Polyethyleneimine-Modified MCM-48 Membranes: Effect of Water Vapor and Feed Concentration on N2/CO2 Selectivity

Abstract

Ordered mesoporous MCM-48 membranes with cubic pore structure were prepared by the solution growth method on symmetric α-alumina supports using cetyltrimethylammonium bromide as a surfactant. The surfactant was removed by Soxhlet extraction using an ethanol/HCl mixture to synthesize defect-free MCM-48 membranes as confirmed by N2 unsteady-state permeation. MCM-48 membranes and powders were successfully modified with a polymer, polyethyleneimine (PEI) containing amino groups as confirmed by N2 adsorption−desorption data, X-ray diffraction, Thermo gravimetric analysis (TGA), and N2 unsteady-state permeation experiments. The PEI/MCM-48 membranes were permeable to N2 after pore modification, suggesting incomplete filling of MCM-48 pores by PEI, which was confirmed by the N2 adsorption−desorption experiments on the bulk PEI/MCM-48 powder. The PEI-modified MCM-48 membranes were highly selective to N2 permeation from N2/CO2 mixtures at room temperature in the presence of ∼2.6% water vapor. Binary-gas N2/CO2 perm...