On The Technology And Mechanism Of Humic Acid Preparation By Coal Under Mild Catalytic Oxidation

Starting from the characteristics of Guizhou coal and Xinjiang coal, this paper aimed to explore the fracture of some special chemical bonds in coal by using highly selective and efficient catalyst under mild condition and acquire a large number of high value-added humic acid through the catalytic oxidation and solvent extraction of coal. The optimum process conditions and catalyst were established by experiments. The impact of process parameters and catalyst on the yield and structure were studied, which help to provide a theoretical basis and basic data for humic acid prepared by coal.Guizhou coal, Xinjiang coal and Shenfu coal were taken been research objects, It was studied the catalytic oxidation process and the influencing factors of the different kinds of coal by using alkali solution and acid precipitation method to extract humic acid.The spectroscopy, elemental analysis, E4/E6 analysis and measurement of the total humic acid were used, and the structure of raw coal and its products were analysed. Meanwhile, The oxidation mechanism was clarified and the dynamic model was established.The results show that catalytic oxidation of different coal obtain different humic acid yield, and the humic acid yield prepared by Xinjiang coal and Guizhou coal, with the NHPI which have the highest catalytic efficiency as catalyst, were up to 36.78% and 33.60%, respectively. Through catalytic oxidation of coal, the content of carbon elements was reduced in coal, and oxygen in Nitrification coal means that a large number of nitro are introduced in coal molecular to generated nitro humic acid. E4/E6 value of the product added the catalyst increased significantly, for Guizhou coal, its value reached 3.201 when NHPI as a catalyst, which increased by 0.916 compared with the one without adding catalyst. For Xinjiang coal and advanced coal, when adding NHPI respectively catalyst, its E4/E6 values were 2.831 and 3.220, and increased by 0.694 and 0.812 compared with those without adding catalyst, respectively, which note the decrease of molecular weight and the deepening of the degree of nitric acid oxidation.In conclusion, the experimental results show that catalytic oxidation process of preparation of humic acid is the free radical chain reactions mechanism. By free radical chain reaction, alkyl, cycloalkanes, benzene methyl and other a series of active functional groups in coal are conversed into functional groups which contain oxidized groups. Calculated by the kinetic data, the activation energy required in the catalytic oxidation of coal is reduced by NHPI catalyst significantly, but the reaction rate is increased. This paper provided certain theoretical basis and basic datas for the preparation of humic acid by by coal under mild catalytic oxidation.