Experimental assessment of hydrogen separation from H2/CH4 mixtures by the “steam-iron process” in an interconnected circulating fluidized bed reactor

An experimental study devoted to the continuous separation of hydrogen from its mixtures with methane in continuous regime is presented. The study was carried out in a single-vessel reactor divided into two interconnected adjoining chambers, operating as fluidized beds and with a continuous flow of solids between them. The process is based on iron oxide being selectively reduced or oxidized, depending on the redox nature of the gas stream being fed to the respective chamber (steam-iron process or SIP). Conditions to minimize gas leakage between the interconnected beds, avoiding insufficient circulation of solids, have been experimentally determined. The effects of different interconnecting designs, spatial gas velocities and partial pressures of reactants have been tested. Also the effects of several operating parameters (primarily hydrogen content in the inlet gas stream and spatial velocities) on process efficiency have been analyzed. Accordingly, a final configuration has been proposed for stable hydrogen separation and tested for several hours of time on stream.