Utilization of Iron Oxides in Chemical Looping Combustion Processes

Abstract

Fossil fuel combustion is the major source of CO₂ emissions. There are a number of techniques that can be used to separate CO₂ from the rest of the flue gas. The main disadvantage of these techniques is the large amount of energy that is required for the separation, which means a relative reduction of the overall efficiency of a power plant. Chemical looping combustion (CLC) is a new developing clean-combustion technology that has the advantage of inherent CO₂ separation ability. Thus, storage-ready, concentrated CO₂ can be obtained without the use of above-mentioned energy-intensive separation operations. This process involves two separate reactors, i.e., an air and a fuel reactor, and an oxygen carrier material which circulates between the reactors in order to extract and transport oxygen from air to fuel for many cycles. It is essential for oxygen carrier to be reactive, cheap to prepare, and durable over many cycles of reduction and oxidation at high reaction temperatures. Because of its good thermodynamical properties, physical strength, low cost, and low toxicity, iron oxide is a good candidate to be an oxygen carrier in CLC. This study will present a brief summary of developments obtained via CLC processes utilizing iron oxides as oxygen carrier.