Síntese da Zeólita Zsm-22 a partir de sistema contendo sementes

Abstract

The ZSM-22 zeolite is a microporous crystalline structure which has dimensional solid belonging to the group called molecular sieves. It is common in their synthesis the use of structure direct agents (SDA's), also called direct organic only, which are costly and render the production of the material on an industrial scale. Furthermore, the crystallization times for the formation of the material are around 20 hours. In this work we propose the development of a synthesis route for the ZSM -22 more economically, from a reaction mixture free from organic director and containing seeds of crystallization. Seeds were synthesized by the hydrothermal method at 160 °C in the presence of 1,6- diaminohexane organic template. Samples of ZSM -22 was synthesized by hydrothermal and hydrosolvothermal at a temperature of 170 °C and fixed percentage of seeds (10%) methods, employing the following reagents: methanol, sodium silicate, aluminum sulfate, potassium hydroxide and sulfuric acid. Through systematic variations in synthesis parameters: content of methanol (0 and 4 mol), SiO2/Al2O3 ratio (50 and 100), alkalinity or basicity of the medium (0.2 and 0.4) and ratio of cations : Na + / Na + + K + ( 0 and 0.5) found that the best conditions for the formation of ZSM -22 . The products were characterized by diffraction X-ray method (XRD). According to the results of crystallinity, the best samples are also characterized by thermal analysis (TG/DTG), nitrogen adsorption at 77 K (BET) and scanning electron microscopy (SEM).