CAPHENIA, a German clean tech company founded in 2018, uses methane, carbon dioxide (CO₂), water, and electricity to produce syngas in an integrated reactor. Using the conventional Fischer-Tropsch (FT) synthesis process, the syngas can then be converted into carbon-neutral synthetic fuels. By making carbon-neutral synthetic fuels, CAPHENIA seeks to contribute to the reduction of carbon emissions in the transportation sector, especially airplanes. The company aims to produce 10 million liters of sustainable aviation fuel by 2027, 100 million liters by 2030, and more than one billion liters by 2035.
Challenges: carbon-neutral fuel
Since the early 1900s, carbon dioxide (CO₂) levels in the atmosphere have increased by 50% due to human activities. When fossil fuels (such as coal, oil, and natural gas) are burned for energy production, transportation, and industrial processes, CO₂ is released into the atmosphere. This excess CO₂ acts as a greenhouse gas, trapping heat and causing the air and ocean temperatures to rise. CO₂ emissions play a crucial role in driving climate change.
Negative emissions technologies (NET) have been developed to remove more CO₂ from the atmosphere than they emit during the process. Examples of NETs include Direct Air Capture (DAC), enhanced weathering, and Ocean Alkalinity Enhancement. For example, Direct Air Capture is a process that extracts CO₂ directly from the atmosphere. The captured CO₂ can then be utilized in various industrial applications.
If captured CO₂ is used in the production of synthetic fuels, then burning those fuels in airplanes, ships, and industrial processes doesn’t add to carbon emissions.
CAPHENIA has developed an integrated reactor that uses CO₂ and steam to convert methane into high-quality syngas in an efficient manner. Syngas is a fuel gas mixture that consists primarily of hydrogen (H₂), carbon monoxide (CO), and occasionally CO₂. It is an important intermediate in the production of various chemicals, fuels, and energy. The syngas can be converted into liquid fuels via the conventional Fischer-Tropsch process.
CAPHENIA’s technology produces high quality syngas from methane or biogas in a single reactor, reducing energy consumption and CAPEX. The process involves plasma pyrolysis of methane at around 2,000 ºC to produce carbon and H₂. Carbon reacts further with supplied CO₂ and steam via the Boudouard reaction and heterogeneous water-gas shift (WGS) reaction, respectively, to produce CO and H₂. Therefore, the CO/H₂ molar ratio of the syngas can be controlled for the subsequent Fischer-Tropsch process to produce liquid carbon-neutral fuels.
CAPHENIA 3-in-1 zone reactor
The diagram below depicts a single reactor developed by CAPHENIA to produce syngas from methane or biogas. Top to bottom, the reactor incorporates zones of methane plasma pyrolysis, carbon converter, and quench.
- Methane plasma pyrolysis zone
The methane plasma pyrolysis zone performs the methane or biogas plasma pyrolysis process.
This zone consists of a conical casing, an upper cylinder casing, an electrode holder, and an upper hood that spans the electrode holder. The conical casing is connected to the upper end of the carbon converter zone’s cylinder casing. The expansion of the cross-section slows the gas flow rate and, consequently, increases the residence time for pyrolysis reaction.
The electrode holder is attached to a plasma generator. The plasma generator has ring electrodes attached to the electrode holder in such a way that they are electrically isolated and arranged concentrically. A plasma gas feed line evenly distributes the plasma gas. An electric discharge occurs at the lower end of the ring electrodes, resulting in the formation of a plasma arc.
The outer annular space is flushed with a protective gas (a small portion of plasma gas) to minimize plasma gas backflows that lead to carbon deposits.
- Carbon converter zone
Carbon converter zone performs the conversion of carbon to CO and H₂.
Near the carbon converter zone’s inlet, preheated CO₂ gas flow is now supplied via a plurality of distribution nozzles distributed over the circumference of the carbon converter. Carbon deposits are minimized by the design of the distribution nozzles. The CO₂ flows at a rate significantly greater than the main gas stream of carbon and hydrogen along the axis of the reactor.
To provide optimal conditions for the endothermic Boudouard reaction, an electric heater is used to heat the reaction gas. The heating element is made of graphite.
At a second addition station, superheated steam is added to the reaction gas via distribution nozzles. To provide optimal reaction conditions for the endothermic heterogeneous WGS reaction, an additional electric heater is used to heat the reaction mixture.
- Quench zone
After the reactions are complete, the reaction mixture is cooled in the quench zone via injection of liquid water and a quench heat exchanger. The quench heat exchanger is arranged downstream of the direct water cooling.
The syngas now essentially contains CO and H₂. In its apex area, the lower hood comprises an outlet connection through which the syngas and water are discharged.
As previously described, CAPHENIA has developed a single reactor that converts methane or biogas into high-quality syngas. The process consists of plasma pyrolysis of methane, the Boudouard reaction, the heterogeneous WGS reaction, and the quenching.
- Methane plasma pyrolysis
To start the reactor, hydrogen gas is used as plasma gas to produce plasma using electric energy. Because hydrogen is expensive, it is only used to start the reactor. For stationary operation, a portion of the syngas produced in the process is recycled as plasma gas. The plasma generates a temperature of around 2,000 ºC.
Methane is supplied to the methane plasma pyrolysis zone. At this high temperature, methane is effectively broken down into carbon (C) and hydrogen gas (H₂):
CH₄ → C + H₂
The carbon and H₂ products flow to the carbon converter zone, where the Boudouard and heterogeneous WGS reactions occur.
- Boudouard reaction
The carbon converter zone is supplied with preheated CO₂ flow, which is then mixed with carbon and H₂ flow. Carbon reacts with CO₂ at temperatures between 800 and 1,700 ºC to form carbon monoxide (CO) via the Boudouard reaction:
C + CO₂ → CO
This reaction is endothermic. Heat is supplied to this process so that the temperature of the reaction gas mixture does not drop below 800 ºC.
At this point, the reaction gas essentially contains carbon monoxide, hydrogen, unconverted carbon, and small amounts of unreacted carbon dioxide.
- Heterogeneous WGS reaction
The carbon converter zone is further supplied with superheat steam, which is mixed with the reaction gas. Carbon reacts further with steam at temperatures between 800 and 1,700 ºC to form carbon monoxide via heterogeneous WGS reaction:
C + H₂O(g) → CO + H₂
This reaction is endothermic as well. Heat is supplied to this process so that the temperature of the reaction gas mixture does not fall below 800 ºC.
At this point, the reaction gas essentially contains carbon monoxide and hydrogen.
After the reactions are complete, the reaction mixture is cooled in the quench zone. After quenching, the temperature of the reaction mixture falls below 400 ºC, the point at which reactions cease.
The syngas is fed to a Fischer-Tropsch converter for producing target hydrocarbons.
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CAPHENIA is building a pilot plant at Industry Park Infraserve in Frankfurt, Germany to produce syngas from a mixture of biogas, CO₂, water, and electricity. The pilot plant is planned to be operational in 2023. It aims to prove the feasibility and scalability of CAPHENIA’s technology for producing carbon-neutral synthetic fuels.
CAPHENIA has raised a total of €5.1 M in funding over a Grant round on Jan 1, 2023.
CAPHENIA has received funding from various investors, including:
- Christoph Franz
- Simone Menne
- Roland Busch
Mark Misselhorn is Founder.
Mark Misselhorn is CEO.