HIGH CO2 PERMEATION FLUX ENABLED BY AL2O3 MODIFIER AND IN-SITU INFILTRATION OF MOLTEN CARBONATE INTO GD-DOPED CEO2 AS A CO2 SEPARATION MEMBRANE

摘要

A new kind of duel-phase electrochemical membrane comprised of a Gd-doped CeO2 (GDC) modified by Al2O3 and a carbonate has been investigated in this study for stable CO2 separation. A porous GDC was used as me membrane matrix and oxide-ion conductor, and a (LiNa)2CO3 eutectic molten carbonate (MC) was used as me carbonate-ion conductor. 5 mol% Al2O3 was added into GDC as a modifier to improve the wettability of GDC with MC so that me retention of MC and subsequently the flux stability can be further enhanced. A CO2 flux density as high as 0.23 ml-min~(-1) ·cm~(-2) at 650°C was achieved with a feeding gas of 50% N2-50%CO2. The CO2 flux measured under a simulated flue gas containing 10% CO2 at 650°C was 0.12-0.15 ml·min~(-1)·cm~(-2) and stable for 100 hours. O2 was also observed to permeate with CO2 through the membrane, but in a smaller fraction. A parallel mechanism for me concurrent O2-transport was proposed.