Counter-diffusion crystallization of continuous SSZ-13 zeolite membranes with reduced organic templates for N2/CH4 separation

SSZ-13 zeolite membranes are promising for N 2 /CH 4 gas separation owing to their unique pore architecture and superior stability. However, for the conventional secondary growth (CSG) of SSZ-13 membranes, the synthetic solution, particularly the organic template, is inefficiently utilized, causing unnecessarily high chemical consumption. To address this issue, this study introduces counter-diffusion crystallization (CDC) strategy that separates the organic template and silica source within and outside porous tube substrates to synthesize SSZ-13 membranes at the interface; this can reduce template usage by 92.5% for the same area of SSZ-13 membranes compared with the CSG method. Moreover, with the CDC strategy, the organic template can be recycled for membrane fabrication, further reducing raw material costs. The optimized SSZ-13 membranes show N 2 permeance of 2.5 × 10 −8  mol m −2  s −1 Pa −1 and N 2 /CH 4 selectivity of 15.7 at 298 K and 2 bar. Meanwhile, SSZ-13 membranes can maintain stable performance over one month of operation and be able to withstand high-temperature (423 K) and high-pressure (10 bar) tests.