Estudo da ativação, pilarização da argila bentonita de Cubati e desativação do catalisador HZSM-5/BT.

Abstract

Clays are used as catalysts on several applications in the industry, in particular the petrochemical industry. One must expose them to chemical treatments in order to increase their catalytic activity. The variation of the specific surface of a material by an acid treatment aims to improve its capacity adsorbent. This work was carried out in three stages. In the first stage it was performed an activation acid of bentonite the Cubati city with HCI (3,0M) followed by characterizations employing several techniques : X-Ray Fluorescence (FRX) ; X-Ray Diffraction (DRX) ; Thermo Diferencial Analysis (ATD) ; Nitrogen Adsorption - BET Methond. It was noticed that the acid treatment modified the structure of the clay minerals. It was tested in the second stage the intercalation of the aluminium oligomers polyhidroxication within the layers of clay minerals smectite present in the bentonite the Cubati city. The intercalation was verified by chemical analysis (FRX) ; Thermo gravimetry analysis and Diferencial Thermal analysis (ATG/ATD). It was also assessed the pilarization of the bentonite the Cubati city wity polyhidroxiction the aluminium. To this end the basal distance of the layers 2 :1 was measured by X-Ray Diffraction. The third stage aimed to verify the system decativation composed by one solid with moderate acidity, such as the treaty smectite and another with medium porosity and high acidity, such as zeolite HZSM-5, by the coke formed during the m-xylene transformation at 350°C. The samples (HZSM-5, 25% HZSM-5, 50% HZSM-5, BT) were employed along the m-xylene transformation for 30 minutes in a reactor of fixe bed which were. The samples were characterized by nitrogen adsorption and coke analysis. From the measurements of capacity of adsorption one could find the isotherms of the type one, according to the BET classification. The results indicate that the presence of clay reduces the specific area and increases the percentage of total coke after the reaction.