Silicalite-2材料吸附分离乙醇/水体系的实验和模拟研究  

EFFECT OF SILANOL GROUPS ON ADSORPTION AND SEPARATION OF EHTANOL/WATER MIXTURE BY SILICALITE-2: A MOLECULAR SIMLATION STUDY

作　　者：曹阳[1] 张琪[1] 徐荣[1] 钟璟[1,2] 

机构地区：[1]江苏省绿色催化材料与技术重点实验室,常州大学石油化工学院,常州213164 [2]常州大学盱眙凹土研发中心,盱眙211700

出　　处：《离子交换与吸附》2016年第5期423-432,共10页Ion Exchange and Adsorption

基　　金：国家自然基金(No.21276029);江苏省自然科学基金(BK20131142);江苏省“333”工程(BRA2015375);淮阴市产学研协同创新项目(HAC2015014)资助

摘　　要：以MEL型沸石分子筛分离回收有机物稀溶液为背景,从实验和模拟角度研究了乙醇/水体系在silicalite-2材料上的吸附行为。基于文献报道的晶体参数,采用密度泛函理论确定了silcalite-2构型以及含有硅羟基的silicalite-2构型,使用GCMC方法计算了乙醇和水在上述吸附剂上单组份吸附等温线,研究了硅羟基对吸附行为的影响,并应用理想溶液吸附理论(IAST)方法预测了silicalite-2吸附分离乙醇/水体系的分离因子。吸附等温线的实验和模拟结果显示,水吸附符合V型吸附等温线特征,乙醇吸附符合I型吸附等温线特征,硅羟基能够增强水在silicalite-2材料上的吸附能力。对于二元体系分离,随着进料浓度与操作压差的增加,分离因子减小。硅羟基的存在会降低乙醇/水的分离因子,模拟结果与silicalite-2材料渗透汽化分离乙醇/水体系的实验报道一致。MEL-typed zeolites were promising materials in separation and recovery of dilute organic solutions, therefore a joint experimental and molecular simulation study on adsorption and separation of water and ethanol through silicalite-2 was reported. A sample of silicalite-2 was synthesized and adsorption isotherms experiments were conducted for the adsorption properties of ethanol and water. The structures of silicalite-2 and the one with silanol groups were optimized with Density Functional Theory （DFT） methods. The unitary adsorption isotherms of ethanol and water were calculated with GCMC simulations. In addition, Ideal Adsorption Solution Theory （IAST） was applied to predict the adsorption and separation of ethanol/water mixture. The results suggested that, the adsorption of water and ethanol were categorized as type V and I adsorption isotherms, respectively. Further simulations also showed that, silanol groups could promote the water adsorption ability of silicalite-2 and decrease the separator factor of ethanol over water. In addition, increasing the ethanol concentration and total pressure could also lead to a decrease in separation factor.

关 键 词：Silicalite-2 硅羟基 吸附分离 巨正则蒙特卡洛(GCMC) 理想溶液吸附理论(IAST) 

分 类 号：O647.3[理学—物理化学] TQ342[理学—化学]