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NOx
About: NOx is a research topic. Over the lifetime, 26367 publications have been published within this topic receiving 496555 citations.
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TL;DR: A series of FTIR spectroscopic and kinetic studies of the selective catalytic reduction (SCR) of nitric oxide by ammonia were conducted on Fe3+-exchanged TiO2-pillared clay (Fe-TiO2)-PILC) catalyst.
124 citations
Patent•
11 Feb 2004TL;DR: In this article, a NOx abatement system comprising a first NOx adsorber (18) capable of being disposed in-line and downstream of and in fluid communication with an engine was presented.
Abstract: A NOx abatement system comprising: a first NOx adsorber (18) capable of being disposed in-line and downstream of and in fluid communication with an engine (12); a selective catalytic reduction catalyst (20) disposed in-line and downstream of and in direct fluid communication with the first NOx adsorber (18), wherein the selective catalytic reduction catalyst (20) is capable of storing ammonia; and an off-line reformer (24) disposed in selective communication with and upstream of the first NOx adsorber (18) and the selective catalytic reduction catalyst (20), wherein the reformer (24) is capable of producing a reformate comprising primarily hydrogen and carbon monoxide.
124 citations
TL;DR: In this article, a water-containing ABE (acetone-butanol-ethanol) solution was tested as a biodiesel-diesel blend additive to lower NOx emissions from diesel engines.
124 citations
TL;DR: In this article, the intensity and spatial extent of the weekend ozone effect are correlated with day-of-week variations in the extent of ozone inhibition caused by titration with nitric oxide (NO), reaction of hydroxyl radical (OH) with nitrogen dioxide (NO2), and rates of O3 accumulation.
Abstract: Since the mid-1970s, ozone (O3) levels in portions of California's South Coast Air Basin (SoCAB) on weekends have been as high as or higher than levels on weekdays, even though emissions of O3 precursors are lower on weekends. Analysis of the ambient data indicates that the intensity and spatial extent of the weekend O3 effect are correlated with-day-of-week variations in the extent of O3 inhibition caused by titration with nitric oxide (NO), reaction of hydroxyl radical (OH) with nitrogen dioxide (NO2), and rates of O3 accumulation. Lower NO mixing ratios and higher NO2/oxides of nitrogen (NOx) ratios on weekend mornings allow O3 to begin accumulating approximately an hour earlier on weekends. The weekday/weekend differences in the duration of O3 accumulation remained relatively constant from 1981 to 2000. In contrast, the rate of O3 accumulation decreased by one-third to one-half over the same period; the largest reductions occurred in the central basin on weekdays. Trends in mixing ratios of O3 precursors show a transition to lower volatile organic compound (VOC)/NOx ratios caused by greater reductions in VOC emissions. Reductions in VOC/NOx ratios were greater on weekdays, resulting in higher VOC/NOx ratios on weekends relative to weekdays. Trends in VOC/NOx ratios parallel the downward trend in peak O3 levels, a shift in the location of peak O3 from the central to the eastern portion of the basin, and an increase in the magnitude and spatial extent of the weekend O3 effect.
123 citations
TL;DR: In this paper, the authors used a two-dimensional cloud model that includes a parameterized source of lightning-generated NOx to study the production and advection of NOx associated with a developing northeast Colorado thunderstorm observed on July 12, 1996, during the Stratosphere-Troposphere Experiment-Radiation, Aerosols, Ozone (STERAO-A) field campaign.
Abstract: Understanding lightning NOx (NO 1 NO2) production on the cloud scale is key for developing better parameterizations of lightning NOx for use in regional and global chemical transport models. This paper attempts to further the understanding of lightning NOx production on the cloud scale using a cloud model simulation of an observed thunderstorm. Objectives are (1) to infer from the model simulations and in situ measurements the relative production rates of NOx by cloud-to-ground (CG) and intracloud (IC) lightning for the storm; (2) to assess the relative contributions in the storm anvil of convective transport of NOx from the boundary layer and NOx production by lightning; and (3) to simulate the effects of the lightning-generated NOx on subsequent photochemical ozone production. We use a two-dimensional cloud model that includes a parameterized source of lightning-generated NOx to study the production and advection of NOx associated with a developing northeast Colorado thunderstorm observed on July 12, 1996, during the Stratosphere-Troposphere Experiment—Radiation, Aerosols, Ozone (STERAO-A) field campaign. Model results are compared with the sum of NO measurements taken by aircraft and photostationary state estimates of NO2 in and around the anvil of the thunderstorm. The results show that IC lightning was the dominant source of NOx in this thunderstorm. We estimate from our simulations that the NOx production per CG flash (PCG) was of the order of 200 to 500 mol flash 21 .N O x production per IC flash (PIC) appeared to be half or more of that for a CG flash, a higher ratio of P IC/PCG than is commonly assumed. The results also indicate that the majority of NOx (greater than 80%) in the anvil region of this storm resulted from lightning as opposed to transport from the boundary layer. The effect of the lightning NOx on subsequent photochemical ozone production was assessed using a column chemical model initialized with values of NOx ,O 3, and hydrocarbons taken from a horizontally averaged vertical profile through the anvil of the simulated storm. The lightning NOx increased simulated ozone production rates by a maximum of over 7 ppbv d 21 in the upper troposphere downwind of this storm.
123 citations