Syngas is a mixture of H₂ and CO. It is widely used, e.g., in methanol synthesis or olefin hydroformulaton. CO₂ is a suitable feedstock for syngas production, as it is easily available, affordable, and can be captured from power stations. Hydrogen or methane are possible co-reactants to convert CO₂. To obtain a carbon saving potential, aditional CO₂ emission has to be avoided during production of H₂ and CH₄.

H₂ can be produced from electrolysis of water with renewable energy, whereby pure oxygen is obtained. The oxygen can be used for simultaneous partial combustion of the energy-rich co-reactants H₂ or CH₄ to obtain high temperatures. This is crucial for both, high CO₂ conversion and to avoid coke formation. René Kelling, Gerhart Eigenberger, and colleagues, University of Stuttgart, Germany, have developed a scalable reactor concept for these harsh reaction conditions. Their multitubular reactor (pictured) consists of ceramic reaction tubes partially coated with a reforming catalyst.

An optimal oxygen flow profile and efficient heat-recovery ensure constant temperatures around 1000 °C in the reaction section. More than 85 vol % of hydrogen and CO are produced with CO₂ conversion of around 70 %. A model predicts high CO₂ conversion and syngas production in industrial scale while maintaining defined temperature limits so that coke formation is avoided.

The researchers think that their reactor concept is applicable also for other high temperature synthesis heated by simultaneous combustion such as autothermal steam reforming or partial oxidation of methane without CO₂.

• Ceramic Counterflow Reactor for Efficient Conversion of CO₂ to Carbon-Rich Syngas,
  René Kelling, Hendrik Dubbe, Gerhart Eigenberger, Ulrich Nieken,
  Chem. Ing. Tech. 2015.
  DOI: 10.1002/cite.201400128