Nitrogen oxide reactions with metal

With the advance of three-way catalysis for pollution control, used mainly in automobile catalytic conversion but also for the purification of gas exhausts from stationary sources, a need has arisen to develop a basic understanding of the reactions associated with the reduction of nitrogen oxides on transition metal catalytic surfaces [1,2]. That conversion is typically carried out by using rhodium-based catalysts [3], which makes the process quite expensive. Consequently, extensive effort has been placed on trying to minimize the amount of the metal needed and/or to replace it with an alternatively cheaper and more durable active phase. However, there is still ample room for improvement in this direction. By building a molecular-level picture of theprocesses involved,... 

Numerous quantum mechanic calculations have been carried out to better understand the bonding of nitrogen oxide on transition metal surfaces. For instance, the group of Sautet et al have reported a comparative density-functional theory (DFT) study of the chemisorption and dissociation of NO molecules on the close-packed (111), the more open (100), and the stepped (511) surfaces of palladium and rhodium to estimate both energetics and kinetics of the reaction pathways [75], The structure sensitivity of the adsorption was found to correlate well with catalytic activity, as estimated from the calculated dissociation rate constants at 300 K. The latter were found to agree with numerous experimental observations, with (111) facets rather inactive towards NO dissociation and stepped surfaces far more active, and to follow the sequence Rh(100) > terraces in Rh(511) > steps in Rh(511) > steps in Pd(511) > Rh(lll) > Pd(100) > terraces in Pd (511) > Pd (111). The effect of the steps on activity was found to be clearly favorable on the Pd(511) surface but unfavorable on the Rh(511) surface, perhaps explaining the difference in activity between the two metals. The influence of... 

Synonyms nitrogen peroxide Formula N02 MW 46.01 CAS [10102-44-0] occurs in the exhausts of automobiles and in cigarette smoke produced by the reaction of nitric acid with metals and decomposition of nitrates or during fire reddish-brown fuming liquid or gas sharp pungent odor liquefies at 21°C solidifies at -9.3°C density of liquid 1.45 at 20°C vapor 1.58 (air= 1) reacts with water to form nitric acid and nitrogen oxide reacts with alkalies to form nitrates and nitrites highly toxic. 

MERCURY CYANIDE or MERCURY(II) CYANIDE (592-04-1) Hg(CN)2 Slowly decomposes in light. A moderate impact- and heat-sensitive explosive. Violent reaction with metal chlorates, fluorine, hydrogen cyanide, magnesium, nitrates, nitrites, metal perchlorates, sodium nitrite. Contact with strong acids evolves flammable and poisonous hydrogen cyanide gas, which can be detonated by this material. Thermal decomposition releases toxic nitrogen oxides, mercury, and hydrogen cyanide. On... 

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