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.

Method and apparatus for producing ammonia (NH3)

Abstract: A method is provided for producing ammonia (NH 3 ) and introducing the produced ammonia (NH 3 ) into an exhaust gas stream as a reduction means for selectively catalytically reducing nitrogen oxides contained in the exhaust gas stream, which is an exhaust stream generated by the combustion process of a motor, a gas turbine, or a burner. The method comprises feeding dry urea from a supply container in a controlled amount to reactor and subjecting the dry urea in the reactor to a sufficiently rapid thermal treatment such that a gas mixture comprising the reaction products of ammonia (NH 3 ) and isocyanic acid (HCNO) is created. Also, the method comprises immediately catalytically treating the thus produced gas mixture in the presence of water such that the isocyanic acid (HCNO) resulting from the rapid thermal treatment is converted, via quantitative hydrolysis treatment, into ammonia (NH 3 ) and carbon dioxide (CO 2 ).

Nitrogen Fixation with Water on Carbon-Nitride-Based Metal-Free Photocatalysts with 0.1% Solar-to-Ammonia Energy Conversion Efficiency

Abstract: Ammonia (NH3), which is an indispensable chemical, is produced by the Haber–Bosch process using H2 and N2 under severe reaction conditions. Although photocatalytic N2 fixation with water under ambient conditions is ideal, all previously reported catalysts show low efficiency. Here, we report that a metal-free organic semiconductor could provide a new basis for photocatalytic N2 fixation. We show that phosphorus-doped carbon nitride containing surface nitrogen vacancies (PCN-V), prepared by simple thermal condensation of the precursors under H2, produces NH3 from N2 with water under visible light irradiation. The doped P atoms promote water oxidation by the photoformed valence-band holes, and the N vacancies promote N2 reduction by the conduction-band electrons. These phenomena facilitate efficient N2 fixation with a solar-to-chemical conversion (SCC) efficiency of 0.1%, which is comparable to the average solar-to-biomass conversion efficiency of natural photosynthesis by typical plants. Thus, this metal-f...

Ammonia Assimilation in the Roots of Nitrate- and Ammonia-Grown Hordeum Vulgare (cv Golden Promise).

Abstract: 15N kinetic labeling studies were performed on seedlings of Hordeum vulgare L. var. Golden Promise growing under steady state conditions. Patterns of label incorporation in the pools of nitrogen compounds of roots fed [15N]ammonium were compared with computer-simulated labeling curves. The data were found to be quantitatively consistent with a three-compartment model in which ammonium is assimilated solely into the amide-N of glutamine. Labeling data from roots fed [15N]nitrate were also found to be at least qualitatively consistent with the assimilation of ammonia into glutamine. Methionine sulfoximine almost completely blocked the incorporation of 15N label into the amino acid pools of barley roots fed [15N]nitrate. These observations suggest that ammonia assimilation occurs solely via the glutamine synthetase/glutamate synthase pathway in both nitrate- and ammonia-grown barley roots.

Volatilization of ammonia from urea applied to soil: Influence of hippuric acid and other constituents of livestock urine

Abstract: Ammonia volatilization from five nitrogenous constituents of urine, assessed over 8 days following their application to columns of soil, and expressed as a proportion of the N applied, decreased in the order: urea, allantoin, creatinine, creatine, hippuric acid. However, hippuric acid, when mixed with urea in solution at a concentration such that hippuric acid-N = 2.5% of urea-N, substantially increased the volatilization of ammonia from the urea, particularly during the first 2 days after application to soil. The presence of the hippuric acid also enhanced the increase in soil pH, measured 24 h after application of the solution, in comparison with urea alone. A concentration of hippuric acid twice that indicated above appeared to exceed the optimum for increasing volatilization. The other constituents of urine listed above had little if any effect on the volatilization of ammonia from urea. Volatilization was greatly influenced by the concentration of total N in solutions of urea plus hippuric acid: the proportion of the N that was volatilized increased with increasing concentration over the range 1–10 g N 1 −1 but declined at the highest concentration examined, 15gNl −1 . With urea (10 gNl −1 ) plus hippuric acid (0.23gNl −1 ), the pH of the solution over the range 5.0–9.0 had no appreciable effect on the extent of volatilization, or on the pH of a soil-solution mixture measured 24 h after the addition. Salt concentration in the solution, examined as potassium chloride and potassium acetate, also had little, if any, effect. A solution containing urea (10 g Nl −1 ) plus hippuric acid (0.25 g Nl −1 ) and adjusted to pH 8 was much closer to cattle urine in the extent and pattern of ammonia volatilization over 8 days than was urea alone.