The performance of Fe−Mn oxide oxygen carriers supported on sepiolite, ZrO 2 , and Al 2 O 3 with simulated synthesis gas/air in a novel combustion technology known as chemical looping combustion (CLC) was evaluated. Thermogravimetric analyses (TGAs) and bench-scale low-pressure (10 psi) flow reactor tests were conducted to evaluate the performance. Multicycle tests were conducted in atmospheric TGA with oxygen carriers using simulated synthesis gas with and without H 2 S. The effect of H 2 S impurities on both stability and oxygen transport capacity was also evaluated. Multicycle CLC tests were conducted in the bench-scale flow reactor at 800 °C with selected samples as well. Chemical-phase composition was investigated by the X-ray diffraction (XRD) technique. Five-cycle TGA tests at 800−900 °C indicated that all oxygen carriers exhibited stable performance. It was interesting to note that there was complete reduction−oxidation of the oxygen carrier during the five-cycle test. Fractional reduction, fractional oxidation, and global reaction rates were calculated from the data. It was found that the support-type had a significant effect on both fractional reduction−oxidation and reaction rate. The oxidation reaction was significantly faster than the reduction reaction for all oxygen carriers. The presence of H 2 S in the synthesis gas resulted in a positive effect on the reaction rate. Bench-scale low-pressure flow reactor data indicate stable reactivity, full consumption of oxygen from the oxygen carrier, and complete combustion of H 2 and CO. XRD data of samples showed stable crystalline phases without the formation of sulfides or sulfites/sulfates and complete regeneration of the oxygen carrier.

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The objective of the research was to prepare Fe-based materials for use as oxygen carriers (OCs) and investigate their reactivity in terms of their applicability to energy systems. The performance of ZrO2 supported Fe-Mn oxide oxygen carriers with hydrogen/air in an innovative combustion technology known as chemical looping combustion (CLC) was analyzed. The influence of manganese addition (15–30 wt.%) on reactivity and other physical properties of oxygen carriers was discussed. Thermogravimetric analyses (TGA) were conducted to evaluate their performance. Multi-cycle tests were conducted in TGA with oxygen carriers utilizing gaseous fuel. The effect of redox cycle number and temperature on stability and oxygen transport capacity and redox reaction rate were also evaluated. Physical-chemical analysis such as phase composition was investigated by XRD, while morphology by SEM-EDS and surface area analyses were investigated by the BET method. For screening purposes, the reduction and oxidation were carried out from 800 °C to 1000 °C. Three-cycle TGA tests at the selected temperature range indicated that all novel oxygen carriers exhibited stable chemical looping combustion performance, apart from the reference material, i.e., Fe/Zr oxide. A stable reactivity of bimetallic OCs, together with complete H2 combustion without signs of FeMn/Zr oxide agglomeration, were proved. Oxidation reaction was significantly faster than the reduction reaction for all oxygen carriers. Furthermore, the obtained data indicated that the materials have a low cost of production, with superior reactivity towards hydrogen and air, making them perfect matching carriers for industrial applications for power generation.