煤的化学降解——Ⅱ.煤硝酸降解的研究

THE CHEMICAL DEPOLYMERIZATION OF COAL——Ⅱ.DEPOLYMERIZATION OF COAL WITH NITRIC ACID

用硝酸氧化方法对煤进行化学降解研究,考察了煤的组成结构、溶剂抽提性能以及表面活性的变化。结果表明,经硝酸降解后煤结构的破坏程度大于氯化降解的程度,其分子量显著减小(丙酮抽出物和碱可溶物的分子量为650左右),碳、氢含量下降,氧、氮含量增加。而氧化结果,羧基和腐植酸含量增加。这种化学组成的变化赋于煤新的特性,如可使其极性溶剂抽出率和表面活性明显增加,因而其水溶液的表面张力下降(最低达46_43×10^(-5)N/cm)。

The depolymerizaton of coal with nitric acid was studied.The variation of chemical constitution of coal and its extractibility in different organic solvents at various reaction conditions has been observed.After depolymerization of coal its content of carbon and hydrogen decreases whereas that of oxygen,nitrogen,humic acid as well as active functional group increases.The following is the sequence of solvent extraction yield(from large to small):benzene-ethanol(1:1),acetone methanol,ethanol,chloroform,benzene.The extraction yield of Zalainuoer brown coal in benzene-ethanol(1:1)increases from 2.82% to 55.1%.The content of carboxylic group and H/C of the extraction product in acetone increases.The surface tension of aqueous solution obtained from Zalainuoer brown coal extraction under various reaction conditions was determined.After degradation the surface tension decreases and its lowest value is 46.43×10^(-5)N/cm.From the data of surface tension,the maximal adsorptino ν_∞ and the cross-sectional area A_∞ were calculated by application of Gibbs absorption equation.The molecular weight calculated from A_∞ is about 650.