Evaluation of different carbon-modified zeolite derivatives preparation methods as a filler in mixed matrix membrane on their gas separation performance

Abstract

Carbon-modified zeolite from different preparation methods, including impregnation and chemical vapor deposition (CVD), was investigated and applied as fillers in polysulfone (PSF) membranes in order to improve gas separation performance. Using the impregnation method and CVD, carbon structures were added into the zeolite template. These fillers are zeolite composite carbons (ZCC). After removing the template, zeolite-templated carbons (ZTC) were obtained and analyzed with XRD, SEM, and the N2 adsorption-desorption isotherm. In addition, further investigations were carried out in MMMs embedded by these fillers with XRD, FTIR, TGA, DSC, and gas permeation tests. PSF/ZTC synthesized using CVD demonstrated favorable improvement, which enhanced the gas permeances and CO2/CH4, O2/N2, H2/CH4, and CO2/N2 selectivity up to 107.66%, 24.79%, 140.56%, and 18.55%, respectively. The improvement in gas selectivity was contributed by the high microporosity of the filler. Moreover, the proposed gas diffusion mechanism in MMMs was elucidated, which was dominated by Knudsen and surface diffusion. It was interesting to note that the use of a very small percentage of ZTC-C loading was sufficiently considered to provide a high enhancement compared to those for a high percentage of loading with different fillers. Therefore, the CVD process is more promising for preparing zeolite-carbon fillers to boost gas separation performance and opens up possibilities for further development of advanced membranes.