Solid‐Phase Extraction of the Aromatic By‐Products Obtained by Fast Pyrolysis of Pretreated Lignocellulose

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. Pyrolysis liquids obtained by fast pyrolysis of birch wood pretreated with diluted sulfuric acid have been separated by solid‐phase extraction to valorize the aromatic by‐products which arise during levoglucosan production. Solid‐phase extraction offers good separation between sugars and phenols, also allowing further selective extraction of different aromatic species.