Products from lignocellulosic biomass

Lignocellulosic biomass is a potential source of several bio-based products according to the biorefinery approach. Currently, the products made from bioresources represent only a minor fraction of the chemical industry production. However, the interest in the bio-based products has increased because of the rapidly rising barrel costs and an increasing concern about the depletion of the fossil resources in the near future (Hatti-Kaul et al., 2007). The goal of the biorefinery approach is the generation of energy and chemicals from different biomass feedstocks, through the combination of different technologies (FitzPatrick et al., 2010).

The biorefinery scheme involves a multi-step biomass processing. The first step concerns the feedstock pretreatment through physical, biological, and chemical methods. The outputs from this step are platform (macro) molecules or streams that can be used for further processing (Cherubini & Ulgiati, 2010). Recently, a detailed report has been published by

DOE describing the value added chemicals that can be produced from biomass (Werpy, 2004). Figure 2 displays a general biorefinery scheme for the production of specialty polymers, fuel, or composite materials (FitzPatrick et al., 2010).

Besides ethanol, several other products can be obtained following the hydrolysis of the carbohydrates in the lignocellulosic materials. For instance, xylan/xylose contained in hemicelluloses can be thermally transformed into furans (2-furfuraldeyde, hydroxymethil furfural), short chain organic acids (formic, acetic, and propionic acids), and cheto compounds (hydroxy-1-propanone, hydroxy-1-butanone) (Gullu, 2010; Bozell & Petersen, 2010).


Fig. 2. Scheme of a lignocellulosic biorefinery. The shape of each step describes the type of process used, chemical, biological, and physical (legend) (FitzPatrick et al., 2010)

Furfural can be further processed to form some building blocks of innovative polymeric materials (i. e. 2, 5-furandicarboxylic acid). In addition, levulinic acid could be formed by the degradation of hydroxymethil furfural (Demirabas, 2008). Another product prepared either by fermentation or by catalytic hydrogenation of xylose is xylitol (Bozell & Petersen, 2010). Furthermore, through the chemical reduction of glucose it is possible to obtain several products, such as sorbitol (Bozell & Petersen, 2010). The residual lignin can be an intermediate product to be used for the synthesis of phenol, benzene, toluene, xylene, and other aromatics. Similarly to furfural, lignin could react to form some polymeric materials (i. e. polyurethanes) (Demirabas, 2008).