Otimização do processo de síntese da zeólita ZSM-22 a partir do método de gel seco

Abstract

ZSM-22 is a high-silica zeolite with a one-dimensional microporous structure, which performs remarkably as a selective form catalyst in industrial reactions. In general, a material synthesis in the presence of organic drivers and in dynamic systems. Because ZSM-22 is a metastable phase it is common to an occurrence of contaminating phases or even a presence of amorphous material in its structure from production systems in static systems. The HDMA / SiO2 (0.15, 0.3 and 0.6) is available in the present work and it is proposed to create a ZSM-22 synthesis system from the gelation method using a reaction mixture containing seeds of crystallization. , in the molar ratio OH-/ SiO2 (0.1 and 0.2), time (12-168 h) and crystallization temperature (140 and 160ºC), from two methods, not first, the dry gel intro In contact, with the steamer vapor, while no method 2 the dry gel and the driver are in direct contact. The obtained material was characterized by X-ray diffusion (XRD) methods and selected samples were characterized by thermogravimetric analysis (ATG-DTG), surface area analysis (BET) and programmed temperature desorption (TPD - NH3). From the obtained results it was observed that the increase of temperature and basicity increased the presence of contamination peaks of the samples, and as samples synthesized by the direct contact method (Method 2) between the driver and the dry gel showed higher peak intensities, higher surface area values and pore volume as samples synthesized by Method 1, and these areas and volumes also increased with increasing HDMA/ SiO2 ratio. It can thus be concluded that the reduction of the base and the temperature, besides the direct contact between the driver and the dry gel favor a formation of the pure and crystalline structure of the ZSM-22.