Nitric acid process technology

T. Ohrui, K. Ohkubo and 0. Imai, Technological Improvements in the Strong Nitric Acid Process , Ammonia P/ant Safety, Volume 21, pp.1 64-I 70, AlChE, New York (1979). 

V. Cavaseno (Ed ), Strong Nitric Acid Process Features Low Utility Costs , Process Technology and Flowsheets, pp.83-86, (reprints from Chemical Engineering) McGraw-Hill Publications, New York (1979). 

The technology described by Asahi is very similar to that used for the synthesis of terephthalic acid by p-xylene oxidation. The selectivity of AA and the total selectivity of dicarboxylic acids are still lower than those in the nitric acid process [13o]. 

Process Licensors. Some of the well-known nitric acid technology licensors are fisted in Table 3. Espindesa, Grande Paroisse, Humphreys and Glasgow, Rhfyne Poulenc, Uhde, and Weatherly are all reported to be licensors of weak acid technology. Most weak acid plant licensors offer extended absorption for NO abatement. Espindesa, Rhfyne Poulenc, Weatherly, and Uhde are also reported (53,57) to offer selective catalytic reduction (SCR) technology. 

Nitric acid oxidation is used where carbohydrates, ethylene glycol, and propylene are the starting materials. The diaLkyl oxalate process is the newest, where diaLkyl oxalate is synthesized from carbon monoxide and alcohol, then hydrolyzed to oxahc acid. This process has been developed by UBE Industries in Japan as a CO coupling technology in the course of exploring C-1 chemistry. 

Initial production of the dimethyl terephthalate started with the oxidation of -xylene to terephthaUc acid using nitric acid both companies reportedly used similar technology (43—45). Versions of the nitric acid oxidation process, which has been abandoned commercially, involved the use of air in the initial oxidation step to reduce the consumption of nitric acid (44,46,47). The terephthaUc acid was then esterified with methanol to produce dimethyl terephthalate, which could be purified by distillation to the necessary degree (48). 

There are two main processes for conversion of celestite, ie, strontium sulfate, to strontium carbonate. The principal process is the black ash process. Strontium nitrate is produced by dissolving celestite in nitric acid and purifying it. Most other strontium compounds are produced from strontium nitrate. To service this market, NOAH Technologies Corporation (San Antonio, Texas) has estabUshed a plant in Mexico to manufacture most commercial- and reagent-grade strontium compounds except strontium carbonate. 

Flue gas treatment (FGT) is more effective in reducing NO, emissions than are combustion controls, although at higher cost. FGT is also useful where combustion controls are not applicable. Pollution prevention measures, such as using a high-pressure process in nitric acid plants, is more cost-effective in controlling NO, emissions. FGT technologies have been primarily developed and are most widely used in Japan. The techniques can be classified as selective catalytic reduction, selective noncatalytic reduction, and adsorption. 

Nitric acid is one of the three major acids of the modem chemical industiy and has been known as a corrosive solvent for metals since alchemical times in the thirteenth centuiy. " " It is now invariably made by the catalytic oxidation of ammonia under conditions which promote the formation of NO rather than the thermodynamically more favoured products N2 or N2O (p. 423). The NO is then further oxidized to NO2 and the gases absorbed in water to yield a concentrated aqueous solution of the acid. The vast scale of production requires the optimization of all the reaction conditions and present-day operations are based on the intricate interaction of fundamental thermodynamics, modem catalyst technology, advanced reactor design, and chemical engineering aspects of process control (see Panel). Production in the USA alone now exceeds 7 million tonnes annually, of which the greater part is used to produce nitrates for fertilizers, explosives and other purposes (see Panel). 

At least rune manufacturing technologies are available for the production of caprolactam and, in most, hydroxylamine (hyam) is one of the important raw materials. In particular, in the HPO process the hydroxylamine is made by using a precious metal powdered catalyst to selectively hydrogenate nitric acid. Evonik... 

Silver II An electrolytic oxidation process for destroying traces of organic substances in water. The oxidizing agent is the silver ion in a nitric acid environment. Developed by AEA Technology, Oxford, and used for destroying war gases. 

