Studium katalyzátorů pro rozklad oxidů dusíku

Abstract

Nitric oxide is among of the substances that significantly pollute the air. Together with nitrogen dioxide and other nitrogen oxides is nitric oxide responsible for the formation of acid rain, smog, or for decrease of stratospheric ozone. Most suitable way how to reduce the concentration of NO in the waste gas should be the catalytic decomposition N2 and O2, which are components that are a part of the atmosphere. This method of liquidation is so far not used, because till nowadays has not yet been found a catalyst which is sufficiently active, stable and selective in particular at temperatures that are economically feasible. In this diploma thesis have been studied activity, selectivity and stability of catalysts containing cobalt oxide K/Co4MnAlOx (AST2 – 100), Cs/ Co4MnAlOx (AST3), Cs/Co3O4 (AST4) and Na/ Co4MnAlOx for direct decomposition of NO. To characterize the physically - chemical properties of the catalysts have been used X-ray diffraction and specific surface area of catalysts. It was found that samples of the catalysts showed low conversion of NO during catalytic decomposition of NO in an inert at a temperature of 650 °C and a load of 0,6 g.s.cm-3 the NO conversion in the range of 7 – 22%, while the cesium-containing catalysts were less active in compared with a catalyst which contain potassium. All three catalysts were observed during experiments as unstable, which resulted in a decrease in NO conversion of long-term experiments. The reason of instability was probably alkali volatilization and variation of specific surface area of the catalysts due to high reaction temperatures. Selectivity of the decomposition of NO to N2 reached 100% in the temperature range from 650 to 540 °C in the presence of a catalyst AST2 – 100. In the presence of a catalyst AST3 was selectivity decomposition of NO to N2 100% in the temperature range from 650 to 550 °C. In the presence of N2O was conversion of NO in the temperatures range 650 to 530 °C lower in the comparison with the decomposition of NO in inert.