| abstract |
Within the scope of hydrothermal carbonization of biomass, not only the main product, coal, but also the platform chemical 5-hydroxymethyl furfural, as well as furfural and levulinic acid, are formed. These are extracted from the process water of the carbonization reaction. However, in this connection, the problem exists that humic substances deposit on the container walls of the extraction column and can only be removed again by means of great cleaning effort. Furthermore, oligomers clearly worsen the purity of the product. This problem is solved by a filtration cascade through which the process water passes before extraction. In this connection, first the impurities mentioned are removed in a first filtration stage, and the remaining products and educts are separated from one another in a second filtration stage. Only the products are passed to extraction. |