Simultaneous overcome of the equilibrium limitations in BSCF oxygen-permeable membrane reactors: Water splitting and methane coupling

摘要

The equilibrium limitations of water splitting and the coupling of methane to C2 hydrocarbons (ethane + ethylene) were simultaneously overcome by using a perovskite Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O-δ) (BSCF) oxygen-permeable membrane reactor. Oxygen produced from thermal water splitting was transported through the BSCF membrane and consumed in the coupling of methane. The BSCF membrane consists of an about 70 μm thick dense BSCF layer on an about 0.8 mm thick porous BSCF layer as support. By applying the membrane reactor concept instead of a fixed bed reactor without oxygen supply, the methane conversion and C2 yield increased from 3.7% to 26% and 3.1 % to 6.5% at 950 °C, respectively. In both experiments, the supported 2 wt.% Mn-5 wt.% Na2WO4 catalyst was used at 950 °C. Simultaneously, about 9% of the H2O injected was converted to hydrogen with a production rate of about 3.3 cm~3 min~(-1) cm~(-2) at 950 °C which is higher than 1 m~3 (STP) H2 m~(-2) h~(-1).