Nanostrukturované heterogenní katalyzátory na bázi TiO2, CeO2 a CuO pro katalytickou oxidaci těkavých organických látek

Abstract

The master thesis focuses on different preparation methods of powder oxide catalysts based on oxides of titanium, cerium, and copper in a combination with calcination, and their catalytic efficiency examination in oxidation of methanol and dichloromethane as model volatile organic compounds. The thesis consists of the theoretical part, methodology, results with discussion and conclusion. The theoretical part focuses on explaining of fundamental concepts needed to understand the subject of interes, and includes a literature review summarizing current knowledge on catalytic methanol and dichloromethane oxidation on TiO2,CeO2 and CuO-based catalysts. The methodology is devoted to preparation of individual powder catalysts, their characterization and measurement of oxidation reactions. Results with discussion part summarize key aspects related to catalyst characterization and their catalytic efficiency in oxidation of methanol and dichloromethane. The conclusion introduces key findings of the work. Powder catalysts were prepared by 3 different methods (coprecipitation, precipitation with impregnation, and sol-gel method) using the same molar ratios of Ti : Ce : Cu = 9 : 1 : 0,3. The effect of individual preparation methods of catalyst on catalyst physicochemical properties was evaluated by using a set of methods including nitrogen physisorption at 77 K, XRD, XRF, NH3-TPD a H2-TRP. Individual catalysts were examined in oxidation of methanol and dichloromethane, where their activity and selectivity to the formation of main products CO2 (in oxidation of methanol) and CO2 and HCl (in oxidation of dichloromethane) were assessed. Despite the similar chemical composition and detected crystalline phase of TiO2 anatase for all catalysts, it was found that the most acidic and reducible catalyst with the largest specific surface area as well as total pore volume was the TiO2/CeO2/CuO KoPre catalyst prepared by coprecipitation method. The CuO/TiO2-CeO2 ImPre catalyst, prepared by the coupled precipitation and impregnation method, showed the best catalytic performance in methanol oxidation due to well-reducible CuO on the surface of the TiO2-CeO2 carrier. In oxidation of dichloromethane, Cu+/Cu2+ incorporated into the −Ti-O2-Ce-O− structure was advantageous, leading to desired acidity and reducibility of the catalyst. The TiO2/CeO2/CuO KoPre and TiO2/CeO2/CuO Sol-Gel catalysts achieved the best results in dichloromethane oxidation, however, none of the catalysts achieved 100 % conversion of dichloromethane.