Molecular layer deposition (MLD) modified SSZ-13 membrane for greatly enhanced H₂ separation

Zeolite membranes with high thermal stability and well-fined pores are attractive for gas separation. However, the defects are almost inevitable in zeolite membranes. Moreover, fine-tuning zeolitic pores for precise molecular separation is challenging. In this study, molecular layer deposition (MLD) was employed to deposit ultrathin microporous coating on SSZ-13 zeolite membrane. The MLD modified SSZ-13 composite membrane was highly selective for H₂ separation. With optimized MLD cycles, H₂/N₂ and H₂/CH₄ ideal selectivities as high as 35.6 and 427, respectively, were obtained, in strong contrast with approximately 5 for base SSZ-13 membrane. These results suggest that MLD is a very promising technology to precisely modify the pore size of zeolite membranes, while minimizing flow through non-selective defects, for gas separation.