Catalytic Conversion of Lignin for the Production of Renewable Chemicals

Lignocellulose is becoming an increasingly important alternative feedstock for biofuels production. Lignocellulosic biorefinery operations must produce base and fine chemicals as well as transportation fuels and materials in order to be competitive, making use of all the major components of lignocellulose, including lignin. Indeed, this complex aromatic polymer holds great potential for the sustainable production of renewable aromatics and phenolics. The catalytic conversion of lignin is highly challenging. This is mainly due to the recalcitrance and highly heterogeneous nature of lignin. It is important to note in this respect that the molecular structure and chemical composition of lignin depends both on the plant species as well as on the biomass pretreatment process. A generic method for catalytic lignin valorization for the production of value-added aromatics or phenolics needs to address the issues of lignin solubility as well as of the subsequent depolymerisation, deoxygenation and functionalization of the lignin soup. In this lecture, we will discuss our progress in transforming different types of lignin, such as Kraft and Organosolv lignin, into mixtures of phenolics. This mixture can then be used for the manufacturing of e.g. renewable detergents via a telomerization process with 1,3-butadiene, produced via the catalytic condensation of bio-ethanol. Other important aspects, which will be discussed in this lecture, include catalyst stability under liquid phase conditions, the use of a specially constructed reactor for on-line spectroscopic measurements at high temperatures and pressures as well as the use of quantitative 2-D NMR to evaluate the details of lignin degradation.