Conversion Of Corn Stalk Research Articles

Nonisothermal Catalytic Liquefaction of Corn Stalk in Subcritical and Supercritical Water

The pyrolysis of corn stalk was performed with thermogravimetry (TG), and its liquefaction was investigated in a semicontinuous apparatus with a nonisothermal fluid extraction technique, both with and without sodium carbonate (Na 2 CO 3 ) as a catalyst. The results indicated that the main pyrolysis region of corn stalk is ∼500-650 K and the maximum rate occurs at ∼600 K on the differential thermogravimetry (DTG) curve. The presence of a catalyst has an obvious effect on the pyrolysis, especially in the temperature range of 550-650 K. When more than 1.0 wt % of catalyst was added, the DTG curve is altered greatly, from two peaks to one, for the catalyst, which has a greater effect on hemicellulose than on cellulose and lignin. Kinetic analysis shows that the activation energy in the main pyrolysis range (10-70 wt %) varies with different amounts of catalyst addition. The liquefaction conversion of corn stalk with 3 mL/min of water as a solvent at a pressure of 25 MPa, with or without the addition of 1.0 wt % of Na 2 CO 3 , is up to 95.7 and 95.4 wt %, respectively. The catalyst mainly improved the yield of bio-oil, from 33.4% without a catalyst, increasing to 47.2% with 1.0 wt % of Na 2 CO 3 . The catalyst has a positive effect on the liquefaction at relatively higher temperatures and can increase the yield of liquid product, as well as improve the quality of liquid product. More bio-oil and less gas can be obtained with a catalyst than that without a catalyst. A two-stage main reaction may occur for both the pyrolysis and liquefaction of corn stalk under the experimental conditions.