One-Step Chemical Looping Process for Producing Hydrogen or Syngas directly from Solid Fuels

Institution: The Ohio State University

Summary
Researchers at The Ohio State University have developed a one-step, highly efficient Chemical Looping Reforming (CLR) process to produce H2, CO or a mixture thereof (syngas) directly from solid carbonaceous fuels like coal and biomass, eliminating the need for a gasifier. The novel process utilizes cyclic redox reactions of metal oxide (MO) particles.

MO + C_xH_yO_z (coal) <-> M + CO₂ + H₂O (unbalanced)
M + H₂O/ CO₂ <-> MO + H₂ /CO

Fe₂O₃ is used as the metal oxide for this process. This approach resolves the problems that are conventionally encountered due to the introduction of coal (tar formation, char conversion, caking of coals, sulfur handling, and ash handling). The reactions of coal and Fe₂O₃ have been demonstrated on a bench scale reactor with significant success. Detailed ASPEN studies have shown that hydrogen production efficiencies ((high heating value - HHV basis) ranging between 80-90% are possible. Preliminary cost analysis suggests a significant reduction in the cost of hydrogen as compared to the SMR (steam methane reforming) process for natural gas.

The process introduces coal directly into the first reactor that allows complete conversion of Fe₂O₃3 to Fe, and forms a ready to sequester CO2 stream after condensation of water. The CLR process can also be used instead of a gasifier to produce syngas. The process can provide any H₂/CO ratio desired in the syngas stream with limited CO₂ concentration. Additionally, optimizing iron oxide particles has led to the development of strong particles durable at high temperatures, demonstrated to maintain full oxygen transfer capacity over a 100 cycles of reduction and oxidation.

Advantage

• Elimination of gasifier and air separation unit
• Integrated CO₂ separation, with no costly separation techniques. Provides ready to sequester CO₂ stream by design, offering several environmental benefits
• Fuel flexibility, allowing for all kinds of solid carbonaceous fuels such as coal, wood, biomass, pet coke, tar sand, and shale rock
• Can help tailor H₂/CO ratio of syngas to any desired level
• High hydrogen production efficiency (80-90%)
• Over 30% costs savings over traditional processes
• Smaller plant footprint due to lesser number of reaction vessels, resulting in a simpler process control
• Produces low cost Fe₂O₃ composite particles, shown to undergo more that 100 redox cycles without loss in activity

Inventor
L.S. Fan

Category
Chemicals; Energy;Environment

Contact Information
Ryan Zinn
zinn.7@osu.edu
http://tlc.osu.edu/technologies/detail.cfm?TechID=230


Keywords
hydrogen, carbon, carbondioxide, syngas, sequestration, coal