Lignin is the most abundant renewable source which has aromatic units in its structure. As shown in Figure 3, the world demand for aromatics is consistent and increasing over the years. The possibility to establish a direct and efficient conversion of lignin to high — volume, low-molecular weight aromatic molecules is therefore extremely attractive. How­ever, there are important technological barriers which must be overcome, given the resistant and robust lignin structure.

The basic chemical units of lignin shows very high potential for making BTX chemicals (Figure 5). Technologies able to efficiently depolymerize the polymer by breaking the C-C and C-O bonds are necessary. An aggressive, nonselective, depolymerization would bring to a mixture of BTX, phenols, and aliphatic fractions (C1-C3). These chemicals should be suitable for being directly used by the conventional petrochemical processes which convert the bulk aromatics into nylons, resins, polymers, and others. Development of the required aggressive and nonselective chemistries is part of the long-term opportunity but is likely to be achievable sooner than highly selective depolymerizations (presented below; Holladay et al., 2007).

A related technological challenge for the production of chemicals from lignin is the elabo­ration of proper separation techniques for the mixture intermediates from which the aromatic chemicals are to be isolated (Huang et al., 2008).