Analytical Pyrolysis Characteristics of Enzymatic/Mild Acidolysis Lignin (EMAL)

Fast pyrolysis is a promising method that is being investigated for application in the degradation of lignin into phenolic chemicals. In this study, enzymatic/mild acidolysis lignin (EMAL) isolated from eucalyptus (E-EMAL) and wheat straw (W-EMAL) were characterized by pyrolysis-gas chromatography/mass spectrometry. The results showed that the compositions and yields of the products were determined by the lignin type and pyrolysis temperature. The identified products from the E-EMAL and W-EMAL pyrolysis mainly included G-phenols such as 2-methoxy-4-vinylphenol and guaiacol, S-phenols such as syringol and 2,6-dimmethoxy-4-(2-propenyl)-phenol, and H-phenols such as phenol, 2-methylphenol, and 4-vinylphenol. The overall yield of these phenolics varied with the investigated conditions. The G- and S-phenols were the primary products during the E-EMAL pyrolysis, while more H-phenols were produced during the W-EMAL pyrolysis. A compromise mild pyrolysis temperature of 450 °C to 650 °C resulted in a high phenolics yield, while a temperature greater than 650 °C led to the production of more aromatic hydrocarbons.