Ce离子对苯在Y分子筛上吸附扩散行为的影响

Effect of Ce ion on adsorption and diffusion behavior of benzene in Y zeolite

采用液相离子交换法制备了不同稀土含量的Y型分子筛(HY、USY和NaY),研究了稀土铈(Ce)阳离子在Y型分子筛上吸附-脱附烃类分子(苯)过程中的作用机理与影响。通过X射线荧光光谱仪(XRF)、智能质量分析仪(IGA)、脱附指数的计算和巨正则蒙特卡罗模拟计算等多种表征计算方法,对引入稀土物种后,Y型分子筛对苯的饱和吸附量、吸附作用力、脱附热力学参数、苯在Y分子筛上的吸附势能分布及扩散行为等方面进行了研究。结果表明,Ce离子对苯在Y分子筛上脱附活化能的降低、吸附作用力的减弱以及吸附态由团聚态向分散态转变等方面具有显著影响,该作用构成了CeY分子筛催化剂在流化催化裂化(FCC)过程中能够优化轻质产品选择性的重要因素。

The liquid ion exchange method was employed to prepare cerium（Ce） cation modified Y zeolite（CeY） with various amount of cerium using different types of Y zeolite（HY,USY and NaY） and characterized by X-ray fluorescence spectrometry（XRF）,intelligent gravimetric analyzer（IGA） and a molecular simulation technology（Grand Canonical Monte Carlo simulation,GCMC）.A novel calculation method of desorption index（DI） has also been proposed to study the influence of cerium cations on the processes of adsorption-desorption of hydrocarbon molecule（benzene） on the CeY zeolites.The saturated adsorption capacity of benzene,adsorption interaction,desorption thermodynamic parameters,potential distribution curves and diffusion processes of benzene in CeY zeolites were analyzed.The results indicate that Ce ion can reduce the desorption activation energy,weaken the adsorption interaction force between benzene and Y zeolites,and modulate the adsorbed state of benzene molecules from agglomerate state to dispersed state,which are main factors to optimize the product selectivity of light oil components in the fluid catalytic cracking（FCC） process with CeY zeolite catalyst.