Thin SAPO-34 zeolite membranes prepared by ball-milled seeds

Abstract

• Small seeds led to thinner SAPO-34 membranes due to enhanced secondary nucleation. • Ball-milling generated nano seed particles easily. • Ultrafine seed particles produced by ball-milling resulted into thinner membrane. • Outstanding CO 2 -CH 4 separation performance realized on 1.6 μm thick SAPO-34 membrane. Zeolite membranes demonstrated great separation performance for many important separation processes, however, high membrane cost is a major obstacle for its commercial application. Reducing membrane thickness is an effective way of lowering its unit cost, which requires a delicate control of nucleation and crystallization processes. Herein, the effect of seed size on the separation performance of SAPO-34 membranes was studied. Smaller seeds facilitated secondary nucleation which led to thinner membrane with higher CO 2 permeance. Ball-milling of regular SAPO-34 crystals can generate ultra-small seed particles easily, which is even better than tailor-made nano SAPO-34 seeds on reducing membrane thickness. Thin SAPO-34 membrane with thickness ~1.4 μm can be prepared with high reproducibility and high CO 2 permeance ~10.2 × 10 −7 mol·m −2 ·s −1 ·Pa −1 and CO 2 -CH 4 selectivity of 59 were obtained for the separation of equalmolar CO 2 -CH 4 mixture at 4.0 MPa and room temperature.