Rapid wood liquefaction by supercritical phenol

Abstract

Wood was rapidly liquefied at the supercritical temperature of phenol. Under these conditions, wood was liquefied by over 90% for 0.5 min, and the combined phenol content of the obtained liquefied wood reached about 75%. The effects of various reaction conditions on liquefaction were investigated. With increases in reaction temperature, phenol/wood weight ratio, and the charged mass-to-reactor capacity (w/v) ratio, the amount of methanol-insoluble residue decreased and combined phenol content increased. The range of molecular weights and polydispersity of the products obtained after the time at which sufficient liquefaction was achieved were from 400 to 600 and from 1.5 to 2.5, respectively. Wood showed a marked decomposition to low molecular weight components early in the reaction, and then the molecular weight increased slightly with increasing reaction time. The properties of liquefied wood were investigated and compared with those obtained with conventional liquefaction methods. Combined phenol content was similar to that obtained by other liquefaction methods, except the sulfuric acid–catalyzed method, which resulted in flow properties comparable to those of other liquefaction methods. The flexural strength of moldings prepared using liquefied wood was also comparable to those prepared by other liquefaction methods.