NOx

About: NOx is a research topic. Over the lifetime, 26367 publications have been published within this topic receiving 496555 citations.

Inductive Effect Boosting Catalytic Performance of Advanced Fe1–xVxOδ Catalysts in Low-Temperature NH3 Selective Catalytic Reduction: Insight into the Structure, Interaction, and Mechanisms

Abstract: A series of vanadium doped Fe2O3 catalysts were synthesized using the homogeneous precipitation method and subjected to laboratory evaluation for selective catalytic reduction of NOx with NH3 (NH3-SCR). The best Fe0.75V0.25Oδ catalyst with a Fe/V mole ratio of 3/1 exhibited superior catalytic performance, achieving 100% NOx conversion at 200 °C over a wide temperature window from 175 to 400 °C, believed to be the best Fe-based low-temperature NH3-SCR catalyst identified to date. The Fe0.75V0.25Oδ catalyst also showed prominent resistance to high gas hourly space velocity (GHSV; 200 000 h–1) and strong durability to SO2 and H2O. Doping of V was shown to remarkably boost the catalytic activity, due to enhancement of the redox ability and surface acidity. XRD, Raman, and morphology results revealed that the incorporation of V had led to the formation of amorphous FeVO4 and Fe2O3. Coupling XPS and UV–vis diffuse reflectance spectra (DRS) results with DFT, it was discovered that the electron inductive effect b...

Thermally regenerable nitric oxide adsorbent

Abstract: A method of reducing nitrogen oxides (NOx) present in a lean gas stream comprising nitric oxide (NO) comprises the steps of: (i) net adsorbing NO per se from the lean gas stream in an adsorbent comprising palladium and a cerium oxide at below 200°C; (ii) thermally net desorbing NO from the NO adsorbent in a lean gas stream at 2000C and above; and (iii) catalytically reducing NOx on a catalyst other than the NO adsorbent with a reductant selected from the group consisting of a hydrocarbon reductant, a nitrogenous reductant, hydrogen and a mixture of any two or more thereof. A system for carrying out such a method is also disclosed.

Photocatalytic abatement of NOx pollutants in the air using commercial functional coating with porous morphology

Abstract: Titanium dioxide is the most important photocatalyst used for purifying applications. The purpose of this study was to investigate the photocatalytic activity of the commercial product Protectam FN2, containing Evonik P25 titanium dioxide nanopowder, with regard to NO and NO2 abatement. Photocatalytic experiments on the photocatalytic coatings on concrete and plaster substrates were carried out in two types of flow reactors, namely one with laminar flow and another with ideally-mixed flow, under “real world conditions” of temperature, relative humidity, irradiation intensity and pollutant concentrations. The results showed that the photocatalytic process significantly reduced the concentration of both nitrogen oxides in the air. The reaction rate, i.e., the decrease in the concentration of NOx achieved in the steady-state for the inlet concentration of NO and NO2 of 0.1 ppmv, which corresponds to highly polluted urban air, was up to 75 and 50 μmol m−2 h−1, respectively, at the flow rate of 3000 cm3 min−1 and relative humidity of 50%. Further, even two years after their application to the surface of concrete walls along a busy thoroughfare, the photocatalytic coating maintained high effectivity.

The effect of swirl burner aerodynamics on NOx formation

Abstract: The problem of pollutant formation in swirling gas flames is a subject of current research at Cardiff University. This paper concentrates on the influence of the levels of swirl on the aerodynamics and NOx emissions at a constant load. Measurements of mean temperature, local velocity and NO−NOx concentrations were taken for swirl numbers from .63 to 3.04. From these a net NOx flow through sections of the flame were calculated. The flames have been classified into 4 broad groups dependent on the influence of the recirculation zone on flame stabilization. These changes in flame type coincide with other changes in the flow structure, as can be seen from the effects on the precessing vortex core. A model based on well stirred and plug flow reactors is proposed for the flows. The results highlight errors in interpretation that can occur by only considering the concentration measurements. In order to establish the source of pollutants in a swirl combustor, it is essential to consider the pollutant mass flow profiles. The formation of NOx in these flows occur in the flame front. The recirculation zone, despite its long residence times and moderate temperatures, does not contribute to NOx formation.