Deep desulfurization by selective adsorption on heteroatom zeolite prepared by secondary synthesis

Gallium atoms had been introduced into the framework of Y zeolite by treatment of zeolites with an aqueous solution of ammonium hexafluoro gallate. At ambient conditions and space velocity of 7 h(-1), desulfurization of various model fuel, containing about 500 mu g . g(-1) sulfur was studied over the synthesized Y zeolite. Every gram adsorbent could adsorb 7.7, 17.4, 14.5 mg sulfur from thiophene, tetrahydrothiophene, 4, 6-dimethyldibenzothiophene (4, 6-DMDBT), respectively. The charge on S atom of thiophene, 4,6-DMDBT, and tetrahydrothiophene, calculated by using density functional theory (DFT), were -0.159, -0.214, and -0.298 respectively, implying that the S-M bond between the adsorption site and thiophene was much weaker than that between the adsorption site and tetrahydrothiophene or 4, 6-DMDBT. The synthesized Y zeolites were evaluated for the adsorptive desulfurization of the FCC gasoline (sulfur content: 299 mu g . g(-1)) supplied by the No.2 Refinery in Fushun. After 2.1 mL gasoline being treated in one gram adsorbent, the sulfur content was 54.8 mu g . g(-1).