Woody biomass is one of the most promising renewable alternatives to fossil resources. However, some physical and chemical treatment is required to convert their chemical components into biofuels and valuable chemicals because of their low degradative properties. Recently, there has been considerable interest in ionic liquid treatment for biorefinery, and many fundamental studies on the reactivity of wood with ionic liquids have been performed from a chemical and morphological point of view. This chapter highlights the findings regarding morphological and topochemical features of wood cell walls in the degradation process as a result of ionic liquid treatment. "right-field microscopy and scanning electron microscopy have revealed the swelling behavior of cell walls and the detailed ultrastructural features of wood tissues treated with ionic liquid. Polarized light microscopy and confocal Raman microscopy have clarified the changes in cellulose crystallinity and distribution of chemical compositions such as polysaccharides and lignin during ionic liquid treatment at the cellular level.Keywords: "iorefinery, Cell wall, Liquefaction, Ionic liquid, Wood
. IntroductionThe efficient use of lignocellulosics has been an important approach to prevent exhaustion of fossil resources and global warming caused by increasing emissions of greenhouse gases. "mong the various types of lignocellulosics, woody biomass is regarded as a promising resource because it is carbon neutral, abundantly available in many regions, and does not compete with agricultural production. Wood cell walls decompose to form persistent organic complexes mainly composed of cellulose % , hemicellulose % , and lignin % [ , ]. To convert ]. However, woody biomass is a very inhomogeneous composite at the cell level. Wood comprises various types of tissues such as the tracheid, wood fibers, vessels, and parenchyma. In addition, wood cell walls consist of several layers a compound middle lamella middle lamella + primary wall CML and a secondary wall S , which is generally composed of S , S , and S sublayers. The chemical components and distribution vary depending on the wood species, types of tissues and their layers [ ]. Therefore, to improve the chemical conversion process using ionic liquids, a better understanding of the effects of ionic liquid treatment of wood, such as the interaction of wood with ionic liquids at the cell level and the deconstruction behavior of various types of tissues in ionic liquids, are required.In this chapter, we focus on morphological and topochemical studies on the liquefaction of wood in ionic liquids, especially -ethyl--methylimidazolium chloride [C mim lignin [ ], respectively. "right-field microscopy and polarized light microscopy were employed to determine the swelling and decomposition behaviors of wood cell walls and the state of cellulose crystallinity during ionic liquids treatment. Scanning electron microscopy SEM was used to observe the detailed ultrastructural changes in various wood tissues treated with ...