Mesoporous Fe₂O₃-CeO₂-Al₂O₃Oxygen Carrier for Chemical Looping Dry Reforming with Subsequent Water Splitting

A combined chemical looping dry reforming (CLDR) of methane and separate water splitting process was devised to produce syngas and hydrogen, respectively. A nonstoichiometric methane-carbon dioxide mixture was supplied to the oxygen carrier to partially oxidize methane and produce syngas. The composition of the syngas was adjusted by changing the methane-to-carbon dioxide ratio of the feed gas mixture. After syngas production, the oxygen-deficient oxygen carrier was replenished by splitting steam into molecular hydrogen and atomic oxygen. The iron-cerium-aluminum mixed oxygen carrier used was prepared by the sol-gel method and showed enhanced redox activity for the proposed CLDR-water splitting process. The mesoporous structure of the aluminum oxide framework and the cerium oxide nanocrystallite incorporated inside the porous structure of the oxygen carrier suppressed solid carbon formation. The hydrogen-to-carbon monoxide ratio of the syngas produced was stably maintained at 2:1 with a CH4 conversion of 0.95 and a CO selectivity of 0.76. Furthermore, hydrogen purity produced by the water splitting reaction was maintained at 0.90 over 20 cycles.