Ceramic membrane reactor for synthesis gas production

Membrane reactors enable synthesis-gas production from methane and air whil e avoiding the need for separation of the nitrogen either before or after t he reaction. A stable membrane was developed by, spray, deposition of a den se thin film of La0.5Sr0.5Fe0.8Ga0.2O3-delta on a high-purity porous alpha -alumina tube. The oxygen permeation rate at 850 degreesC was 2.5 X 10(-7) mol(.)cm(-2.)s(-1). A quartz tube was placed coaxially around the membrane and the shell filled with a rhodium catalyst. Air was fed to the tube and m ethane to the shell. At 850 degreesC the methane conversion was 97% and the selectivity to carbon monoxide approached 100%. Rapid radial mixing Of the oxygen in the shell is essential to prevent coking and undesirable reactio ns. The membrane decomposes at 780 degreesC in pure CH4, but remains stable up to 970 degreesC in a mixture of 90-mol% CH4 and 10-mol % CO2.