自由基浓度测定方法的再验证及其在煤化学中应用

对前人建立的标准曲线法测煤中自由基浓度进行优化,以DPPH标准样品和基准样品的二次积分面积比值为新参数,结果显示新参数标准曲线法的实测值与理论值相对误差都在5%以内;重复性、复现性实验的相对标准偏差都小于3%。将新参数标准曲线法用于分析不同煤化程度煤和新疆黑山煤(HS)沥青质的自由基浓度,发现随着煤化程度增加,其煤中自由基浓度逐渐增大,从低阶褐煤的8.531×10~(17)/g上升到高阶无烟煤3.37899×10~(19)/g;而在HS煤液化过程中,随着加氢液化温度的升高,其沥青质自由基浓度逐渐下降,从290℃的1.5793×10~(18)/g降到450℃的7.410×10~(17)/g,沥青质自由基浓度变化趋势与其产率变化趋势相一致。

Revalidation of measurement method of free radical concentration and its application in coal chemistry

The standard curve method established by predecessors to measure the concentration of free radicals in coal was optimized to take the quadratic integral area ratio of the DPPH standard sample to the reference sample as new parameters. The results show that the relative error between the measured and theoretical values of the new parameter standard curve method is less than 5%, and the relative standard deviations of repeatability and reproducibility are less than 3%. The new parameter standard curve method was used to analyze the free radical concentration of the coal with different coal ranks and the asphaltene of Xinjiang Heishan Coal (HS). It is found that with the increase of coal rank, the free radical concentration in the coal increases gradually, from 8.531×10¹⁷/g for low-rank lignite to 3.37899×10¹⁹/g for high-rank anthracite. In the process of HS coal liquefaction, with the increase of liquefaction temperature, the free radical concentration of asphaltene decreases gradually, from 1.5793×10¹⁸/g at 290℃ to 7.410×10¹⁷/g at 450℃. The change trend of free radical is concentration in the asphaltene consistent with that of asphaltene yield.