Quantum Chemical and Theoretical Kinetics Study of the O(<sup>3</sup>P) + CS<sub>2</sub>Reaction

Saheb, Vahid

doi:10.1021/jp200216b

Cited by 11 publications

(10 citation statements)

References 55 publications

(84 reference statements)

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“…Vahid Saheb also studied the reaction mechanism of O with CS 2 using DFT in levels of B3LYP/6-311+G (d, p). And the theoretical result revealed that the products of the reaction of CS 2 + O are CS and SO, also in agreement with experimental observation [32]. Jianqiang Zhao et al used DFT to perform geometric optimization on all azobenzene at the B3LYP/6-311+G(d, p) theoretical level, and the structure proved to be reliable for describing the structure and properties of organic molecules, the theoretical calculation agrees with the experiment [33].…”

Section: Introductionsupporting

confidence: 70%

New insights on the theoretical study of hydrolysis mechanism of carbon disulfide (CS2) at low temperature: A density functional theory study

Wang

Zhang

Shi

et al. 2022

Preprint

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Density functional theory (DFT) is used to investigate the two-step hydrolysis mechanism of CS2. By optimizing the structure of reactants, intermediates, transition states, and products, the conclusion shows that the first step of CS2 (CS2 reacts with H2O first to form COS intermediate); The second step (COS intermediate reacts with H2O to form H2S and CO2). Therefore, hydrogen migration is crucial to the mechanism of CS2 hydrolysis. In the first step of the reaction, the rate-determining step in both the single C=S path and the double C=S path has a higher barrier of 199.9 kJ/mol, but the 127.9 kJ/mol barrier in the double C=S path has a lower barrier of 142.8 kJ/mol in the single C=S path. So the double C=S path is better. Similarly, the order of the barriers for the three paths in the second reaction is C=S path < C=S path and C=O path < C=O path. So the C=S path is better. Also, to further explore the reaction of CS2 hydrolysis, the natural bond orbital (NBO) analysis of the transition states was carried out. Besides, to further explain which reaction path is better, the hydrolysis kinetics of CS2 was analyzed. It was found that the hydrolysis of CS2 was an exothermic reaction, and the increase in temperature was unfavorable to the reaction. During the hydrolysis of CS2, the six reaction paths are parallel and competitive. The results will provide a new way to study the catalytic hydrolysis of CS2.

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Section: Introductionsupporting

confidence: 70%

New insights on the theoretical study of hydrolysis mechanism of carbon disulfide (CS2) at low temperature: A density functional theory study

Wang

Zhang

Shi

et al. 2022

Preprint

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“…Our initial exploration at the B3LYP/6-311G(2d,d,p) level of density functional theory yields a minimum energy ISC point close to the geometry of cis -OSCS, 100 kJ mol –1 below that of O + CS 2 . This opens the possibility that a small fraction of triplet O + CS 2 trajectories, having passed over a minor barrier, cross to the lower-lying singlet OSCS structure. This may undergo a series of rearrangements or dissociation via barriers that are significantly lower relative to the reactants than those on the triplet surface .…”

Section: Detailed Kinetic Modelmentioning

confidence: 99%

Oxidation of Reduced Sulfur Species: Carbon Disulfide

et al. 2014

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A detailed chemical kinetic model for oxidation of CS 2 has been developed, on the basis of ab initio calculations for key reactions, including CS 2 + O 2 and CS + O 2 , and data from literature. The mechanism has been evaluated against experimental results from static reactors, flow reactors, and shock tubes. The CS 2 + O 2 reaction forms OCS + SO, with the lowest energy path involving crossing from the triplet to the singlet surface. For CS + O 2 , which yields OCS + O, we found a high barrier to reaction, causing this step to be important only at elevated temperatures. The model predicts low temperature ignition delays and explosion limits accurately, whereas at higher temperatures it appears to overpredict both the induction time for CS 2 oxidation and the formation rate of [O] upon ignition. The predictive capability of the model depends on the accuracy of the rate constant for the initiation step CS 2 + O 2 , which is difficult to calculate due to the intersystem crossing, and the branching fraction for CS 2 + O, which is measured only at low temperatures. The governing reaction mechanisms are outlined on the basis of calculations with the kinetic model. ■ INTRODUCTIONOff-gases containing carbon disulfide (CS 2 ) are produced together with other sulfur containing compounds such as H 2 S from a range of industrial processes, including the Claus process 1−3 and production of viscous fibers, 4 and in gasification of coal 5 and biomass. 6 Similar to H 2 S and the oxidation product SO 2 , carbon disulfide is toxic and harmful to the environment. Efficient treatment of the sulfur containing off gases becomes a bottleneck in these processes as strict emission requirements must be met. Hence, knowledge of the CS 2 oxidation mechanism is important. Investigations have shown that CS 2 / O 2 mixtures are able to autoignite at low temperature and low pressure 7−13 under conditions of negligible self-heating. Two explosion limits have been reported in the literature, 7−9 and studies have been carried out to determine the effect upon the limits with a change in surface conditions and addition of inert gases. The induction times range from a few seconds to several minutes. 9,11,14 At higher temperatures, CS 2 oxidation has been investigated in flow reactors, 2,15 shock tubes, 16−18 and laminar premixed flames. 19−23 Much of the high-temperature work has been motivated by interest in the CO laser. CS 2 /O 2 flames form CO with its vibrational population inverted, facilitating production of a CO flame laser.Previous studies of the reaction mechanism of carbon disulfide oxidation have mostly been restricted to fuel-lean, dry conditions. 17,18,20,24,25 No reported chemical kinetic models are found to satisfactory describe experimental data across a wider range of mixture composition, temperature, and pressure as the mechanism is complex and accurate kinetic data have been unavailable for several important reactions. The objective of the present study is to develop a detailed chemical kinetic model for oxidation of...

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“…Therefore, oxygen atom transfer to form CO and S 2 products should be energetically accessible for 4PNO À . Formation of CS + SO is approximately 3 eV less favorable [49] than formation of CO + S 2 and is therefore highly endothermic in the reaction of 4PNO À with CS 2 .…”

Section: Reaction With Csmentioning

confidence: 99%

“…However, CO has also been observed in the reaction [50], indicating that CO + S 2 is a possible decomposition pathway of CS 2 O. In fact, CO + S 2 is energetically the most favored pathway [49] but is slow because there is a slight (6.6 kcal/mol) barrier [49] for the initial formation of CS 2 O. However, this barrier can be overcome in the reaction of CS 2 with 4PNO À by the energy released upon formation of the initial ion/molecule complex in combination with the oxygen atom transfer exothermicity.…”

Section: Reaction With Csmentioning

confidence: 99%