Containing Titanium Mesoporous Molecular Sieve Synthesis, Characterization And Catalytic Performance

Mesoporous MCM-41 reported by Mobil Corporation in 1992 has many advantages as follows: very high surface area, periodic hexagonal pore channels, tailoring of pore dimension, high chemical and thermal stability, facile modification of the surface properties, et al. So it has very wide potential applications in the catalytic chemistry and the adsorption-separation field. In this paper the novel synthesis and the catalytic properties of mesoporous materials are mainly investigatedFirstly MCM-41 is synthesized hydrothermally in alkaline condition with C16TMABr as template and TEOS as silica source, and is characterized by a variety of techniques including XRD, FT-IR, TEM, SEM, nitrogen adsorption measurements. The results show that the samples have the better periodicity and reliable reproductive ability when crystallization time is 3 days, ammonia or n-butylamine is used as alkali source, and C^TMABr/Si molar ratio is 0.14. It is also found that seed can accelerate the crystalline process even if the seed amount is very low. SBA-15 and HMS mesoporous materials have also been synthesized in large scale.Ti-MCM-41 has been synthesized with H2O2as the chelating agent to restrain the formation of non-framework titanium (TiO2) and increase the framework titanium amount. And a reasonable reaction network has been proposed to explain the chelate effect between Ti source and H2O2. The amount of hydrogen peroxide which chelated with titanium hydrolysate to form chelate complex is the key factor in the synthesis.Ti-containing micro-mesoporous complex sieve has been synthesized hydrothermally though the template self-assembling with Ti-Si gel as the microporous primary units. The results show that the final sample has micropore and mesopore at the same time, the particle shape is of abnormity and mostly Ti atoms are incorporated in the framework. Suitable aging treatment can accelerate the formation of mesopore, and it is more rapid in the high temperature. But aging treatment with too long time results in the disappearance of mesopore units. It is also ascertained that the proper crystallization temperature is around 100癈.Finally, the catalytic properties of Ti-containing molecular sieves are evaluated briefly in the vapor-phase epoxidation of propylene and the oxidative desulfurization with thiophene, dibenzothiophene as the model sulfide.