A reduced mechanism for methane and one-step rate expressions for fuel-lean catalytic combustion of small alkanes on noble metals

Journal Article · Fri Jun 15 00:00:00 EDT 2007 · Combustion and Flame

DOI:https://doi.org/10.1016/J.COMBUSTFLAME.2007.02.006· OSTI ID:20909783

Deshmukh, S R; Vlachos, D G ^[1]

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1. Department of Chemical Engineering and Center for Catalytic Science and Technology (CCST), University of Delaware, Newark, DE 19716-3110 (United States)

A reduced mechanism and a one-step rate expression for fuel-lean methane/air catalytic combustion on an Rh catalyst are proposed. These are developed from a detailed microkinetic model using a computer-aided model reduction strategy that employs reaction path analysis, sensitivity analysis, partial equilibrium analysis, and simple algebra to deduce the most abundant reaction intermediate and the rate-determining step. The mechanism and the one-step rate expression are then tested on Pt catalyst. It is found that the reaction proceeds effectively via the same mechanistic pathway on both noble metals, but the effective reaction orders differ due to the difference in the adsorption strength of oxygen. Based on the homologous series idea, the rate expression is extended to small alkanes (ethane and propane; butane is also briefly discussed) and is found to reasonably describe experimental data. Estimation of the relevant parameters in the rate expression for various fuels and catalysts using the semiempirical bond-order conservation theory, quantum mechanical density functional theory, and/or simple experiments is discussed. Finally, it is proposed that detailed microkinetic models with coverage-dependent parameters can assist in rationalizing the apparent discrepancies between experimental data from various research groups. (author)

• OSTI ID: 20909783
• Journal Information: Combustion and Flame, Vol. 149, Issue 4; Other Information: Elsevier Ltd. All rights reserved; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
08 HYDROGEN
METHANE
PLATINUM
RHODIUM
BUTANE
ETHANE
PROPANE
COMBUSTION
DENSITY FUNCTIONAL METHOD
AIR
CATALYSTS
OXYGEN
ADSORPTION
REACTION INTERMEDIATES
MATHEMATICAL MODELS
SENSITIVITY ANALYSIS
EQUILIBRIUM
COMPUTERIZED SIMULATION
CHEMICAL REACTION KINETICS
HYDROGEN PRODUCTION