Catalytic partial oxidation of methane rich mixtures in non-adiabatic monolith reactors

In this work the partial oxidation of hydrocarbons on a rhodium-based catalyst is studied experimentally and numerically. A unidimensional heterogeneous mathematical model for catalytic partial oxidation of hydrocarbons is applied to adiabatic and non-adiabatic honeycomb monolith reactors. The model is validated for the non-adiabatic case with good agreement against experimental measurements of temperature and species concentrations for three fuel compositions over a wide range of operating conditions. The influence of radiative heat losses on the non-adiabatic reactor performance is numerically investigated under varying operating conditions: fuel flow rate, air to fuel equivalence ratio and fuel composition. The radiative heat losses change the heat release relatively to the adiabatic configuration and a slightly more exothermic reaction pathway is observed. This higher chemical heat release points out a lower importance of endothermic reforming reactions in the overall chemical scheme justifying the lower outlet fuel conversion registered. It is also observed during non-adiabatic operation that the H-2 selectivity can present higher values than in adiabatic conditions. The potential of the non-adiabatic reactor configuration to improve catalyst thermal stability is confirmed since a significant decrease of surface hot spots in relation to adiabatic operation may occur. Copyright (c) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.