Nickel catalyst turns Co₂ into high octane fuel assembly

The researchers developed a fluorine-doped nickel catalyst that converts carbon dioxide into long-chain hydrocarbons suitable for gasoline and aviation fuel production.

The catalyst can create linear and branched hydrocarbons with up to six carbon atoms over the long term, with branched varieties particularly valuable for high octane fuels.

The study, published in Nature Catalysis, demonstrates how fluorine doping prevents catalyst poisoning and keeps nickel active during the electrical process of carbon dioxide. Compared with linear chains, using pulsed electrical technology, the team achieved a significant doubling of branched hydrocarbon production.

Fluorine Advantages

Traditional nickel catalysts suffer from carbon monoxide poisoning, which prevents active sites and reduces efficiency. The Singapore-based research team found that the addition of fluorine atoms to the nickel structure kept the metal in a partially oxidized state, thus preventing the poisoning.

Three fluorine-doped catalysts were tested, with the highest fluorine content, achieving a carbon dioxide production efficiency of 38.7%. More importantly, the catalyst with a moderate fluorine content produced a hydrocarbon efficiency of 8.3% and a current density of 0.7 mA cm -2.

The researchers used late spectroscopy techniques to show that fluorine-doped catalysts retained 75-78% fluoride content after reducing carbon dioxide, thus maintaining their beneficial properties. In contrast, the uncontained nickel oxide catalyst reduced the metal nickel by 19%, which seriously hindered performance.

Cracking branch code

This study reveals how branched hydrocarbons can be formed through specific mechanisms involving carbon monoxide intermediates. The group found that when the branch is mate with two CH2 groups at the same time, a branch occurs, forming a central carbon atom that can act as a branch point.

Key mechanical insights include:

• Unsaturated hydrocarbon intermediates drive chain growth through CO coupling
• Initiation of branching from CO response with two CH2 species
• Pulse latent technology enhances branches by preventing premature chain termination
• Deuterium substitution increases overall hydrocarbon selectivity to 22.2%

The researchers used isotope labeling experiments to track the carbon pathway, confirming their proposed branching mechanism. When formaldehyde was added as the CH2 source, the branched hydrocarbon ratio of the five-carbon chain increased by 295%.

Pulse power enhancement branch

The team developed a pulse electrochemical method that alternates between high and low potentials to facilitate branched hydrocarbon formation. For tetracarbon alkanes, the technology increases the branch-to-linear ratio by 119% and the olefin by 124%.

The pulsed method works by preventing the hydrogenation of the reactive intermediates, thereby allowing more carbon-carbon coupling reactions leading to branched structures. Combined with formaldehyde addition, this technology can achieve a branched hydrocarbon ratio of alkane 2.9 and a hydrocarbon ratio of olefins of 4.7.

Unexpected discoveries occurred when deuterated oxide was used instead of water as the electrolyte. This creates a reaction kinetic isotope effect in which deuterated hydrocarbons form more easily than their hydrogen isotopes, thus achieving the highest selectivity of long-chain hydrocarbons in carbon dioxide electrical.

Bridge laboratory and fuel tank

Hydrocarbon products follow the Anderson-Schulz-Flory distribution pattern, similar to industrial Fischer-Tropsch synthesis. This similarity suggests that electrochemical processes may complement or replace energy-intensive petroleum refining methods currently used to produce high-octane gasoline components.

This study provides both basic insights into carbon-carbon bond formation and practical strategies for producing valuable chemicals from waste CO2. The ability to control linear or branched hydrocarbon forms represents a significant improvement in electrochemical carbon dioxide utilization.

Although current levels of efficiency require increased commercial viability, this work identifies important principles for designing next-generation CO2 conversion catalysts. The combination of fluorine doping, pulse electrolysis and mechanical understanding provides a pathway for the generation of sustainable hydrocarbon fuels.

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