Reproducible synthesis of all-silica CHA zeolite membranes in a homogeneous mother liquor

Abstract

All-silica CHA zeolite membrane is superior to other small pore zeolite membranes because of its outstanding stability, ideal pore size and high porosity. However, the conventional synthesis of all-silica CHA membranes was constrained in a solid-like precursor which created issues like excessive consumption of raw materials and poor reproducibility. Herein, all-silica CHA membranes were prepared in a homogeneous mother liquor with (NH4)2SiF6 as silica source, which resulted into fast synthesis of thin all-silica CHA membranes with high reproducibility. Outstanding CO2-CH4 separation performance (CO2 permeance ~ 2.5 × 10-6mol/(m2 s Pa) and decent CO2-CH4 selectivity ~ 150 at room temperature and 0.14 MPa) were obtained on the 1.3 μm thick CHA membrane. This method not only simplified the conventional synthesis of all-silica CHA membranes, but also improved membrane performance with substantially reduced material cost.