Hydrolysis of carbonyl sulfide: Comparison to reactions of isocyanates

proached and exceeded by conducting DPO at conventional pressures (-6 MPa) but at unusually high temperatures (530-730 vs 450 "C). Also important according to the model was short reaction time (on the order of tens to hundreds of milliseconds) to prevent combustion.The model predictions for conditions roughly corresponding to our experiments (550 "C, 6.2 MPa, 13-15% O2 in the feed, and 13-15% CHI conversion) indicated that -4 5 4 % CHBOH selectivity might be expected (assuming that our estimated residence times-as low as -1500 ms-were sufficiently short). The dominance of Cz+ in the present study's results suggest that further testing of the model's predictions in other experimental configurations (e.g., empty tubes with very low surface/volume ratios) would be desirable to determine if its chemical basis requires modification. ConclusionsAt elevated pressure (6.2 MPa), significant amounts of Cz+ oxidative coupling products could be obtained without a catalyst (-35% carbon selectivity at -15% methane conversion) at temperatures much lower than those of conventional catalytic operation (550-600 vs 75O-WO "C). However, the observed selectivity behavior is typical of much of the conventional catalytic low-pressure, hightemperature data at similar conversion. This observation, coupled with a modest influence on selectivity by samarium oxide catalyst when run at the same atypical conditions, supports the view that noncatalytic gas-phase radical reactions play a strong role in conventional oxidative coupling.At the elevated pressure and moderate temperatures investigated, the direct conversion of CHI to CHBOH and Cz+ appears to depend upon the relative contributions of two parallel pathways: increasing oxygen partial pressure and/or temperatures favors the Cz+ path while reducing these parameters favors CH30H production. The reaction between COS and various tertiary alkanolamines in aqueous solutions has been studied in an intensely stirred batch reactor. Experiments for TEA, DMMEA, and DEMEA were carried out at 303 K the reaction between COS and aqueous MDEA has been studied at temperaturm ranging from 293 to 323 K. A two-step reaction mechanism haa been proposed which describes all observed phenomena. This mechanism can be regarded as the base-catalyzed analogue of the reaction mechanism for the hydrolysis of COS. The proposed reaction mechanism was confirmed by absorption experiments into nonaqueous solutions of tertiary alkanolamines.

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“…-COS & comparison to the more common tertiary alkanolamines (Ernst and Chen, 1988;Ernst et al, 1990; R e i y et al, 1990).…”

Section: Literaturementioning

confidence: 99%

Kinetic study of COS with tertiary alkanolamine solutions. 1. Experiments in an intensely stirred batch reactor

Littel¹,

Versteeg²,

Swaaij³

1992

Ind. Eng. Chem. Res.

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“…Ernst and Chen (1988) reported absorption data for COS into solutions consisting of a heterocyclic amine (e.g. The observations presented by Ernst et al (1990) for solutions of various heterocyclic amines were analogous to those reported by Ernst and Chen (1988). The heterocyclic amines studied by Ernst and Chen (1988) were claimed to show substantially higher activity in COS hydrolysis than common tertiary alkanolamines at about the same base strength.…”

Section: Literaturementioning

confidence: 68%

On the Kinetics Between Cos and Heterocyclic Amines in Aqueous Solutions

Littel

1993

Chemical Engineering Communications

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The reaction kinetics between COS and aqueous solutions of some heterocyclic amines have been studied at 303 K. The reaction of COS with 1,4-Diazabicyclo[2.2.2]octane (DAB) and 1,2-DimethyJimidazole (DMI) has been investigated in an intensely stirred balch reactor; the reaction between COS and aqueous solutions of 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) has been studied by means of the stirred ceJl technique.The reaction of COS with aqueous DMI and DAB was found to be extremely slow and the observed reaction order in the amine concentration was about 0.8. The overall reaction rate for the reaction of COS with aqueous DBU solutions was rather high, whereas the observed reaction order in the DBU concentration was found to be about 1.7.

