Scientists at Rice University in Houston, USA, have developed a relatively simple and cheap way to convert carbon dioxide into a new type of fuel. This is formic acid, which, although not suitable for direct use in engines, can serve as an effective carrier of hydrogen. Gaseous hydrogen is difficult to compress, but in the composition of formic acid concentrate it can be stored a thousand times more per unit volume of the container.
The production and purification of formic acid has its own challenges, so the plant for converting CO 2 into concentrate was designed from scratch. The technological process is based on two know-hows: the use of solid electrolytes and the use of a bismuth catalyst. A solid electrolyte from a polymer base is very important because, unlike a liquid solution, it does not contain impurities. And this already eliminates the need for additional purification of formic acid.
As for bismuth, then, according to the author of the development Chuan Xia, if earlier it was produced in grams, now they have found a way to get kilograms of this metal at no special cost. This allows CO 2 to pass through a multilayer bismuth lattice to convert it into a negatively charged molecule, formate. It diffuses into the electrolyte, where it meets hydrogen ions released from the second catalytic reaction with water. The output is 30% formic acid concentrate.
Experiments have shown that a similar process can convert 42% of electrical energy into the energy of chemical bonds. Not the worst efficiency for fuel systems, and if you take CO 2 directly from emissions into the atmosphere, and energy from renewable sources, then the technology becomes many times more cost-effective. Now scientists are working on the modernization of the installation in order to learn how to obtain even purer acid.