Oxidative coupling of methane over lithium doped magnesium oxide catalysts

Korf, S.J.; Roos, J.A.; Bruijn, N.A. De; Ommen, J.G. van; Ross, J.R.H.

doi:10.1016/0920-5861(88)85017-x

Cited by 83 publications

(34 citation statements)

References 4 publications

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“…The more promosing catalysts include certain members of the lanthanide oxide series [1,2] as well as a number of metal oxides promoted with alkali metal ions [3-81. We have recently presented results which allowed us to postulate a possible model for the nature of the surface sites involved in the methane coupling reaction over a Li/MgO catalyst adjacent surface site. These ideas are in agreement with the model for the formation of the active site [4].…”

Section: Introductionsupporting

confidence: 79%

“…this poisoning probably arises from competitive adsorption of the CO, with the methane and/or the oxygen [4,9].…”

Section: Catnlvst Prenarationmentioning

confidence: 99%

“…The Li/MgO material used as precursor for the Li/Sn/MgO material was prepared by wet impregnation of Mg(OH), with an aqueous solution of LiOH; this was done in the presence of a stream of CO, [4]. After drying at 140°C, this material was physically mixed with SnOz.…”

Section: Catnlvst Prenarationmentioning

confidence: 99%

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A study of the kinetics of the oxidative coupling of methane over a Li/Sn/MgO catalyst

et al. 1990

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The rate of reaction of methane with oxygen in the presence of a Li/Sn/MgO catalyst has been studied as a function of the partial pressures of CH,, 0, and CO, using a well-mixed reaction system which is practically gradientless with respect to gas-phase concentrations. It is concluded that the rate-determining step involves reaction of a molecule of CH, adsorbed on the catalyst surface with an adsorbed di-atomic oxygen species. The kinetics are consistent with a Langmuir-Hinshelwood type mechanism involving competitive adsorption of CH4, 0, and CO, on a single site. A comparison is made with previously published results for the Li/MgO material.

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Section: Introductionsupporting

confidence: 79%

“…this poisoning probably arises from competitive adsorption of the CO, with the methane and/or the oxygen [4,9].…”

Section: Catnlvst Prenarationmentioning

confidence: 99%

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A study of the kinetics of the oxidative coupling of methane over a Li/Sn/MgO catalyst

et al. 1990

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“…We have previously presented results which suggested a possible model for the reactions which occur on the surface ofa Li/MgO catalyst [5 ]. Active sites are created on the surface in the presence of oxygen by the gradual loss of carbon dioxide from surface lithium carbonate species.…”

Section: Introductionmentioning

confidence: 99%

“…The partial oxidation of methane to form C2 and higher hydrocarbons is an alternative to the conversion of methane into synthesis gas (by steam reforming or partial oxidation) and subsequent reaction of the synthesis gas to produce refinery or petrochemical feedstocks [1][2][3][4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Lithium chemistry of lithium doped magnesium oxide catalysts used in the oxidative coupling of methane

et al. 1990

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Active sites are created on the surface of a Li/MgO catalyst used for the selective oxidation of methane by the gradual loss of carbondioxide from surface carbonate species in the presence of oxygen. Decomposition of the carbonat~ species in the absence of oxygen is detrimental to the activity of the cataIy~t. The active sites'created are not stable but disappear either as a result of reaction with SiO2~ fort 0 Li2SiQ Dr by the formation and subsequent loss of the volatile compound LiOH. hug~neral th~adAti~on of water to the gas feed is detrimental to the stability of the catalyst. In the case of Li2CO3 strongly bonded on the surface of Li/MgO catalyst, the decomposition of the carbo~te and thus the initial activity, can be enhanced by the addition of water to the gas feed. The addi~bn-of carbon dioxide to the gas feed results in a poisoning of the catalyst, the degree of this poisoning depending on the activity of the catalyst. The deactivation of the catalyst can be retarded if low concentration of carbon dioxide are added to the reaction mixture. It is possible to improve the stability of the catalyst by periodic reversal of the direction of flow of the gas steam.

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Influence of precursors of Li2O and MgO on surface and catalytic properties of Li-promoted MgO in oxidative coupling of methane

Choudhary¹,

Mulla²,

Pandit³

et al. 2000

J. Chem. Technol. Biotechnol.

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The in¯uence of the catalyst precursors (for Li 2 O and MgO) used in the preparation of Lidoped MgO (Li/Mg = 0.1) on its surface properties (viz basicity, CO 2 content and surface area) and activity/selectivity in the oxidative coupling of methane (OCM) process at 650±750°C (CH 4 /O 2 feed ratio = 3.0±8.0 and space velocity = 5140±20550 cm 3 g À1 h À1 ) has been investigated. The surface and catalytic properties are found to be strongly affected by the precursor for Li 2 O (viz lithium nitrate, lithium ethanoate and lithium carbonate) and MgO (viz magnesium nitrate, magnesium hydroxide prepared by different methods, magnesium carbonate, magnesium oxide and magnesium ethanoate). Among the Li±MgO (Li/MgO = 0.1) catalysts, the Li±MgO catalyst prepared using lithium carbonate and magnesium hydroxide (prepared by the precipitation from magnesium sulfate by ammonia solution) and lithium ethanoate and magnesium acetate shows high surface area and basicity, respectively. The catalysts prepared using lithium ethanoate and magnesium ethanoate, and lithium nitrate and magnesium nitrate have very high and almost no CO 2 contents, respectively. The catalysts prepared using lithium ethanoate or carbonate as precursor for Li 2 O, and magnesium carbonate or ethanoate, as precursor for MgO, showed a good and comparable performance in the OCM process. The performance of the other catalysts was inferior. No direct relationship between the basicity of Lidoped MgO or surface area and its catalytic activity/selectivity in the OCM process was, however, observed.

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Oxidative coupling of methane over lithium doped magnesium oxide catalysts

Cited by 83 publications

References 4 publications

A study of the kinetics of the oxidative coupling of methane over a Li/Sn/MgO catalyst

A study of the kinetics of the oxidative coupling of methane over a Li/Sn/MgO catalyst

Lithium chemistry of lithium doped magnesium oxide catalysts used in the oxidative coupling of methane

Influence of precursors of Li2O and MgO on surface and catalytic properties of Li-promoted MgO in oxidative coupling of methane

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