Nitric oxide reduction with carbon monoxide

This indicates that the amount of carbon dioxide formed by this experiment coincided with the amounts of both carbon monoxide and nitric oxide consumed. Thus the use of carbon monoxide reduced the consumption of carbon to approximately zero and the char provided catalytic surfaces for nitric oxide reduction by carbon monoxide as ... 

A. Ueda, andM. Haruta, Nitric oxide reduction with hydrogen, carbon monoxide, and hydrocarbons over gold catalysts. Gold Bull. 32, 3-11 (1999). 

Studies with gold catalysts have focused on the selective reduction of nitric oxide by propene, carbon monoxide and hydrogen urea,10 methane11 and other hydrocarbons9,11,13 have also been used. NOx removal using the first three of these will now be discussed. 

Bollinger, M.J., R.E. Sievers, D.W. Fahey, and F.C. Fehsenfeld. 1983. Conversion of nitrogen dioxide, nitric acid, and w-propyl nitrate to nitric oxide by gold-catalyzed reduction with carbon monoxide. Anal. Chem. 55 1980-1986. 

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],... 

Cyclopentanecarboxaldehyde has been prepared by the procedure described above 2 3 by the reaction of aqueous nitric acid and mercuric nitrate with cyclohexene 6 by the action of magnesium bromide etherate 6 or thoria 7 on cyclohexene oxide by the dehydration of frarei-l, 2-cyclohexanediol over alumina mixed with glass helices 8 by the dehydration of divinyl glycol over alumina followed by reduction 9 by the reaction of cyclopentene with a solution of [HFe(CO)4] under a carbon monoxide atmosphere 10 and by the reaction of cyclopentadiene with dicobalt octacarbonyl under a hydrogen and carbon monoxide atmosphere.11... 

In this chapter, recent results are discussed In which the adsorption of nitric oxide and its Interaction with co-adsorbed carbon monoxide, hydrogen, and Its own dissociation products on the hexagonally close-packed (001) surface of Ru have been characterized using EELS (13,14, 15). The data are interpreted In terms of a site-dependent model for adsorption of molecular NO at 150 K. Competition between co-adsorbed species can be observed directly, and this supports and clarifies the models of adsorption site geometries proposed for the individual adsorbates. Dissociation of one of the molecular states of NO occurs preferentially at temperatures above 150 K, with a coverage-dependent activation barrier. The data are discussed in terms of their relevance to heterogeneous catalytic reduction of NO, and in terms of their relationship to the metal-nitrosyl chemistry of metallic complexes. 

The reduction of nitric oxide by char in the presence of hydrogen or carbon monoxide was carried out over a temperature range of 500 -900°C. The reaction could be analyzed by assuming first order with respect to nitric oxide. The predominant mechanisms are the catalytic reduction of nitric oxide by hydrogen or carbon monoxide over char surface. The rate obtained under a = 4W7 was approximately equal to the rate of noncatalytic reduction of... 

Under diesel conditions, carbon monoxide and hydrocarbon oxidation is favoured. Under the highly oxidising conditions encountered in the diesel gas stream, reduction of nitric oxide is not expected. A nitric oxide conversion window is observed at temperatures between 493 and 623 with a T50 value of 523 K. However, large NO absorption bands are observed at temperatures above and below the conversion window.28... 

Yamanaka and co-workers (364-366) have crystallized a cytochrome oxidase from P. aeruginosa which oxidizes Pseudomonas ferrocytochrome c-551. It is also capable of nitrite reduction with a turnover number of 4000 moles nitrite reduced under anaerobic conditions to nitric oxide per minute at 37°. It is an adaptive enzyme, nitrate being essential for its biosynthesis. The enzyme has a molecular weight of 120,000, with two subunits of equivalent molecular weight, 2 heme c and 2 heme d groups per mole (Fig. 38) (366a). Nitrite reductase activity is 94% inhibited by 8 X 10 M KCN, but only by CO. The lack of CO inhibition appears to be related to the fact that the enzyme has a greater affinity for nitrite than for carbon monoxide. 

Inhibitors. Carbon monoxide is a potent inhibitor of all N2ase-cata-lyzed reductions with the exception of H2 evolution (32,64, 65). Inhibitor constants (Ki) of about 4 X lO W have been reported 48, 49, 50, 71) however, the type of inhibition is in dispute and may not be totally competitive (72, 73). Nitric oxide is also reported to be a competitive inhibitor of N2ase-catalyzed reductions with a Ki similar to CO (71). The various substrates are mutual inhibitors of each other. H2 is a competitive inhibitor of only No reduction (68, 72, 73, 74) with a Ki of about 1 X 10" mM (47,48,49,50,66,71). 

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