Ming-Fei Li, Shao-Ni Sun, Feng Xu and Run-Cang Sun

11.1 Introduction

Fractionation of lignocellulosic materials into their major macromolecular fractions—cellulose, hemicelluloses and lignin, is a challenging work that attracted increased attention in recent years. As a matter of fact, in addition to chemical pulping, an existing fractionation process used worldwide, numerous approaches for the separation of lignocelluloses have been studied lastingly for more than a century. These approaches are generally categorized into physical, physico-chemical, chemical and biological processes. Among these approaches, one of the most promising processes is organosolv fractionation, which degrades the lignocellulosic feedstocks by using organic solvents under mild conditions in an environmentally friendly manner to mainly produce cellulose for energy or materials usage. In addition, the dissolved sugars and lignin are easy to be recovered and are valuable feedstocks for chemicals and materials applications.

This chapter updates and extends the previous reviews on organic solvents fractionation of lignocelluloses for pulping [1-6], lignin extraction [7] and bio­ethanol production [8], focusing particularly on new research on the fractionation process and product utilization for fuels, chemicals and materials via organic solvents in a biorefinery manner. After a brief introduction of the development of

M.-F. Li • S.-N. Sun • F. Xu (&) • R.-C. Sun (&)

Institute of Biomass Chemistry and Technology, Beijing Forestry University, Qinghua Road No. 35, Haidian District, 100083 Beijing, China e-mail: xfx315@bjfu. edu. cn

R.-C. Sun

State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Wushan Road No. 381, Tianhe District, 510640 Guangzhou, China e-mail: rcsun3@bjfu. edu. cn

C. Baskar et al. (eds.), Biomass Conversion,

DOI: 10.1007/978-3-642-28418-2_11, © Springer-Verlag Berlin Heidelberg 2012 organosolv fractionation, this chapter will focus on the recent achievements in organosolv fractionation of cellulose, hemicelluloses and lignin from traditional and novel feedstocks including wood, grasses, forestry residues and so on. Etha­nol-based fractionation process, the main organosolv fractionation process used for ethanol production especially in the past decade, is discussed extensively. Formic acid and acetic acid fractionations, two useful processes used for fractionation of lignin under mild conditions, are also discussed in detail. The fractionation mechanism and technical flow involved in the fractionation process are elaborated, and the potential applications of the fraction products (mainly cellulose-rich fraction, degraded sugars and soluble lignin) are discussed. Other types of organic solvents for fractionations attracted current attention are also covered in this chapter.