Pyrolytic behavior of waste corn cob

The powder of the agricultural waste corn cob was pyrolyzed in a tube-typed stainless steel reactor of 200 ml volume under N2 atmosphere. The compositions of the gases and liquid obtained at different pyrolytic temperatures below 600 °C at the heating rate of 30 K/min were analyzed. With the increment of the pyrolytic temperature, the yields of the solid and the liquid products were decreased, but the yield of gas products was increased. The liquid products were approximately 34–40.96% (wt%), the gas products were 27–40.96% (wt%) and the solid products 23.6–31.6% (wt%). There were less changes for the yields of these products above 600 °C. The gas products were analyzed by gas chromatography (GC) as CO2, CO, H2, CH4, C2H4, C3H6, C3H8, etc. When the temperature was 350–400 °C, the gases had CO2 and CO 80–95% (v/v). When the temperature increased continuously, yields of H2, CH4, C2H4, C3H6 and C3H8 gradually increased. The liquid products were identified by GC–MS as phenols, 2-furanmethanol, 2-cyclopentanedione, etc. The Fourier transform infra-red spectrophotometer (FT-IR) analysis of the liquid product showed a strong –OH group absorption peak. Differential thermogravimetric analysis (DTG) showed that thermal decomposition process involves two steps. The heating rate affects not only the activation energy of the decomposition reaction, but also the path of the reaction. With the increment of the heating rate, the maximum rate temperature of the decomposition reaction was shifted to a higher temperature, and the order and activation energy of the total decomposition reaction were decreasing.