Kinetics of the Decomposition of Nitric Oxide in the Range 700–1800°

Yuan, Edward L.; Slaughter, J.; Koerner, William B.; Daniels, Farrington

doi:10.1021/j150576a042

Cited by 39 publications

(9 citation statements)

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“…However, HNO 3 was detected instead of H 2 O. The generated H 2 O may react with NO 2 derived from a decomposition reaction of NO under high temperature, 58 yielding HNO 3 . Furthermore, atomic dispersion of bulk Pd in CHA zeolites was theoretically studied.…”

Section: Resultsmentioning

confidence: 96%

Transformation of Bulk Pd to Pd Cations in Small-Pore CHA Zeolites Facilitated by NO

Yasumura

Ide

Ueda

et al. 2021

JACS Au

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Atomic dispersion of metal species has attracted attention as a unique phenomenon that affects adsorption properties and catalytic activities and that can be used to design so-called single atom materials. In this work, we describe atomic dispersion of bulk Pd into small pores of CHA zeolites. Under 4% NO flow at 600°C, bulk Pd metal on the outside of CHA zeolites effectively disperses, affording Pd 2+ cations on Al sites with concomitant formation of N 2 O, as revealed by microscopic and spectroscopic characterizations combined with mass spectroscopy. In the present method, even commercially available submicrosized Pd black can be used as a Pd source, and importantly, 4.1 wt % of atomic Pd 2+ cations, which is the highest loading amount reported so far, can be introduced into CHA zeolites. The structural evolution of bulk Pd metal is also investigated by in situ X-ray absorption spectroscopy (XAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), as well as ab initio thermodynamic analysis using density functional theory (DFT) calculations.

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Section: Resultsmentioning

confidence: 96%

Transformation of Bulk Pd to Pd Cations in Small-Pore CHA Zeolites Facilitated by NO

Yasumura

Ide

Ueda

et al. 2021

JACS Au

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“…The rate coefficients for the reaction 19) and 21) are determined from the backward rates given in Refs. [37][38][39], respectively, by use of the equilibrium constant for the corresponding reaction.…”

Section: Flowfield Calculationmentioning

confidence: 99%

Prediction of Forebody and Aftbody Heat Transfer Rate for Mars Aerocapture Demonstrator

Fujita

Matsuyama

Suzuki

2012

43rd AIAA Thermophysics Conference

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Forebody and aftbody heat transfer rates of a small-sized Martian aerocapture demonstrator are assessed for the preliminary design study of an aeroshell equipped with lightweight thermal protection system. Flowfields around the vehicle in hypersonic lifting flight are computed in a three-dimensional manner for representative flight conditions along the aerocapture trajectory. Finite rate chemistry and thermal relaxation for the Martian atmosphere are taken into consideration. Radiative heat transfer rates are calculated as well for both forebody and aftbody, taking into account not only electronic transitions producing vacuum ultra violet to visible radiation but also molecular ro-vibrational transitions generating infra-red radiation. The results indicate that the radiative heat transfer can be comparative to the convective heat transfer in a certain part of the aftbody aeroshell, though its absolute magnitude is much less intense than that of the forebody aeroshell. NomenclatureC A , C N Axial and normal coefficient, respectively C D , C L Drag and lift coefficient, respectively C m Pitching moment coefficient h Altitude, km K n Knudsen number L/D Lift-to-drag ratio n Number density, m −3 p Pressure, Pa q Heat transfer rate, W/m 2 R n Radius of local curvature at stagnation point, m R s Radius of local curvature at shoulder, m T Atmospheric gas temperature, or translational-rotational temperature, K T v Vibrational-electronic temperature, K t Time from atmospheric entry interface point, s V a Velocity relative to the ground, m/s V inf Velocity of approach at infinity, m/s X,Y ,Z Cartesian coordinates, m α Angle of attack, deg. ΔV Velocity increment required for periapsis raise maneuver, m/s Subscript c, r Convective and radiative heat transfer rate, respectively

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“…Even though NO is a free radical, and under normal conditions it is thermodynamically unstable with respect to oxygen and nitrogen (DHZC90 kJ mol K1 ), under practical conditions dissociation does not happen 2 (Yuan et al 1959), and it can only be converted to nitrogen via a reductive process. The first approach for controlling NO x from car engines was to reduce it over a platinum/rhodium catalyst in the rich reducing exhaust gas before air was added to permit oxidation of the reducing HC and CO species over an oxidation catalyst (Acres & Cooper 1973).…”

Section: (C) Early No X Control Systemsmentioning

confidence: 99%

Controlling automotive exhaust emissions: successes and underlying science

Twigg

2005

Phil. Trans. R. Soc. A.

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Photochemical reactions of vehicle exhaust pollutants were responsible for photochemical smog in many cities during the 1960s and 1970s. Engine improvements helped, but additional measures were needed to achieve legislated emissions levels. First oxidation catalysts lowered hydrocarbon and carbon monoxide, and later nitrogen oxides were reduced to nitrogen in a two-stage process. By the 1980s, exhaust gas could be kept stoichiometric and hydrocarbons, carbon monoxide and nitrogen oxides were simultaneously converted over a single 'three-way catalyst'. Today, advanced three-way catalyst systems emissions are exceptionally low. NOx control from lean-burn engines demands an additional approach because NO cannot be dissociated under lean conditions. Current lean-burn gasoline engine NOx control involves forming a nitrate phase and periodically enriching the exhaust to reduce it to nitrogen, and this is being modified for use on diesel engines. Selective catalytic reduction with ammonia is an alternative that can be very efficient, but it requires ammonia or a compound from which it can be obtained. Diesel engines produce particulate matter, and, because of health concerns, filtration processes are being introduced to control these emissions. On heavy duty diesel engines the exhaust gas temperature is high enough for NO in the exhaust to be oxidised over a catalyst to NO2 that smoothly oxidises particulate material (PM) in the filter. Passenger cars operate at lower temperatures, and it is necessary to periodically burn the PM in air at high temperatures.

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Kinetics of the Decomposition of Nitric Oxide in the Range 700–1800°

Cited by 39 publications

References 0 publications

Transformation of Bulk Pd to Pd Cations in Small-Pore CHA Zeolites Facilitated by NO

Transformation of Bulk Pd to Pd Cations in Small-Pore CHA Zeolites Facilitated by NO

Prediction of Forebody and Aftbody Heat Transfer Rate for Mars Aerocapture Demonstrator

Controlling automotive exhaust emissions: successes and underlying science

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