Síntese de zeólita ZSM-5 a partir do caulim e preparação de catalisadores (Co/ZSM-5 e Co/Ru/ZSM-5) visando aplicação na reação de Fischer-Tropsch.

Abstract

This work had as objectives to prepare the ZSM-5 zeolite using calcined kaolin as a source of Si and Al and reduce the of template content (TPABr). Furthermore, impregnating Co and Ru promoter in the ZSM-5 zeolite content of 25% TPABr and evaluation in the Fischer-Tropsch (FT) synthesis. The samples were characterized by XRD, EDX, SEM, Physical Adsorption of N2 , FTIR and RTP. The FT synthesis was conducted at 220 °C, pressure of 20 bar using a molar ratio of H2/CO = 2 in the fixed bed reactor during a reaction time of 135 hours. The XRD analysis showed that the hydrothermal synthesis at 170 °C for 48 hours with calcined kaolin was sufficient to obtain a ZSM-5CC zeolite of high crystallinity considering content of 100, 75, 50 and 25% TPABr. In the sample without TPABr were observed only characteristic spectrum of amorphous material. After the impregnation and calcination process of the zeolite support with Co content of 15 to 20% was observed cobalt oxide species (C03O4) in the support structure, but the presence of ruthenium oxide in the catalysts 20%Co/0.5%Ru/ZSM-5 and 20%Co/0.5%Ru/ZSM-5CC was not observed, and this was attributed to the small percentage of impregnated metal. The physical adsorption of N2 revealed for the catalysts 20%Co/ZSM-5 and 20%Co/0.5%Ru/ZSM-5 a decrease in specific surface area compared to the ZSM-5 zeolite. When the catalyst 20%Co/ZSM-5CC was also observed a decrease in this parameter from the sample adopted as a support ZSM-5CC/25%TPABr. According to the performance of catalysts in the FT synthesis was concluded that the catalyst 20%Co/0.5%Ru/ZSM-5 showed the CO conversion values higher than 20%Co/ZSM-5 catalyst, but showed similar behavior, i.e, high selectivity to C5 + liquid hydrocarbons and low selectivity for C02 and C2-C4. The low methane production has also been considered to be significant in terms beneficial to the conditions of FT synthesis and in fixed bed reactor. With respect to the catalyst 20%Co/ZSM-5CC, this conversion values presented to CO very low, but a good stability and high selectivity to C5 +.