Supported Organoactinides. Surface Chemistry and Catalytic Properties of Alumina-Bound (Cyclopentadienyl)-and (Pentamethylcyclopentadienyl)thorium and -uranium Hydrocarbyls and Hydrides

Ming Yuan He; Tobin J. Marks; Guoxing Xiong; Paul J. Toscano; Robert L. Burwell

doi:10.1021/ja00289a016

Supported Organoactinides. Surface Chemistry and Catalytic Properties of Alumina-Bound (Cyclopentadienyl)-and (Pentamethylcyclopentadienyl)thorium and -uranium Hydrocarbyls and Hydrides

Ming Yuan He, Tobin J. Marks, Guoxing Xiong, Paul J. Toscano, Robert L. Burwell

Chemistry

Research output: Contribution to journal › Article › peer-review

107 Scopus citations

Abstract

This contribution reports a detailed, quantitative investigation of surface chemistry and catalysis involving selected organoactinides and partially dehydroxylated (PDA) or dehydroxylated (DA) alumina supports. For the complexes Cp'₂M(CH₃)₂and Cp'₂M(CD₃)₂(Cp' = η⁵-(CH₃)₅C₅; M = Th, U), methane-evolving surface reaction pathways are identified as M-CH₃protonolysis via surface OH (especially on PDA), Cp' H atom abstraction, and intramolecular elimination of methane within M(CH₃)₂units. This latter process is proposed on the basis of methylene transfer to acetone and some olefin metathesis activity to result in Al³⁺-stabilized alkylidenes. Hydrogenolysis studies indicate that ca. 25% of the Cp'₂M(CH₃)₂/DA surface M-CH₃groups are removable as methane; reduction of methyl chloride to methane confirms the presence of surface M-H groups produced by hydrogenolysis. The Cp'₂M(CH₃)₂/DA complexes are active catalysts for propylene hydrogenation following a variety of pretreatment conditions, with N_x≈ 0.5 s^-1in a flow reactor at -63 °C (about 10 times more active than typical Pt/Si0₂catalysts under the same conditions). M = Th and U are comparable in hydrogenation activity, and CO poisoning experiments indicate that ca. 3% of the adsorbed molecules is catalytically active. Cp'₂M(CH₃)₂complexes on PDA and silica gel are considerably less active catalysts. The Cp'₂M(CH₃)₂/DA systems are also active catalysts for ethylene polymerization and weakly active for butene isomerization. Experiments with Cp'₂Th[CH₂C(CH₃)₃]₂and [Cp'₂Th(μ-H)H]₂on DA reveal activity for propylene hydrogenation comparable to the Cp'₂M(CH₃)₂systems. In contrast, more coordinatively saturated Cp₃UCH₃and Cp₃Th(n-C₄H₉) (Cp = η⁵-C₅H₅) are far less active, while Cp'Th(CH₂C₆H₅)₃is far more active (N_t≈ 10 s^-1). Much of the stoichiometric and catalytic surface chemistry can be understood in terms of solution organoactinide reactivity patterns.

Original language	English (US)
Pages (from-to)	641-652
Number of pages	12
Journal	Journal of the American Chemical Society
Volume	107
Issue number	3
DOIs	https://doi.org/10.1021/ja00289a016
State	Published - Feb 1985

ASJC Scopus subject areas

Catalysis
General Chemistry
Biochemistry
Colloid and Surface Chemistry

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10.1021/ja00289a016

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@article{515dc1bcf943470b9d47ff644dc5673c,

title = "Supported Organoactinides. Surface Chemistry and Catalytic Properties of Alumina-Bound (Cyclopentadienyl)-and (Pentamethylcyclopentadienyl)thorium and -uranium Hydrocarbyls and Hydrides",

