Synthesis of ZSM-58 crystals with improved diffusivity in gas separation applications

摘要

A method is provided for synthesizing ZSM-58 crystals with improved (reduced) crystal defect levels, as reflected by improved (lower) diffusivity for the gas adsorbent. By controlling conditions during the synthesis of ZSM-58 crystals, crystals of useful diameter with a narrow diameter distribution can be produced. Furthermore, it has been unexpectedly found that by controlling the ratio of the water content of the synthesis mixture to the silica content, ZSM-58 crystals with improved morphology can be formed. Improved morphology can result in ZSM-58 crystals having a more uniform diameter across the various dimensions of the crystal, which allows for more uniform diffusion within the crystal. This is in contrast to conventional synthesized crystals where the crystal size varies along different axes of the crystal. Furthermore, by introducing post-synthetic processing of ZSM-58 crystals with larger average diameter, more uniform size distribution and improved morphology, either can be introduced or confined during synthesis. Crystal defects can also be reorganized, removed and / or minimized.