“EFEITO DA ADIÇÃO DE LANTÂNIO EM CATALISADORES DE ÓXIDO DE FERRO ISENTOS DE POTÁSSIO NA DESIDROGENAÇÃO DO ETILBENZENO”.

M. DE SANTANA SANTOS, S. G. MARCHETTI, A. ALBORNOZ, M. DO CARMO RANGEL.

Gramado, Rio Grande do Sul, Brasil,

Simposio; “XX Simposio Iberoamericano de Catálisis”; 2006

The ethylbenzene dehydrigenation in the presence of steam is the dominant technology for styrene production, one of the most important high value chemicals. The most widely used industrial catalysts comprise potassium-promoted iron oxide, which deactivates with time, due to potassium loss. In order to find alternative free-potassium catalysts, the effect of lanthanum on hematite-based catalysts was studied in this work. Samples with different amounts of lanthanum and with different precipitants were obtained. It was found that lanthanum led to the production of solids with small particles when ammonium hydroxide was used, a fact which was assigned to lanthanum species on the surface where they keep the hematite particles apart avoiding sinterization. On the other hand, bigger particles were produced with sodium hydroxide and sodium carbonate, which resulted in small apecific surface area. This was related with the sodium apecies which covered the surface imparing the lanthanum action. The most promising catalyst was that prepared with ammonium hydroxide and with La/Fe= 0,1, which showed the highest specific activity and the highest intrinsec activity.