Deep Desulfurization By Selective Adsorption On A Heteroatoms Zeolite Prepared By Secondary Synthesis

Adsorptive desulfurization was a new method to remove sulfur compounds from the transportation fuels. The governments in many countries had paid attention to adsorptive desulfurization in that it would be accomplished at lower temperature and pressure. The success in this method, however, depended on the development of highly selective adsorbents. It was possible to obtain fine results and new mechanism if the heteroatom zeolites could be used to adsorption desulfurization.In this paper, the introduction of heteroatom gallium into the framework of a Y zeolite by the isomorphous substitution method had been reported and the desulfurization of various model fuels over the synthesized Y zeolite ([Ga]AlY) was studied. The charge on S atom of sulfide, calculated by using molecule simulation, was correlated to the sulfur adsorption capacity. The desulfurization over the synthesized CeMCM-41 zeolite was studied. At last, nanosized NaY zeolite had been synthesized inside the mesopore of carbon nanotube. A brief introduction was given as follows:In chapter 1, the adsorption desulfurization development was described in detail, The application and the synthesize method of the heteroatoms zeolites were also introduced.In chapter 2, NaY zeolite whose crystallinity was greater than 95% was synthesized . The NH4Y zeolite could be obtained by several times cation exchange of the NH₄⁺ form. [Ga]AlY with different content of gallium was synthesized from raw material NH4Y by using isomorphous substitution of heteroatoms. The cell parameter of [Ga]AlY, determined by XRD using the internal standard method, was 2.656 nm and that of NH₄Y was 2.547 nm, implying that the Ga atoms had been introduced into the framework of Y zeolite. The internal tetrahedral symmetrical stretching of IR showed a blue shift due to the substitution Ga for Al. ICP analysis showed that the aluminium content decreased from 11.9% for the NH4Y to 8.8 % for the [Ga]AlY. While the gallium content of [Ga]AlY was 4.3%. The results of ICP and IR indicated further that Ga had been substituted into the faujasitic framework.