Finally, two catalytic pathways (hydrolysis and hydrogenolysis) were proposed for
lignin revalorization into high value added bulk chemicals. Lignin hydrothermal
depolymerization was studied in terms of screening the best catalyst (homogeneous
catalysts) and of optimizing the reaction conditions (temperature and time).
Comparatively, lignin hydrogenolytic depolymerization was also considered in order
to reach the same goal. In this sense, different heterogeneous metallic catalysts and
hydrogen donating solvents were proposed so as to improve simple phenolic
compounds production. The optimized conditions of each depolymerization process
were applied to define lignin fractions in order to study the influence of lignin
properties on depolymerization reactions yields and to compare which catalytic
proposal presented the best challenge for lignin revalorization.