Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

Glarborg, Peter; Marshall, Paul

doi:10.1002/kin.20778

Cited by 40 publications

(38 citation statements)

References 93 publications

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“…The rate constants for forward reactions, k f , are described in the form, E2, where R is the gas constant and T the gas temperature. The pre-exponential factor, A, the temperature exponent, β, and activation energy E, are specified in the mechanism file (see Glarborg and Marshall, 2013).…”

Section: Chemical Kinetic Modelmentioning

confidence: 99%

“…The reverse reaction rate constant, k r , is given by E3 where K is the equilibrium constant that is determined by thermodynamic properties (molar enthalpies and entropies as a function of temperature); these properties are specified in the thermodynamic data file (see Glarborg and Marshall, 2013).…”

Section: Chemical Kinetic Modelmentioning

confidence: 99%

“…There are very few studies at high-temperature dealing with sulfur species oxidation and their interactions with carbon, nitrogen oxides, or halogens. Here, the mechanism proposed by Glarborg and Marshall (2013) was selected for its good performance in comparison to laboratory shock-tube experiments, as recently highlighted by Mathieu et al (2017). It includes 38 species involved in 161 reversible reactions.…”

Section: Chemical Kinetic Modelmentioning

confidence: 99%

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Reaction Rates Control High-Temperature Chemistry of Volcanic Gases in Air

2019

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When volcanic gases enter the atmosphere, they encounter a drastically different chemical and physical environment, triggering a range of rapid processes including photochemistry, oxidation, and aerosol formation. These processes are critical to understanding the reactivity and evolution of volcanic emissions in the atmosphere yet are typically challenging to observe directly due to the nature of volcanic activity. Inferences are instead drawn largely from observations of volcanic plumes as they drift across a crater's edge and further downwind, and the application of thermodynamic models that neglect reaction kinetics as gas and air mix and thermally equilibrate. Here, we foreground chemical kinetics in simulating this critical zone. Volcanic gases are injected into a chain-of-reactors model that simulates time-resolved high-temperature chemistry in the dispersing plume. Boundary conditions of decreasing temperature and increasing proportion of air interacting with volcanic gases are specified with time according to an offline plume dynamics model. In contrast to equilibrium calculations, our chemical kinetics model predicts that CO is only partially oxidized, consistent with observed CO in volcanic plumes downwind from source. Formation of sulfate precursor SO 3 at SO 3 /SO 2 = 10 −3 mol/mol is consistent with the range of reported sulfate aerosol to SO 2 ratios observed close to crater rims. High temperature chemistry also forms oxidants OH, HO 2 , and H 2 O 2. The H 2 O 2 will likely augment volcanic sulfate yields by reacting with SO 2(aq) in the cooled-condensed plume. Calculations show that hightemperature OH will react with volcanic halogen halides (HBr and HCl) to yield reactive halogens (Br and Cl) in the young plume. Strikingly, high-temperature production of radical oxidants (including HO x) is enhanced by volcanic emissions of reduced gases (CO, H 2 , and H 2 S) due to chemical feedback mechanisms, although the kinetics of some reactions are uncertain, especially regarding sulfur. Our findings argue strongly that the chemistry of the hot near-source plume cannot be captured by equilibrium model assumptions, and highlight the need for development of more sophisticated, kinetics-based, high-temperature CHONS-halogen reaction models.

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Section: Chemical Kinetic Modelmentioning

confidence: 99%

Section: Chemical Kinetic Modelmentioning

confidence: 99%

Section: Chemical Kinetic Modelmentioning

confidence: 99%

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Reaction Rates Control High-Temperature Chemistry of Volcanic Gases in Air

2019

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“…proposed a detailed reaction network involving H 2 , CO, COS, and CS 2 decomposition and formation with relevance to the Claus furnace. During COS combustion, the reaction of COS with O atoms was found to be one of the most sensitive reactions involved in COS consumption, as observed by Glarborg and Marshall . Isshiki et al .…”

Section: Introductionmentioning

confidence: 67%

“…Cullis and Mulcahy published early studies on the COS reaction mechanism. Recently, Glaborg and Marshall developed a detailed chemical kinetic model for the dry oxidation of COS using the kinetic parameters from previous studies. They validated their mechanism using experimental data from batch reactors, flow reactors, and shock tubes for the oxidation of COS over a wide range of air–fuel ratio (0.5 ≤ λ ≤ 7.3), temperature (450–1700 K), and pressure (0.02–3.0 atm).…”

