Simultaneous absorption of carbon dioxide, carbonyl sulfide and hydrogen sulfide in aqueous methyldiethanolamine

Al-Ghawas, Hani A.; Sandall, Orville C.

doi:10.1016/0009-2509(91)80027-v

Cited by 12 publications

(8 citation statements)

References 12 publications

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“…The reactions (1) and (2) have been discussed in the literature [2][3][4][5][7][8][9]12,[14][15][16] and catalyzed reaction (1) has also been studied [3,17]. Other possible reactions discussed in the literature [3,8] involving the two sulfur species in the hot coal gas streams at different temperatures include: Reactions (4) to (9) usually take place at temperatures above 1,000 o C. Reaction (10) may take place at low temperatures in the presence of MoS 2 catalyst [18].…”

Section: Thermodynamic Analysismentioning

confidence: 99%

Correlation of H2S and COS in the hot coal gas stream and its importance for high temperature desulfurization

Chang

Xie

et al. 2011

Korean J. Chem. Eng.

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Thermodynamic analysis of the correlation of H 2 S and COS has been carried out at the temperature range of 400-650 o C at which high temperature desulfurization of coal gas is usually performed. The correlation of the two sulfur species is mainly through the reaction H 2 S+CO→COS+H 2 . Simulated coal gas with the following composition CO 32.69%, H 2 39.58%, CO 2 18.27%, N 2 8.92% and H 2 S 0.47% was used in this study, and the equilibrium concentrations of the two species at different temperatures were calculated. The results of Fe-based sorbents during sulfidation were compared with calculations. It is concluded that the above reaction may reach equilibrium concentration in the presence of the Fe-based sorbents, which means the Fe-based sorbents may effectively catalyze the reaction between H 2 S and CO. Because of the correlation of the two sulfur species, both can be effectively removed at high temperatures simultaneously, offering high temperature desulfurization some advantages over low temperature desulfurization processes.

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Section: Thermodynamic Analysismentioning

confidence: 99%

Correlation of H2S and COS in the hot coal gas stream and its importance for high temperature desulfurization

Chang

Xie

et al. 2011

Korean J. Chem. Eng.

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“…14 To make progress in these hybrid systems and their application in COS absorption, we decided to determine accurately the reaction rate constants of COS-DEA-methanol absorption by modeling the two-step zwitterion mechanism, at temperatures from 298 to 323 K. By analogy to CO 2 absorption and according to the works of Danckwerts 15 and Blauwhoff et al, 16 the first stage of the mechanism is assumed to be the zwitterion formation, followed by the stage of deprotonation of this zwitterion by any base present in the system. Nevertheless, the physicochemical properties of COS-methanol systems needed to model the gas absorption are not available in the open literature, so as a first approach, we estimated the properties of COS assuming the COS-N 2 O analogy in aqueous systems, validated experimentally by Al-Ghawas et al 7 This assumption has been considered in several works on aqueous and alcohol-aqueous systems, such as those by Littel et al 9 and Lammers et al, 13 and is frequently used because of the difficulty in measuring reactive systems directly. The physicochemical properties of COS-aqueous systems were estimated by using different correlations: the works of Pani et al, 17 Versteeg and Swaaij, 18 and Tsai et al 19 were used for diffusivity estimation, and Henry constants for COS were estimated in analogy with N 2 O, based on the works of Wang et al 20 and Sandall.…”

Section: Literaturementioning

confidence: 99%

Reaction Kinetics of Carbonyl Sulfide (COS) with Diethanolamine in Methanolic Solutions

Rivera-Tinoco

Bouallou

2008

Ind. Eng. Chem. Res.

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In this work, the kinetics of carbonyl sulfide (COS) absorption in a hybrid solvent containing diethanolamine (DEA) dissolved in methanol was studied. The amine concentrations and temperatures ranged from 380 to 2030 mol m -3 and from 298 to 323 K, respectively. With the purpose of estimating reaction rate constants for the COS-DEA system, the rigorous modeling of COS absorption was carried out based on the two-step zwitterion mechanism, used until now in the modeling of the absorption of carbon dioxide and sulfur compounds by alkanolamine aqueous solutions. A downhill simplex optimization method was developed to determine the reaction rate constants, and simultaneously an iterative procedure was followed to estimate the enhancement factor of the COS absorption. As the results show, these optimization procedures led successfully to the appropriate fitting between the experimental and modeled data and also confirm the two-step zwitterion mechanism for this absorption system.

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“…The reaction between C02 and tertiary alkanolamines has been studied extensively (see, e.g., Littel et al, 1990b), whereas the reaction between COS and tertiary alkanolamines has received almost no attention. Recently, Al-Ghawas et al (1989) presented kinetic data for the reaction between COS and MDEA in aqueous solutions at temperatures ranging from 293 to 313 K. Their kinetic data were applied to describe absorption experiments for the simultaneous absorption of H2S, COS, and C02 into aqueous MDEA solutions (Al-Ghawas and Sandall, 1991).…”

Section: Introductionmentioning

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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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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Simultaneous absorption of carbon dioxide, carbonyl sulfide and hydrogen sulfide in aqueous methyldiethanolamine

Cited by 12 publications

References 12 publications

Correlation of H2S and COS in the hot coal gas stream and its importance for high temperature desulfurization

Correlation of H2S and COS in the hot coal gas stream and its importance for high temperature desulfurization

Reaction Kinetics of Carbonyl Sulfide (COS) with Diethanolamine in Methanolic Solutions

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

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