Fabrication and hydrothermal stability of microporous Nb2O5 membrane for pre-combustion capture of CO2

Polymeric Nb2O5 sols were successfully synthesized via sol-gel process by using niobium penta (n) butoxide as a precursor. Effects of synthesis parameters, including pH of system, hydrolysis ratio, reaction temperature, reaction time and chelating agent, on the state and size of Nb2O5 sols were investigated in detail. Microporous Nb2O5 membranes were deposited on defect-free γ-alumina membranes with an average pore size of ca. 3 nm, by using polymeric Nb2O5 sol with an average size of 4.8 nm. The properties of Nb2O5 powder and the supported Nb2O5 membranes were characterized by TG, XRD, NH3 adsorption-desorption, CO2 adsorption, Fourier-transform infrared spectroscopy of pyridine adsorption (Py-IR) and single gas permeance test. Results showed that the single hydrogen permeance and H2/CO2 permselectivity of 350°C-calcined microporous Nb2O5 membrane were 3.1 × 10-9 mol · m-2 · s-1 · Pa-1 and 21, respectively, measured at 200°C and 0.3 MPa. The single gas permeance and H2/CO2 permselectivity of the membrane remained fairly stable after in-situ exposure to 150 kPa steam for 8 h. © All Rights Reserved.