Soot oxidation activity of doped ceria. Influence of dopants.

Identifier:  TFG:1354

Handle: https://hdl.handle.net/20.500.11797/TFG1354

Authors:  Huertas Osta, Elisabet

Abstract:
Catalytic conversion of carbon monoxide (CO) and nitrogen oxides (NOx) has been studied due to its importance for reducing hazardous emissions of vehicles to the environment.Typically, the exhaust gases from automobiles are purified by a three-way catalyst (TWC) which aims at the simultaneous treatment of carbon monoxide, hydrocarbons and nitrogen oxides. Soot particles are released from diesel engine exhausts and they are dangerous for the environment and health. At the moment there are several solutions for this problem, but most of them need periodic regeneration to avoid the filters being blocked by the soot. However, the best solution is controlling this emissions by catalytic conversion of the particles to harmless CO2 and H2O. Designing advanced doped ceria materials has extensive uses in several environmental, energy and industrial catalytic applications. CeO2 has a significant oxygen storage capacity, relative ease of oxygen vacancy formation and a great facility to switch between the oxidation states of the cerium ion (Ce3+/Ce4+). The aim of this project has been to study different series of doped ceria catalysts using different dopants and preparation methods and testing them withthe soot oxidation catalysis. Various transition metals of varying size and reducibility namely, copper, iron and manganese have been selected as dopants. Different preparation methods for the synthesis of ceria-based nanomaterials have been employed: co-precipitation, hydrothermal synthesis and flame spray pyrolysis. The formation of homogeneous solid solutions and their respective physicochemical properties have been confirmed by employing XRD analysis and BET surface area measurements. The reaction we used for evaluating the catalysts, soot oxidation, was carried out using a thermogravimetric analyzer (TGA). This technique provided us with data about the standard oxidation temperature of soot without a catalyst, and the extent of the decrease of the oxidation temperature when a catalyst is added.