反应时间对淖毛湖煤加氢液化中间产物自由基浓度影响研究

以新疆淖毛湖煤(NMH)为原料,在间歇高压反应釜中进行加氢液化实验,通过电子顺磁共振波谱仪(EPR)分析了加氢液化过程中间产物-沥青质(PAA)自由基浓度随停留时间的变化。结果表明,在实验温度下NMH煤加氢液化总转化率先升高后降低,在60 min达到峰值96.87%,油产率为53.01%;淖毛湖原煤自由基浓度为2.6654×10~(18)/g,PAA自由基浓度在1.2519×10~(18)/g-1.9121×10~(18)/g,随着反应停留时间的延长先上升后下降,中间产物PAA自由基浓度数值可以反映液化反应进行的程度,与油产率变化趋势一致;反应中间产物PAA的g值小于原煤g值(2.00434),在2.00301-2.00403,在液化加氢过程中其g值呈先上升后下降的趋势,与PAA中N、S、O等杂原子成分的变化一致,与元素分析结果相吻合。

Effect of reaction time on free radical concentration in hydrogenation liquefaction of Naomaohu coal

Coal from Naomaohu (NMH) in Xinjiang as raw material, hydroliquefaction experiments were performed in a batch high-pressure liquefaction reactor. Variations of free radical concentration of PAA and the intermediate products of hydroliquefaction with reaction residence time were examined with an EPR spectrometer. The results show that conversion rate of NMH coal hydroliquefaction first rises and then decreases. The maximum conversion rate and oil yield is 96.87% and 53.01% in 60 min. The free radical concentration of NMH is 2.6654×10¹⁸/g. PAA's free radical concentration ranges between 1.2519×10¹⁸/g and 1.9121×10¹⁸/g, which first increases and then decreases with increasing reaction time. As for the intermediate products, PAA, its free radical concentration could reflect extent of hydroliquefaction reaction, which has the same variation tendency with the oil yield. PAA's g value is between 2.00301 and 2.00403, which is lower than that of NMH (2.00434). In the process of hydroliquefaction, its g value first rises and then decreases, which is closely related with the heteroatom content of N, S, O in PAA and is consistent with the element analysis result.