Breakdown of lignin for the production of aromatic compounds

After cellulose, lignin is the most common organic compound found on Earth and, due to its chemical structure, it could serve as a renewable resource for the production of aromatic chemicals. Due to its complex structure and great firmness, its transformation through chemical processes has only produced results after decades of research. Chemical processes achieve good results but they require high temperatures and a lot of chemicals. Biological processes inspired from the natural breakdown of lignin through fungi could therefore render the process less resource-intensive and lower the cost of chemicals.

To protect the climate and secure supplies, there is a growing interest in fuels and chemicals based on renewable sources. Today's production of biofuels creates significant amounts of lignin that are currently being burnt. The chemical structure of lignin suggests that it could be used as a basis for producing aromatics, which are currently produced with oil.

The researchers tested a combination of successive chemical and enzymatic treatments for breaking down lignin. In a first step, wood is treated with a gentle biochemical reaction, recycling the used biocatalysts. This biocatalytic step renders the lignin more accessible for the chemical treatment. The second step consists of a chemical process using formic acid to produce aromatics. Based on the knowledge gained from the first two steps, the researchers established the ideal specifications of the two processes to ensure the largest yield of useful products. At the same time, they were able to reduce the energy consumption and the need for chemicals.

The results of the project could contribute to the development of a new technology for bio-refineries that utilise ligneous plant material. In addition, the researchers expect to gain new insights into processes such as the enzymatic breakdown of lignin and synergies between enzymatic and chemical catalysis.

By testing various pre-treatments and the successive breakdown of lignin, the researchers gained new insights into the solubility of lignin and the possibilities of recycling biocatalysts.

Sequential treatment of lignins by advanced chemical oxidation processes and nanobiocatalysis for the production of industrially relevant oligomers and monolignols