Solvent recovery – How to re-use the key ingredient of the process

By Hochschule Bremerhaven

Bringing a novel process all the way to the market is not an easy task. A key factor to succeed is to minimize all losses that can potentially destroy the overall profitability. In Flexi-Green Fuels, KIRAM has studied and validated the delicate process of recovering the solvent used in Organosolv to enable efficient recirculation. One of the main challenges of the process step is to evaporate the solvent while keeping the lignin dissolved in the liquor in a form manageable for further downstream isolation. By applying a method of low-pressure distillation, the liquor temperature can be kept sufficiently low to not soften the lignin into a sticky and difficult to handle form. The lignin is then isolated from the remaining liquor by diluting it with water, forcing the lignin to precipitate. The evaporated solvent is received at a high level of purity, and the result of the operation are three isolated streams – the solvent, the lignin and the sugar residue containing water stream. The results of the solvent recycling task provide additional information to how the Organosolv process can be implemented on an industrial scale, and what process conditions and material qualities that can be expected.

Distillation products – isolated solvent (left) and remaining lignin/sugar liquor (right)


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This project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 101007130.