Carbon dioxide splitting and hydrogen production using a chemical looping concept: A review

The gradually increasing atmospheric concentration of greenhouse gases has caused global climate change and subsequent environmental problems. To negate the emission of greenhouse gases from human activities, converting captured carbon into value-added products and changing our energy paradigm from fossil fuels to hydrogen both are significantly investigated. Chemical looping technology can offer several advantages since CO/H-2 production efficiency can be enhanced due to the inherent product separation and autothermal operation. This report presents a brief review of the chemical looping process combined with CO2 or H2O splitting to provide CO or H-2, respectively. Thermodynamic analysis was carried out to determine viable transition metal oxides. Various oxygen carriers for the chemical looping CO2/H2O splitting were categorized according to their structural characteristics. In addition, studies on different reactors, including fluidized-, moving bed-, and fixed bed-types which have proven their potential for realizing large-scale operation of chemical looping processes were summarized. Based on past advances and additional aspects of chemical looping, the authors strongly believe that this process offers a promising commercial technology that will contribute to carbon neutrality.