Microstructure analysis with TEM for zeolite layer formed in pore of porous alumina substrate

Abstract A zeolite membrane for CO 2 gas separation was synthesized on a porous Al 2 O 3 substrate by hydrothermal synthesis. Observations using transmission electron microscopy (TEM) showed that zeolite had formed in the pores of the substrate (in the “composite layer”). High-resolution TEM observations showed that the zeolite in the pores was MFI and that the crystal grains of the zeolite were connected directly without any grain boundary phases. This suggests that the composite layer can be pinhole free, so the zeolite membrane could function as an effective gas filter. EDS analysis showed that Al/Si ratio of a zeolite framework was larger in the composite layer. This will be a primary factor in densification of zeolite grains at the composite layer.