高硅SSZ-13分子筛膜二次水热生长过程

Hydrothermal Secondary Growth Process of High-Slica SSZ-13 Zeolite Membrane

采用稀释模板剂合成溶胶在管状莫来石支撑体上制备高硅SSZ-13分子筛膜以研究膜的二次水热生长过程。对433 K下二次生长2~72 h的膜和底料进行表征,XRD表明膜和底料中的SSZ-13特征峰均在6 h后出现。底料中的晶粒尺寸基本不随晶化时间的延长而变化。在298 K和0.4 MPa测试条件下,433 K晶化72 h的SSZ-13分子筛膜CO2渗透通量为2.08×10-7 mol·m-2·s-1·Pa-1,CO2/CH4理想选择性为24。探讨了SSZ-13分子筛膜的生长过程:涂覆在支撑体上的晶种首先溶解并形成大量有序的结构单元,诱导溶胶中晶粒形成并快速生长,晶粒沉积在支撑体的表面共生形成无缺陷的膜层。

High-silica SSZ-13 zeolite membranes were prepared on tubular mullite supports using a diluted organic template gel composition to investigate the hydrothermal growth process.Membranes and powders at the bottom of autoclave were characterized after secondary growth from 2 to 72 h at 433 K,and the XRD patterns show SSZ-13 characteristic peaks appeared in the membranes and powders simultaneously after 6 h.The size of zeolite crystals in the powder was almost the same when the synthesis time delayed.The SSZ-13 membrane synthesized at 433 K and 72 h had a CO2 permeance of 2.08×10-7 mol·m-2·s-1·Pa-1 with an ideal selectivity of CO2/CH4 of 24 at 298 K and 0.4 MPa.The possible growth process of SSZ-13 zeolite membrane was proposed with the seeds coated on supports dissolved and formed numerous orderly structure units in the gel firstly,inducing SSZ-13 zeolite crystals generated and grew rapidly,the crystals deposited on the supports,grew up and intergrew for limited space to from a defect-free layer.