Effect of liquefaction parameters of cornstalk cellulose in sub-supercritical methanol on dominant chemical products

The direct liquefaction of cornstalk cellulose in sub-supercritical methanol using an autoclave was investigated under reaction temperature range of 240-320℃, methanol dosage range of 0-200 mL and reaction time range of 0-200 min. The effects of various liquefaction parameters on the yields of bio-oil and dominant components (alkanes, esters, acids and alcohols, etc.) obtained from cornstalk cellulose liquefaction were investigated combining with GC/MS. The results show that the cellulose is transformed to alkanes, esters and alcohols, and the increasing of reaction temperature and methanol dosage can result in an increase in the yields of water soluble organic matter, heavy oil and various chemicals. The yield of bio-oil reaches to 25.1% under the optimum operating conditions:methanol dosage is 160 mL; reaction temperature is 320℃; reaction time is 30 min. The relative contents of dominant components in bio-oil are in the order:alkanes > alcohols > esters > acids, with the highest relative contents of 77.2%, 19.0%, 30.9%, 20.8%, respectively. The reaction temperature and methanol dosage have an obvious influence on the distribution and yields of dominant chemicals. As the reaction temperature and methanol dosage further increases, the concentration and activity of free radical will increase, and the components of alcohols and esters can be oxidized and condensed to transform into acids and so on when the reaction temperature and methanol usage are more than 160 mL and 300℃, respectively, leading to a decline in the yields of chemicals and bio-oil.