Catalytic Membrane Reactors: Next Generation Mixed Conducting Membranes
DOE Phase I Contract No. DE-FG02-04ER83938
The objective of this program was to develop the next generation of mixed oxygen ion and electron conducting ceramic membranes for achieving the spontaneous conversion of natural gas to synthesis gas. This project aimed to both improve the mechanical properties and enhance oxygen anion conductivity of ceramic membranes. Mechanical properties were improved by reducing the expansion coefficients to reduce likelihood of thermal or chemical shock, allow faster start up/shut down procedures, decrease fabrication time, and improve production yield.
In the Phase I work, 62 compounds were prepared and tested. Three of these possess exceptional properties of low expansion and high oxygen permeation. One of these has expansion similar to a commercially acceptable material, but has a five times higher oxygen permeation. The results of the Phase I prove the validity of the proposed doping strategy and show it is possible to reduce expansion properties without loss of oxygen permeation.
Reduction in capital and operating costs of oxygen separation plants relative to cryogenic separation, and simultaneous oxygen separation and partial oxidation of natural gas made possible with ceramic membranes will improve the economics of gas-to-liquid technology. Gas-to-liquid plants will provide a source of ultra pure diesel fuel and intermediates for specialty chemicals to compete with oil-derived products. In addition, the intermediate formation of synthesis gas serves as a source of hydrogen which may serve as a long-term transitional resource as the use of fossil fuels is phased out and renewable sources of hydrogen are developed.