A structured test reactor for the evaporation of methanol on the basis of a catalytic combustion

The kinetics of the catalytic deep oxidation of methanol was studied in stacked sagments of a turbulence insert (SSTIs) coated with Pt/gamma -Al2O3 and Pt/zeolite catalysts. These geometries, which are termed a structured test reactor in the heading, are intended to replace plane expanded metal discs (PEMDs) used in the so-called catalytic burner at Research Centre Julich, up to the present. The catalytic burner performs the low-pollution combustion inter alia of the anode exhaust gases of the fuel cell. SSTIs coated with Pt/gamma -Al2O3 showed different kinetics for differential conversions as a function of temperature. At low reaction temperatures (100-130 degreesC) ignition kinetics with a very high activation energy of 60.3 kJ/mol was found. In the further course of the reaction, the kinetically controlled reaction with an activation energy of 48.5 kJ/mol was observed. In the range of non-differential conversions, the activation energy decreased significantly, which suggests a limitation of the reaction process by mass transport phenomena. Compared to the PEMDs, clearly higher reaction rates were observed, which enable a reduction of the catalyst mass. This as well as the spatial structure of the SSTIs make it possible to achieve a reduction in volume and weight and thus improved dynamics in constructing a novel catalytic burner. The SSTIs coated with Pt/zeolite showed perceptibly lower reaction rates than the Pt/gamma Al2O3 substrates and could thus not compete with the PEMDs. (C) 2001 Elsevier Science B.V. All rights reserved.