Catalytic decomposition of sulfuric acid on mixed Cr/Fe oxide samples and its application in sulfur-iodine cycle for hydrogen production

The present paper deals with the catalytic decomposition of sulfuric acid reaction which is common to several sulfur based thermochemical water splitting cycles including the sulfur-iodine thermochemical cycle. The activity and stability of Cr substituted Fe oxide catalysts were studied for the sulfuric acid decomposition reaction. The samples Fe2(1-x)Cr2xO3 were synthesized using ceramic route and characterized by XRD, N-2-BET and IR spectroscopy. The stability of catalysts toward repeated reduction-oxidation cycle was monitored by recording multiple TPR/TPO profiles. The temperature dependent activity was evaluated using gas chromatography in temperature range of 400-800 degrees C for the sulfuric acid decomposition reaction having a feed rate of space velocity of 1200 ml g(-1) h(-1). The SO2 in the effluent gases was identified by IR and mass spectrometry. The mechanism involves the formation of metastable metal sulfate (M-SO4) on the surface of oxides during SO3 -> SO2 conversion as suggested by XRD and IR studies on used Fe2(1-x)Cr2xO3 samples. (C) 2007 International Association for Hydrogen Energy.