Ab initio thermal rate coefficients for H + NH3 ⇌ H2 + NH2

Nguyen, Thanh Lam; Stanton, John F.

doi:10.1002/kin.21255

Cited by 22 publications

(9 citation statements)

References 40 publications

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“…333 Finally, Nguyen and Stanton recently applied stateof-the-art HEAT SCTST/VPT2+ level calculations to determine the kinetics of eq 29. 334 The reaction rate coefficients for eq 29 based on the kinetics from the works above are presented in Figure 21, while the kinetic parameters are listed in Table S2. The only pre-1985 work found to be in agreement with modern reaction rate coefficient values is that of Oganesyan and Nalbandyan.…”

Section: Ammonia Chemistrymentioning

confidence: 99%

Progress and Prospective of Nitrogen-Based Alternative Fuels

et al. 2020

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Alternative fuels are essential to enable the transition to a sustainable and environmentally friendly energy supply. Synthetic fuels derived from renewable energies can act as energy storage media, thus mitigating the effects of fossil fuels on environment and health. Their economic viability, environmental impact, and compatibility with current infrastructure and technologies are fuel and power source specific. Nitrogen-based fuels pose one possible synthetic fuel pathway. In this review, we discuss the progress and current research on utilization of nitrogen-based fuels in power applications, covering the complete fuel cycle. We cover the production, distribution, and storage of nitrogen-based fuels. We assess much of the existing literature on the reactions involved in the ammonia to nitrogen atom pathway in nitrogen-based fuel combustion. Furthermore, we discuss nitrogen-based fuel applications ranging from combustion engines to gas turbines, as well as their exploitation by suggested end-uses. Thereby, we evaluate the potential opportunities and challenges of expanding the role of nitrogen-based molecules in the energy sector, outlining their use as energy carriers in relevant fields.

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Section: Ammonia Chemistrymentioning

confidence: 99%

Progress and Prospective of Nitrogen-Based Alternative Fuels

et al. 2020

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“…It can be seen that the rate constants used by Konnov and Mathieu are different from those used in the Zhang and Glarborg mechanisms. The computed rate constants in this work are lower than those used in the Zhang and Glarborg mechanisms at temperatures below 1000 K. Moreover, as the initial major consumption reactions of NH 3 , the abstraction reactions by Ḣ atoms and ȮH radicals were theoretically investigated by Nguyen and Stanton , by combining the high-accuracy extrapolated ab initio thermochemistry protocol with semi-classical transition state theory. The computed results for NH 3 + Ḣ were found to be in good correlation with the experimental results of Michael et al, which were employed in detailed mechanisms.…”

Section: Resultsmentioning

confidence: 99%

“…The calculated and fitted rate constants for NH 3 + ȮH by Nguyen and Stanton slightly deviate from the previous results, but the overall deviations are within 30%. The computed and fitted rate coefficients by Nguyen and Stanton , extend the temperature ranges and are employed in the updated mechanism.…”

Section: Resultsmentioning

confidence: 99%

Comparative Chemical Kinetic Analysis and Skeletal Mechanism Generation for Syngas Combustion with NO_x Chemistry

2019

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Emission of nitrogen oxides (NOx) are one of the major environmental concerns arising from the combustion of syngas. Strategies to reduce emission and improve the efficiency of syngas combustion can be developed using computational fluid dynamic simulations to design cleaner and more efficient combustors. Toward this end, an accurate and efficient chemical kinetic mechanism that can describe the combustion chemistry of syngas with NOx under engine-relevant conditions is critical. In this work, a comprehensive survey of detailed mechanisms available in the literature for syngas/NOx combustion reaction system is first conducted. A systematic and comparative chemical kinetic analysis of five detailed mechanisms is performed based on reaction pathway and sensitivity analyses to identify the key reactions of the nitrogen species for a wide range of mixtures including the formation of NOx during syngas combustion, ignition of NH3, H2/N2O, and H2/NO2 mixtures.Comparisons of the reaction pathways from different detailed mechanisms indicate that the detailed 2 chemistry is controlled by a small set of reactions and species. Recent high-level theoretical studies on HONO and HNO2 chemistry including previously neglected important reactions are updated. The rate constants for HNO + O2 = NO + HȮ2 are calculated using ab initio calculations in this work. An efficient high-fidelity skeletal mechanism consisting of 27 species and 130 reactions is developed based on a combination of the directed relation graph with error propagation (DRGEP) method and the simplified iterative screening and structure analysis (ISSA) method. Compared to the detailed mechanisms, the skeletal mechanism retains the major species and reactions for the syngas/NOx system and is validated against typical experimental data resulting in a very good performance.

