Rapid reduction of nitrogen oxides in exhaust gas streams

Perry, R. A.; Siebers, Dennis L.

doi:10.1038/324657a0

Cited by 226 publications

(129 citation statements)

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“…The NBO results showed the lone electron pair of O-atom in 3 OH anions interacted with σ * (C-N) of HNCS in 3 IM1 which was used as the precursor complex to accomplish absorption OH -reaction.…”

Section: Ohmentioning

confidence: 99%

“…In the meanwhile, as important intermediates of sulfur-containing fuel combustion process, HNCS and its derived free radical NCS can participate in the process of removal the toxic NO 4 compounds from rapid combustion exhaust gas too. [1][2][3][4][5][6] Due to its important role, the theoretical study on the reaction mechanism of HNCS with small molecules by quantum chemistry calculation also become the focus of the chemical workers' research. [7][8][9][10][11][12][13][14][15][16][17][18][19] Because its oxidation ability is very strong, hydroxide ion (OH -) is one of the key intermediates in the interstellar environment and a large number of combustion reaction, not only represents a very important role that OH -can oxidized volatile organic compounds in the troposphere gas, 20 but also plays an important role in atmospheric chemistry where it is the primary process responsible for removal of the H 2 CO pollutant.…”

Section: Introductionmentioning

confidence: 99%

“…IM2 formed due to the interaction between σ * (N-H) of HNCS with the lone electron pair of O-atom in 3 OH, which leaded to the weakening of N-H bond and the occurring of H1-atom transfer to OH -reaction.…”

mentioning

confidence: 99%

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Theoretical research on the multi-channel reaction mechanism and kinetics of HNCS with OH anions

Hou¹,

Wu²,

Han³

et al. 2017

Quim. Nova

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publicado na web em 15/08/2017We presented a theoretical study on the detailed reaction mechanism and kinetics of the HNCS molecule with the OH -. The barrierless minimum energy path and the most favorable entrance channel have been determined by study the thermodynamic and kinetic characters of the channel with low energy barrier. The B3LYP/6-311++G** method was employed for all the geometrical optimizations and a multi-level extrapolation method based on the G3 energies was employed for further energy refinements. In addition, the analysis of the combining interaction between hydroxide ion and HNCS was performed by natural bond orbitals (NBO) analysis. The calculation results indicated that the reaction of OH -with HNCS had four channels, and the channel of H-atom in HNCS direct extraction to OH -(OH -+HNCS→IM1→TS3→IM4→P2(SCN -+H 2 O)) in singlet state was the main channel with the low potential energy and high equilibrium constant and reaction rate constant. SCN -and H 2 O were main products.Keywords: hydroxide ion; isothiocyanic acid; mechanism; equilibrium constant INTRODUCTIONThe problem of the severe air pollution in developing countries has caused wide public concern over the recent years, heavy power plant smoke and car emissions, mainly in the form of sulfate, organic, nitric acid and particles, have always been a threat to the global public health. In the meanwhile, as important intermediates of sulfur-containing fuel combustion process, HNCS and its derived free radical NCS can participate in the process of removal the toxic NO 4 compounds from rapid combustion exhaust gas too. [1][2][3][4][5][6] Due to its important role, the theoretical study on the reaction mechanism of HNCS with small molecules by quantum chemistry calculation also become the focus of the chemical workers' research. [7][8][9][10][11][12][13][14][15][16][17][18][19] Because its oxidation ability is very strong, hydroxide ion (OH -) is one of the key intermediates in the interstellar environment and a large number of combustion reaction, not only represents a very important role that OH -can oxidized volatile organic compounds in the troposphere gas, 20 but also plays an important role in atmospheric chemistry where it is the primary process responsible for removal of the H 2 CO pollutant.21-25 Molecular anions play an important role in the chemistry of the interstellar medium, of carbon stars , and the Earth' s ionosphere. One such species is the hydroxide ion. Madura and Jorgensen applied ab initio calculation to discuss the addition of hydroxyl anion to the aldehydic carbon atom. 26 Herein, we used the density functional theory (DFT) to explore the reaction mechanism of OH -with HNCS, We hope our work might provide theoretical guidance to control NO x substance-related air pollution effectively. CALCULATION METHODSAll calculations were performed with the Gaussian 03 package. 27 The geometries of reactants, intermediates, transition states and products were optimized at the DFT-B3LYP/6-311++G** level. 28-31The harmonic vibration ...

