A kinetic study of ammonia oxidation on a Pt catalyst in the explosive region in a microstructured reactor/heat-exchanger

The application of an aluminum-based microstructured reactor/heat-exchanger for measuring reaction kinetics in the explosive region is presented. Platinum-catalyzed ammonia oxidn. was chosen as a test reaction to demonstrate the feasibility of the method. The reaction kinetics was investigated in a wide range of conditions [NH3 partial pressure: 0.03-0.20 atm, O2 partial pressure: 0.10-0.88 atm; reactant flow 2000-3000 cm3 min-1 (STP); temp. 240-360 DegC] over a supported Pt/Al2O3 catalyst (mass of Al2O3 layer in the reactor, 1.95 mg; Pt/Al molar ratio, 0.71; Pt dispersion, 20%). The max. temp. non-uniformity in the microstructured reactor was ca. 5 DegC, even at conditions corresponding to an adiabatic temp. rise of 1400 DegC. Based on the data obtained, a previous kinetic model for ammonia oxidn. was extended. The modified 13-step model describes the data in a considerably wider range of conditions including those with high ammonia loadings and high reaction temps. The results indicate the large potential of microstructured devices as reliable tools for kinetic research of highly exothermic reactions. [on SciFinder (R)]