CuNaY分子筛的有效吸附位与其脱硫性能的关联性研究

Insight into the correlation between the effective adsorption sites and adsorption desulfurization performance of CuNaY zeolite

以液相离子交换法制备了一系列不同Cu负载量的Cu Na Y分子筛;采用XRD及N2吸附-脱附表征分子筛的微观结构和织构性质,采用动态吸附法考察其对噻吩模拟油的吸附脱硫性能,结合NH_3-TPD和Py-FTIR方法对CuNaY分子筛的酸量和有效Cu^+物种进行定量分析,研究了CuNaY分子筛的表面酸性和铜物种形态结构对其吸附脱硫性能的影响机制。结果表明,通过改变铜负载量可有效调控改性Y分子筛的表面酸性以及铜物种化学形态;适量铜物种的引入可以最大限度的形成有效吸附位,从而获得最优吸附脱硫性能,而过量的Cu物种会在Y分子筛笼内形成多核铜物种结构,导致有效吸附位点的减少,影响其对噻吩的吸附能力。

A series of CuNaY zeolites with different Cu loadings were prepared from NaY by liquid-phase ion exchange(LPIE)method.The microstructure and textural properties of CuNaY zeolites were characterized by XRD and N 2 sorption and their adsorption desulfurization performance were evaluated with a model oil containing thiophene by the dynamic adsorption method.Combined with the Py-FTIR and NH 3-TPD methods,the amounts of surface acid sites and effective Cu+species were determined quantitatively and a correlation between the effective adsorption sites and adsorption desulfurization performance of CuNaY zeolite towards thiophene was then established.The results revealed that the surface acidity and the active copper species in Y zeolite can be regulated effectively by controlling the copper loading;an adsorbent provided with abundant effective adsorption sites and excellent adsorption desulfurization performance can be obtained by loading appropriate amount of copper.On the contrary,an excessively high copper loading may promote the formation of polymeric copper species in the cavity of Y zeolite,which leads to a decrease in the number of effective adsorption sites as well as a decrease in the adsorption capacity of CuNaY zeolite towards thiophene.