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Section: Ohmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Theoretical research on the multi-channel reaction mechanism and kinetics of HNCS with OH anions

Hou¹,

Wu²,

Han³

et al. 2017

Quim. Nova

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“…Since that time, researchers have investigated the effectiveness of other reagents, such as urea [Muzio, et al, 1976] and cyanuric acid [Perry and Siebers, 1986] and effects of process parameters such as temperature, residence time, normalized stoichiometric ratio (i.e. chemical N/NOx molar ratio, NSR), equivalence ratio, initial NOx level, and various additives [Zamansky et al, 1999].…”

Section: Sncr Simulation and Validationmentioning

confidence: 99%

Combustion 2000

Levasseur¹,

Goodstine²,

Ruby³

et al. 2001

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. The objective of this report is to emphasize the results and achievements of the program and not to archive every detail of the past six years of effort. These details are already available in the twenty-two quarterly reports previously submitted to DOE and in the final report from Phase I. The report is divided into three major foci, indicative of the three operational groupings of the program as it evolved, was restructured, or overtaken by events. In each of these areas, the results exceeded DOE goals and expectations.HIPPS Systems and Cycles (including thermodynamic cycles, power cycle alternatives, baseline plant costs and new opportunities) HITAF Components and Designs (including design of heat exchangers, materials, ash management and combustor design)Testing Program for Radiative and Convective Air Heaters (including the design and construction of the test furnace and the results of the tests)There are several topics that were part of the original program but whose importance was diminished when the contract was significantly modified. The elimination of the subsystem testing and the Phase III demonstration lessened the relevance of subtasks related to these efforts. For example, the cross flow mixing study, the CFD modeling of the convective air heater and the power island analysis are important to a commercial plant design but not to the R&D product contained in this report. These topics are of course, discussed in the quarterly reports under this contract.The DOE goal for the High Performance Power Plant System ( HIPPS ) is high thermodynamic efficiency and significantly reduced emissions. Specifically, the goal is a 300 MWe plant with > 47% (HHV) overall efficiency and ≤ 0.1 NSPS emissions. This plant must fire at least 65% coal with the balance being made up by a premium fuel such as natural gas.To achieve these objectives requires a change from complete reliance of coal-fired systems on steam turbines (Rankine cycles) and moving forward to a combined cycle utilizing gas turbines (Brayton cycles) which offer the possibility of significantly greater efficiency. This is because gas turbine cycles operate at temperatures well beyond current steam cycles, allowing the working fluid (air) temperature to more closely approach that of the major energy source, the combustion of coal. In fact, a good figure of merit for a HIPPS design is just how much of the enthalpy from coal combustion is used by the gas turbine.The efficiency of a power cycle varies directly with the temperature of the working fluid and for contemporary gas turbines the optimal turbine inlet temperature is in the range of 2300-2500 °F (1260-1371 °C). These temperatures are beyond the working range of currently available alloys and are also in the range of the ash fusion temperature of most coals. These two sets of physical properties combine to produce the major engineering challenges for a HIPPS design. ivThe UTRC team developed a design hierarchy to impose more rigor in our approach. Once the size of the plant had been determined by t...

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“…These processes use agents, including urea (Arand et al, 1980) and cyanuric acid (Perry and Siebers, 1986). These alternative agents decompose to form 3 NH and HNCO under high temperatures and reduce NO to 2 N or O N 2 .…”

Section: Introductionmentioning

confidence: 99%

Improvement on Hybrid SNCR-SCR Process for NO Control: a Bench Scale Experiment

Chen

2006

Aerosol Air Qual. Res.

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The reducing agent [ammonia ( 3 NH )] injection procedure was improved for the hybrid process of selective non-catalytic reduction followed by selective catalytic reduction (hybrid SNCR-SCR) to remove nitric oxide (NO) through a bench-scale experiment. Instead of injecting all of the 3 NH from the SNCR inlet, part of it was injected from the SNCR inlet and part from the SCR inlet, to react with NO in the flue gas. The experiment resulted in the significant reduction of NO. The effects of the operational conditions such as the SNCR reaction temperature, the SCR reaction temperature, and the initial concentration ratio of 3 NH to NO were also investigated. Under the initial NO concentration of 300 ppm (dry, 6% 2 O ), the space velocities of SNCR 5100-6300 1 hr  , the space velocities of SCR 7100-10000 1 hr  , and with the initial concentration ratios of 3 NH to NO 1.0-1.5, the best operational temperatures were discovered to be SNCR reaction of 850℃ and SCR reaction of 350℃ for the improved hybrid SNCR-SCR process. In addition, a correlation equation has been developed of the maximum NO reduction under the above bestoperational temperatures for the hybrid SNCR-SCR process, and closely fits with the experiment results.

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Rapid reduction of nitrogen oxides in exhaust gas streams

Cited by 226 publications

References 4 publications

Theoretical research on the multi-channel reaction mechanism and kinetics of HNCS with OH anions

Theoretical research on the multi-channel reaction mechanism and kinetics of HNCS with OH anions

Combustion 2000

Improvement on Hybrid SNCR-SCR Process for NO Control: a Bench Scale Experiment

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