Hydrogen‐assisted Carbon Dioxide Thermochemical Reduction on La0.9Ca0.1FeO3−δ Membranes: A Kinetics Study
First published: 04 November 2017
Abstract
Kinetics data for CO2 thermochemical reduction in an isothermal membrane reactor is required to identify the rate‐limiting steps. A detailed reaction kinetics study on this process supported by an La0.9Ca0.1FeO3‐δ (LCF‐91) membrane is thus reported. The dependence of CO2 reduction rate on various operating conditions is examined, such as CO2 concentration on the feed side, fuel concentrations on the sweep side, and temperatures. The CO2 reduction rate is proportional to the oxygen flux across the membrane, and the measured maximum fluxes are 0.191 and 0.164 μmol cm−2 s−1 with 9.5 mol% H2 and 11.6 mol% CO on the sweep side at 990 °C, respectively. Fuel is used to maintain the chemical potential gradient across the membrane and CO is used to derive the surface reaction kinetics. This membrane also exhibits stable performances for 106 h. A resistance‐network model is developed to describe the oxygen transport process and the kinetics data are parameterized using the experimental values. The model shows a transition of the rate limiting step between the surface reactions on the feed side and the sweep side depending on the operating conditions.
Ahmed Ghoniem the Ronald C. Crane Professor of Mechanical Engineering, Director of the Center for Energy and Propulsion Research and the Reacting Gas Dynamics Laboratory at MIT. He received his B.Sc. and M.Sc. degree from Cairo University, and Ph.D. at the University of California, Berkeley. His research covers computational engineering with application to turbulence and combustion, multiphase flow and multiscale phenomena, clean energy technologies with focus on CO2 capture, renewable energy and alternative fuels. His research has made fundamental contributions to multiscale simulations, thermochemistry, combustion dynamics, energy systems and materials chemistry. He supervised more than 100 M.Sc., Ph.D. and post-doctoral students, many are leaders in academia, industry and governments; published more than 500 refereed articles in leading journals and conferences; lectured extensively around the World; and consulted for the aerospace, automotive and energy industry. He is fellow of the American Society of Mechanical Engineer (ASME), the American institute of Physics (APS), the Combustion Institute (CI), and associate fellow of the American Institute of Aeronautics and Astronautics (AIAA). He received several prestigious awards including the ASME James Harry Potter Award in Thermodynamics, the AIAA Propellant and Combustion Award, the KAUST Investigator Award and the Committed to “Committed to Caring Professor” at MIT.
See: http://meche.mit.edu/people/faculty/ghoniem@mit.edu
Dr. XiaoYu Wu 吴晓雨 is a postdoc associate atReacting Gas Dynamics Lab, Center for Energy Propulsion Research, MIT. He received his PhD degree at MIT in June 2017 under the supervision of Professor Ahmed F. Ghoniem. He received both his Bachelor and Master degrees in Engineering in Zhejiang University, China.
His research interests focus on the fundamental understanding of the kinetics in the thermo-electro-chemical processes under harsh operating conditions, i.e., high temperature/pressure, supercritical conditions and corrosive environment. Harsh operating conditions are inevitable in many energy and food processing applications such as fusion, combustion, supercritical fluid extraction and membrane filtration. The insights for both the chemical kinetics and process/reactor kinetics, i.e., the reaction kinetics, thermo-fluid transport, material stability and degradation under these conditions are essential for the optimal design of such systems in a safe and efficient manner. Both experimental and simulation tools are used to investigate these processes.
Examples are:
Energy storage: oxygen permeation membranes supporting water/carbon splitting for hydrogen/syngas production at elevated temperatures (link, MIT News link).
Value added chemicals from methane: perovskite oxides replacing precious metal as catalysts for syngas production from methane (link).
Supercritical fluid: heat transfer characteristics of supercritical nanofluid kerosene for regenerative cooling system in engines (link).
Falling film evaporation: enhanced evaporation heat transfer by decreasing liquid film thickness under ultra-low pressure.
