Solvent will provide energy savings to paper industry

Professor Maaike Kroon, from Eindhoven University of Technology (TU/e), has developed a solvent that will potentially enable the paper industry to make big energy savings in production.

In the production of paper, the basic vegetable material (lignocellulose), such as wood chips or other biomass, has to be separated into lignine and cellulose. The cellulose is used to make paper. The problem is that the two components are difficult to separate - the process requires high pressures and temperatures, and is costly to operate.

Dissolving the wood chips was previously not an option because lignine is normally insoluble. But Professor Kroon discovered that wood fibres easily dissolve in specific deep eutectic solvents (DES) - a mixture of two compounds which, once combined, has a much lower melting point than that of the individual components.

Professor Kroon has now patented the solvent which makes wood fibre dissolution possible. The solvent is entirely vegetable based and biodegradable and the process also produces very pure lignine, which the paper industry can use to develop new applications and markets such as making biodegradable plastics.

Softwood dissolved in DES. The lignine in the last bottle has been separated (the remaining pulp is at the bottom of the bottle). Photo: Eindhoven University of Technology.

The European paper industry has been focused on innovation and efficiency for a number of years. The Dutch paper industry took the initiative in 2004 to halve energy consumption by 2020, while the Confederation of European Paper Industries (CEPI) intends to reduce CO₂ emissions by 80% before 2050. In its search for breakthrough technologies, CEPI organised a competition last year to find the best new ideas. The winner was deep eutectic solvents, a concept which Professor Kroon had already been working on for several years.

TU/e has now signed an agreement with 14 European paper producers, including seven from the Netherlands, for the further development of the solvent. Professor Kroon will use the funding to recruit two PhD candidates for a further four years of research at TU/e to prepare the way for the building of a pilot plant. The laboratory research will take another five to 10 years, with a similar period being required for optimisation in the pilot plant. Large-scale applications are expected to be possible in around 15 years.

Professor Kroon noted that the agreement has been reached directly with the companies and does not rely on government financial support. It underlines the potential the companies see in the solvent and the importance they place on quickly implementing it in practice.

Henk van Houtum is the chairman of VNP, the Royal Netherlands’ paper and board association. He expects Professor Kroon’s solvent will make a substantial contribution to meeting the industry’s energy targets, hoping that the use of DES will lead to 40% lower energy costs and 20% less CO₂ emissions.

“This is a game changer, and it means the paper industry will look very different 20 years from now,” he said.

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