Carbon dioxide conversion to hydrocarbons using structured carbon nanotube supports

Dealing with carbon dioxide waste is an ongoing societal and technological challenge. One attractive proposition is to chemically convert waste carbon dioxide into useful chemical products. One possible route is to combine two well-known chemical processes, reverse water gas shift and Fischer-Tropsch synthesis, to make a catalyst capable of converting carbon dioxide directly into hydrocarbons.

Iron nanoparticles supported on carbon nanofibres have shown promise in the Fischer-Tropsch process.1 We have shown that iron nanoparticles supported on carbon nanotubes (Fe@CNT) are also effective catalysts for the coupled reverse water gas shift and Fischer-Tropsch reactions.2 Using an oxidation process the iron nanoparticles embedded in the carbon nanotubes from the synthesis process can be regenerated to act as catalysts for the Fischer-Tropsch reaction (see figure 1a).2

Carbon nanotube powders generated in this way are difficult to handle, and could be difficult to scale-up. We have, therefore, developed a method to grow long, aligned carbon nanotubes on a commercial cordierite monolith support (see figure 1b. 3 Using the same oxidation method we have now activated these Fe@CNTs-monoliths to act as catalysts for carbon dioxide conversion. Here we report on the first promising results.