Periodic Reporting for period 1 - HAEMOGLOBIN (From biomass to catalysts and chemicals: exploiting blood and food waste towards high-value products.)
Reporting period: 2020-06-10 to 2022-06-09
Catalysts are entities that are able to accelerate chemical reactions. This is crucial for our society, since they can drastically reduce the reaction time (from years to hours in the most extreme cases) to prepare useful chemicals, while also lowering energy consumption of a given process. Their contribution to society amounts to almost 40% of world's GDP since they are needed in most chemical processes, ranging from drug manufacturing to agricultural applications, or plastics for instance. However most catalysts are based on precious and expensive metals, such as Palladium or Platinum. For the countries of the EU, these metals have to be imported from foreign countries, with questionable labour laws and with ever-increasing and volatile prices. Furthermore, most metals are toxic and need to be treated carefully if they are involved in the making of products destined to be consumed by human beings, such as drugs. Alternatives mustbe found to reduce our reliance on precious metals.
One solution consists in extracting metals from industrial waste. For instance, slaughterhouses produce considerable amounts of blood waste, that cannot be easily disposed of, and could be reused. In particular, the oxygen-carrying protein contained in blood, hemoglobin, naturally contains iron atoms. While these atoms are normally involved in the transportation of oxygen, it could be used for other catalytic applications.
Our goal here is to make an iron-based catalyst from hemoglobin, and apply it to industrially-relevant catalytic applications.
One solution consists in extracting metals from industrial waste. For instance, slaughterhouses produce considerable amounts of blood waste, that cannot be easily disposed of, and could be reused. In particular, the oxygen-carrying protein contained in blood, hemoglobin, naturally contains iron atoms. While these atoms are normally involved in the transportation of oxygen, it could be used for other catalytic applications.
Our goal here is to make an iron-based catalyst from hemoglobin, and apply it to industrially-relevant catalytic applications.
Around 10 preparation methods have been tried at the beginning of the project to convert haemoglobin into an iron-based catalyst. The most successful process consisted in a simple two-step thermal treatment, first by heating haemoglobin in presence of xylose, a molecule derived from waste wood products, in water in a pressurised vessel at 220C. The resulting solid was then heated in an oven in dry conditions, under reduced oxygen atmosphere. This particular set of conditions allowed the haemoglobin's iron to retain most of its properties while converting the rest of the protein and xylose into a porous carbon structure.
The material was characterised with high-end techniques, to understand better its structure. By using high resolution Scanning Transmission Electron Microscopy, we showed that the carbon formed small spheres (around 2-5 micrometers). We also saw that that iron we present within the carbon sphere as single atoms, meaning it was not aggregated to other iron atoms. By X-ray absorption techniques, we further proved that the iron's former configuration in haemoglobin was retained in the final material as planned, showing the efficiency of our method despite its simplicity. Indeed, we showed that each iron atom was surrounded by four to five nitrogen atoms, that are anchored to the carbon material.
We then tested the material for hydrogenation reactions, that is to attach hydrogen atoms to target molecules. We first focused on a particularly important reaction, the hydrogenation of molecules called nitroarenes into anilines (to convert -NO2 groups into -NH2 groups). This reaction is highly relevant in the industry since anilines are crucial intermediates in the preparation of dyes, plastics and fertilisers. In a second time we worked on a similar intermediate, formamides, transformed in one go from nitroarenes (-NO2 to -NH2 then to -NH-C(O)H groups).
The results of this investigation will be published in two papers.
The material was characterised with high-end techniques, to understand better its structure. By using high resolution Scanning Transmission Electron Microscopy, we showed that the carbon formed small spheres (around 2-5 micrometers). We also saw that that iron we present within the carbon sphere as single atoms, meaning it was not aggregated to other iron atoms. By X-ray absorption techniques, we further proved that the iron's former configuration in haemoglobin was retained in the final material as planned, showing the efficiency of our method despite its simplicity. Indeed, we showed that each iron atom was surrounded by four to five nitrogen atoms, that are anchored to the carbon material.
We then tested the material for hydrogenation reactions, that is to attach hydrogen atoms to target molecules. We first focused on a particularly important reaction, the hydrogenation of molecules called nitroarenes into anilines (to convert -NO2 groups into -NH2 groups). This reaction is highly relevant in the industry since anilines are crucial intermediates in the preparation of dyes, plastics and fertilisers. In a second time we worked on a similar intermediate, formamides, transformed in one go from nitroarenes (-NO2 to -NH2 then to -NH-C(O)H groups).
The results of this investigation will be published in two papers.
This work shows for the first time the conversion of haemglobin waste into a catalyst applied to an organic reaction. In particular, this specific single-atom configuration of iron is difficult to prepare, let alone from haemoglobin. We reported here a simple two-step thermal method to prepare it, compared to more wasteful or harsher preparations techniques for similar materials in fuel cell applications.