Gas-Phase Oxidation of Nitric Oxide: Chemical Kinetics and Rate Constant

Tsukahara, Hirokazu; Ishida, Takanobu; Mayumi, Mitsufumi

doi:10.1006/niox.1999.0232

Cited by 151 publications

(116 citation statements)

References 44 publications

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“…The kinetics of this reaction is well known from atmospheric chemistry. 86 Using a third order rate law r = k c 2 NO c O 2 and the rate constant k (in L mol −2 s −2 ) given by k = 1.2 · 10 3 e 530/T , (T is the temperature in K), 86 it is calculated that it takes only a few seconds to produce 2-20 ppb NO 2 in a mixture of 500 ppm NO and 10% oxygen at 200 • C. This means that, in practice, a mixture of NO and O 2 contains an amount of NO 2 that is higher than the estimated equilibrium concentration, and hence, the equilibrium is usually shifted towards the nitrates in the presence of NO and O 2 . It is noted that the gas phase oxidation of NO to NO 2 is several orders of magnitude slower than the catalytic SCR reaction, which is capable of converting a few hundred ppm of NO 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 in milliseconds.…”

Section: A More Detailed Analysis Of the Xas And Ftir Data In Figuresmentioning

confidence: 99%

A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia

et al. 2015

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For the first time, the standard and fast selective catalytic reduction (SCR) of NO by NH3 are described in a complete catalytic cycle that is able to produce the correct stoichiometry while allowing adsorption and desorption of stable molecules only. The standard SCR reaction is a coupling of the activation of NO by O2 with the fast SCR reaction, enabled by the release of NO2. According to the scheme, the SCR reaction can be divided into an oxidation of the catalyst by NO + O2 and a reduction by NO + NH3; these steps together constitute a complete catalytic cycle. Furthermore, both NO and NH3 are required in the reduction, and finally, oxidation by NO + O2 or NO2 leads to the same state of the catalyst. These points are shown experimentally for a Cu-CHA catalyst by combining in situ X-ray absorption spectroscopy (XAS), electron paramagnetic resonance (EPR), and Fourier transform infrared spectroscopy (FTIR). A consequence of the reaction scheme is that all intermediates in fast SCR are also part of the standard SCR cycle. The activation energy calculated by density functional theory (DFT) indicates that the oxidation of an NO molecule by O2 to a bidentate nitrate ligand is rate-determining for standard SCR. Finally, the role of a nitrate/nitrite equilibrium and the possible influence of Cu dimers and Brønsted sites are discussed, and an explanation is offered as to how a catalyst can be effective for SCR while being a poor catalyst for NO oxidation to NO2.

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Section: A More Detailed Analysis Of the Xas And Ftir Data In Figuresmentioning

confidence: 99%

A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia

et al. 2015

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“…Both NO and H 2 S are oxidized by oxygen (Eqs. 2, 4, 5, and 6) (38,44,73,119). This becomes more impactful when concentrations of NO, H 2 S, and O 2 are high, as may be the case during inhalation and in hydrophobic cellular compartments.…”

Section: H 2 S Therapeutics For Airway and Pulmonary Vascular Diseasesmentioning

confidence: 99%

Working with nitric oxide and hydrogen sulfide in biological systems

Yuan

Patel

Kevil

2015

American Journal of Physiology-Lung Cellular and Molecular Phys

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(H 2S) are gasotransmitter molecules important in numerous physiological and pathological processes. Although these molecules were first known as environmental toxicants, it is now evident that that they are intricately involved in diverse cellular functions with impact on numerous physiological and pathogenic processes. NO and H 2S share some common characteristics but also have unique chemical properties that suggest potential complementary interactions between the two in affecting cellular biochemistry and metabolism. Central among these is the interactions between NO, H 2S, and thiols that constitute new ways to regulate protein function, signaling, and cellular responses. In this review, we discuss fundamental biochemical principals, molecular functions, measurement methods, and the pathophysiological relevance of NO and H 2S. thiol; oxidation; redox; pulmonary; cardiovascular HISTORICALLY CONSIDERED ONLY as industrial pollutants, nitric oxide (NO) and hydrogen sulfide (H 2 S) are now appreciated as two key physiologically produced signaling molecules that control multiple cellular functions. Appreciation that dysfunction in how these solvated gases affect these functions, through either deficient formation or downstream reactivity, has opened up new therapeutic avenues for a host of diseases in all major organ systems including the lung. Our understanding of NO homeostasis mechanisms are relatively advanced compared with H 2 S, primarily because of the latter's discovery as a biologically relevant entity being postdated by a decade or more compared with NO. Although they are chemically distinct, there are intriguing parallel mechanisms/concepts in NO and H 2 S biology that include overlapping functions, technical challenges in how each of these gases are measured in biological milieu, appreciation of the mechanisms and factors that modulate how metabolism of each of these is regulated, and therapeutic potential for either inhibiting or repleting NO or H 2 S. In this article, and within the framework outlined above, we provide a general overview of NO and H 2 S biology. Nitric Oxide Formation: Enzymatic and Nonenzymatic SourcesEnzymatic sources. Nitric oxide is synthesized by one of three different isoforms of nitric oxide synthase (NOS) that differ in enzymatic activity, in how they are regulated (transcriptional, translational, and posttranslational mechanisms), and in how they are expressed/compartmentalized in tissues as well as the subcellular level. These are called NOS I, II, and III, corresponding to the inducible (iNOS), neuronal (nNOS), and endothelial (eNOS) isoforms, typically with high, mid, and low activities, respectively. In the systemic and pulmonary vasculature, eNOS plays a key role in controlling blood flow and maintaining an antithrombotic and anti-inflammatory luminal surface. On the other hand, iNOS is induced by inflammatory stimuli in leukocytes, airway epithelial cells, and alveolar macrophages to mediate pathogen killing. However, production of NO at higher concentrations in ...

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“…NO + ½ O 2 = NO 2 (1) has been studied by many authors in the 20 th century, and their results are reviewed in reference [4]. At the high temperatures at which NOx is formed, the equilibrium dictates that mostly NO will be formed.…”

Section: Nox Sox and Hg Removal In Oxyfuel Combustionmentioning

confidence: 99%

“…Air Products has recognized that during the process of compressing oxyfuel flue gas, unexpected conditions within the CO 2 stream are created that result in the complete reaction of SO 2 , catalyzed by NO 2 , to form sulfuric acid [4]. Once most of the SO 2 has reacted, NO 2 will then be converted to nitric acid by the addition of water, resulting in conditions in which all of the SOx and about 90% of the NOx can be removed from the flue gas.…”

Section: Introductionmentioning

confidence: 99%

Flue Gas Perification Utilizing SOx/NOx Reactions During Compression of CO2 Derived from Oxyfuel Combustion

Fogash¹

2010

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Gas-Phase Oxidation of Nitric Oxide: Chemical Kinetics and Rate Constant

Cited by 151 publications

References 44 publications

A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia

A Consistent Reaction Scheme for the Selective Catalytic Reduction of Nitrogen Oxides with Ammonia

Working with nitric oxide and hydrogen sulfide in biological systems

Flue Gas Perification Utilizing SOx/NOx Reactions During Compression of CO2 Derived from Oxyfuel Combustion

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