高渗透性能丝光沸石膜的合成及在醇/水分离体系中的应用  

Preparation of High Permselective Mordenite Membrane and Its Use for Separation of Alcohol/Water Mixture

作　　者：张延风[1] 许中强[2] 陈庆龄[2] 

机构地区：[1]华东理工大学化学与制药学院,上海200237 [2]中国石油化工股份公司上海石油化工研究院,上海201208

出　　处：《催化学报》2002年第3期235-244,共10页

摘　　要：以四乙基溴化铵为模板剂 ,用原位水热合成法在α Al2 O3 陶瓷管上合成出丝光沸石膜 ,系统研究了合成母液的组成、晶化时间、老化时间、硅源和铝源以及氟化钠助剂的添加等因素对丝光沸石膜成膜和表面形貌的影响 .结果表明 ,老化可使成膜沸石的晶粒从 30 μm减小到 5 μm ;添加氟化钠也能减小晶粒的大小 ;使用异丙醇铝为铝源能制得高度定向的丝光沸石膜 .提出了丝光沸石膜的成膜机理 ,认为成核发生在载体表面 ,凝胶层的晶化过程是从载体的表面开始 ,不断转化 ,充分生长后达到凝胶层的表面 .丝光沸石膜对醇 /水混合体系的分离研究表明 ,水 /甲醇、水 /乙醇、水 /正丙醇和水 /异丙醇的分离因子分别可达到 15 0 0 (32 3K ,水含量xw=15 % ) ,4 2 0 0 (343K ,xw=15 % ) ,4 2 0 0 (343K ,xw=5 0 % )和 340 0 (343K ,xw=5 0 % ) ,所合成的丝光沸石膜能选择性地透过水 ,对醇The research on zeolite membranes was focused on small or medium pore zeolite membranes, such as zeolite A and MFI zeolite membranes, but little effort was made to investigated large pore zenlite membranes, such as the mordenite membrane, which will be promising in the separation of large molecules. Until now there is no systematic research on the preparation and characterization of the mordenite membrane. In this study, the mordenite membrane was prepared on an alpha-Al2O3 tube with tetraethylammonium bromide (TEABr) as the template agent by in-situ hydrothermal synthesis. Silica Sol (40% SiO2) and sodium aluminate (43% Al2O3) were used as the sources of silicon and aluminum, respectively. A synthesis solution used has a molar composition of 11.4Na(2)O : 1.5Al(2)O3 : 40SiO(2) : 2500H(2)O : 1.5TEABr. The mother liquor was crystallized at 443 K for 2 similar to 4 days. SEM, XRD and NMR were used to characterize the mordenite powder and the mordenite membrane. It has been proven that the mordenite membrane had excellent intergrowth, full coverage and little impurity. The effects of the synthesis conditions, aluminum source, silicon source, crystallization time, and aging time on the membrane morphology were investigated. The crystal size could be reduced from 30 mum to about 5 mum by the application of the aging process. The addition of sodium fluoride was also beneficial to the decrease of the crystal size in the synthesized membrane. A highly oriented mordenite membrane could be prepared with aluminum isopropoxide as the aluminum source. A mechanism for the formation of the zeolite membrane has been proposed based on the experimental results. The nucleation and crystallization started on the surface of the support, and the gel layer was gradually transformed into zeolitic crystals up to the surface of the gel layer. The separation factors toward water/methanol, water/ethanol, water/n-propanol, and water/i-propanol could reach 1 500 (323 K, x(w)= 15%), 4200(343 K, x(w) = 15%), 4200(343 K, x(w) = 50%), and 3400(343

关 键 词：渗透性能 丝光沸石膜 分子筛膜 水热合成 醇水分离 渗透蒸发 

分 类 号：TQ028.8[化学工程] TQ424.25