Selective Production of Phenol, Guaiacol and 2,6-Dimethoxyphenol by Alkaline Hydrothermal Conversion of Lignin

The process for selective production of phenol, guaiacol and 2,6-dimethoxyphenol based on corn stalk lignin via mild alkaline hydrothermal decomposition was proposed. Disodium tetraborate decahydrate (DTD) was used to catalyze the degradation of corn stalk lignin with water as solvent. It turned out that the catalyst could not only improve the yield of the liquid product (LP) significantly, but also increase the selectivity of liquid production markedly. The influences of reaction temperature and reaction time were also investigated on the process of degradation of lignin. Gas chromatograph with mass selective detector (GC-MS) suggested that lignin was mainly transformed into monomeric phenolic compounds, especially phenol, guaiacol and 2,6-dimethoxyphenol. The highest yields referred to liquid product weight of target compounds-phenol (7.15%), guaiacol (7.92%) and 2,6-dimexhoxypheol (8.18%) were obtained simultaneously from degradation of corn stalk lignin. The results of this study showed it is an efficient way to obtain target phenolic compounds through alkaline hydrothermal conversion.