Síntese de zeólita Y via tratamento hidrotérmico convencional e assistido por micro-ondas.

Abstract

In this study we investigated the hydrothermal synthesis of zeolite Y by two different methods: convencional heating and microwave assisted. An analysis of the influence of synthesis method and time of exposure to microwaves was performed. The samples were characterized by: X- ray diffraction (XRD), scanning electron microscopy (SEM), N2 adsorption (BET) and evaluated as catalysis in the production of biofuels. The results showed that when zeolitic gels are heated in a microwave oven, produce zeolite crystals much faster than when heated in a conventional oven, with only 60 minutes the time required to obtain the zeolite Y with good crystallinity by microwave while 72 hours was required by the conventional method. The size of the crystals of zeolite Y was the same for both methods of synthesis, this value is changed from 29 nm to 11 nm with decreasing temperature microwave synthesis from 100°C to 90°C. The sample synthesized by microwave had a greater surface area, of 476,2 m2/g, while that for conventional heating value was 413,1 m2/g. The morphological characteristics were also influenced by the heating method, microwave samples being more defined and uniform. As for the catalytic tests, zeolites synthesized by two synthesis methods showed low activity as catalysts in the cracking of soybean oil, need to optimize the conditions of pyrolysis. The use of microwave energy in the hydrothermal synthesis changed much of the characteristics of the powders obtained in relation to conventional hydrothermal synthesis, proving to be a promising method for the synthesis of zeolites. iii