Cesium jako promotor Co3O4 pro katalytický rozklad N2O

Abstract

The aim of dissertation thesis is catalytic decomposition of N2O on Co3O4 spinel oxidic catalyst modified with cesium. For preparation of Co3O4 spinel, five methods using NaOH, aq. NH3 or Na2CO3 as precipitation agent, were used. These methods differed in time of precipitates maturation and time of precipitation agent adition Samples of the catalysts were characterized by several analytical methods – AAS, XRD, SBET, TPR-H2. The measurements of catalytic decomposition of N2O were performed in a laboratory stainless steel tubular reactor with integral bed of catalyst in temperature range 300 – 450 °C. From the group of five catalyst, two catalysts exhibiting the highest conversion of N2O were chosen for modification of surface with cesium promotor. Content of cesium was chosen in the range of 1-4 wt. %. The highest conversion of N2O was observed for cesium content of 1 wt. % for both catalysts. The further increase in cesium content led to lower conversion of N2O. It was found that cesium acts as electron promoter whereas its presence caused decrease in specific surface of the catalyst, improvement of catalyst reducibility and had influence on size of Co3O4 crystallites. On the basis of laboratory results, the method for preparation of semiproduction scale catalyst containing 1 wt.% of cesium was chosen. Prepared catalyst was tested in pilot plant processing waste gas from production of nitric acid in Borsod Chem company, Ostrava. Obtained results showed high activity of the catalyst for decomposition of N2O in real waste gas. Unfortunately, during the test significant decrease of mechanical resistence of catalyst tablets was observed.