Session: 08-02: Solar Chemistry: Thermochemical Fuel Production II

Paper Number: 131100

131100 - Solar Thermochemical Carbon Dioxide Splitting Using Ceria and Iron Aluminate Foam Devices and Simulation of a Plant System for Demonstration 

Abstract: 

An international research project has been carried out for integrating a unique solar thermal processing reactor system with ceria and iron aluminate active redox materials for splitting CO2. A series of experiments for CO2 splitting has been conducted with a complimentary solar simulator in Niigata University, followed by demonstration using the high-flux solar furnace (HFSF) at the NREL User’s Facility in Golden, CO. In each experimental setup, foam devices of ceria and iron aluminate were fabricated using the replica method then subjected to a two-step redox reaction separating a stream of CO2 into O2 and CO iteratively.

Direct heating of the active redox material using a quartz window was employed for both the lab and pilot demonstration experiments. During reduction, the reactive material is heated up to 1500℃ under an Ar atmosphere, releasing O2. During oxidation, the material is maintained at 900℃, releasing CO.

The lab experiment using a tubular furnace mimics the indirect heating reactor with high-temperature thermal media. The furnace electrically heats up the reactive foam device in the circular tube through the tube wall for thermochemical CO2 splitting.

The reactivity was evaluated using the CO production per mass of reactive material. For the ceria foam devices, the measured productivity was between 4.15 – 4.73 mL CO/g at the reduction temperature of 1500 degree Celsius and was between 3.34 – 4.69 mL CO/g using the HFSF where a reduction temperature of 1500 – 1580 degree Celsius was achieved. Similarly, the results from the tubular furnace were between 6.208 – 7.577 mL CO/g at a reduction temperature of 1550 – 1650 degree Celsius. For the iron aluminate foam devices, using the HFSF, the measured productivity was 12.6 mL CO/g at a reduction temperature of 1450 degree Celsius. These results are somewhat higher than the previous experiment at the lower reduction temperatures 1400 – 1500 degree Celsius. The production of CO in the case of the ceria foam device was compared with the steady flow model simulation which assumed the chemical equilibrium at various level of oxygen partial pressure at the reduction process. It was found that the experimental values nearly corresponded to the theory at the oxygen partial pressure level of 10^-4 atm.

The system analysis was performed for the plant system with the recuperation of exhaust heat of released gas. The analysis revealed that the plant using iron aluminate in a pressure-swing mode between oxidation and reduction could surpass that of using ceria.

Presenting Author: Mitsuho Nakakura Niigata University

Presenting Author Biography: Nakakura got doctor of engineering from Niigata University in 2019. His major is heat transfer and solar engineering. He studied fundamental physics of conjugate radiation convection and conduction heat transport in porous media. He analyzed the mechanisms of the receiver efficiency enhancement with decreasing the cell size of porous structures through conjugate simulation and experiment. Based on such fundamental work, his research field has extended to cover the high-temperature solar receiver and solar receiver reactor. He is one of key players in the international collaboration on research and development of highly efficient receiver reactor for carbon dioxide dissociation using concentrated solar thermal.

Authors:

Mitsuho Nakakura Niigata University
Yoshiko Koyama Niigata University
Sofu Shibuya Niigata University
Kent Warren University of Colorado Boulder
Alan Weimer University of Colorado Boulder
Tucker Farrell National Renewable Energy Laboratory
Tatsunori Asaoka Shinshu University
Koji Matsubara Niigata University