Lignin catalytic hydroconversion towards valuable products
Résumé
Nowadays, transformation of lignocellulosic biomass is deeply investigated to provide biofuels and chemicals in a near future. Lignin, which represents almost 30% of this biomass, is a macromolecule containing mainly phenyl-propane linkages with phenolic and ether functions [ , ]. Each year, more than 50 millions of tons of lignin are co-produced from pulp industry and burned as a low-value fuel. It has been established that a non-negligible part of this lignin can be used as a precursor of hydrocarbons or phenol type compounds (fuel additives or chemicals intermediates), without weakening the pulp industry. In addition, the improvement of the pulping processes (highly pure sulfur-free lignins) and the intensive investigations towards cellulosic ethanol should provide even greater quantities of high grade lignin materials [ ]. Recently, the hydroconversion of a wheat straw soda lignin (Protobind 1000), under hydrogen pressure, over a supported sulfided catalyst (NiMoS/Al2O3), in tetralin solvent, in a batch reactor, was reported and an experimental product recovery protocol was proposed leading to 98% of mass balance [ ]. Gases, liquids, lignin residue and solids (catalyst + char) were separated and characterized.