Scientists from the Czech Institute of Research and Advanced Technologies (CATRIN) at Palacký University in Olomouc and the research centres CEET and IT4Innovations at the Technical University of Ostrava have developed a unique technology that will enable the conversion of biodiesel production waste – glycerol – into a useful product and thus increase the efficiency of existing biofuels.
In addition, the graphene-based biomaterial they have designed will replace the acids that have so far been used to convert glycerol. But unlike them, it is non-toxic and fully recyclable. The discovery, which was made in collaboration between Czech scientists and Indian colleagues, was recently published in the journal Nature Communications.(1)
Although the production and use of biofuels is currently a hot topic and faces criticism, their consumption is growing dramatically worldwide and will continue to play an important role in the years to come. The production process therefore needs to be optimised. Biodiesel is an environmentally friendly fuel of plant origin, the addition of which to diesel significantly reduces the emission of toxic gases in the air. However, the production of biodiesel from vegetable oils produces glycerol as a waste product, also known as glycerine, used for example in antifreeze for cars.
“Our goal was to find a way to convert glycerol into a chemical form that can be reused in biofuels. We have developed a graphene-based carbon material chemically modified with a natural amino acid,” explained Radek Zbořil, researcher at CATRIN-RCPTM at Palacký University and head of the Materials-Envi Lab of CEET at the VSB- Technical University of Ostrava.
This eco-friendly material can accelerate the conversion of glycerol into a high value-added compound with the highest efficiency to date. “The resulting alcohol, the so-called solketal, when added to the fuel, significantly improves its quality and octane number, reduces the unwanted formation of microparticles, as well as the emission of carbon monoxide and other organic toxic substances. In addition, it increases the viscosity and stability of the biofuel, which is important for long-term storage of biodiesel,” said the first author of the publication, Aby Cheruvathoor Poulose from CATRIN.
The development of new nanomaterials derived from the “Nobel Prize” graphene has been a long-standing focus of Olomouc scientists, including in the context of prestigious European Research Council (ERC) projects. This time, the anchoring of a simple amino acid into the structure of graphene helped to achieve the desired result.
“Experimental and computational studies have shown that this particular amino acid significantly increases the ability of graphene to bind reaction components, in this case acetone and glycerol, to its surface. The new biomaterial is significantly more efficient for glycerol conversion than the acids used industrially so far, such as sulphuric or hydrochloric acid. However, it is environmentally friendly. It also allows the chemical conversion of glycerol to be controlled exclusively towards the production of useful biofuel additives, without any additional waste,” added Aristeidis Bakandritsos, who works at CATRIN and the CEET.
In 2021, the market for biofuels exceeded $110 billion, and is expected to approximately double by 2030 (2). Biodiesel can be used directly as an environmentally friendly fuel in diesel engines, but is largely added to petroleum-derived diesel. The production of biodiesel generates around 40 billion tonnes of waste glycerol per year, which poses a huge challenge, especially in view of the principles of the circular economy. Despite the ever-increasing consumption of biofuels, there are critical voices, not only in the European Union, pointing to the waste of food resources and the burden on the landscape. In addition, the use of rapeseed oil, for example, as a source for biodiesel production results in carbon dioxide emissions throughout the entire rapeseed processing chain, from sowing to processing. The overall reduction in the carbon footprint is therefore not entirely optimal, as Czech scientists have also pointed out.
“Personally, I am in favour of developing completely carbon-neutral and sustainable fuels, especially based on hydrogen obtained from renewable sources. However, the production of biofuels cannot be ignored; on the contrary, it is desirable to improve the process. The material we have developed can not only utilise waste glycerol from biodiesel production, but in pilot experiments it has also proved extremely effective in the actual production of biofuel from vegetable oils, including waste fats. We therefore want to continue our research and focus on more efficient conversion of already used waste vegetable oils for the development of second-generation biofuels so that the overall biodiesel production process is both energy and environmentally sustainable and does not damage the agricultural landscape,” Zbořil concluded.
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