Effect of Hydrogen Sulfide on Chemical Looping Combustion of Coal-Derived Synthesis Gas over Bentonite-Supported Metal-Oxide Oxygen Carriers

The effect of hydrogen sulfide (H2S) on the chemical looping combustion of coal-derived synthesis gas with bentonite-supported metal oxides-such as iron oxide, nickel oxide, manganese oxide, and copper oxide-was investigated by thermogravimetric analysis, mass spectrometry, and X-ray photoelectron spectroscopy (XPS). During the reaction with synthesis gas containing H2S, metal-oxide oxygen carriers were first reduced by carbon monoxide and hydrogen, and then interacted with H2S to form metal Sulfide, which resulted in a weight gain during the reduction/sulfidation step. The reduced/sulfurized compounds could be regenerated to form sulfur dioxide and oxides during the oxidation reaction with air. The reduction/oxidation capacities of iron oxide and nickel oxide were not affected by the presence of H,S, but both manganese oxide and copper oxide showed decreased reduction/oxidation capacities. However, the rates of reduction and oxidation decreased in the presence of H2S for all four metal oxides.