A method and apparatus for contacting and reacting fine cellulosic material with acid to produce partly-hydrolyzed cellulose, in which the cellulose is compressed to form higher density material, resulting in reduced consumption of acid and increased uniformity of reaction times. Cellulosic material, such as ground wood pulp, is compressed to reduce the interstitial spaces therein. The compressed material is contacted with an acid, such as sulfuric acid, which is allowed to wick into the interstitial spaces and react with the cellulose to produce partly-hydrolyzed cellulose.

Provided is a processing device which includes a fluffing section for fluffing fibers contained in a sheet-like material, the fibers being at least near a surface of the sheet-like material, and a particle supplying section for supplying particles having Mohs hardness of 2 to 5 to the fluffed fibers. In addition, in such processing device, the particle supplying section preferably has an ejecting portion for ejecting the particles.

Methods of fractionating lignocellulosic biomass using hydrotropic sulfonic acids are provided. Also provided are methods of forming lignin particles, furans, sugars, and/or lignocellulosic micro- and nanofibrils from the liquid and solid fractions produced by fractionation process. The fractionation can be carried out at low temperatures with short reaction times.

Provided is a processing device which includes a fluffing section for fluffing fibers contained in a sheet-like material, the fibers being at least near a surface of the sheet-like material, and a particle supplying section for supplying particles having Mohs hardness of 2 to 5 to the fluffed fibers. In addition, in such processing device, the particle supplying section preferably has an ejecting portion for ejecting the particles.

Methods of fractionating lignocellulosic biomass using hydrotropic sulfonic acids are provided. Also provided are methods of forming lignin particles, furans, sugars, and/or lignocellulosic micro- and nanofibrils from the liquid and solid fractions produced by fractionation process. The fractionation can be carried out at low temperatures with short reaction times.