Section: Introductionmentioning

confidence: 99%

A reaction kinetics study and model development to predict the formation and destruction of organosulfur species (carbonyl sulfide and mercaptans) in Claus furnace

Rahman

Raj

2018

Int J of Chemical Kinetics

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Carbonyl sulfide (COS), carbon disulfide (CS 2 ), and mercaptans (e.g., CH 3 SH) are unwanted sulfurous species that are produced in sulfur recovery units (SRUs). They can cause equipment corrosion, reduce catalyst activity, and are pollutants for the environment. This necessitates process optimization to minimize their formation in the SRUs using an accurate kinetic model. In this paper, new reactions of COS and mercaptans are studied using the CBS-QB3 level of theory, and their kinetics are evaluated using transition state theory. Such reactions are added to a detailed SRU reaction mechanism, and the updated mechanism is validated using the data on COS and mercaptans from lab-scale experimental setups and an industrial plant. Compared to the previous models, significant improvements in the predicted concentrations of the important species such as COS, carbon monoxide (CO), and sulfur oxides (SO and SO 2 ) are observed due to the inclusion of the new reactions in the mechanism. The simulation studies in a homogeneous reactor within the temperature range of 800-2000 K revealed that furnace temperatures near 1300 K are required to minimize CO and COS formation, while ensuring the oxidation of methane (CH 4 ), mercaptans, and aromatics. Mercaptan formation mainly took place at low temperatures near 900 K.Claus furnace simulations are conducted using industrial feed and operating conditions to show that the optimized inlet air temperature and fuel gas flow rate can assist in simultaneously reducing the emissions of CO and harmful sulfurous species such as COS, CH 3 SH, and CS 2 from the furnace.

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An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

Song

Hashemi

Christensen

et al. 2016

Int J of Chemical Kinetics

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Hydrogen sulfide oxidation experiments were conducted in O2/N2 at high pressure (30 and 100 bar) under oxidizing and stoichiometric conditions. Temperatures ranged from 450 to 925 K, with residence times of 3–20 s. Under stoichiometric conditions, the oxidation of H2S was initiated at 600 K and almost completed at 900 K. Under oxidizing conditions, the onset temperature for reaction was 500–550 K, depending on pressure and residence time, with full oxidization to SO2 at 550–600 K. Similar results were obtained in quartz and alumina tubes, indicating little influence of surface chemistry. The data were interpreted in terms of a detailed chemical kinetic model. The rate constants for selected reactions, including SH + O2 ⇄ SO2 + H, were determined from ab initio calculations. Modeling predictions generally overpredicted the temperature for onset of reaction. Calculations were sensitive to reactions of the comparatively unreactive SH radical. Under stoichiometric conditions, the oxidation rate was mostly controlled by the SH + SH branching ratio to form H2S + S (promoting reaction) and HSSH (terminating). Further work is desirable on the SH + SH recombination and on subsequent reactions in the S2 subset of the mechanism. Under oxidizing conditions, a high O2 concentration (augmented by the high pressure) causes the termolecular reaction SH + O2 + O2 → HSO + O3 to become the major consumption step for SH, according to the model. Consequently, calculations become very sensitive to the rate constant and product channels for the H2S + O3 reaction, which are currently not well established.

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Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

Cited by 40 publications

References 93 publications

Reaction Rates Control High-Temperature Chemistry of Volcanic Gases in Air

Reaction Rates Control High-Temperature Chemistry of Volcanic Gases in Air

A reaction kinetics study and model development to predict the formation and destruction of organosulfur species (carbonyl sulfide and mercaptans) in Claus furnace

An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

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Oxidation of Reduced Sulfur Species: Carbonyl Sulfide

Cited by 40 publications

References 93 publications

Reaction Rates Control High-Temperature Chemistry of Volcanic Gases in Air

Reaction Rates Control High-Temperature Chemistry of Volcanic Gases in Air

A reaction kinetics study and model development to predict the formation and destruction of organosulfur species (carbonyl sulfide and mercaptans) in Claus furnace

An Exploratory Flow Reactor Study of H2S Oxidation at 30–100 Bar

Contact Info

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Resources

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An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar