Integrating air separation with partial oxidation of methane-A novel configuration of asymmetric tubular ceramic membrane reactor

This paper reports a new design of ceramic asymmetric tubular reactor for correlating air separation with catalytic partial oxidation of methane (POM). The tubular membrane reactor consists of three annular layers, a porous and thin La0.2Sr0.8MnO3−δ (LSM80)-Ce0.8Gd0.2O2−δ (CGO20) cathodic layer, a dense and thin YSZ⊥(Pd-TiO2) mixed conducting layer as the electrolyte layer, and a porous and thick YSZ-Ni anodic layer. For realizing mixed-conducting electrolyte layer, an electronic conductive Pd-TiO2 stripe was wedged into a dense YSZ coating layer via a specially designed two-step calcination process. The resulting membrane reactor was assessed by its POM output in a broad temperature range as well as by its capability to clean up the coke deposited on Ni(0) catalyst. It demonstrated high methane conversion (>90%), CO selectivity (>90%) and H2 selectivity (>80%) at 850 °C. Besides the experimental work, a mathematical model including the two major POM mechanisms responsible for the methane conversion over the temperature span of study was developed and employed to simulate the experimental XCH4 (conversion) ∼1/T data. The kinetic parameters obtained well accounted for the characteristics of these two reaction mechanisms.