(492h) Chemical Looping Technology – Beyond CO2 Capture

The concept of chemical looping reactions has been widely applied in chemical industries, e.g., the production of hydrogen peroxide (H₂O₂) from hydrogen and oxygen using 9,10-anthraquinone as the looping intermediate. Fundamental research on chemical looping reactions has also been applied to energy systems, e.g., the splitting of water (H₂O) to produce oxygen and hydrogen using ZnO as the looping intermediate. Fossil fuel chemical looping systems had been applied to the steam-iron process for coal processing in the 1900s to the1940s and to the carbon dioxide acceptor process in the 1960s to 1970s. There are presently no chemical looping processes using fossil fuels in commercial operation. A key factor that hampered the continued use of these earlier processes for fossil energy operation was the inadequacy of the reactivity and recyclability of the oxygen carrying particles. This factor led to higher product costs for using the chemical looping processes, compared to using traditional techniques that processed petroleum or natural gas. With CO₂ emission control now being of a serious issue, interest in chemical looping technology has resurfaced. In particular, chemical looping processes are appealing due to their unique ability to generate a sequestration-ready CO₂ stream. Under the CO₂ constraint environment, the chemical looping technology clearly exhibits considerable advantage over traditional processes when accompanied by a CO₂ capture unit. However, if the CO₂ emission regulation is not enacted, under the CO₂ unconstrained environment, processes based on the chemical looping technology would require to be a standalone, commercially viable process without considering the benefit of the CO₂ capture.

This presentation will describe the fundamental and applied aspects of modern chemical looping technology that can convert fossil and biomass feedstock directly to various commercial products such as syngas, chemicals and liquid fuels. The chemical looping scheme linking to solid oxide fuel cell applications for high efficient electricity generation can also lead to an attractive chemical looping process option. The presentation will focus on reaction engineering issues associated with the complex metal oxide synthesis for performing selective oxidation reactions. Opportunities and challenges for chemical looping process scale-up and commercialization for these applications will also be illustrated.