Utilize este identificador para referenciar este registo: http://hdl.handle.net/10362/13934
Título: Ageing on commercial automotive catalysts, a structure reactivity study
Autor: Furtado, Nélida Sofia Tavares
Orientador: Costa, Patrick
Eusébio, Mário
Palavras-chave: Diesel exhaust oxidation catalyst
Hydrothermal aging
Synthetic gas bench
Structure characterization
Methane oxidation
Data de Defesa: Nov-2014
Resumo: Increasingly stringed regulations for diesel engine emissions have a significant impact on the required efficiency of DOC. Lowered DOC oxidation efficiency due to thermal aging effects influences the efficiency of the exhaust aftertreatment systems downstream of the DOC. In this work carried out in the Jean Le Rond d’Alembert Institute the effect of hydrothermal aging on the reactivity and structure of a commercial DOC was investigated. The characterization of the catalytic performance was carried out on a synthetic gas bench using carrots catalyst under conditions close to the realistic conditions i.e. using a synthetic gas mixture, representative of the exhaust gases from diesel engines. Different structural characterization techniques were performed: textural and morphological proprieties were analyzed by BET and TEM, the characterization of the presented crystallographic phases was performed by DRX and the determination of the number of reducible species was possible by TPR. TEM results shown, an increase of the metal particle size with the aging caused by the agglomeration of metal particles, revealing the presence of metal sintering. DRX results also suggest the presence of support sintering. Furthermore, DRX and BET results unexpectedly reveal that the most drastic aging conditions used actually activated the catalyst surface. As expected, the aging affected negatively the catalyst performance on the oxidation of methane and CO, however an improvement of the NO oxidation performance with the aging was observed. Nevertheless, for the aging conditions used, catalytic activity results show that the influence of aging in DOC performance was not significant, and therefore, more drastic aging conditions must be used.
URI: http://hdl.handle.net/10362/13934
Designação: Dissertação
Aparece nas colecções:FCT: DQ - Dissertações de Mestrado

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