Sulfuric acid decomposition catalysts and reaction considerations for sulfur-based thermochemical water splitting cycles

The sulfur-based family of thermochemical cycles appears promising for producing hydrogen from water. These cycles employ a high-temperature sulfuric acid decomposition reaction step. The temperature dependent activity of several complex metal oxide catalysts for the decomposition reaction is presented. The most promising material examined, a CuFe₂O₄ spinel, had significantly higher activity than the 1% Pt/TiO₂ catalyst at temperatures of 850°C and above, but much lower activity than the supported Pt catalyst at below 825°C. To minimize reactor size and maximize energy conversion efficiency for the water splitting cycles, a minimum of two catalyst zones, utilizing both a supported Pt and a spinel catalyst should be employed. This is an abstract of a paper presented at the 2006 AIChE Spring National Meeting (Orlando, FL 4/23-27/2006).