Ammonia

About: Ammonia is a research topic. Over the lifetime, 16217 publications have been published within this topic receiving 271940 citations. The topic is also known as: NH3 & azane.

Production of nitrous oxide by ammonia-oxidizing chemoautotrophic microorganisms in soil.

Abstract: Gas chromatographic studies showed that nitrous oxide was produced in each instance when sterilized (autoclaved) soil was incubated after treatment with ammonium sulfate and inoculation with pure cultures of ammonia-oxidizing chemoautotrophic microorganisms (strains of Nitrosomonas, Nitrosospira, and Nitrosolobus). Production of N(2)O in ammonium-treated sterilized soil inoculated with Nitrosomonas europaea increased with the concentration of ammonium and the moisture content of the soil and was completely inhibited by both nitrapyrin and acetylene. Similar effects of nitrapyrin, acetylene, ammonium concentration, and soil moisture content were observed in studies of factors affecting N(2)O production in nonsterile soil treated with ammonium sulfate. These observations support the conclusion that, at least under some conditions, most of the N(2)O evolved from soils treated with ammonium or ammonium-producing fertilizers is generated by chemoautotrophic nitrifying microorganisms during oxidation of ammonium to nitrite.

Sulfuric acid nucleation: An experimental study of the effect of seven bases

Abstract: Nucleation of particles with sulfuric acid, water, and nitrogeneous bases was studied in a flow reactor. Sulfuric acid and water levels were set by flows over sulfuric acid and water reservoirs, respectively, and the base concentrations were determined from measured permeation rates and flow dilution ratios. Particle number distributions were measured with a nano-differential-mobility-analyzer system. Results indicate that the nucleation capability of NH3, methylamine, dimethylamine, and trimethylamine with sulfuric acid increases from NH3 as the weakest, methylamine next, and dimethylamine and trimethylamine the strongest. Three other bases were studied, and experiments with triethylamine showed that it is less effective than methylamine, and experiments with urea and acetamide showed that their capabilities are much lower than the amines with acetamide having basically no effect. When both NH3 and an amine were present, nucleation was more strongly enhanced than with just the amine present. Comparisons of nucleation rates to predictions and previous experimental work are discussed, and the sulfuric acid-base nucleation rates measured here are extrapolated to atmospheric conditions. The measurements suggest that atmospheric nucleation rates are significantly affected by synergistic interactions between ammonia and amines.

Low temperature selective oxidation of ammonia to nitrogen on silver-based catalysts

Abstract: The low temperature gas phase oxidation of ammonia to nitrogen has been studied over alumina-supported, silica-supported and unsupported silver catalysts. TPD, TPR, TEM, XRD and FT-Raman were used to characterize the different silver catalysts. The results showed alumina-supported silver to be the best catalyst due to the interaction of silver with alumina. Pre-treatment had a great affect on the catalyst performance. Reduction in hydrogen at 200 °C without any pre-calcination gave the best activity. At least four types of oxygen species were observed when silver was present in oxygen at high temperature. These species are adsorbed molecular oxygen, adsorbed atomic oxygen, subsurface oxygen and bulk dissolved oxygen, respectively. Ammonia oxidation activity at low temperature is related to the catalysts ability to dissociative or non-dissociative adsorption of oxygen. In addition, a good correlation existed between the N2 selectivity for selective catalytic oxidation (SCO) reaction and the selective catalytic reduction (SCR) activity of NO with NH3 for the silver-based catalysts, i.e. the higher SCR yield of nitrogen, the higher the SCO selectivity N2.