Ammonia oxidation reactor

The first observation of sensitivity-stability was reported by Liljenroth (1918) in connection with the autothermal operation of ammonia oxidation reactors. Papers of Damkdhler (1937) and Wagner (1945) went unnoticed. At Union Carbide Corp. Perkins (1938) used zero order kinetics to define a safe range for ethylene oxidation in an unpublished report. His result,... 

The space velocity in the ammonia oxidation reactor can also affect yield and should be high to avoid decomposition of ammonia in the feed gas. This... 

Scheuer A, Hirsch O, Hayes R, Vogel H, Votsmeier M (2011) Efficient simulation of an ammonia oxidation reactor using a solution mapping approach. Catal Today 175 (1) 141-146 Votsmeier M, Scheuer A, Droehner A, Vogel H, Gieshoff J (2010) Simulation of automotive NH3 oxidation catalysts based on pre-computed rate data from mechanistic surface kinetics. Catal Today 151 (3-4) 271-277... 

Nitric acid production ammonia oxidation reactor and catalyst support grid up to 950 °C Nitriding/oxidation... 

The reaction is exothermic reaction rates decrease with increased carbon number of the oxide (ethylene oxide > propylene oxide > butylene oxide). The ammonia—oxide ratio determines the product spht among the mono-, di-, and trialkanolamines. A high ammonia to oxide ratio favors monoproduction a low ammonia to oxide ratio favors trialkanolamine production. Mono- and dialkanolamines can also be recycled to the reactor to increase di-or trialkanolamine production. Mono- and dialkanolamines can also be converted to trialkanolamines by reaction of the mono- and di- with oxide in batch reactors. In all cases, the reaction is mn with excess ammonia to prevent unreacted oxide from leaving the reactor. 

Ammonia Oxidation Kinetics in a High Temperature Flow Reactor , Univ California, Berkeley UCB-TS-71-6, AFOSR (1971)... 

Rebrov, E. V., Duinkerke, S.A., de Croon, M. H. J. M., Schouten, J. C., Optimization of heat transfer characteristics, flow distribution, and reaction processing for a microstructured reactor/ heat-exchanger for optimal peformance in platinum catalyzed ammonia oxidation, Chem. Eng. 93 (2003) 201-216. 

Figure 3.27 Conversion of NHj (open symbols) and selectivity to N2O (closed symbols) for the ammonia oxidation process on Pt catalyst. Micro reactors A1 (A), A2 ( ), A3 ( ), B ( ) and C ( ) were used (see Table 3.1) [98].

Figure 3.28 Unexpected increase in NO/N2 selectivity for ammonia oxidation reaction in a micro membrane reactor [19],...

Figure 3.29 Ammonia oxidation over a Pt catalyst in different membrane micro reactors. Experimental results show good temperature uniformity across the catalyst regions [19].

Figure 3.30 Ignition/extinction loops for ammonia oxidation over platinum performed in micro reactors with different membranes [19],...

Investigations with the modular multi-channel [28,98] and silicon chip [19, 56-62] micro reactors demonstrate that by exact temperature control the oxidation of ammonia can be run with increased and deliberately steered selectivity. A major application is provided by carrying out former high-temperature reactions in the low-temperature regime. In the case of ammonia oxidation in the chip micro reactor, the yield of the value product NO was actually lower in that regime. In the case of the multi-plate-stack micro reactor, higher yields of the value product NO2 were achieved. 

Togetherwiththe ammonia oxidation (see Section 3.3.3), thisreactionwas the first published, giving substantial details on how micro reactor properties affect theperformanceofgas-phasereactions. 

Fixed Bed Reactors. In its most basic form, a fixed bed reactor consists of a cylindrical tube filled with catalyst pellets. Reactants flow through the catalyst bed and are converted into products. Fixed bed reactors are often referred to as packed bed reactors. They may be regarded as the workhorse of the chemical industry with respect to the number of reactors employed and the economic value of the materials produced. Ammonia synthesis, sulfuric acid production (by oxidation of S02 to S03), and nitric acid production (by ammonia oxidation) are only a few of the extremely high tonnage processes that make extensive use of various forms of packed bed reactors. 

The gas leaving an ammonia oxidation unit in a continuous process is cooled rapidly to 20°C and contains 9 mol % NO, 1% N02, 8% O2, and 82% N2 (all the water formed by reaction is assumed to be condensed). It is desirable to allow oxidation of NO to N02 in a continuous reactor to achieve a molar ratio of N02 to NO of 5 before absorption of the N02 to make HNO3. Determine the outlet temperature of the reactor, if it operates adiabatically (at essentially 6.9... 

Figure 3-7 Plot of nominal space times (or reactor residence times) required for several important industrial reactors versus the nominal reactor temperatiwes. Times go from days (for fermentation) down to milliseconds (for ammonia oxidation to form nihic acid). The low-temperature, long-time processes involve liquids, while the high-temperature, short-time processes involve gases, usually at high pressures.

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