Although the research activities show that in 2013 there is a great interest in using lignin as a renewable resource for the production of aromatic chemicals, it is also clear that commercial utilization will take substantial time. So far the literature results show that relatively low conversion yields to about 10 wt% based on dry lignin and resulting complex mixtures hinder the commercial utilization of these processes.

The Netherlands can play an important role in the lignin aromatics valorization technologies as technology provider with the strong presence and strategic location of academia, chemical industries and other stakeholders in the value chain. In the Port of Rotterdam in the Netherlands about 5 million tons of aromatic building blocks are currently produced and distributed to the chemical industry in the Netherlands, Germany, Belgium and other countries. These aromatic bulk chem­icals used and produced consist of so-called aromatic monomers like BTX, styrene and phenol.

In the Netherlands in 2010 the Wageningen UR Lignin Platform was established, which plays an impor­tant role in this lignin valorization value chain develop­ment (http://www. wageningenur. nl/Lignin-Platform. htm). This is a joint research program with academia and industry dedicated to develop the entire lignin bio­aromatics value chain. Besides this initiative other net­works in Canada and Scandinavia work on lignin valorization topics.

Considering these increased research activities on lignin conversion and valorization technologies it can be concluded that the race to produce bioaromatics from renewable feedstocks is wide open. Next to lignin as aromatic feedstock conversion of carbohydrates to aromatic chemicals is also under investigation (Dodds and Humpheys, 2013). It should also be emphasized that many of the above-discussed technologies are at a very early stage, which makes it at present unclear if and which of those routes can become cost competitive as well as sustainable.

CONCLUSIONS AND FURTHER
PERSPECTIVES

The use of lignocellulosic feedstocks as an important source for chemicals and fuels is gaining momentum. This chapter has indicated that there are many vari­ables to take into consideration. We have learned that lignocellulosic biomass consists of three major groups: the softwoods, hardwoods and grasses and that there is also great heterogeneity within each group. There are multiple pretreatment routes developed that are currently scaled up to pilot, demonstration and com­mercial scales. The optimal pretreatment technology needs to be selected based on the available feedstock and the desired product. At the moment there are no indications that one pretreatment method will be the optimal route for all feedstocks and products. Many routes toward chemical building blocks based on monomeric carbohydrates are ready for scaling up; lignin conversion into monomeric building blocks needs substantial additional R&D before economical processes are within reach.