Microwave heating in wood liquefaction

Microwave radiation was used as the sole heating source to achieve liquefaction of Central European hardwoods, with glycols and organic acid anhydrides, using phosphoric acid as the acid catalyst. Pulsed microwaves of 300-700 W power were applied for 5-20 min. The efficiency of liquefaction increased with higher microwave power, longer radiation time, and higher phosphoric acid addition. With minor amounts of added acid it was possible to achieve complete liquefaction in 20 min. The method was tested for different hardwood types, with a series of glycols and anhydrides, and was found to be generally applicable. (c) 2006 Wiley Periodicals, Inc.