, as will be illustrated in the following with the example of ammonia oxidation on a Ru02(1 10) surface [34]. This Ostwald process is the basis for large-scale production of nitric acid that operates with platinum-based catalysts at temperatures >1000K where the rate... 

CrN- and TiN-supported Pt have also been studied for methanol oxidation [69, 87]. The supports were synthesized by ammonolysis of the parent oxide under flows of ammonia using slow ramp rates and high temperatures (>700 C). Surface areas for the materials were 28 m g for TiN and 72 m g for the CrN. Electrocatalytic oxidation studies demonstrated that both supported Pt materials had higher catalytic activity compared to the standard Pt/C materials. This can be attributed to the higher conductivity of the nitride over the carbon as well as a possible synergy between the support and the Pt for the methanol oxidation reaction. Martinez-Huerta and [88] coworkers have also observed enhanced catalytic activity for acidic methanol oxidation when nitrogen is featured into a Ti support. 

To a 1001 sample, 500 ml of 12 mol 1 hydrochloric acid, 10 ml of cobalt carrier solution (Img Co mH ), and 400 ml of l-nitroso-2-naphthol solution (5mgmH in ethanol) are added. With peristaltic pumps, the sample solution, 1 mol 1 aqueous ammonia, and anionic surfactant solution (O.SmgmH in 70% ethanol, sodium oleate-SDS = 1 3) are fed into a 11 reaction bottle at flow rates of 500, 35, and 10 ml min respectively. In the reaction bottle, the cobalt chelate is captured by a flocculent precipitate of indium hydroxide at pH 8.5-9. The contents of the bottle are continuously transferred to a flotation cell and flotation continues until the completion of sample feeding. The precipitate is sucked into a sampling bottle and then dissolved in 100 ml of 6molH hydrochloric acid. The cobalt chelate is separated from indium ions by extraction with chloroform and destroyed by dry oxidation. After dissolving the residue in 5 ml of 8 mol 1 hydrochloric... 

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