Influence of Microwave Heating on the Liquefaction Kinetics of Corn Stover in Ethylene Glycol

The microwave liquefaction kinetics of corn stover in the presence of ethylene glycol (EG) using sulfuric acid as a catalyst was studied. The liquefaction apparent rate constant (k) was examined using a first-order reaction model. The k values of corn stover increased from 0.080 min(-1) to 0.165 min(-1), with the reaction temperature increasing from 120 degrees C to 180 degrees C. The k value of cellulose at 160 degrees C was close to that of corn stover, indicating that cellulose was involved in the rate-determining step in the microwave liquefaction. The microwave liquefaction rate of corn stover at 160 degrees C was seven times greater than that of conventional liquefaction with external heating. The apparent activation energy (E-a) was 22.6 kJ mol(-1) and the frequency factor (A) was found to be 12.98x10(5) s(-1). The decrease in apparent activation energy and the increase in the frequency factor as compared to conventional liquefaction kinetic parameters indicates a non-thermal effect of microwave in the liquefaction of corn stover, which explains the acceleration mechanism of liquefaction with microwaves.