Tvarované katalyzátory s obsahem přechodných kovů a jejich účinnost pro katalytický rozklad N2O

Abstract

This diploma thesis deals with the catalytic decomposition of nitrous oxide (N2O). Nitrous oxide is considered as an important pollutant contributing to a greenhouse effect. N2O also belongs to the group of compounds depleting stratospheric ozone layer of Earth. Decomposition of N2O to natural components of atmosphere, N2 and O2, in the presence of suitable catalyst is the best possibility of nitrous oxide abatement. In this diploma thesis, laboratory experiments of catalytic decomposition of N2O (0.1 mol% N2O, 300-450 ° C) were compared to the catalytic activity of three groups of shaped catalysts containing active ingredient as a cobalt, manganese and cesium or a potassium as a promoter. These were mixed oxide Co4MnAlOy deposited on sieves of stainless steel, oxide CoxOy modified by cesium deposited on Al2O3 hollow tablets and tablets of the mixed oxide Co4MnAlOy. Chemical analysis, X-ray diffraction, nitrogen physisorption, scanning electron microscopy and temperature-programmed reduction with hydrogen were used to characterize the physicochemical properties of the catalysts. A mathematical model of a catalytic reactor was set. This model was verified by laboratory data of catalytic decomposition of N2O. The model was used for the simulative calculation of pilot test reactor for the catalytic decomposition of N2O placed in the plant of nitric acid in BC-MCHZ Ostrava. Results showed that, regardless the high specific activity (number of moles of N2O,which reacted on unitary amount of active components per time unit), catalysts supported on the sieves and the hollow tablets showed lower conversion of N2O in the model pilot plant reactor compared to tablets of mixed oxid Co4MnAlOy.