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West, John; Williams, B. Peter; Young, Nicola; Rhodes, Colin; Hutchings, Graham J.

doi:10.1023/a:1016681030065

Cited by 35 publications

(28 citation statements)

References 8 publications

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“…After 400 min on line, the activities of all catalysts decline, but marked differences are observed. c-Al 2 O 3 and 0.4%ZnO/Al 2 O 3 catalysts show very similar activity while 1.3%ZnO/Al 2 O 3 and 4.1%ZnO/Al 2 O 3 are more active than the unmodified alumina, and this is in agreement with our previous findings at lower reaction temperatures [6,12].…”

Section: Resultssupporting

confidence: 92%

“…COS hydrolysis was carried out using a standard laboratory microreactor with on line analysis of the products using gas chromatography fitted with a flame photometric detector, as described previously [12,13].…”

Section: Catalyst Characterisation and Cos Hydrolysismentioning

confidence: 99%

“…This process does not affect COS which is a potent catalyst poison, and consequently a different strategy is used to form H 2 S and this is COS hydrolysis (COS + H 2 O=CO 2 + H 2 S). This process has been well studied and to date alumina and titania have been found to be promising catalysts [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…George [7] and Fiedorow et al [8] demonstrated that the rate of COS hydrolysis could be increased by the presence of a base and that basic sites were essential for the reaction. To date, a wide range of alkali metals (Li, Na, K, Cs), alkaline earth metals (Mg, Ca, Sr, Ba), first row transition metals (Fe, Co, Ni, Cu, Zn) and Sn have been considered as catalyst promoters [9][10][11][12][13]. In our previous studies we have shown that modification of alumina with Zn 2+ is effective at temperatures as low as 30°C but we did not study the effects of temperatures above 100°C, where inhibition by water is not so pronounced.…”

Section: Introductionmentioning

confidence: 99%

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COS Hydrolysis Using Zinc-promoted Alumina Catalysts

et al. 2005

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The effect of doping alumina catalysts with zinc oxide is investigated for the COS hydrolysis reaction (COS + H 2 O=CO 2 + H 2 S) at 150°C. The effect of the catalyst preparation method is described and discussed, and two methods are compared, namely: impregnation by incipient wetness of zinc nitrate followed by calcination to form the oxide and coprecipitation to form a hydroxide followed by calcination. The most effective zinc-promoted catalysts are prepared using the incipient wetness impregnation method. The promotional effect of zinc oxide on alumina is only observed on the basis of intrinsic activity and is not particularly significant at the initial time on stream, but becomes more marked with increased reaction time. The addition of the zinc oxide therefore decreases the deactivation and experiments using catalysts pretreated with H 2 S and H 2 O show that the alumina is deactivated by adsorption of these reactants. However, the effect is related to ZnO acting as a sulfur scavenger at 150°C and we conclude that any promotional effect is likely to be relatively short lived.

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Section: Resultssupporting

confidence: 92%

Section: Catalyst Characterisation and Cos Hydrolysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

COS Hydrolysis Using Zinc-promoted Alumina Catalysts

et al. 2005

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“…It is known that the rate of COS hydrolysis can be increased by the presence of a base [6,7] and that basic sites were essential for the reaction. To date, a wide range of alkali metals (Li, Na, K, and Cs), alkaline earth metals (Mg, Ca, Sr, and Ba), first row transition metals (Fe, Co, Ni, Cu and Zn) and Sn have been considered as catalyst promoters [4,[8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

High temperature COS hydrolysis catalysed by γ-Al2O3

et al. 2006

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The COS hydrolysis reaction (COS + H 2 O = CO 2 + H 2 S) using c-Al 2 O 3 at 220°C is described and discussed. The stoichiometric reaction of COS in the absence of water proceeds and the extent of reaction is comparable to the moisture content of the alumina that can be removed during TGA. The reaction of COS and H 2 O is long lived at this temperature but the sulphur balance based on H 2 S is ca. 80%. It is found that elemental sulphur is deposited in the reactor and on the catalyst during this reaction. Reaction in the presence of H 2 increases the sulphur balance to 100% and no sulphur is deposited on the catalyst. The beneficial effect of hydrogen is demonstrated by mixing sulphur with c-Al 2 O 3 which on reaction with H 2 leads to the formation of COS and H 2 S. The addition of formic acid to the reactants leads to a reversible loss of activity, but detailed long term studies show that formic acid is not formed during the operation of the catalyst over a wide range of conditions.

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A comprehensive theoretical study on the hydrolysis of carbonyl sulfide in the neutral water

Deng

Ren

et al. 2007

J Comput Chem

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The detailed hydration mechanism of carbonyl sulfide (COS) in the presence of up to five water molecules has been investigated at the level of HF and MP2 with the basis set of 6-311++G(d, p). The nucleophilic addition of water molecule occurs in a concerted way across the C==S bond of COS rather than across the C==O bond. This preferential reaction mechanism could be rationalized in terms of Fukui functions for the both nucleophilic and electrophilic attacks. The activation barriers, DeltaH( not equal) (298), for the rate-determining steps of one up to five-water hydrolyses of COS across the C==S bond are 199.4, 144.4, 123.0, 115.5, and 107.9 kJ/mol in the gas phase, respectively. The most favorable hydrolysis path of COS involves a sort of eight-membered ring transition structure and other two water molecules near to the nonreactive oxygen atom but not involved in the proton transfer, suggesting that the hydrolysis of COS can be significantly mediated by the water molecule(s) and the cooperative effects of the water molecule(s) in the nonreactive region. The catalytic effect of water molecule(s) due to the alleviation of ring strain in the proton transfer process may result from the synergistic effects of rehybridization and charge reorganization from the precoordination complex to the rate-determining transition state structure induced by water molecule. The studies on the effect of temperature on the hydrolysis of COS show that the higher temperature is unfavorable for the hydrolysis of COS. PCM solvation models almost do not modify the calculated energy barriers in a significant way.

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Untitled

Cited by 35 publications

References 8 publications

COS Hydrolysis Using Zinc-promoted Alumina Catalysts

COS Hydrolysis Using Zinc-promoted Alumina Catalysts

High temperature COS hydrolysis catalysed by γ-Al2O3

A comprehensive theoretical study on the hydrolysis of carbonyl sulfide in the neutral water

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