Reactions of ammonia Oxidation

In contrast to the hydrogen and CO oxidation reactions, the reaction of ammonia oxidation can proceed along several paths and so can be used to study not only activity but also selectivity. 

TABLE 28.13 Equilibrium Constants for Reactions of Ammonia Oxidation... 

Etliyleiie oxide [75-21-8] propylene oxide [75-56-9] or butylene oxide [106-88-7] react widi aminonia to produce alkanolainines (Table 1). Etlianolainines, (n = 1, 2,3, mono-, di-, and tri-), are derived from the reaction of ammonia witli ethylene oxide. Isopropanolamines,... 

CH- CHOHCH3 ), (mono-, di-, and tri-), result from the reaction of ammonia with propylene oxide. Secondary butanolamines,... 

Isopropa.nola.mines. Reaction of propylene oxide with ammonia yields mono-, di-, and triisopropanolamines. These products find use as soluble oils and solvents, emulsifiers, waterless hand cleaners, cosmetics, cleaners, and detergents. In industrial apphcations isopropanolamines are used in adhesives, agricultural products, corrosion inhibitors, coatings, epoxy resins, metalworking, and others (51). 

Rates and selectivities of soHd catalyzed reactions can also be influenced by mass transport resistance in the external fluid phase. Most reactions are not influenced by external-phase transport, but the rates of some very fast reactions, eg, ammonia oxidation, are deterrnined solely by the resistance to this transport. As the resistance to mass transport within the catalyst pores is larger than that in the external fluid phase, the effectiveness factor of a porous catalyst is expected to be less than unity whenever the external-phase mass transport resistance is significant, A practical catalyst that is used under such circumstances is the ammonia oxidation catalyst. It is a nonporous metal and consists of layers of wire woven into a mesh. 

Ethanolamines. These are produced by the reaction of ethylene oxide and ammonia (see Alkanolamines). Approximately one-third of the production is used in detergents. Other appHcations include natural gas purification, cosmetics, metalworking, textiles, and chemical intermediates (282). 

Nitrogen cannot have an oxidation number lower than —3, which means that when NH3 takes part in a redox reaction, it always acts as a reducing agent. Ammonia may be oxidized to elementary nitrogen or to a compound of nitrogen. An important redox reaction of ammonia is that with hypochlorite ion ... 

F.G. Liljenroth, ChemMetEng 19, 287—393 (1918) (Starting and stability phenomenon of ammonia oxidation and similar reactions)... 

H.20 The first stage in the production of nitric acid by the Ostwald process is the reaction of ammonia gas with oxygen gas, producing nitric oxide gas, NO, and liquid water. The nitric oxide further reacts with oxygen to produce nitrogen dioxide gas, which, when dissolved in water, produces nitric acid and nitric oxide. Write the three balanced equations that lead to the production of nitric acid. 

The reinforcing fibers are usually CVD SiC or modified aluminum oxide. A common matrix material is SiC deposited by chemical-vapor infiltration (CVI) (see Ch. 5). The CVD reaction is based on the decomposition of methyl-trichlorosilane at 1200°C. Densities approaching 90% are reported.b l Another common matrix material is Si3N4 which is deposited by isothermal CVI using the reaction of ammonia and silicon tetrachloride in hydrogen at 1100-1300°C and a total pressure of 5 torr.l" " ] The energy of fracture of such a composite is considerably higher than that of unreinforced hot-pressed silicon nitride. 

Nitric acid, a leading industrial chemical, is used in the production of fertilizers and explosives. One step in the industrial production of nitric acid is the reaction of ammonia with molecular oxygen to form nitrogen oxide 4 NH3 + 5 O2 4 NO + 6 H2 O In a study of this reaction, a chemist mixed 125 g of ammonia with 256 g of oxygen and allowed them to react to completion. What masses of NO and H2O were produced, and what mass of which reactant was left over ... 

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. 

