Fluorine-free synthesis of all-silica STT zeolite membranes for H2/CH4 separation

Abstract

Hydrogen (H2) is the most promising alternative to fossil energy for zero-emission of CO2. However, the by-produced H2 from coking process was generally burned as fuel. It is highly desired to recycle the H2 from coke oven gas as the clean energy resource. Herein all-silica STT zeolite membranes were prepared from the fluorine-free precursor for H2/CH4 separation. The crystallization period was shortened by 75% at the elevated temperature. After hydrothermal synthesis of 2 days, the membrane showed H2 permeance up to 2.8 × 10−8 mol·m−2·s−1·Pa−1 and H2/CH4 selectivity up to 49.6 at 0.2 MPa and 298 K. More importantly, STT zeolite membrane was resistant to CO and H2S, which should be prevented from feeding to the commercial polymeric and Pd membranes. The membrane was stable up to 336 h in the simulated coke oven gas of 63 H2: 28 CH4: 7 CO: 2 C2H6 containing 100 ppm H2S. This would pave the way of zeolite membranes to H2 separation in practical applications.