Abstract: The preparation methods of lignin, alkali lignin and ammonium lignin were introduced in this research and the above three kinds of lignins were characterized by physicochemical properties including specific gravity detection, sodium detection, X-ray diffraction detetion, thermogravimetric detection and solubility test. The results indicated that ammonium lignin did not contain metallic sodium and had excellent water-solubility as well. That is to say ammonium lignin settled the problem of poor solubility of pure lignin in water. Meanwhile, it also overcame the damages to diesel burner cylinder after emulsification of alkali lignin and diesel and succeeded in avoiding the risk of carbon deposit owing to long term usage. Therefore, the conclusion could be obtained that ammonium lignin was more suitable to be mixed up through emulsification with diesel, to be an additive of traditional fossil energy compared with lignin and alkali lignin. Ammonium lignin supplies a potential way for the comprehensive utilization of biomass wastes and the development of alternative energy.

Key words: lignin, alkali lignin, ammonium lignin, physicochemical properties