Experimental Study of Chemical-Looping Reforming in a Fixed-Bed Reactor: Performance Investigation of Different Oxygen Carriers on Al2O3 and TiO2 Support

This study examines the hydrogen production by the steam reforming of methane integrated to chemical-looping reforming (CLR) as a novel technology in a fixed-bed reactor at 700-1200 degrees C. The particles are present in two consecutive oxidation and reduction steps. In the reduction step, the oxygen carrier is reduced with the fuel, which, in turn, is partially oxidized to H-2 and CO (synthesis gas), and in the oxidation step, the reduced oxygen carrier is reoxidized with oxygen (O-2 + argon). The oxygen carriers Fe, Mn, Co, and Cu using inert materials Al2O3 and TiO2 as a support are prepared by the precipitation method. The samples are analyzed using energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), and X-ray diffraction (XRD) to check the carrier specifications before and after the process. The main goal of this study is investigation of the reactivity of different metal oxides on Al2O3 and TiO2 support. The conversion of fuel into products depends upon the type of oxygen carriers and experimental conditions. All of the oxygen carriers show favorable hydrogen production over the 3 cycle experiments at optimum temperature. Among used metals, Fe has the highest hydrogen yield. The optimum temperature for maximum conversion of methane over Fe-, Mn-, Co-, and Cu-based carriers is nearly 1025, 1030, 900, and 800 degrees C, respectively. According to experimental results, at higher temperatures, Fe- and Mn-based carriers have better performance, but at lower temperatures, the Cu-based carrier is more efficient compared to other carriers. The comparison of supports represents that the reactivity of Al2O3 is better than TiO2, so that the conversion of the fuel over Fe/Al2O3 is 95-100% in comparison to Fe/TiO2, which is 78-80%.