Oxygen permeation and oxidative coupling of methane with NiFe2O4-Gd0.1Ce0.9O2-δ composite membrane

Abstract

Oxygen permeability and oxidative coupling of methane (OCM) characteristics of a 30 vol.% NiFe₂O₄-70 vol.% Gd_0.1Ce_0.9O_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 < CH₄ < H₂. The maximum OCM yield and C₂H₄/C₂H₆ ratio were observed at 900 °C and for CH₄ 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/Na₂WO₄/SiO₂ catalyst to the permeate side of the composite membrane. The NFO-GDC membrane with the Mn/Na₂WO₄/SiO₂ catalyst exhibited the maximum yield and a C₂H₄/C₂H₆ ratio of 8.6% and 3.21, respectively.