A Comparative Experimental and Numerical Investigation of the Heterogeneous and Homogeneous Combustion Characteristics of Fuel-Rich Methane Mixtures over Rhodium and Platinum


The heterogeneous and homogeneous combustion of fuel-rich CH4/O2/N2/CO2 mixtures (φ = 1.8-3.5) was studied at 5 bar in an optically accessible channel-flow reactor which was coated with either Rh or Pt and involved in situ spatially-resolved Raman measurements of major gas-phase species concentrations for the evaluation of the heterogeneous processes and planar laser induced fluorescence of formaldehyde for the assessment of homogeneous combustion. Simulations were performed with an elliptic two-dimensional code that included detailed heterogeneous and homogeneous chemical reaction mechanisms. The surface reaction mechanism for Rh modestly overpredicted the formation of partial oxidation products (H2/CO) and underpredicted the total oxidation products (H2O/CO2) at φ ≥ 3.0. Rhodium was superior to Pt in syngas production and maintained a good catalytic partial oxidation capacity even at the low φ = 1.8 where Pt exhibited minimal H2/CO yields. The higher syngas production in Rh and in particular of the highly reactive hydrogen had a drastic impact on the ensuing gas-phase combustion characteristics. Homogeneous combustion did not affect the reactor thermal management and that it promoted the syngas yields at the reactor outlet. The presence of gaseous combustion in Rh substantially reduced the oxidation zone length such that the reforming action could be initiated farther upstream.


Mechanical and Aerospace Engineering

Keywords and Phrases

Catalytic partial oxidation of methane on rhodium and platinum; Homogeneous ignition in catalytic partial oxidation; Planar laser induced fluorescence of formaldehyde; Raman measurements; Syngas production

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Article - Journal

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© 2017 Elsevier Ltd, All rights reserved.

Publication Date

01 Mar 2017