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Title: Ab Initio Studies of Coke Formation on Ni Catalysts During Methane Reforming

Abstract

The atomic-scale processes that control the formation of carbon deposits on Ni catalysts in reforming applications are poorly understood. Ab initio Density Functional Theory calculations have been used to examine several key elementary steps in the complex network of chemical reactions that precedes carbon formation on practical catalysts. Attention has been focused on the disproportionation of CO. A comparative study of this reaction on flat and stepped crystal planes of Ni has provided the first direct evidence that surface carbon formation is driven by elementary reactions occurring at defect sites on Ni catalysts. The adsorption and diffusion of atomic H on several flat and stepped Ni surfaces has also been characterized experimentally.

Authors:
Publication Date:
Research Org.:
Carnegie Mellon University
Sponsoring Org.:
USDOE
OSTI Identifier:
882882
DOE Contract Number:
FG26-02NT41538
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 03 NATURAL GAS; ADSORPTION; CARBON; CATALYSTS; CHEMICAL REACTIONS; COKE; DEFECTS; DIFFUSION; FUNCTIONALS; METHANE; OXIDATION; REDUCTION

Citation Formats

David S. Sholl. Ab Initio Studies of Coke Formation on Ni Catalysts During Methane Reforming. United States: N. p., 2006. Web. doi:10.2172/882882.
David S. Sholl. Ab Initio Studies of Coke Formation on Ni Catalysts During Methane Reforming. United States. doi:10.2172/882882.
David S. Sholl. Sun . "Ab Initio Studies of Coke Formation on Ni Catalysts During Methane Reforming". United States. doi:10.2172/882882. https://www.osti.gov/servlets/purl/882882.
@article{osti_882882,
title = {Ab Initio Studies of Coke Formation on Ni Catalysts During Methane Reforming},
author = {David S. Sholl},
abstractNote = {The atomic-scale processes that control the formation of carbon deposits on Ni catalysts in reforming applications are poorly understood. Ab initio Density Functional Theory calculations have been used to examine several key elementary steps in the complex network of chemical reactions that precedes carbon formation on practical catalysts. Attention has been focused on the disproportionation of CO. A comparative study of this reaction on flat and stepped crystal planes of Ni has provided the first direct evidence that surface carbon formation is driven by elementary reactions occurring at defect sites on Ni catalysts. The adsorption and diffusion of atomic H on several flat and stepped Ni surfaces has also been characterized experimentally.},
doi = {10.2172/882882},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Mar 05 00:00:00 EST 2006},
month = {Sun Mar 05 00:00:00 EST 2006}
}

Technical Report:

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  • The atomic-scale processes that control the formation of carbon deposits on Ni catalysts in reforming applications are poorly understood. Ab initio Density Functional Theory calculations have been used to examine several key elementary steps in the complex network of chemical reactions that precedes carbon formation on practical catalysts. Attention has been focused on the disproportionation of CO. A comparative study of this reaction on flat and stepped crystal planes of Ni has provided the first direct evidence that surface carbon formation is driven by elementary reactions occurring at defect sites on Ni catalysts.
  • The atomic-scale processes that control the formation of carbon deposits on Ni catalysts in reforming applications are poorly understood. Ab initio Density Functional Theory calculations have been used to examine several key elementary steps in the complex network of chemical reactions that precedes carbon formation on practical catalysts. Attention has been focused on the disproportionation of CO. A comparative study of this reaction on flat and stepped crystal planes of Ni has provided the first direct evidence that surface carbon formation is driven by elementary reactions occurring at defect sites on Ni catalysts. The adsorption and diffusion of atomic Hmore » on several flat and stepped Ni surfaces has also been characterized experimentally.« less
  • Cited by 7
  • The mechanism of carbon formation on nickel autothermal steam reforming catalysts has been studied by temperature-programming, thermogravimetric and electron microscopic techniques. Temperature-programmed surface reaction (TPSR) studies of carbon deposited on nickel reforming catalysts by the decomposition of C/sub 2/H/sub 4/ and C/sub 2/H/sub 2/ exhibit seven forms of carbon that are distinguished by their characteristic reactivity with H/sub 2/ and 3.0-vol % H/sub 2/O/He. The relative population of the different carbon states depends primarily on the temperature during deposition. C/sub 2/H/sub 2/ exposure populates the same carbon states as C/sub 2/H/sub 4/ exposure but at approximately 100/sup 0/K lower depositionmore » temperature. Similar carbon states were found on all nickel catalysts studies including Ni/..gamma..-Al/sub 2/O/sub 3/ and Ni/MgO-Al/sub 2/O/sub 3/ leading to the conclusion that the support has little effect on carbon deposit formation and reactivity. The reactivity of the carbon states is not altered by exposure to steam in C/sub 2/H/sub 4/-H/sub 2/O mixtures, but the amount of carbon deposited decreases to zero as H/sub 2/O/C increases past a critical ratio.« less