Organosolv fractionation of lignocelluloses has a long history, which undergoes a change from structure study to pulping, and currently to energy usage. The earliest study applying organic solvents to treat lignocellulosic material was back in 1893, when Klason [9, 10] used ethanol and hydrochloric acid to separate wood into its components to study the structure of lignin and carbohydrates. After that, Pauly et al. [11, 12] applied formic and acetic acids to delignify wood for the purpose of characterization of the main components of wood in 1918. Subsequently, a wide variety of other organic solvents, e. g., various alcohols, phenol, acetone, propionic acid, dioxane, various amines, esters, formaldehyde, chloroethanol, whether pure or in aqueous solutions, and in the presence or absence of acids, bases or salts as catalysts, were used to delignify lignocellulosic materials [3]. Since 1980s, a number of pulping processes involving the aforementioned solvents have been investigated as alternatives to the classic pulping process in the field of pulp and paper industry [13]. The main advantage of the so-called organosolv pulping process was a higher efficient use of the raw materials in an environmentally friendly way, as compared to the drawbacks of the classic pulping process (e. g., odors, low yields, high pollution, poor bleachability of pulp and high investment cost). In 1992, two organosolv pulping processes based on methanol— Orgnaocell and alkaline sulfite-antraquinone-methanol (ASAM) were first oper­ated at a full scale. Meanwhile, the organic acid pulping processes, Acetosolv (based on acetic acid) and Milox (based on formic acid with the addition of hydrogen peroxide) were at a pilot scale [14]. Many such processes were employed to obtain multiple products, i. e., hydrolyzable cellulose, sugars and high quality lignin other than pulp, aimed at exploiting the full potential of the feedstocks. More recently, ethanol pulping process is modified from a pulping process to a pretreatment process integrated with biofuel production, mainly aimed at obtaining hydrolyzable cellulose fraction for the production of ethanol [15].