REDEX process, 3 606 Red-figures ceramic techniques, 5 745 Red fuming nitric acid, 17 188 Redingtonite, 6 4 7 It Red iron oxide(s), 19 397, 398-399 wet preparation of, 19 399 Redistribution technology, 19 816 Red Lake C... 

AEA Technology Modified reverse assembly (high-pressure wash, new rocket shearing). Electrochemical oxidation using silver ions in nitric acid (SILVER II ). Treated with SILVER II process. High-pressure acid wash thermal treatment to 5X.b Shredded and treated with SILVER II process. 

Some of the important reactions in contemporary technology involve NO, which is a designation of N2O, NO, and NO2, and was one of the first examples in this book. The formation of these molecules in combustion processes is a major source of air pollution, and the catalytic oxidation of NH3 to NO on R surfaces is used to produce nitric acid, a major industrial chemical. The decomposition of NO, to N2 is a major process in the automotive catalytic converter. 

Potassium nitrate may be produced by several methods. It is made commercially by reacting potassium chloride with nitric acid at high temperature. Nitrosyl chloride, a product obtained in the reaction, is converted into chlorine in this manufacturing process. Also, nitric acid is partly recycled in the process. The reactions are (Dancy, W.B. 1981. Potassium Compounds. In Kirk-Othmer Encyclopedia of Chemical Technology, 3 i ed. Pp. 939-42. New York Whey Interscience) ... 

Mediated electrochemical oxidation (MEO) is an ex situ treatment technology that uses electricity, acid, and a metal catalyst to destroy organic wastes at low temperatures and pressures. The proprietary CerOx Corporation MEO configuration uses cerium metal as a catalyst to oxidize organic waste into carbon dioxide and water. The process occurs in an acidic solution, typically nitric acid. The first step involves the generation of an oxidant at the anode, followed by the reduction of water or another chemical species at the cathode. This technology serves as a nonthermal alternative to incineration. 

The CCA technology uses sulfuric and nitric acid to oxidize pit waste contaminated with CCA or waste products generated by wood preserving plants. In the process, CCA is recovered for recycling and the remaining solids are decontaminated for disposal. 

In tlie PUREX process, the spent fuel and blanket materials are dissolved in nitric acid to form nitrates of plutonium and uranium. These are separated chemically from the other fission products, including the highly radioactive actinides, and then the two nitrates are separated into tv/o streams of partially purified plutonium and uranium. Additional processing will yield whatever purity of the two elements is desired. The process yields purified plutonium, purified uranium, and high-level wastes. See also Radioactive Wastes in the entry1 on Nuclear Power Technology. Because of the yield of purified plutonium, the PUREX process is most undesirable from a nuclear weapons proliferation standpoint,... 

The process chosen for the nitric acid plant is the single pressure process based on the technology developed by C I Girdler. 

During World War 1, the intense demand for explosives and synthetic dyestuffs created an expansion of the nitric acid industry. Many new plants were constructed, all of which employed the ammonia oxidation process. This increased demand served as the impetus for several breakthroughs in process technology. These included ... 

The most comprehensive reference in this group was undoubtedly Kirk and Othmer (Ref. Gl). It provided an excellent historical background into process development and market characteristics, and also provided a broad coverage of the physical and chemical properties of nitric acid, handling methods, and materials of construction. A warning on using this or other process encyclopedias is that much of the technology presented in the first five references has now been superseded. 

Gregory (Ref. G6) is a very comprehensive source specific to the industrial and commercial applications of chemicals. It includes a three page list of the uses of nitric acid. Similar information is presented for many other chemicals in this book. The one fault of this source is that it is 50 years old In that period many process technologies have changed and the applications list, whilst very comprehensive, tends to be dated. 

Section 3.2.2 compares these leading process technologies in order to select the most applicable method of weak nitric acid production. The most appropriate process is discussed fully in Section 4.2. Summaries of both processes are included in Appendix C. 

---