Abstract
Continuous and high silica SSZ-13 zeolite membranes were prepared on porous mullite supports from high SiO₂/Al₂O₃ ratio or aluminum-free precursor synthesis gel. Single gas permeance (CO₂ and CH₄) of the high silica SSZ-13 zeolite membrane was decreased with the SiO₂/Al₂O₃ ratio in the precursor synthesis gel, while the ideal CO₂/CH₄ selectivity of the membrane was gradually increased. Moreover, effects of synthesis conditions (such as H₂O/SiO₂ and RNOH/SiO₂ ratios of precursor synthesis gel, crystallization time) on the single gas permeance performance of high silica SSZ-13 zeolite membranes were studied in detail. Medium H₂O/SiO₂ and RNOH/SiO₂ ratios in the initial synthesis gel were crucial to prepare the good CO₂ perm-selective SSZ-13 zeolite membrane. When the molar composition of precursor synthesis gel, crystallization temperature and time were 1.0 SiO₂: 0.1 Na₂O: 0.1 TMAdaOH: 80 H₂O, 160 °C and 48 h, CO₂ permeance and ideal CO₂/CH₄ selectivity of the SSZ-13 zeolite membrane were 0.98 × 10(-7) mol/(m²·s·Pa) and 47 at 25 °C and 0.4 MPa. In addition, the SiO₂/Al₂O₃ ratio of the corresponding SSZ-13 zeolite was 410 by X-ray fluorescence spectroscopy.