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“…Thus, we do not include this reaction in the subsequent work. For reaction [35], the UMIST2012 values overestimate the reaction rate compared to the computations by Nguyen & Stanton (2019), as can be seen in figure A.6. The recently published values based on highly accurate semiclassical transition state theory (SCTST) calculations are state of the art and are shown to deviate just slightly from experimental values.…”

Section: Use Of Correct Reaction Rate Constantsmentioning

confidence: 91%

The role of atom tunneling in gas-phase reactions in planet-forming disks

Meisner

Kamp

Thi

et al. 2019

A&A

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Context. Gas-phase chemical reactions of simple molecules have been recently revised to include atom tunneling at very low temperatures. This paper investigates the impact of the increased reaction rate constant due to tunneling effects on planet-forming disks. Aims. Our aim is to quantify the astrophysical implications of atom tunneling for simple molecules that are frequently used to infer disk structure information or to define the initial conditions for planet (atmosphere) formation. Methods. We quantify the tunneling effect on reaction rate constants by using H 2 + OH → H 2 O + H as a scholarly example in comparison to previous UMIST2012 rate constants. In a chemical network with 1299 reactions, we identify all chemical reactions that could show tunneling effects. We devise a simple formulation of reaction rate constants that overestimates tunneling and screen a standard T Tauri disk model for changes in species abundances. For those reactions found to be relevant, we find values of the most recent literature for the rate constants including tunneling and compare the resulting disk chemistry to the standard disk model(s), a T Tauri and a Herbig disk. Results. The rate constants in the UMIST2012 database in many cases already capture tunneling effects implicitly, as seen in the curvature of the Arrhenius plots of some reactions at low temperature. A rigorous screening procedure identified three neutral-neutral reactions where atom tunneling could change simple molecule abundances. However, by adopting recent values of the rate constants of these reactions and due to the layered structure of planet-forming disks, the effects are limited to a small region between the ion-molecule dominated regime and the ice reservoirs where cold (< 250 K) neutral-neutral chemistry dominates. Abundances of water close to the midplane snowline can increase by a factor of two at most compared to previous results with UMIST2012 rates. Observables from the disk surface, such as high excitation (> 500 K) water line fluxes, decrease by 60% at most when tunneling effects are explicitly excluded. On the other hand, disk midplane quantities relevant for planet formation such as the C-to-O ratio and also the ice-to-rock ratio are clearly affected by these gas-phase tunneling effects.

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Ab initio thermal rate coefficients for H + NH₃ ⇌ H₂ + NH₂

Cited by 22 publications

References 40 publications

Progress and Prospective of Nitrogen-Based Alternative Fuels

Progress and Prospective of Nitrogen-Based Alternative Fuels

Comparative Chemical Kinetic Analysis and Skeletal Mechanism Generation for Syngas Combustion with NO_x Chemistry

The role of atom tunneling in gas-phase reactions in planet-forming disks

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Ab initio thermal rate coefficients for H + NH3 ⇌ H2 + NH2

Cited by 22 publications

References 40 publications

Progress and Prospective of Nitrogen-Based Alternative Fuels

Progress and Prospective of Nitrogen-Based Alternative Fuels

Comparative Chemical Kinetic Analysis and Skeletal Mechanism Generation for Syngas Combustion with NOx Chemistry

The role of atom tunneling in gas-phase reactions in planet-forming disks

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Product

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Ab initio thermal rate coefficients for H + NH₃ ⇌ H₂ + NH₂

Comparative Chemical Kinetic Analysis and Skeletal Mechanism Generation for Syngas Combustion with NO_x Chemistry