Ceramic membrane reactor for synthesis gas production

Membrane reactors enable synthesis‐gas production from methane and air while avoiding the need for separation of the nitrogen either before or after the reaction. A stable membrane was developed by spray deposition of a dense thin film of La 0.5 Sr 0.5 Fe 0.8 Ga 0.2 O 3 − δ on a high‐purity porous α‐alumina tube. The oxygen permeation rate at 850°C was 2.5 × 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 methane to the shell. At 850°C 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 reactions. The membrane decomposes at 780°C in pure CH 4 , but remains stable up to 970°C in a mixture of 90‐mol % CH 4 and 10‐mol % CO 2 .