Rather than being released into the atmosphere and exacerbating the problem of climate change, CO2 can also be used as a raw material for substances required in industrial processes, such as formic acid or methanol. The conversion of CO2 has already been investigated in detail in laboratory studies, with nanodiamonds serving as an environmentally friendly photocatalyst. Researchers from the Fraunhofer Institute for Microengineering and Microsystems IMM are now working with partners to turn this reaction into a continuous process – bringing it much closer to real-world application. Given the damage that CO2 does to the climate, governments and companies are working hard to limit their emissions as much as possible. In cases where it cannot be avoided, however, CO2 could soon be used as a raw material in the production of industrially relevant C1 building blocks such as formic acid or methanol, which only contain one carbon atom. One possible method involves nanodiamonds: CO2 is converted into formic acid by using nanodiamonds as a catalyst and irradiating them with short-wave UV-C light in an aqueous environment. This method is currently being studied in the laboratories of Prof. Anke Krüger at the University of Würzburg (although Prof. Krüger is now working at the University of Stuttgart). Using diamond as a catalyst might sound expensive, but the diamond used in this process is not a costly jewelry-grade diamond; it is a detonation diamond which is produced on an industrial scale and is therefore relatively inexpensive as a catalyst. Furthermore, it largely consists of carbon and is therefore an environmentally friendly, “green” catalyst. Researchers from Fraunhofer IMM – together with Prof. Krüger and Sahlmann Photochemical Solutions GmbH – are now taking these reactions one step closer to real-world application within the framework of the CarbonCat project. “Up to now, the experiments have been carried out in a batch reactor; i.e., a stirred flask. There are certain disadvantages to this method,” says Dr. Thomas Rehm, one of the scientists at Fraunhofer IMM . “Firstly, the contacting between the gas and liquid phase and the catalyst is less than ideal; secondly, the catalyst – i.e., the nanoparticles that are floating around – needs to be separated from the solution after the reaction.”
