Oxygen permeation and oxidative coupling of methane with NiFe 2 O 4 -Gd 0.1 Ce 0.9 O 2- δ composite membrane

Oxygen permeability and oxidative coupling of methane (OCM) characteristics of a 30 vol.% NiFe 2 O 4 -70 vol.% Gd 0.1 Ce 0.9 O 2- δ (NFO-GDC) composite membrane were systematically investigated by varying operational conditions for oxygen permeation and OCM experiments. The NFO-GDC membrane showed the maximum oxygen permeation flux of 2.24 mL∙cm −2 ∙min −1 under an Air/He gradient at 900 °C, and flux increased with increasing oxygen partial pressure gradient in the order He < CH 4 < H 2 . The maximum OCM yield and C 2 H 4 /C 2 H 6 ratio were observed at 900 °C and for CH 4 flowing at 12.5 mL∙min -1 , respectively, and the yield and ratio both increased with increasing temperature in the range 700–900 °C. The overall coupling yield was notably enhanced by applying a Mn/Na 2 WO 4 /SiO 2 catalyst to the permeate side of the composite membrane. The NFO-GDC membrane with the Mn/Na 2 WO 4 /SiO 2 catalyst exhibited the maximum yield and a C 2 H 4 /C 2 H 6 ratio of 8.6% and 3.21, respectively.