Fabrication and CO2 separation performance of carbon membranes doped with TiO2 nanoparticles

A TiO2 sol was prepared from tetrabutyltitanate using polyethylene glycol as a stabilizer, and this was homogeneously mixed with polyfurfuryl alcohol, dip-coated on a porous Al2O3 substrate and carbonized at 700 degrees C for 4h to produce TiO2-doped carbon membranes. SEM, TEM, XRD and granulometry were used to characterize the membranes, and their permeation performance for CO2, N-2 and CH4 were tested. It was found that polyethylene glycol is effective in controlling the hydroxylation of the tetrabutyltitanate. This not only favored the formation of spherical TiO2 nanoparticles with a small size and narrow size distribution but also improved the homogeneity of the dispersion of the TiO2 nanoparticles in polyfurfuryl alcohol. The doping of the membranes with TiO2 nanoparticles greatly improved the CO2 perrneance and permselectivity. The TiO2 doping helps to create diffusion paths, but it may also block the pores in the carbon matrix. Therefore, the CO2 permeance reached a maximum of 7.0x10(-8) mol.m(-2) . s(-1)Pa(-1) with a mass ratio of TiO2 sol to polyfurfuryl alcohol of 2, where the CO2/N-2 and the CO2/CH4 selectivities were 34 and 64, respectively.