Cu/CeₓZr₁₋ₓO₂ catalysts for solid oxide fuel cell anodes

Abstract

CeₓZr(₁₋ₓ)O₂ mixed oxides of varying compositions were prepared by a sol-gel citrate complexion technique. In order to improve the catalytic activity of the oxides they were impregnated with copper using two different impregnation techniques. The bare oxides and copper impregnated samples were investigated using a range of Temperature Programmed (TP) techniques, in an attempt to establish their effectiveness as anode materials for solid oxide fuel cells (SOFCs) run on hydrocarbon fuels. In order to conduct the TP experiments a novel system was designed and constructed.

The high Ce containing mixed oxides were shown to be reduced at lower temperature than high Zr content samples. TPRx experiments were employed to investigate which of the oxides was most prone to carbon deposition when reacted in methane, with the high ceria sample displaying the lowest level of carbon deposition. Lightoff experiments were undertaken to establish which oxide composition was the most active for methane oxidation. The activity of the oxides increased with ceria content up to 75 mole% (ZCe75), before decreasing for ZCe90. All the mixed oxides were shown to be more active for methane oxidation than CeO₂.