Preparation of Si-rich LTA zeolite membrane using organic template-free solution for methanol dehydration

摘要

A novel organic template-free Si-rich LTA (Si/Al ratio of 1.5) zeolite membrane was successfully fabricated on the tubular alpha-alumina support via the secondary growth method. The membranes showed excellent separation performance for water/methanol, water/ethanol and water/isopropanol separations even under high temperature and water-rich conditions. The effect of the operating temperature and feed composition on dehydration performance was also investigated. The best membrane showed ultra-high water selectivity of more than 100,000 at a vapor temperature of 378 K in a 10/90 wt% vapor of water/methanol mixtures through vapor permeation. Moreover, high water selectivity of 3500 was obtained at high temperature of 473 K for water/methanol separation. The Si-rich LTA membranes showed good hydrothermal stability in a pervaporation of a 50 wt% aqueous methanol solution at 333 K for one week, as well as a good thermal stability in a vapor permeation with an equimolar vapor of water/methanol mixture at a high temperature of 423 K for one week.