An electrolysis technique developed at JGU could make an important contribution to the electrification of the chemical industry

Researchers at Johannes Gutenberg University Mainz (JGU) have developed a method which gives access to the valuable raw materials formate and hydrogen from the waste product glycerol. Formates are the salts of formic acid and are widely used in the chemical industry, while hydrogen can serve, for example, as an energy carrier to power vehicles. The new method can be operated with sustainable electricity and does not produce CO₂. The results of the research have been recently published by the team in the journal Advanced Energy Materials. Professor Carsten Streb of JGU's Department of Chemistry, who supervised the study, pointed out: "The approach we have devised could make a significant contribution to the electrification of the chemical industry. This is a major driver for large-scale commercial developments to reduce industrial CO₂ emissions. Processes which currently require considerable amounts of petroleum or natural gas could in future be operated using sustainable electricity."

CO₂-neutral production of formate

The new process is based on the established method of water electrolysis. This involves the use of electricity to split water into hydrogen and oxygen. Employing so-called hybrid electrolysis, the researchers used glycerol in addition to water as a source material; the former is created in large quantities as a byproduct of biodiesel production. The second product generated during electrolysis was thus the corresponding formate rather than oxygen. Formates are usually produced from petroleum, but the corresponding process is associated with the emission of large amounts of CO₂. Streb added: "On the other hand, the electrochemical generation of formates from glycerol is CO₂-neutral if it is undertaken using green electricity." In chemical terms, what the researchers have achieved by means of their electrolysis of glycerol is to break down the glycerol, which has a three-carbon atom backbone, to create a formate that contains just a single carbon atom.

New catalyst developed

The new process is based on an innovative catalyst developed by the researchers. On the molecular level, the catalyst combines in close vicinity the two metals copper and palladium. Streb revealed: "We have not only managed to create this catalyst, but already have a very good idea what the material does and how we can optimize its operation." Theoretical and experimental insights into this were provided by a cooperating team at the National Taiwan University of Science and Technology.

Subsequently, the team headed by Streb plans to investigate whether it is possible to replace the expensive noble metal palladium in the catalyst with earth-abundant metals. The team also targets the development of a new method to convert formate into methanol – the demand for methanol is substantially greater than that for formate. This may prove possible by means of the introduction of a second reductive electrolysis process.

Developments in the SusInnoScience Top-level Research Area

The research performed at JGU was undertaken in the context of the Top-level Research Area SusInnoScience (Sustainable chemistry as the key to innovation in resource-efficient science in the Anthropocene), the purpose of which is to develop sustainable chemical and biotechnological production processes. This Top-level Research Area at JGU is funded through the Research Initiative of the State of Rhineland-Palatinate. The corresponding work was additionally a feature of the Sustainable Processes and Materials program of the Rhine-Main Universities (JGU, Goethe University Frankfurt am Main, and Technical University of Darmstadt). It is also noteworthy that five of the postdocs involved were sponsored by the Alexander von Humboldt Foundation. "This is an international project that benefits considerably from the fact that we are able to recruit international talent through the Humboldt Foundation," concluded Streb.