abstract = "This contribution reports a detailed, quantitative investigation of surface chemistry and catalysis involving selected organoactinides and partially dehydroxylated (PDA) or dehydroxylated (DA) alumina supports. For the complexes Cp'2M(CH3)2and Cp'2M(CD3)2(Cp' = η5-(CH3)5C5; M = Th, U), methane-evolving surface reaction pathways are identified as M-CH3protonolysis via surface OH (especially on PDA), Cp' H atom abstraction, and intramolecular elimination of methane within M(CH3)2units. This latter process is proposed on the basis of methylene transfer to acetone and some olefin metathesis activity to result in Al3+-stabilized alkylidenes. Hydrogenolysis studies indicate that ca. 25% of the Cp'2M(CH3)2/DA surface M-CH3groups are removable as methane; reduction of methyl chloride to methane confirms the presence of surface M-H groups produced by hydrogenolysis. The Cp'2M(CH3)2/DA complexes are active catalysts for propylene hydrogenation following a variety of pretreatment conditions, with Nx≈ 0.5 s-1in a flow reactor at -63 °C (about 10 times more active than typical Pt/Si02catalysts under the same conditions). M = Th and U are comparable in hydrogenation activity, and CO poisoning experiments indicate that ca. 3% of the adsorbed molecules is catalytically active. Cp'2M(CH3)2complexes on PDA and silica gel are considerably less active catalysts. The Cp'2M(CH3)2/DA systems are also active catalysts for ethylene polymerization and weakly active for butene isomerization. Experiments with Cp'2Th[CH2C(CH3)3]2and [Cp'2Th(μ-H)H]2on DA reveal activity for propylene hydrogenation comparable to the Cp'2M(CH3)2systems. In contrast, more coordinatively saturated Cp3UCH3and Cp3Th(n-C4H9) (Cp = η5-C5H5) are far less active, while Cp'Th(CH2C6H5)3is far more active (Nt≈ 10 s-1). Much of the stoichiometric and catalytic surface chemistry can be understood in terms of solution organoactinide reactivity patterns.",

author = "He, {Ming Yuan} and Marks, {Tobin J.} and Guoxing Xiong and Toscano, {Paul J.} and Burwell, {Robert L.}",

year = "1985",

month = feb,

doi = "10.1021/ja00289a016",

language = "English (US)",

volume = "107",

pages = "641--652",

journal = "Journal of the American Chemical Society",

issn = "0002-7863",

publisher = "American Chemical Society",

number = "3",

}

Supported Organoactinides. Surface Chemistry and Catalytic Properties of Alumina-Bound (Cyclopentadienyl)-and (Pentamethylcyclopentadienyl)thorium and -uranium Hydrocarbyls and Hydrides. / He, Ming Yuan; Marks, Tobin J.; Xiong, Guoxing et al.
In: Journal of the American Chemical Society, Vol. 107, No. 3, 02.1985, p. 641-652.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Supported Organoactinides. Surface Chemistry and Catalytic Properties of Alumina-Bound (Cyclopentadienyl)-and (Pentamethylcyclopentadienyl)thorium and -uranium Hydrocarbyls and Hydrides

AU - He, Ming Yuan

AU - Marks, Tobin J.

AU - Xiong, Guoxing

AU - Toscano, Paul J.

AU - Burwell, Robert L.

