Rational design of defect-free carbon-silica-zirconia ceramic membrane derived from crosslinked organic structure for highly efficient gas separation

Carbon-SiO2-ZrO2 ceramic membranes, fabricated via in-situ carbon deposition through the calcination of organic chelating ligands (OCLs), hold great promise for use in energy-efficient gas separation process. However, fabricating a defect-free membrane poses a significant challenge. In this study, we propose a facile one-pot sol-gel combining aldimine condensation strategy to design homogeneous carbon-SiO2-ZrO2 ceramic membranes using 3-aminopropyltriethoxysilyl (APTES), zirconium (IV) tert-butoxide (ZrTB), and glyoxylic acid (GA) as precursors. The aldehyde-amine condensation between APTES and GA resulted in a crosslinked organic structure, enhancing the porosity of the membrane. The increased rigidity and orderliness reduced the migration of crosslinked organic components at elevated temperatures, leading to a uniform distribution of free carbon derived from pyrolysis. This method effectively suppresses the defect formation, thereby significantly improving the stability and separation performance of the obtained membranes. Owing to the high pore volume and uniform pore size distribution, APTES-ZrTB-GA calcined at 550 degrees C demonstrated a remarkable H2 permeance of 4.1 x 10-7 mol m-2 s- 1 Pa- 1, together with outstanding H2/CO2, H2/N2 and H2/CH4 selectivities of 13, 100 and 120, respectively. This study is expected to provide guidance for the design of defect-free carbon-SiO2-ZrO2 ceramic membranes toward more challenging separation processes.