NITRIC OXIDE REMOVAL

Some controversy exists over the reactive species produced when nitrogen is passed through an R.f. or microwave discharge. Verbeke and Winkler investigated the reactions of active nitrogen with nitric oxide and ethylene and found that the amount of nitric oxide removed was greater than the maximum amount of HCN produced from ethylene. To account for this difference they postulated that vibrationally excited molecules were decomposing nitric oxide, viz. 

Kumar, A., Ergas, S. I, Yuan, X.,Fitch, M., Min, K. -N., Dewulf, J. and van Langenhove, H. 2010a. Modeling of a hollow fiber membrane biofilm reactor for nitric oxide removal model development and experimental validation./oarnaZ of Chemical Technology and Biotechnology, 85,423-428. 

Min, K.-N., Ergas, S. J. and Harrison, J. M. 2002. HoUow-fiber membrane bioreactor for nitric oxide removal. Environmental Engineering Science, 19,575-583. 

Nitric oxide removal is possible only in a narrow temperature range centered at T 1250 K. At temperatures below 1100 K no reaction takes place, and at temperatures above 1400 K the ammonia is oxidized to form NO rather than destroy it. 

Thus in order for the process to sustain itself, it must produce OH. Otherwise, what little OH might be present initially would be exhausted and the reaction would die out with little or no nitric oxide removed. It has been obvious from the outset that the NH2 + NO reaction is key. This reaction must simultaneously remove NO and produce free radicals. It is clear both from experiment [21-27,31-33] and theory [10-14] that this reaction has two channels,... 

Caton JA, Siebers DL (1989) Comparison of Nitric Oxide Removal by Cyanuric Acid and by Ammonia. Combust Sci Technol 65(4—6) 277-293... 

Reduction of metal oxides with hydrogen is of interest in the metals refining industry (94,95) (see Metallurgy). Hydrogen is also used to reduce sulfites to sulfides in one step in the removal of SO2 pollutants (see Airpollution) (96). Hydrogen reacts directiy with SO2 under catalytic conditions to produce elemental sulfur and H2S (97—98). Under certain conditions, hydrogen reacts with nitric oxide, an atmospheric poUutant and contributor to photochemical smog, to produce N2 ... 

The reaction vessel (nitrator) is constructed of cast iron, mild carbon steel, stainless steel, or glass-lined steel depending on the reaction environment. It is designed to maintain the required operating temperature with heat-removal capabiUty to cope with this strongly exothermic and potentially ha2ardous reaction. Secondary problems are the containment of nitric oxide fumes and disposal or reuse of the dilute spent acid. Examples of important intermediates resulting from nitration are summarized in Table 3. 

Nitric acid, removal of nitrogen oxides from, 43, 84... 

The reactions that occur to auto-exhaust emissions when exposed to plasma include oxidation of HCs, carbon monoxide, and partially diesel PM also. Nitric oxide (NO) can be oxidized by plasma to N02. Plasma alone, due to its oxidizing character, is not a viable NO control method. However, combinations of plasma with catalysts, referred to as plasma-assisted catalysts or simply plasma catalysts , have been suggested for NO reduction. The plasma is believed to show potential to improve catalyst selectivity and removal efficiency. Current state-of-the-art plasma catalysts have efficiencies comparable to those of active DeNO systems, removing about 50% of NO at a fuel economy penalty of less than 5% [85],... 

Van Deyck, F., Weiss, F.J., Verbeck, R. el al. (1985) Removal of nitrous oxide from gases containing hydrogen, nitric oxide and nitrous oxide, US Patent 4507271. 

Takaki, K., Jani, M.A. and Fujiwara, T. (1999) Removal of nitric oxide in flue gases by multi-point to plane dielectric barrier discharge, IEEE Trans. Plasma Sci. 27, 1137—45. 

Presently, there is a general consensus that heterogeneous catalytic processes play an important role in environmental issues regarding their high selectivity towards the removal of undesired side products, such as atmospheric pollutants, in comparison with that obtained from non-catalysed processes. However, such a benefit could be disputed in the future with the implementation of severe restrictions on standard emission of those atmospheric pollutants, particularly nitric oxide, which is a very challenging aspect. 

Shiny silvery metal that is relatively soft in its pure form. Forms a highly resistant oxide coat. Used mainly in alloys, for example, in construction steel. Tiny amounts, in combination with other elements such as chromium, makes steel rustproof and improves its mechanical properties. Highly suited for tools and all types of machine parts. Also applied in airplane turbines. Chemically speaking, the element is of interest for catalysis (for example, removal of nitric oxides from waste gases). Vanadium forms countless beautiful, colored compounds (see Name). Essential for some organisms. Thus, natural oil, which was formed from marine life forms, contains substantial unwanted traces of vanadium that need to be removed. 

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