摘要
针对分子筛吸附分离间/对甲酚异构体体系,筛选出分离系数较高的硅铝比为50的NaZSM-5分子筛,以不同浓度NaOH溶液作为碱处理试剂,成功制备出一系列具有多级孔结构的改性ZSM-5分子筛,并利用N_2吸附-脱附、X射线衍射表征(XRD)等手段对吸附剂进行了表征。通过静态和动态吸附实验,考察了改性ZSM-5分子筛吸附剂对间/对甲酚异构体的吸附分离性能,并探究了该过程的动力学原理。结果表明,以0.2 mol·L^(-1)NaOH溶液85℃下碱处理1 h得到的0.2-85-1分子筛成功引入了介孔,其存在增强了传质性能,从而提高了吸附速率,相较于处理前的分子筛样品,改性后的0.2-85-1分子筛对甲酚吸附平衡时间缩短了50%,最大处理量提升了50%(303 kg·m^(-3)·d^(-1)提升至454 kg·m^(-3)·d^(-1))。结合动力学拟合结果分析,间/对甲酚在0.2-85-1分子筛上的吸附行为符合拟二级动力学模型,速率常数相较于改性前样品提升了一个数量级。
For the adsorption separation of m/p⁃cresol isomers,NaZSM⁃5 molecular sieve with a Si/Al ratio of 50 was selected as precursor due to its superior separation factor.Accompanied by alkali⁃treatment in various concen⁃tration NaOH solutions,a series of modified ZSM⁃5 with hierarchical pores were successfully synthesized.The ad⁃sorbents were characterized by N2 adsorption⁃desorption and X⁃ray diffraction(XRD).Static and dynamic adsorp⁃tion experiments were employed to investigate the adsorption separation performance of such modified ZSM⁃5 adsor⁃bents,followed by kinetic principles analysis.From the results,compared with the bare molecular sieves,the ad⁃sorption rate of p⁃cresol on modified ZSM⁃5 especially that treated by 02 mol·L^(-1) NaOH solution at 85℃for 1 h,so⁃called 02⁃85⁃1 sample,was greatly enhanced.This improvement could be attributed to the enhanced mass trans⁃fer caused by introduced mesopores in 02⁃85⁃1.In detail,on 02⁃85⁃1,the adsorption equilibrium time for p⁃cresol was shortened by 50%,and its maximum adsorption capacity increased by 50%,from 303 kg·m^(-3)·d^(-1) to 454 kg·m^(-3)·d^(-1).In addition,according to the kinetic fitting results,the adsorption behaviors of p⁃cresol and m⁃cresol on the 02⁃85⁃1 were in accordance with pseudo⁃second⁃order kinetic model,confirming an order of magnitude in⁃crease in adsorption rate after alkali treatment.
作者
陈光敏
孙永杰
陈鹏飞
刘定华
刘晓勤
CHEN Guangmin;SUN Yongjie;CHEN Pengfei;LIU Dinghua;LIU Xiaoqin(College of Chemical Engineering,Nanjing Tech University,Nanjing 211800,China)
出处
《高校化学工程学报》
北大核心
2025年第3期401-409,共9页
Journal of Chemical Engineering of Chinese Universities
