Oxygen Transport Membranes and their Role in CO₂ Capture and Syngas Production

摘要

Membrane technology for gas separation has seen remarkable improvements in the last 20 years, particularly in the area of air separation for a cost-effective production of highly pure oxygen gas. It is rapidly paving way for alternate route to orthodox separation processes like cryogenic distillation. Solid-state electrochemical cells based on oxygen-ion conduction permit high temperature selective transport of O2 in the form of ionic flux. Hence these systems can act as filters for molecular oxygen either for generation or separation of oxygen gas. The solar thermochemical conversion of CO2 and H2O into syngas is usually carried out at a high temperature of above 1500°C in repeated heating−cooling cycles with the help of durable metal oxide catalysts. Oxygen Transport Membranes (OTMs) are high density ceramic membranes which display mixed conductivity of oxygen ions and electrons and a two-phase mixed metal oxide OTM could thermo-chemically convert CO2 and H2O to syngas in a single step with an H2/CO ratio of 2:1; thus offering an alternative route for syngas production. OTMs also propose a favourable technology for oxy-fuel and CO2 capture processes for gas and coal based power plants. Latest progresses in the field of ceramic membrane for oxygen separation from air at high temperatures vis-à-vis numerous materials and the prospect of ceramic-based membranes for the same are reviewed.