Deuterium exchange reactions of isobutane, n-hexane and n-heptane catalyzed over platinum single crystal surfaces

Davis, S. M.; Somorjai, G.A.

doi:10.1021/j100232a019

Cited by 27 publications

(9 citation statements)

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“…Platinum single crystals of different orientation crystal faces have been used for H 2 /D 2 exchange [1][2][3], CO oxidation [4,5], and hydrocarbon conversion reactions like ethylene hydrogenation [6][7][8][9][10][11][12][13][14][15][16]. They revealed the surface structure sensitivity or insensitivity of different catalytic reactions, the roles of surface defects such as steps and kinks, and additives that are bonding or structure modifiers.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of platinum nanoparticles and nanowires by electron beam lithography (EBL) and nanoimprint lithography (NIL): comparison of ethylene hydrogenation kinetics

et al. 2005

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Electron beam lithography (EBL), size reduction lithography (SRL), and nanoimprint lithography (NIL) have been utilized to produce platinum nanoparticles and nanowires in the 20-60-nm size range on oxide films (SiO 2 and Al 2 O 3 ) deposited onto silicon wafers. A combination of characterization techniques (SEM, AFM, XPS, AES) has been used to determine size, spatial arrangement and cleanliness of these fabricated catalysts. Ethylene hydrogenation reaction studies have been carried out over these fabricated catalysts and have revealed major differences in turnover rates and activation energies of the different nanostructures when clean and when poisoned with carbon monoxide. The oxide-metal interfaces are implicated as important reaction sites that remain active when the metal sites are poisoned by adsorbed carbon monoxide.

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Section: Introductionmentioning

confidence: 99%

Fabrication of platinum nanoparticles and nanowires by electron beam lithography (EBL) and nanoimprint lithography (NIL): comparison of ethylene hydrogenation kinetics

et al. 2005

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“…This field developed rapidly by use of model catalysts, first single-crystal surfaces (7)(8)(9)(10)(11)(12), then monodispersed nanoclusters deposited on oxide surfaces by lithography techniques (13)(14)(15)(16)(17) (Fig. 1).…”

mentioning

confidence: 99%

Clusters, surfaces, and catalysis

Somorjai¹,

Contreras

Montano

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

245

187

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The surface science of heterogeneous metal catalysis uses model systems ranging from single crystals to monodispersed nanoparticles in the 1-10 nm range. Molecular studies reveal that bond activation (C-H, H-H, C-C, CAO) occurs at 300 K or below as the active metal sites simultaneously restructure. The strongly adsorbed molecules must be mobile to free up these sites for continued turnover of reaction. Oxide-metal interfaces are also active for catalytic turnover. Examples using C-H and CAO activation are described to demonstrate these properties. Future directions include synthesis, characterization, and reaction studies with 2D and 3D monodispersed metal nanoclusters to obtain 100% selectivity in multipath reactions. Investigations of the unique structural, dynamic, and electronic properties of nanoparticles are likely to have major impact in surface technologies. The fields of heterogeneous, enzyme, and homogeneous catalysis are likely to merge for the benefit of all three.catalytic bond activation ͉ high selectivity catalyst design ͉ molecular ingredients of catalysis M etal containing catalysts are clusters of 1-10 nm in size. These are grouped into three types: heterogeneous catalysts that are embedded in high surface area supports, usually oxides, to optimize their surface area and thus the number of molecules they produce per second and also to optimize their thermal and chemical stability. They are used mostly at high temperatures (400-800 K) and in the presence of vapor phase reactants and product molecules. Enzyme catalysts operate in solution, mostly in water near 300 K, and the metal-containing active sites are surrounded by proteins that maintain structural mobility (1). Homogeneous catalysts function in the same solution in which the reactant and product molecules are dissolved, mostly in organic solvents, and used in the 300-500 K temperature range. Because of the different operating conditions and for reasons of history, the three fields of catalysis developed independently and became separate fields of science within different subdisciplines of chemistry. Heterogeneous catalysis was practiced mostly by physical chemists and chemical engineers, enzyme catalysis by biochemists, and homogeneous catalysis by inorganic and organometallic chemists.Catalytic reactions are distinguished from stoichiometric reactions by having many turnovers per reacting active site producing 10 2 to 10 6 molecules per site. Some of these catalytic reactions are very fast. For instance, the catalytic oxidation of carbon monoxide (CO) produces thousands of CO 2 molecules per metal surface site per second above ignition where the exothermicity of the process makes it self-sustaining in temperature and the reaction rate is only limited by the speed of transport of molecules to and from the catalyst surface (2-4). Ethylene hydrogenation, another exothermic reaction, turns over to produce ethane Ϸ10 times per metal surface site per second at 300 K on Pt(111) (5). The catalytic conversion of n-hexane to benzene or to branched...

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“…All steps except the final step of hydrogenation of intermediate species, which is commonly considered rate-limiting, 9 were treated as reversible. We neglected HrD exchange reactions of propane and propylene that in principle may occur over platinum single crystal surfaces, 10 because otherwise, all conceivable distributions of deuterium labels in propane will be possible and the example would not serve the illustration. Moreover, deuterium exchange in propane can be ruled out at low temperatures.…”

Section: Horiuti᎐polanyi Mechanism For Propylene Hydrogenationmentioning

confidence: 99%

Systematic prediction of the products and intermediates of isotopic labeling in reaction pathway studies

Zeigarnik

Valdés-Pérez

1998

J. Comput. Chem.

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Deuterium exchange reactions of isobutane, n-hexane and n-heptane catalyzed over platinum single crystal surfaces

Cited by 27 publications

References 4 publications

Fabrication of platinum nanoparticles and nanowires by electron beam lithography (EBL) and nanoimprint lithography (NIL): comparison of ethylene hydrogenation kinetics

Fabrication of platinum nanoparticles and nanowires by electron beam lithography (EBL) and nanoimprint lithography (NIL): comparison of ethylene hydrogenation kinetics

Clusters, surfaces, and catalysis

Systematic prediction of the products and intermediates of isotopic labeling in reaction pathway studies

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