Lignin offers a significant opportunity for enhancing the operation of a lignocellulosic biorefinery. It is an extremely abundant raw material contributing as much as 30% of the weight and 40% of the energy con­tent of lignocellulosic biomass (Holladay et al., 2007). Lignin’s native structure suggests that it could play a central role as a new chemical feedstock, particularly in the formation of supramolecular materials and aro­matic chemicals (Holladay et al., 2007; Hatakeyama and Hatakeyama, 2010). Up to now the vast majority of industrial applications have been developed for

lignosulfonates. These sulfonates are isolated from acid sulfite pulping and are used in a wide range of lower value applications where the form but not the quality is important. The solubility of this type of lignin in water is an important requirement for many of these applica­tions. Around 67.5% of world consumption of lignosul­fonates in 2008 was for dispersant applications followed by binder and adhesive applications at 32.5%. Major end-use markets include construction, mining, animal feeds and agriculture uses. The use of lignin for chemical production has so far been limited due to contamination from salts, carbohydrates, particulates, volatiles and the molecular weight distribution of lignosulfonates. The only industrial exception is the limited production of vanillin from lignosulfonates (Evju, 1979). Besides ligno — sulfonates, kraft lignin is produced as commercial prod­uct at about 60 kton/year. New extraction technologies, developed in Sweden, will lead to an increase in kraft lignin production at the mill side for use as external energy source and for the production of value-added applications (Ohman et al., 2009).

The production of bioethanol from lignocellulosic feedstocks could result in new forms of higher quality lignin becoming available for chemical applications. The Canadian company Lignol Energy has announced the production of cellulosic ethanol at its continuous pi­lot plant at Burnaby, British Columbia. The process is based on a wood pulping process using Canadian wood species but the pilot plant will test a range of feed­stocks while optimizing equipment configurations, enzyme formulations and other process conditions (Lignol Energy. 2013). The Lignol Energy process pro­duces a lignin product (HP-L lignin) upon which the company is developing new applications together with
industrial partners. Also other lignin types will result from the different biomass pretreatment routes under development and unfortunately there is not one lignin macromolecule that will fit all applications. However, if suitable cost-effective and sustainable conversion technologies can be developed, a lignocellulosic bio­refinery can largely benefit from the profit obtained from this side stream lignin (Gosselink, 2011).

The production of more value-added chemicals from lignin (e. g. resins, composites and polymers, aromatic compounds, carbon fibers) is viewed as a medium — to long­term opportunity that depends on the quality and func­tionality of the lignin that can be obtained (Figure 17.3, Table 17.8). The potential of catalytic conversions of lignin (degradation products) has been recently reviewed (Zakzeksi et al., 2010).

The main chemical building blocks can be organized by their carbon number, i. e. C1— Cn. In the following sec­tions, examples of biobased chemicals are discussed with respect to their current status and the companies that are pursuing the development of these new chemicals.