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Fast, Efficient Isothermal Redox to Split Water or Carbon Dioxide using Solar Energy

University of Colorado

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Technology Marketing Summary

A University of Colorado research team led by Alan Weimer has developed a technique for a substantially isothermal hercynite cycle, in which the entire reaction cycle is performed isothermally at 1200-1400°C (though the cycle can be performed at temperatures as low as 940°C). Because no significant heating or cooling is required between the respective cycles, the hercynite cycle allows faster, more efficient cycling and less wear on the equipment and materials used for the process. Furthermore, any materials degradation that might be associated with high/low temperature cycling will be eliminated.

Description

Various redox (reduction-oxidation) processes are used industrially to split gas-phase reactants; for example, they may be used to split water (to produce hydrogen fuels) or CO2 (to reduce harmful pollution). These reactions are typically run with reduction temperatures hundreds of degrees Celsius above the corresponding oxidation temperatures. The ceria cycle is typically reduced at 1500°C and then oxidized at 850-1000°C, the standard ferrite cycle is reduced at 1450°C and then oxidized between 900-1100°C, and the standard hercynite cycle is reduced at 1200-1400°C (significantly lower than the other competing cycles) and then oxidized at 900-1100°C.

Running the oxidation and reduction steps of the redox cycles at substantially different temperatures causes significant heat loss with each temperature change, requires additional time to heat or cool the system, and causes materials to degrade more quickly than if the reaction could be run at substantially isothermal conditions.

A University of Colorado research team led by Alan Weimer has developed a technique for a substantially isothermal hercynite cycle, in which the entire reaction cycle is performed isothermally at 1200-1400°C (though the cycle can be performed at temperatures as low as 940°C). Because no significant heating or cooling is required between the respective cycles, the hercynite cycle allows faster, more efficient cycling and less wear on the equipment and materials used for the process. Furthermore, any materials degradation that might be associated with high/low temperature cycling will be eliminated.

Additionally, Dr. Weimer’s group has developed a process for simultaneously conducting both steps of the water- and/or carbon dioxide-splitting process, using concentrated solar energy to provide thermal energy to the reaction, reducing latent heat loss. The time required to carry out rapid redox cycling is decreased, providing for higher productivity.

Furthermore, use of this concurrent two-step process can eliminate the need to perform high-temperature separation of gaseous reaction products: since the oxidation reaction of the isothermal redox reaction is typically much faster than the reduction reaction, product gas(es) of the oxidation stage are produced first and/or can easily be separated from gas(es) produced during the reduction reaction. The newly discovered process can be used to split gasses in a timely, energy-efficient, and economical manner.

More Information

Efficient Generation of H2 by Splitting Water with an Isothermal Redox Cycle. Science 341 (2013): 540-542. PDF available upon request.

CU-Boulder team develops new water splitting technique that could produce hydrogen fuel.

Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Date
Application 20130266502
Application
20130266502
METHODS AND APPARATUS FOR GAS-PHASE REDUCTION/OXIDATION PROCESSES
A method and apparatus for gas-phase reduction/oxidation is disclosed. The apparatus includes a reactor including at least one reactor tube or containment vessel with active redox material within the reactor tube or containment vessel, a first reactant gas or vacuum for reducing the active redox material, and a second reactant gas for oxidizing the active redox material. The method may be run under substantially isothermal conditions and/or energy supplied to the apparatus may include solar energy, which may be concentrated.
04/05/2013
Filed
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
CU3054BPrototypeAvailable10/14/201310/14/2013

Contact CU About This Technology

To: Lola Underwood<lola.underwood@cu.edu>