Influence of chemical phases on the mechanical strength of oxygen carrier bed particles

In a chemical looping setup, oxygen carriers bind oxygen from air through oxidation in an air reactor and releases it in a fuel reactor, oxidizing the fuel without the presence of nitrogen. Its ability to absorb and release oxygen in different conditions is the feature that makes chemical looping systems possible. Therefore, investigations of oxygen carrier’s performance and characteristics are essential and necessary. Our study aims to examine the effect of oxidation states on physical properties of several iron-based oxygen carriers, such as their attrition tendency. Oxidation state of an oxygen carrier can affect its fluidization performance, especially in certain conditions that involve a more reduced oxygen carrier. The examined oxygen carriers in this work will be Norwegian ilmenite ore, synthetic ilmenite, Swedish copper slag, Swedish steel converter slag, and the Spanish Tierga iron ore. The oxygen carriers will be calcined and activated in a high temperature furnace and a fluidized bed batch reactor, respectively. The oxygen carrier will then be reduced to reach certain reduction levels, or mass conversion degrees, which correspond to different oxidation states. The attrition examination of these materials will be conducted in a customized jet cup rig, where the materials will be exposed to a harsh physical attrition at room temperature using air. Fine fragments from the materials will be trapped in a filter and weighed. Based on the weight data, the attrition tendency of the oxygen carriers can be compared and the effect of mass conversion degree of the oxygen carriers on it can be investigated. Furter investigations will be conducted with XRD, BET, and SEM/EDX. This will provide data on oxygen carriers’ physical properties which are affected by the materials’ reduction degree.