Liquefaction of Wood and Its Several Applications.

Abstract

The present slate of the studies on liquefaction of biomass with or without catalysts and its application to prepare thermosetting resins is reviewed. Untreated wood has been found to be liquefied in the presence of several organic solvents. For example, after treating wood at around 250 degrees C for 15 to 180 minutes, wood chips and wood meal were liquefied in phenols or polyhydric alcohols. The liquefaction of untreated wood can also be achieved at a lower temperature (around 150 degrees C) and at atmospheric Pressure in the presence of organic solvents and acid catalysts. It has been found that liquefactions without catalysts proceed mainly through homolysis, while in the presence of a strong acid the reactions proceed through heterolytic solvolysis, For instance, a treatment of cellobiose in the presence of phenol and sulfuric acid at 150 degrees C resulted in phenyl glucosides including the C-C glucosides, the typical solvolytic products of the case. On the other hand, treatment of cellobiose in the presence of phenol without acid at 250 degrees C gave products resulting mainly through homolytic cleavage and coupling reactions. In contrast, treatment of the same pair of compounds in the presence of sulfuric acid yielded various heterolytically cleavaged products which further reacted with phenol to form extensively phenolated products. Cased on the abo ire results, the chemical structures and compositions of the liquefied product could he purposefully controlled by the liquefaction method and conditions. Also, products with various properties could be derived from the liquefied biomasses obtained.