淖毛湖煤直接液化中沥青质反应性与油产率

Asphaltene reactivity and oil yield in direct hydro-liquefaction of Naomaohu coal

为探究煤直接液化过程中沥青质的生成与裂解对油产率的影响,对新疆淖毛湖煤在高压反应釜中进行加氢液化试验,用电子顺磁共振波谱仪分析沥青质自由基浓度,从自由基反应角度解释煤直接液化过程中沥青质的生成与裂解反应行为,同时用萃取的沥青质为原料进行再加氢验证。结果表明:随着反应温度升高,淖毛湖煤加氢液化沥青质产率先升高后降低,沥青质里自由基浓度变化与其产率变化趋势一致,在350℃分别达到最大值177.8×10^(16)g^(-1)和34.13%;总转化率在390℃达到97.38%,反应温度继续升高,总转化率变化不大,而油产率不断增加,430℃最高64.96%。萃取的沥青质在煤加氢液化条件下能继续裂解,430℃时其油产率最高39.99%,但温度过高,沥青质主要发生缩聚和裂解反应,导致油产率减少,气产率增加。

To explore the effect of the formation and fragmentation of asphaltene on oil yield in direct coal hydro-liquefaction,hydrogenation liquefaction experiments of Naomaohu(NMH)lignite from Xinjiang were carried out in a lab autoclave.The free radical concentration of asphaltene was monitored by electron paramagnetic resonance(EPR).The free radical concentration plays a significant role in formation and fragmentation reaction process of asphaltene in direct coal liquefaction.Rehydrogenation liquefaction experiments of extracted asphaltene were performed for verification.The results show that asphaltene yield of NMH lignite hydro-liquefaction first increases and then decreases with increasing reaction temperature.The free radical concentration of asphaltene has the same variation trend with the asphaltene yield,reaching the maximum 177.8×10^(16) g^(-1) and 34.13%at 350℃.The conversion rate of NMH coal hydro-liquefaction increases to 97.38%at 390℃and then tends to flatten at high temperatures.The oil yield from coal liquefaction increases to 64.96%at 430℃.Extracted asphaltene can crack under the same conditions of coal hydro-liquefaction.The oil yield of extracted asphaltene hydro-liquefaction reaches the maximum 39.99%at 430℃.However,the oil decreases and the gas increases as the result of the cleavage and polycondensation of asphaltene when the temperature rises too high.