Seeded-gel synthesis of SAPO-34 single channel and monolith membranes, for CO ₂/CH ₄ separations

SAPO-34 zeolite membrane synthesis was scaled up by preparing membranes on seven-channel monolith alumina supports. These monoliths have CO ₂ permeances and CO ₂/CH ₄ separations selectivities at 4.6MPa feed pressure that were similar to SAPO-34 membranes on single channel supports. They also exhibited the same pressure dependence. SAPO-34 membrane preparation was improved by adding SAPO-34 seed crystals to the synthesis gel instead of placing seeds on the support surface. Membranes prepared by seeded-gel synthesis had higher CO ₂ permeances, higher CO ₂/CH ₄ separation selectivities, and smaller standard deviations for these values. Using seeded-gel synthesis also decreased the number of synthesis steps, but increased the amount of seeds needed by two orders of magnitude.