Liquefaction of wood

The priorities in terms of liquid fuel production in Canada should be exploration for crude oil, further development of the oil sands, and, perhaps, liquefaction of coal. Liquefaction of wood should be pursued at a lower priority. Nevertheless, the attraction of security of supply of liquid fuel from a renewable resource does justify some research, development and demonstration on wood production and wood liquefaction. 

Although a reasonable amount of research effort has been expended on thermochemical liquefaction of wood, extensive commercialization of this process is not anticipated in the near future. The basis of the method is a high-pressure and high-temperature treatment of wood chips in the presence of hydrogen gas or syngas to produce an oil instead of a gas. The... 

The first trial of the liquefaction of wood was accomplished by using very severe dissolving conditions [10]. One example used wood samples esterified with a series of aliphatic acids, which could be liquified in benzyl ether, styrene oxide, phenol, resorcinol, benzaldehyde, aqueous phenols, a chloro-form-dioxane mixture, or a benzene-acetone mixture after treating at 200-270°C for 20-150 min. 

Liquefaction of untreated wood can also be achieved at a lower temperature of 150°C and at atmospheric pressure in the presence of a catalyst [12]. Phenolsulfonic acid, sulfuric acid, hydrochloric acid, and phosphoric acid were used as catalysts. In this acid catalyst method, phenols and polyhydric alcohols can also be used for the coexisting organic solvents. Phenol, cresol, bisphenol A and F, and so forth are successfully adoptable as the phenols. Polyethylene glycols, polyether polyols (epoxide additionally reacted polyether polyol, polyethylene terephthalate polyol) have been found to liquify wood resulting in polyol solutions [13]. Liquefaction of wood in the presence of -caprolactone, glycerin, and sulfuric acid has also been accomplished. It was confirmed in this case that liquefaction and polymerization, the latter of which produces polycaprolactone, take place in the reaction system at the same time [14]. Besides the wood material, it has become apparent that trunk and coconut parts of palm, barks, bagasse, coffee bean wastes, and used OA papers can also be liquified [15]. 

In order to further elucidate the mechanism of phenol liquefaction of wood, several experiments have been continued. From these negligible conversion of wood into gaseous substances during the liquefaction treatment, lowering... 

FIGURE 8.6 Process schematic for pressurized solvent liquefaction of wood chips—present technology. 

The Direct Liquefaction of Wood Using Nickel Catalysts... 

Bouvier, J.M. Gelus, M. Maugendre. S. "Direct liquefaction of wood by solvolysis." In This Volume. 

Direct liquefaction of wood can be based on a two steps scheme solvolysis then upgrading. 

The thermochemical liquefaction of wood in water to produce fuel or chemical intermediates has been studied intensively over the last decade ( l). The earlier works used either sodium carbonate as soluble catalyst and carbon monoxide as reducing gas ( ) ( ), or nickel catalyst ( U) or palladium on activated charcoal ( 5) in the presence of hydrogen. Then it has been shown that the presence of a reducing gas was not necessary if iron powder was used as additive, with moderate heating rates ( ). When the wood suspended in water was rapidly heated to 350°C, and then quenched, no catalyst was necessary and a yield in acetone solubles as high as 50 wt was obtained (T ) ( ). 

Fierz-David, H.E. (1925). The Liquefaction of Wood and Cellulose, and some General Remarks on the Liquefaction of Coal. Chemistry and Industry. Vol. 44. (Sept. 1925), pp. 942 - 944... 

Lin, L., Yoshioka, M., Yao, Y. and Shiraiahi N.. (1994) Liquefaction of Wood in the Presence of Phenol Using Phosphoric Acid as a Catalyst and the Flow Properties of the Liquefied Wood, J. Appl Polym. ScL 52,1629-1636... 

Pu S, Shiraishi N. 1993a. Liquefaction of wood without a catalyst I. Time course of wood liquefaction with phenols and effects of wood/phenol ratios. J the Japan Wood Research Society 39 446-452. 

Yao Y, Yoshioka M, Shiraishi N. 1993. Combined liquefaction of wood and starch in a polyethylene glycol/ glycerin blended solvent. J the Japan Wood Research Society 39 930-938. 

---