Ammonia oxidation was a prototype system, but subsequently a number of other oxidation reactions were investigated by surface spectroscopies and high-resolution electron energy loss spectroscopy XPS and HREELS. In the case of ammonia oxidation at a Cu(110) surface, the reaction was studied under experimental conditions which simulated a catalytic reaction, albeit at low... 

Figure 1.4. Reaction and conditions used by Fritz Fiaber to produce ammonia from hydrogen and nitrogen. The reaction of ammonia with water to form ammonium and the oxidation of ammonia to nitric acid, a common reaction in soil, are also given.

The surface complex [=Si-NH2] can be obtained on siUca by reaction of ammonia on silicajiooo) (Scheme 2.7) [9]. The addition of ammonia on siUca, normally unable to induce N-H cleavage at room temperature, becomes possible in this case because of the drastic dehydroxylation treatment, which produces a few highly strained [=Si-0-Si=] bridges (0.15 nm ) that undergo cleavage by bimolecular oxidative addition of otherwise unreactive bonds [10-13]. 

Nitrite reductase (NAD(P)H) [EC 1.6.6.4] catalyzes the reaction of three NAD(P)H with nitrite to yield three NAD(P)+, NH4OH, and water. Cofactors for this enzyme include FAD, non-heme iron, and siroheme. (2) Nitrite reductase (cytochrome) [EC 1.7.2.1] is a copper-depen-dent system that catalyzes the reaction of nitric oxide with two ferricytochrome c and water to produce nitrite and two ferrocytochrome c. (3) Ferredoxin-nitrite reductase [EC 1.7.7.1], a heme- and iron-dependent enzyme, catalyzes the reaction of ammonia with three oxidized ferredoxin to produce nitrite and three reduced ferredoxin. (4) Nitrite reductase [EC 1.7.99.3] is a copper- and FAD-dependent enzyme that catalyzes the reaction of two nitric oxide with an acceptor substrate and two water to produce two nitrite and the reduced acceptor. 

The reaction of iminium ions with dihydropyridines is a method, suggested from biosynthetic studies, for the formation of carbon-carbon bonds to these six-membered heterocycles. The 1,4-dihydropyridine (8), a presumed intermediate from the reaction of ammonia with glutaraldehyde, reacts with the cyclic iminium ion (159) to give, after oxidation, nicotine (160) (72CC1091). Another example of this reaction has provided a total synthesis of olivacine (163). The 1,2-dihydropyridine ring system in (161), generated from its chromium tricarbonyl complex, was observed to undergo an intramolecular cyclization... 

Ethanolamines became available commercially in the early 1930s they assumed steadily growing commercial importance as intermediates after 1945, because of the large-scale production of ethylene oxide. Since the mid-1970s, economical production of very pure, colourless ethanolamines has been possible. Ethanolamines are produced on an industrial scale exclusively by reaction of ethylene oxide (see lARC, 1994) with excess ammonia. This reaction takes place slowly but is accelerated by water. An... 

From the thermodynamic data of Appendix C, show that the product of the reaction of ammonia gas with oxygen would be nitrogen, rather than nitric oxide, under standard conditions and in the absence of kinetic control by, for example, specific catalysis of NO formation by platinum. (Assume the other product to be water vapor.)... 

The reaction of ammonia with oxygen over V-based catalysts produces mainly nitrogen, according to the stoichiometry of R5 in Table V. Analogously to the case of the ammonia adsorption-desorption, specific runs were carried out in order to extract the intrinsic kinetics of ammonia oxidation and at the same time to validate the previously fitted kinetics of the ammonia adsorption-desorption process. 

By mixing the gases (NO, + 04 + HaO) obtained as by-products of ammonia oxidation plants, with ammonia gas and extra air in order to bring about the following reaction 4NO + O, + 2H,0 + 4NH, - 4NH4NOs. In this process, AN is deposited as a powder... 

---