Chemical looping technology and its applications in fossil fuel conversion and CO<sub>2</sub> capture

Abstract

Chemical looping is a reaction scheme to decompose one reaction into multiple subreactions via chemical intermediates. The concept of chemical looping has been applied to the generation of hydrogen through the steam iron reaction, as well as the production of carbon dioxide since the 20th Century. However, there are currently no chemical looping processes in commercial operation. Under the circumstances of growing global warming and energy crisis, chemical looping processes have attracted extensive interests for the unique ability to convert carbonaceous fuel to energy or chemicals with affordable CO2 control. Recent developments in chemical looping technology have overcome some of the earlier shortcomings. New research on direct conversion of solid feedstock, such as coal has also been conducted. Through the current sub-pilot/pilot scale tests and process analysis, it has been demonstrated that chemical looping process can effectively reduce the energy cost for CO2 separation with enhanced energy efficiency. This paper presents the status of existing research activities on chemical looping development for fossil fuel conversion, with emphasis on large scale demonstration of chemical looping combustion (CLC) and chemical looping gasification (CLG). The opportunities as well as the challenges on the way to commercialize chemical looping processes have also been briefly discussed.