Jeong, Yanghwan Lee, Minseong Lee, Gihoon Hong, Sungwon Jang, Eunhee Choi, Nakwon Choi, Jungkyu 2024-01-19T14:31:37Z 2024-01-19T14:31:37Z 2021-10-21 2021-06-07 2050-7488 https://pubs.kist.re.kr/handle/201004/116868 We prepared a hydrophobic deca-dodecasil 3 rhombohedral@chabazite (DDR@CHA) zeolite hybrid film comprised mainly of DDR zeolite. Specifically, the pore size of the DDR zeolite (0.36 x 0.44 nm(2)) is ideal for molecular-sieve-based CO2 (0.33 nm) separation from CH4 (0.38 nm), which is critical for upgrading biogas. We demonstrated that an appropriate choice of calcination conditions was the key factor controlling the formation of defects and, consequently, determining the final membrane performance. Simply put, low-temperature calcination in O-3 eliminated defect formation and, thus, achieved a very high performance for dry CO2 permselectivity over CH4 (CO2/CH4 separation factor (SF) of ca. 523 +/- 96 at ca. 50 degrees C, which is a representative temperature of biogas streams). Surprisingly, high separation performances (CO2/CH4 SF of 422) for water-vapor-containing CO2/CH4 mixtures (at 100% humidity and 50 degrees C) required the formation of a few defects, which in turn necessitated optimal calcination at ca. 450 degrees C in O-2. The defect structures were quantitatively analyzed by combining fluorescence confocal optical microscopy with gas-permeation modeling. Furthermore, the inhibition of water-molecule-adsorption on CO2 permeation rates was estimated. This clearly revealed that fully opening the all-silica hydrophobic DDR zeolite micropores, while minimizing the formation of concomitant defects, helped to achieve the highest ever CO2 permselectivities for wet CO2/CH4 mixtures. In contrast, the elimination of defects by calcination in O-3 was the key to achieving a very high dry CO2/CH4 separation performance. English ROYAL SOC CHEMISTRY MIXED-MATRIX MEMBRANES METAL-ORGANIC FRAMEWORK CARBON-DIOXIDE CAPTURE ZIF-90 MEMBRANE MICROSTRUCTURAL OPTIMIZATION SSZ-13 MEMBRANES GAS SEPARATION CO2 CAPTURE BIOGAS SELECTIVITY Unavoidable but minimizable microdefects in a polycrystalline zeolite membrane: its remarkable performance for wet CO2/CH4 separation Article 10.1039/d1ta01286j 1 JOURNAL OF MATERIALS CHEMISTRY A, v.9, no.21, pp.12593 - 12605 JOURNAL OF MATERIALS CHEMISTRY A 9 21 12593 12605 scie scopus 000643916200001 2-s2.0-85107808399 Chemistry, Physical Energy & Fuels Materials Science, Multidisciplinary Chemistry Energy & Fuels Materials Science Article MIXED-MATRIX MEMBRANES METAL-ORGANIC FRAMEWORK CARBON-DIOXIDE CAPTURE ZIF-90 MEMBRANE MICROSTRUCTURAL OPTIMIZATION SSZ-13 MEMBRANES GAS SEPARATION CO2 CAPTURE BIOGAS SELECTIVITY