杂原子Y分子筛的二次合成及其吸附脱硫性能

采用液-固相同晶取代反应制备了骨架含Ga的Y型分子筛, 并对其吸附脱硫性能进行了研究. 在室温, 空速为7 h−1的条件下, 镓化Y型分子筛(Ga]AlY)处理噻吩、四氢噻吩、4,6-二甲基二苯并噻吩(4,6-DMDBT)正壬烷溶液(硫含量500 μg•g−1), 每克吸附剂吸附硫的量分别为7.7、17.4、14.5 mg. 采用密度泛函理论(DFT)中的广义梯度近似方法(GGA)计算各分子中硫原子上的电荷数, 噻吩中硫原子的电荷数为−0.159, 而4,6-DMDBT和四氢噻吩分别为−0.214、0.298. 四氢噻吩和4, 6-DMDBT中硫原子上的电子密度大于噻吩中硫原子上的电子密度, 这就使得四氢噻吩和4,6-DMDBT中的硫原子与吸附位间的作用会远大于噻吩中的硫原子与吸附位间的作用, 吸附容量必然会大很多. 采用Ga]AlY处理抚顺石油二厂的催化裂化汽油(硫含量：299 μg•g−1), 每克吸附剂处理2.1 mL汽油时, 处理后汽油的硫含量为54.8 μg•g−1, 说明Ga]AlY对汽油脱硫有一定的效果.

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 μg•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 μg•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 μg•g-1.