What is lignin?

Before talking about lignin, maybe we should start talking about biomass, which is defined by Biomass Energy center as "biological material derived from living, or recently living organisms. In the context of biomass for energy this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material."

As all knows, in the last few years the cost of fossil fuels has increased as well as the concern of their environmental impact and greenhouse gas effects. By what, has been carried out extensive research and development programs to find a new resource that could help to solve these problems.

Biomass, viewed as a feedstock for the future of Green Chemistry, is the most abundant renewable resource and one of the possible solution to the aformentioned problems.

Biomass plays an important role not only in providing energy for cooking or heating, but also is a unique source of renewable energy as it can be provided as solid, gaseous or liquids fuels.

Biomass based chemicals and fuels used today are produced by sugar and strach. These products are containing in crops such as beet, corn or grain. They are called first generation biomass. These crops are also used for foods and animal feed, resulting an inapropiate competitive situation on the crops. Because of that, it is important to develop second generation biomass, where waste products are used as raw material.

Second generation biofuels and chemicals are made from lignocelullosic biomass, which is composed of three main fractions; cellulose, hemicellulose and lignin.

Fig 1. Structure of lignocellulosic biomass with cellulose, hemicellulose and lignin represented.(undbiomass) 

Lignin represents about 40% of the biomass energy content and furthermore is the obvious candidate to serve as an avaible feedstock for the production of basic aromatic chemicals such as benzene, xylene, toluene.

References:

 P. T. Patil et al., Energy Fuels, 25 (2011) 4713

 R.J.A. Gosselink et al., Bioresour. Technol., 106 (2012) 173

 J. Zakzeski, P.C.A. Bruijnincx et al., Chem. Rev. 110 (2010) 3552