Pyrolysis is a recognized technology for lignocellulose conversion into bio‐based fuels, materials, and chemicals. In this work, pyrolysis liquids were obtained by fast pyrolysis of wood after pretreatment with diluted sulfuric acid. The pyrolysis liquids were separated by solid‐phase extraction with an anion exchange resin Lewatit VPOC 1074 as the stationary phase. The aromatic constituents of the pyrolysis liquids were adsorbed on the resin, while the sugar derivative fraction was eluted with water. Different desorption solvents were tested for batch and continuous elution of phenol derivatives. Most promising results were obtained for selective separation of phenol carboxylic acids by changing the ratio of water, methanol, and acetic acid in the solid‐phase extraction solvent system.

Fast pyrolysis of pre-treated lignocellulose gives a high yield of levoglucosan and other anhydrosugars, which are considered as the main product. However, the chemical composition of the liquid pyrolysis products is a complex mixture of hundreds of individual compounds. To implement the biorefinery principles, it is important to find applications for the side-streams which arise during levoglucosan production. First, we separated the anhydrosugars by eluting the pyrolysis product water solution through an anion exchange resin column. The anhydrosugars were eluted, but the aromatic by-products were adsorbed on the resin. The by-products were desorbed from the resin with a mixture of methanol/water/acetic acid, and the chemical composition of the obtained by-products was analyzed by UHPLC-UV, and the Folin-Ciocalteu method. Alternatively, the pyrolysis products were separated by crystallization, which yielded levoglucosan with >90% purity, and a mother liquor enriched with aromatic chemical compounds. The antioxidant activity in all samples was evaluated by the DPPH method with corrections to compensate for the color of the by-product samples, which interfered with the UV/VIS spectrophotometry readings.