Extraction and revalorization of olive tree (Olea europea) pruning lignin

Traditionally, lignin has being considered just for energy generation. 2nd generation bioethanol plants are said to shift this fact since lignin revalorization is one of the key economical points for these plants. Bulk chemicals is one the most interesting applications for lignin. In this work, organosolv lignin was obtained from olive tree pruning under optimized conditions. Base catalyzed lignin depolymerization was achieved changing the applied severity parameter to study the influence of reaction conditions on oil yield and composition. The major difference was the oil composition suggesting that reactions conditions controlled depolymerization mechanism. Catechol and 4-methylcatechol were the main products. Residual lignin contents were very high for all the experiments. Related to this find, it was studied how repolymerization reactions decreased lignin depolymerization degree.

► Olive tree pruning was proved to be a good candidate for biorefinery process.
► Lignin was successfully depolymerised into interesting compounds such as catechol and 4-methylcatechol.
► Time (15–90 min) and temperature (250–310 °C) reaction were evaluated using severity factor.
► No trend in repolymerization reactions along with reaction conditions was observed.