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 sta cked sagments of a turbulence insert (SSTIs) coated with Pt/gamma -Al2O3 an d Pt/zeolite catalysts. These geometries, which are termed a structured tes t reactor in the heading, are intended to replace plane expanded metal disc s (PEMDs) used in the so-called catalytic burner at Research Centre Julich, up to the present. The catalytic burner performs the low-pollution combust ion inter alia of the anode exhaust gases of the fuel cell. SSTIs coated wi th Pt/gamma -Al2O3 showed different kinetics for differential conversions a s 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 f ound. In the further course of the reaction, the kinetically controlled rea ction with an activation energy of 48.5 kJ/mol was observed. In the range o f non-differential conversions, the activation energy decreased significant ly, which suggests a limitation of the reaction process by mass transport p henomena. Compared to the PEMDs, clearly higher reaction rates were observe d, which enable a reduction of the catalyst mass. This as well as the spati al structure of the SSTIs make it possible to achieve a reduction in volume and weight and thus improved dynamics in constructing a novel catalytic bu rner. The SSTIs coated with Pt/zeolite showed perceptibly lower reaction ra tes than the Pt/gamma Al2O3 substrates and could thus not compete with the PEMDs. (C) 2001 Elsevier Science B.V. All rights reserved.