MEASUREMENT OF GAS-COMPOSITION AT THE CENTER OF A POROUS PELLET DURING ADSORPTION AND CATALYTIC REACTION UNDER DYNAMIC CONDITIONS

Gas composition is measured at the center of one-dimensional porous pl atinum/alumina pellets during carbon monoxide adsorption and catalytic oxidation. The apparatus is based on a single-pellet diffusion reacto r that has been modified to allow continuous gas analysis and miniatur ized in order to reduce the time constants of gas flow and mixing. Ana lysis of the CO adsorption response demonstrates that the centerplane volume and sample leak perturb the system only slightly and in a manne r that can be accounted for during data analysis. A detailed kinetic m odel described previously is able to predict the qualitative features of the external concentration responses during carbon monoxide oxidati on. However, the model is not able to predict major features of the re sponses measured at the pellet center, demonstrating that the reactor is able to provide stricter tests of kinetic models than reactors in w hich only external compositions can be measured. (C) 1997 Academic Pre ss.