Avaliação de aditivos para remoção catalítica de SOx em unidades de fcc

• Autor(a) principal: Pereira, Hugo Borges
• Data de Publicação: 2007
• 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/1/11960
• topic: SOx removal additives; Hydrotalcites; FCC; Mg,Al-mixed oxides/spinels; Copper; Manganese; CeO2; Aditivos para remoção de SOx; Hidrotalcitas; FCC; Óxidos mistos/espinélios de Mg e Al; Cobre; Manganês; CeO2; CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA

The sulfur dioxide emissions are one of the most atmospheric pollutant and precursor of acid rain. A survey carried out by Petrobras shows that around 17% of the SOx emissions of its refineries derive from the FCC process. In recent years, the strengthening of environmental controls with more restrictive legislation turns the incorporation of additives for SOx removal into a low-cost alternative technique compared with other technologies of SOx abatement. The purpose of this work is to study additives composed by derivated hydrotalcite compounds with partial substitution of magnesium and aluminium for copper and/or manganese, and with or without dioxide cerium impregnation. The performance of these additives has been tested in a multi-proposal unit coupled with a micro-GC/TCD. In all the tests it was used a gas stream of 1700 ppm of SO2 and 1,5% O2 in He for the oxidative adsorption step and for the regeneration step a 30% H2 in He stream. In the first test, it was carried out an adsoprtion step at 720ºC for 10 minutes and a regeneration step at a 530ºC level, flollowed by an TPR until 800ºC. The cerium dioxide impregnated samples showed a better result for SO2 removal, which implies cerium may play a role as catalyst for SO2 to SO3 oxidation. The TPR results show cerium and manganese may diminish the temperature of sulfates reduction, besides copper samples releases more H2S gases. In the second test, the adsorption step was carry out at 720ºC for 35 minutes and the regeneration step at 650ºC for 5 minutes folloewd by a TPR until 800ºC. In short times reaction (5 or 10 min) the results confirm the positive effect of cerium in the SO2 oxidantion adsorption. However, for longer time reaction (35 min), it can t be observed a relationship between chemical composition of the aditive and the total amount of SOx removed. Additives were still tested in reaction-regeneration cycles in the same conditions of the second test described above. In general, the additives without copper in their composition has a life time minor than that with copper; possibly, because copper plays an important role in the additive regeneration