Estudo das variáveis operacionais na síntese da peneira molecular mesoporosa Al-SBA-15

Abstract

A study was made of the synthesis of mesoporous SBA-15 molecular sieve in stirred autoclaves, with directly incorporated of aluminum. This synthesis gels were prepared with molar composition: 14 SiO2: 1 Al2O3: 0.235 P123: 1800 H2O. These gels were aged at 40 ° C for a certain time and then heated to 100 ° C. A study was made of the aging time, synthesis time, temperature and agitation in the synthesis of molecular sieve. The resulting samples were analyzed by X-ray diffraction (XRD), nitrogen adsorption– desorption at 77 K, transmission electron microscopy (TEM) and laser diffraction. It was observed that the aging of the synthesis gel for 15 hours at a temperature of 40 ° C significantly affect the textural properties of the samples. The samples showed no aging lower volume of mesopores and a pore size distribution wider than those obtained with aging. In the study of stirring, it was observed that the samples with more vigorous agitation had values slightly higher volume of mesopores. It was also observed that the samples were shaken formed in shorter times synthesis. The sample synthesized at a temperature above 120 ° C showed a value higher volume of mesopores and pores larger than those obtained at a temperature of 100 ° C. It was an experiment done by increasing the scale reactors 300mL to 5L reactors. It was observed that the sample resulting from this study had a volume of mesopores primary slightly lower than the sample obtained under similar conditions in reactors of 300mL. For transmission electron microscopy it was observed that the samples had mesopores regularly arranged in space