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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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Journal ArticleDOI
TL;DR: In this article, the initial hydrocarbon reactivity in petrochemical source plumes in the Houston, TX, metropolitan area is primarily due to routine emissions of the alkenes propene and ethene.
Abstract: [1] Petrochemical industrial facilities can emit large amounts of highly reactive hydrocarbons and NOx to the atmosphere; in the summertime, such colocated emissions are shown to consistently result in rapid and efficient ozone (O3) formation downwind. Airborne measurements show initial hydrocarbon reactivity in petrochemical source plumes in the Houston, TX, metropolitan area is primarily due to routine emissions of the alkenes propene and ethene. Reported emissions of these highly reactive compounds are substantially lower than emissions inferred from measurements in the plumes from these sources. Net O3 formation rates and yields per NOx molecule oxidized in these petrochemical industrial source plumes are substantially higher than rates and yields observed in urban or rural power plant plumes. These observations suggest that reductions in reactive alkene emissions from petrochemical industrial sources are required to effectively address the most extreme O3 exceedences in the Houston metropolitan area.

300 citations

Journal ArticleDOI
TL;DR: In this paper, a review describes several methods for removing NO by photocatalytic reactions, which can be classified into three major groups: photo selective catalytic reduction (photo-SCR), photo-oxidation and photo decomposition.
Abstract: The photocatalytic methods for nitrogen oxides removal were recently very intense areas of scientific research. Photo-deNOx processes offer interesting ways for abatement of these harmful gases. This review describes several methods for removing NO by photocatalytic reactions. These methods can be classified into three major groups: photo selective catalytic reduction (photo-SCR), photo-oxidation and photo-decomposition. The application of photocatalysts and photo-processes for NOx abatement in real-scale cases are presented. The fast-growing development of these methods is revealed by the large number of issued patents in photo-deNOx applications. The mechanism of NO creation and the traditional methods (primary and secondary) of NOx removal are summarized and discussed. A cooperative system that combines the traditional (thermal) process and a photo-process is then proposed for improving NOx removal efficiency.

297 citations

Journal ArticleDOI
TL;DR: In this paper, the first systematic study of aerosol formation from the atmospheric reactions of amines is presented, based on laboratory chamber experiments and theoretical calculations, and the authors evaluate the formation from reaction of OH, ozone, and nitric acid with trimethylamine.
Abstract: Although aliphatic amines have been detected in both urban and rural atmospheric aerosols, little is known about the chemistry leading to particle formation or the potential aerosol yields from reactions of gas-phase amines. We present here the first systematic study of aerosol formation from the atmospheric reactions of amines. Based on laboratory chamber experiments and theoretical calculations, we evaluate aerosol formation from reaction of OH, ozone, and nitric acid with trimethylamine, methylamine, triethylamine, diethylamine, ethylamine, and ethanolamine. Entropies of formation for alkylammonium nitrate salts are estimated by molecular dynamics calculations enabling us to estimate equilibrium constants for the reactions of amines with nitric acid. Though subject to significant uncertainty, the calculated dissociation equilibrium constant for diethylammonium nitrate is found to be sufficiently small to allow for its atmospheric formation, even in the presence of ammonia which competes for available nitric acid. Experimental chamber studies indicate that the dissociation equilibrium constant for triethylammonium nitrate is of the same order of magnitude as that for ammonium nitrate. All amines studied form aerosol when photooxidized in the presence of NOx with the majority of the aerosol mass present at the peak of aerosol growth consisting of aminium (R3NH+) nitrate salts, which repartition back to the gas phase as the parent amine is consumed. Only the two tertiary amines studied, trimethylamine and triethylamine, are found to form significant non-salt organic aerosol when oxidized by OH or ozone; calculated organic mass yields for the experiments conducted are similar for ozonolysis (15% and 5% respectively) and photooxidation (23% and 8% respectively). The non-salt organic aerosol formed appears to be more stable than the nitrate salts and does not quickly repartition back to the gas phase.

297 citations

Journal ArticleDOI
TL;DR: A series of iron titanate catalysts with different Fe−Ti molar ratios were synthesized via a facile coprecipitation method and tested for the selective catalytic reduction (SCR) of NOx in this article.
Abstract: A series of iron titanate catalysts, FeaTibOx, with different Fe−Ti molar ratios are synthesized via a facile coprecipitation method and tested for the selective catalytic reduction (SCR) of NOx wi...

297 citations

Journal ArticleDOI
TL;DR: A series of W-doped CeO2/TiO2 catalysts prepared by different impregnation methods assisted with ultrasonic energy were investigated for the selective catalytic reduction (SCR) of NOx (NO and NO2) by NH3 as mentioned in this paper.

297 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20241
20231,699
20223,249
20211,405
20201,353
20191,367