Steps in CH<sub>4</sub> oxidation on Pt and Rh surfaces: High‐temperature reactor simulations

AICHE Journal - Tập 39 Số 7 - Trang 1164-1177 - 1993
Daniel A. Hickman1, L.D. Schmidt1
1Dept. of Chemical Engineering and Materials Science University of Minnesota Minneapolis MN, 55455

Tóm tắt

AbstractThe direct oxidation of CH4 to H2 and CO in O2 and in air at high temperatures over alumina foam monoliths coated with high loadings of Pt and Rh has been simulated using a 19‐elementary‐step model of adsorption, desorption and surface reaction steps with reaction parameters from the literature or from fits to previous experiments. The surface reaction model for Pt is in good agreement with previously reported low‐pressure(0.1 to 1 torr) reactor measurements of CH4 oxidation rates at temperatures from 600 to 1,500 K and of OH radical desorption during CH4 oxidation at 1,300 to 1,600 K over polycrystalline Pt foils. The model predictions for both catalysts are also consistent with product selectivities observed over monolithic catalysts in an atmospheric‐pressure laboratory‐scale reactor, and the differences between Pt and Rh can be explained by comparing individual reaction steps on these surfaces. Because of the good agreement between the model and both low‐and atmospheric‐pressure reactor simulations, a complete energy diagram for methane oxidation at low coverages is proposed. The model results show that under CH4rich conditions at high temperatures, H2 and CO are primary products of the direct oxidation of methane via a pyrolysis mechanism.

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Tài liệu tham khảo

10.1021/j100314a043

10.1016/0039-6028(89)90235-5

10.1016/0039-6028(84)90149-3

10.1021/j100329a030

10.1063/1.452886

10.1063/1.455224

10.1021/j100480a015

10.1063/1.440029

10.1016/0039-6028(81)90621-X

10.1016/0039-6028(78)90444-2

Cussler E. L., 1984, Diffusion: Mass Transfer in Fluid Systems

10.1016/0039-6028(88)90603-6

10.1016/0039-6028(80)90018-7

Gear C. W., 1971, Numerical Initial Value Problems in Ordinary Differential Equations

10.1063/1.444801

Hasenberg D.“HCN Synthesis on Polycrystalline Platinum and Rhodium ” PhD Thesis Univ. of Minnesota (1984);.

10.1002/aic.690220310

10.1016/S0039-6028(87)80521-6

10.1007/BF00766145

10.1016/0021-9517(92)90022-A

10.1016/0021-9517(92)90063-N

10.1016/0009-2509(87)85012-1

10.1016/0039-6028(85)90688-0

Kislyuk M. U., 1991, Reaction of Oxygen with Carbon on a Platinum Surface and the Spatial Distribution of the Carbon Monoxide Produced, Kinet. Catal., 31, 1219

10.1016/0039-6028(86)90266-9

10.1063/1.456132

10.1016/0009-2614(91)90265-B

10.1016/0039-6028(85)90674-0

10.1016/0039-6028(77)90301-6

10.1016/0021-9517(86)90103-X

10.1016/0021-9517(91)90310-Z

10.1016/0021-9517(91)90149-X

10.1063/1.461508

10.1016/0039-6028(83)90310-2

10.1016/0009-2509(90)80059-N

10.1021/j100281a027

10.1063/1.430415

10.1116/1.576712

10.1016/0039-6028(79)90279-6

10.1063/1.440097

10.1016/0009-2509(75)85122-0

10.1016/S0039-6028(87)81052-X

Wagner M. L. andL. D.Schmidt “Model Oxidation Reactions: The Coadsorption of O2with H2 NH3and N2H4on Rh(111) ” J. Phys. in press (1993).

10.1021/j100193a051

10.1016/0021-9517(89)90133-4

10.1016/0039-6028(79)90317-0

10.1002/aic.690220216

10.1021/j100105a016

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AICHE Journal

Tập 39 Số 7

1164-1177

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