Oxygen syngas membrane process

One example of membrane reactors is oxidation, in which oxygen from one phase diffuses from one side of an oxygen-permeable membrane to react with a fuel on the other side of the membrane. This avoids a high concentration of O2 on the fuel side, which would be flammable. A catalyst on the fuel side of the membrane oxidizes the fuel to partial oxidation products. One important process using a membrane reactor is the reaction to oxidize methane to form syngas,... 

On the basis of this principle, oxygen membranes are operated for the production of pure oxygen from air, accumulating the oxygen at the product side in a vacuum. Modifying the principle as a membrane reactor, the oxygen at the product gas side may be used for processes of partial oxidation, e.g., of natural gas to syngas. This process had been demonstrated in many variations at laboratory scale [7]. 

The mixed-conducting perovskite oxides have attracted particular interest for use as dense ceramic membrane to control partial oxidation of methane to C2 products or syngas. Such a process bypasses the use of costly oxygen since air can be used as oxidant on the oxygen-rich of the membrane. 

All three major processes - post-combustion capture, oxy-fuel combustion, pre-combustion capture - require a step that, variously, involves the separation of carbon dioxide, oxygen or hydrogen from a bulk gas stream (flue gas, air or syngas, respectively). These separations can be accomplished by means of physical/chemical solvents, membranes, solid sorbents or cryogenic processes. 

These estimates give only an upper limit of oxygen permeation rate because surface exchange reactions may result in some suppression of the overall transport. For the conditions typical for syngas generation (pO2=0.21 atm, pOj = 10 atm, 950°C), the results for the membranes with L = 0.1cm and different chromium contents are shown in Fig. 3. In the calculations at high pressures the ion conductivity values were assumed to be nearly equal to those at low pressures. Fig. 2. It is seen that the permeation rate in chromium doped samples is smaller than in the parent ferrite. Nonetheless, it may achieve a value of about 4 ml cm min in the sample with y = 1, which corresponds to the syngas production rate of about 20-25 ml-cm -min in the methane partial oxidation process. In combination... 

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