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“…In addition, Ernst and co-workers considered whether cyclic tertiary amines could catalyze the hydrolysis reaction of COS: A cyclic tertiary amine (denoted as “CTA”) reacts with COS to form an active intermediate (denoted as “complex”) which subsequently hydrolyzes fast to form H 2 S, CO 2 , and the cyclic tertiary amine. The intermediate formation described by eq 6 is the rate-determining step for the overall reaction.…”

Section: Resultsmentioning

confidence: 99%

“…Ernst et al and Reilly et al. investigated the reaction kinetics of several cyclic amines with COS; − the results show that the reaction rates of 1,4-diazabicyclo[2.2.2]octane (DAB), quinuclidine and 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) are dozens of times as much as that of MDEA.…”

Section: Resultsmentioning

confidence: 99%

“…The intermediate formation described by eq 6 is the rate-determining step for the overall reaction. Kinetics study has shown that both the basicity and steric hindrance effects of cyclic tertiary amines govern their catalytic activity, 32 and strong basicity and weak steric hindrance effect can lead to an enhancement in reaction rate. Energy & Fuels In conclusion, strong basicity and weak steric hindrance effect for amines are beneficial to improve the reaction rate.…”

Section: Energy and Fuelsmentioning

confidence: 99%

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Rational Formulation Design and Commercial Application of a New Hybrid Solvent for Selectively Removing H₂S and Organosulfurs from Sour Natural Gas

et al. 2015

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Based on the investigation on nonbonded interactions between solvent and organosulfur molecules, the reaction kinetics of carbonyl sulfide (COS) with chemical solvents in aqueous solutions, and experimental validation, a hybrid solvent (named UDS-2) was designed to simultaneously remove H2S and organosulfurs from sour natural gas at high removal efficiency. The solvent components, which could enhance physical and chemical absorption of methyl mercaptan and COS, were screened using quantum chemistry method coupled with kinetics analysis. The results show that the five-membered sulfur heterocyclic compound (SUL) exhibits significant advantage of physical solubility of methyl mercaptan and COS. Meanwhile, the cyclic amine (CA) with weak steric hindrance effect as well as moderate basicity could enhance chemical removal of COS. UDS-2 solvent was obtained by blending SUL and CA with N-methyldiethanolamine (MDEA) at optimal proportion, and the removal efficiencies for methyl mercaptan, COS, and total organosulfur of UDS-2 were 53.1, 23.9, and 42.4 percentage points higher than those of MDEA. UDS-2 was successfully applied in a natural gas purification plant. Under the operation conditions of absorption pressure of 5.5 MPa, gas flow rate of 8.48 × 103 N m3/h, gas–liquid ratios of 240 in absorber-I and 471 in absorber-II, the removal efficiencies for methyl mercaptan, COS, and total organosulfur are 77.6%, 74.5% and 75.6%, respectively. The contents of H2S, CO2, and total sulfur in purified gas can be reduced below 0.7 mg/(N m3), 0.16 vol % and 43.5 mg/(N m3), respectively, which all met the corresponding specification for Chinese first-grade commercial natural gas. Additionally, the low hydrocarbon loss of 1.34 N m3/(N m3 solution) indicates UDS-2 solvent has good selectivity for sulfur compounds over hydrocarbons.

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Hydrolysis of carbonyl sulfide: Comparison to reactions of isocyanates

Cited by 12 publications

References 9 publications

Kinetic study of COS with tertiary alkanolamine solutions. 1. Experiments in an intensely stirred batch reactor

Kinetic study of COS with tertiary alkanolamine solutions. 1. Experiments in an intensely stirred batch reactor

On the Kinetics Between Cos and Heterocyclic Amines in Aqueous Solutions

Rational Formulation Design and Commercial Application of a New Hybrid Solvent for Selectively Removing H₂S and Organosulfurs from Sour Natural Gas

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Hydrolysis of carbonyl sulfide: Comparison to reactions of isocyanates

Cited by 12 publications

References 9 publications

Kinetic study of COS with tertiary alkanolamine solutions. 1. Experiments in an intensely stirred batch reactor

Kinetic study of COS with tertiary alkanolamine solutions. 1. Experiments in an intensely stirred batch reactor

On the Kinetics Between Cos and Heterocyclic Amines in Aqueous Solutions

Rational Formulation Design and Commercial Application of a New Hybrid Solvent for Selectively Removing H2S and Organosulfurs from Sour Natural Gas

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Product

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Rational Formulation Design and Commercial Application of a New Hybrid Solvent for Selectively Removing H₂S and Organosulfurs from Sour Natural Gas