Solar thermochemical production of fuels from CO2 and H2O using ceria redox reactions (SOLAR FUELS)
Schematic of the solar reactor for the two-step, solar-driven thermochemical production of fuels. It consists of a thermally insulated cavity-receiver containing a porous monolithic ceria cylinder. Concentrated solar radiation enters through a
windowed aperture and impinges on the ceria inner walls. Reacting gases flow radially across the porous ceria towards the
cavity inside, while product gases exit the cavity through an axial outlet port at the bottom. Inset shows the scanning electron
micrograph of the porous ceria tube after 23 cycles. Red arrow indicates ceria reduction (oxygen evolution); blue arrow indicates
oxidation (fuel production).
Scope of project
This project is aimed at developing the science and technology required to efficiently produce liquid
hydrocarbon fuels from H2
, and solar energy. A 2-step H2
-splitting thermochemical cycle is
investigated based on non-stoichiometric ceria redox reactions, encompassing:
1st reduction step: the high-temperature thermolysis of ceria to oxygen-deficient ceria and O2
endothermic process driven by concentrated solar energy; and
2nd oxidation step: the reaction of the oxygen-deficient ceria with H2
O and CO2
to produce H2
and CO –
syngas, the precursor to diesel, kerosene, and other liquid hydrocarbon fuels.
The optimization of the ceria structures is an essential endeavor for reaching high fuel production rates at
high solar-to-fuel energy conversion efficiencies.
To engineer robust and stable reticulate porous ceramic (RPC) ceria foams and examine a wide range
of ceria dopants to increase the oxygen release and uptake during cycling. RPC foams will be fabricated
with open 3D network structures of high interconnecting porosity, high specific surface area, low density,
and good permeability, for the purpose of obtaining efficient mass/heat transfer and fast reaction
- To determine the effective heat and mass transport properties of the RPC foams.
- To prepare doped cerium mixed oxides with enhanced oxygen-release capabilities and thermal stability.
- To identify mixed-oxide oxygen storage sites and relate structural properties to reaction mechanism and kinetics by operando spectroscopy and scattering (in situ HERFD-XAS, Raman and XRD).
- To identify the fundamental reaction mechanisms and determine kinetic rates for different ceria structures exposed directly to high-flux solar irradiation.
Objectives of the parallel EU-Project are
- To formulate and experimentally validate a reactor model for heat/mass transfer and fluid flow.
- To develop and optimize the solar reactor technology for producing syngas by simultaneously splitting H2O and CO2, and to further process the syngas to kerosene (jet fuel).