Nitric acid gas

HNO3 (nitric acid) gas, aqueous, solid phases HNO2 (nitrous acid) gas, aqueous phases Sulfur based ... 

Aris R, Christian D, Tager I, et al Effects of nitric acid gas alone or in combination with ozone on healthy volunteers. Am Rev Respir Dis 148 965-73, 1993... 

The catalytic effect of the nitric acid gas has been attributed to (a) increase in the concentration of active oxygen and (b) greater oxidizing power of nitrogen peroxide.27 The formation of phenol from benzene by electrochemical oxidation has been explained on the basis of atomic oxygen,18 a hypothesis that may hold in this case. A mechanism for the catalytic effect of nitrogen peroxide based on the conclusion that it is readily activated by the absorption of radiation over a relatively wide range of frequencies is as follows ... 

HN03[g] NITRIC ACID (GAS) 795 HgS04 MERCURY SULFATE 832... 

Other preparative possibilities From copper and nitric acid. Gas prepared in this manner is rather Impure. 

Catalytic gas-phase reactions play an important role in many bulk chemical processes, such as in the production of methanol, ammonia, sulfuric acid, and nitric acid. In most processes, the effective area of the catalyst is critically important. Since these reactions take place at surfaces through processes of adsorption and desorption, any alteration of surface area naturally causes a change in the rate of reaction. Industrial catalysts are usually supported on porous materials, since this results in a much larger active area per unit of reactor volume. 

Procedure for Bromine and Iodine Estimations. Again cover the beaker as before, but before adding the nitric acid add i g. of hydrazine sulphate and heat the solution on the water-bath until evolution of gas ceases. To ensure complete decomposition of an iodate, however, the heating should be continued for i hour. 

The urea produced is normally either prilled or granulated. In some countries there is a market for Hquid urea—ammonium nitrate solutions (32% N). In this case, a partial-recycle stripping process is the best and cheapest system. The unconverted NH coming from the stripped urea solution and the reactor off-gas is neutralized with nitric acid. The ammonium nitrate solution formed and the urea solution from the stripper bottom are mixed, resulting in a 32—35 wt % solution. This system drastically reduces investment costs as evaporation, finishing (priQ or granulation), and wastewater treatment are not required. 

Control of NO emissions from nitric acid and nitration operations is usually achieved by NO2 reduction to N2 and water using natural gas in a catalytic decomposer (123—126) (see Exhaust control, industrial). NO from nitric acid/nitration operations is also controlled by absorption in water to regenerate nitric acid. Modeling of such absorbers and the complexities of the NO —HNO —H2O system have been discussed (127). Other novel control methods have also been investigated (128—129). Vehicular emission control is treated elsewhere (see Exhaust control, automotive). 

Sulfur Dioxide Processing, Repriuts of 1972—1974 Chem. Eng. Prog, articles, AIChE, New York (1975). Contaius thirteen papers on flue gas desulfurization, two on SO2 control iu pulp and paper, one on sulfuric acid tail gas, one on SO2 from ore roasting, and two on NO from nitric acid. 

The cooled, dried chlorine gas contains - 2% HCl and up to 10% O2, both of which are removed by Hquefaction. A full scale 600-t/day plant was built by Du Pont ia 1975. This iastaHatioa at Corpus Christi, Texas operates at 1.4 MPa (13.8 atm) and 120—180°C and uses tantalum-plated equipment and pipes. Oxidation of HCl Chloride by JSHtricHcid. The nitrosyl chloride [2696-92-6] route to chlorine is based on the strongly oxidi2iag properties of nitric acid... 

The hydrated nitrate, Ga(N02(3 9H20, is formed by dissolving gallium ia nitric acid. 

Nickel sulfate also is made by the reaction of black nickel oxide and hot dilute sulfuric acid, or of dilute sulfuric acid and nickel carbonate. The reaction of nickel oxide and sulfuric acid has been studied and a reaction induction temperature of 49°C deterrnined (39). High purity nickel sulfate is made from the reaction of nickel carbonyl, sulfur dioxide, and oxygen in the gas phase at 100°C (40). Another method for the continuous manufacture of nickel sulfate is the gas-phase reaction of nickel carbonyl and nitric acid, recovering the soHd product in sulfuric acid, and continuously removing the soHd nickel sulfate from the acid mixture (41). In this last method, nickel carbonyl and sulfuric acid are fed into a closed-loop reactor. Nickel sulfate and carbon monoxide are produced the CO is thus recycled to form nickel carbonyl. 

Weak Acid. Stainless steels (SS) have exceUent corrosion resistance to weak nitric acid and are the primary materials of constmction for a weak acid process. Low carbon stainless steels are preferred because of their resistance to corrosion at weld points. However, higher grade materials of constmction are required for certain sections of the weak acid process. These are limited to high temperature areas around the gau2e (ca 900°G) and to places in which contact with hot Hquid nitric acid is likely to be experienced (the cooler condenser and tail gas preheater). 

Nitrometer Method. The nitrometer method also is used to determine nitric acid or nitrates in mixed acid or oleum. It involves the measurement of the volume of NO gas that is Hberated when mercury is oxidized by nitric acid. The method is based on the following reaction ... 

Gas chromatography is probably the most versatile method for analysing nitroparaffins (93—95), eg, in the presence of nitric acid esters (96). 

The reaction solution is flushed under reduced pressure after it is sent out from the column, to remove CO2 gas formed as a by-product. The water formed is then removed from the reaction solution by a2eotropic distillation with BN, and most of the resultant reaction solution is recycled to the reaction column as the circulating solution. Part of the circulating solution is taken out from the reaction system and processed further to obtain DBO. The catalyst is first filtered, then BN, C H OH, and by-products are removed from the resultant solution. Purified DBO is thus obtained. The catalyst, BN, and C4H2OH are recovered and recycled to the circulating solution. After the make-up C H OH and nitric acid are added, the circulating solution is pressuri2ed and fed back to the reaction column. 

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