Preparation of SSZ-13 membranes with enhanced fluxes using asymmetric alumina supports for N₂/CH₄ and CO₂/CH₄ separations

High-quality SSZ-13 membranes were synthesized on 200 nm asymmetric α-alumina supports via a single hydrothermal secondary growth. Single CO₂, N₂ and CH₄ permeances and mixed gas separations in CO₂/CH₄ and N₂/CH₄ binary mixtures through SSZ-13 membranes were measured. Synthesis conditions such as membrane substrate, gel composition and membrane calcination were modified. The best SSZ-13 membrane displayed N₂ and CO₂ permeance as high as 8.9 × 10⁻⁸ mol/(m² s Pa) and 5.6 × 10⁻⁷ mol/(m² s Pa) and N₂/CH₄ and CO₂/CH₄ selectivities of 10 and 56.5 for equimolar N₂/CH₄ and CO₂/CH₄ gas mixtures at 298 K and 0.2 MPa feed pressure, respectively. Nitrogen permeance of current SSZ-13 membrane in the mixture was 3.7 times higher than that of our previous SSZ-13 membrane. The membrane synthesis was reproducible. Temperature and pressure dependences of separation performance in the two binary mixtures were also discussed. Single CO₂, N₂ and CH₄ permeances dependent of pressure were predicted by the Maxwell–Stefan diffusion model and the predicted values were fitted well with the measured ones. The stability of SSZ-13 membrane in the wet mixture was investigated. The current SSZ-13 membrane has excellent potentials for CO₂ and N₂ removals from natural gas.