Influência da fase hidrotalcita de Cu-Al na redução do NO pelo CO

• Autor(a) principal: Corrêa, Carla Levi Oliveira
• Data de Publicação: 2015
• Outros Autores: [e-mail]
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/18909
• topic: Hydrotalcite; Malachite; Copper; Emission N2O; Catalizadores; Hidrotalcita; Cobre; Malaquita; Emissões de N2O; ENGENHARIAS::ENGENHARIA QUIMICA::PROCESSOS INDUSTRIAIS DE ENGENHARIA QUIMICA

In order to minimize the emission of pollutants in the atmosphere it has been made an effort in researching the copper-based catalysts as a cheaper alternative to traditional catalysts, which use noble metals. In this work, it was prepared catalysts from hydrotalcite like compounds in Cu-Al-CO3 system in order to apply them in the reduction reaction of NO by CO and thus to evaluate the conversion of reactants and yield to N2O and N2. The parameters in the synthesis of hydrotalcite type precursors such as the relative amount of water, metal (Cu and Al) ratio, pH and drying temperature were varied. The precursors were more sensitive to the relative amount of water, showing clearly the proportionality between this parameter with the purity of the precursor. The hydrotalcite type precursors were characterized by X-ray diffraction and thermal analysis techniques. Then, six of them were selected to be subjected to calcination and then to originate the catalysts, which were analyzed by X-ray diffraction, Raman spectroscopy, N2physisorption and chemical analysis by Inductively Coupled Plasma. Through X-ray diffraction and Raman spectroscopy the presence of CuO was identified, and by chemical analysis aluminum species(amorphous) was confirmed. The N2physisorption was used to quantify the surface area of the catalysts.One of the catalysts was selected to study its behavior in reaction after heat treatment at 900 °C and 1000 °C for 12 hours. The goal was to simulate the aging suffered by automotive catalysts. Additionally, the pretreatment with H2 flow in aged sample at 900 °C was done and subsequently tested in the reaction. The catalytic tests showed that when the catalyst has higher purity,lower is the formation of N2O, but the opposite happens when the copper ratio increases. Finally, it was observed that the thermal aging improved the activity of the catalyst and reduction pretreatment increases furtheractivity.