PY - 1985/2

Y1 - 1985/2

N2 - This contribution reports a detailed, quantitative investigation of surface chemistry and catalysis involving selected organoactinides and partially dehydroxylated (PDA) or dehydroxylated (DA) alumina supports. For the complexes Cp'2M(CH3)2and Cp'2M(CD3)2(Cp' = η5-(CH3)5C5; M = Th, U), methane-evolving surface reaction pathways are identified as M-CH3protonolysis via surface OH (especially on PDA), Cp' H atom abstraction, and intramolecular elimination of methane within M(CH3)2units. This latter process is proposed on the basis of methylene transfer to acetone and some olefin metathesis activity to result in Al3+-stabilized alkylidenes. Hydrogenolysis studies indicate that ca. 25% of the Cp'2M(CH3)2/DA surface M-CH3groups are removable as methane; reduction of methyl chloride to methane confirms the presence of surface M-H groups produced by hydrogenolysis. The Cp'2M(CH3)2/DA complexes are active catalysts for propylene hydrogenation following a variety of pretreatment conditions, with Nx≈ 0.5 s-1in a flow reactor at -63 °C (about 10 times more active than typical Pt/Si02catalysts under the same conditions). M = Th and U are comparable in hydrogenation activity, and CO poisoning experiments indicate that ca. 3% of the adsorbed molecules is catalytically active. Cp'2M(CH3)2complexes on PDA and silica gel are considerably less active catalysts. The Cp'2M(CH3)2/DA systems are also active catalysts for ethylene polymerization and weakly active for butene isomerization. Experiments with Cp'2Th[CH2C(CH3)3]2and [Cp'2Th(μ-H)H]2on DA reveal activity for propylene hydrogenation comparable to the Cp'2M(CH3)2systems. In contrast, more coordinatively saturated Cp3UCH3and Cp3Th(n-C4H9) (Cp = η5-C5H5) are far less active, while Cp'Th(CH2C6H5)3is far more active (Nt≈ 10 s-1). Much of the stoichiometric and catalytic surface chemistry can be understood in terms of solution organoactinide reactivity patterns.

AB - This contribution reports a detailed, quantitative investigation of surface chemistry and catalysis involving selected organoactinides and partially dehydroxylated (PDA) or dehydroxylated (DA) alumina supports. For the complexes Cp'2M(CH3)2and Cp'2M(CD3)2(Cp' = η5-(CH3)5C5; M = Th, U), methane-evolving surface reaction pathways are identified as M-CH3protonolysis via surface OH (especially on PDA), Cp' H atom abstraction, and intramolecular elimination of methane within M(CH3)2units. This latter process is proposed on the basis of methylene transfer to acetone and some olefin metathesis activity to result in Al3+-stabilized alkylidenes. Hydrogenolysis studies indicate that ca. 25% of the Cp'2M(CH3)2/DA surface M-CH3groups are removable as methane; reduction of methyl chloride to methane confirms the presence of surface M-H groups produced by hydrogenolysis. The Cp'2M(CH3)2/DA complexes are active catalysts for propylene hydrogenation following a variety of pretreatment conditions, with Nx≈ 0.5 s-1in a flow reactor at -63 °C (about 10 times more active than typical Pt/Si02catalysts under the same conditions). M = Th and U are comparable in hydrogenation activity, and CO poisoning experiments indicate that ca. 3% of the adsorbed molecules is catalytically active. Cp'2M(CH3)2complexes on PDA and silica gel are considerably less active catalysts. The Cp'2M(CH3)2/DA systems are also active catalysts for ethylene polymerization and weakly active for butene isomerization. Experiments with Cp'2Th[CH2C(CH3)3]2and [Cp'2Th(μ-H)H]2on DA reveal activity for propylene hydrogenation comparable to the Cp'2M(CH3)2systems. In contrast, more coordinatively saturated Cp3UCH3and Cp3Th(n-C4H9) (Cp = η5-C5H5) are far less active, while Cp'Th(CH2C6H5)3is far more active (Nt≈ 10 s-1). Much of the stoichiometric and catalytic surface chemistry can be understood in terms of solution organoactinide reactivity patterns.

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U2 - 10.1021/ja00289a016

DO - 10.1021/ja00289a016

M3 - Article

AN - SCOPUS:0022419685

SN - 0002-7863

VL - 107

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EP - 652

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

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Supported Organoactinides. Surface Chemistry and Catalytic Properties of Alumina-Bound (Cyclopentadienyl)-and (Pentamethylcyclopentadienyl)thorium and -uranium Hydrocarbyls and Hydrides

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