Effect of reaction time on free radical concentration in hydrogenation liquefaction of Naomaohu coal
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摘要: 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2.6654×1018/g,PAA自由基浓度在1.2519×1018/g-1.9121×1018/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。Abstract: 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.
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Key words:
- Naomaohu coal /
- EPR /
- free radical concentration /
- asphaltene /
- hydrogenation liquefaction
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表 1 煤样的工业分析和元素分析
Table 1 Proximate and ultimate analyses of sample
Sample Proximate analysis w/% Ultimate analysis wdaf/% H/C
(atomic ratio)Mad Ad Vdaf FCdaf C H N St O* NMH coal 15.59 4.98 51.82 48.18 73.52 5.68 0.96 0.24 19.60 0.93 *:by difference 表 2 NMH煤的液化气体产物分析
Table 2 Liquefaction gas products analysis of NMH sample
NMH coal φ/% H2 CO CO2 CH4 C2-4 5 min 90.68 1.19 5.07 2.19 0.87 15 min 90.61 1.30 5.34 1.79 0.96 30 min 89.53 1.46 5.42 2.31 1.28 45 min 88.96 1.54 5.51 2.59 1.40 60 min 88.43 1.52 5.59 3.10 1.36 90 min 86.60 1.68 6.48 3.53 1.71 表 3 原煤和液化中间产物自由基浓度
Table 3 Free-radicals concentrations analysis of raw coal and PAAs
t/min Raw coal 5 15 30 45 60 90 Ng/(×1016·g-1) 266.54 125.19 138.22 177.80 191.21 183.24 164.78 表 4 原煤和液化中间产物的g因子值
Table 4 g-factors analysis of raw coal and PAAs
t/min Raw coal 5 15 30 45 60 90 g 2.00434 2.00347 2.00301 2.00403 2.00384 2.00313 2.00305 Heteroatom 20.80% 10.51% 11.44% 13.22% 11.88% 11.39% 11.58% 表 5 PAA元素分析
Table 5 Ultimate analysis of PAAs
Ultimate analysis
wdaf/%Time t/min 0 5 15 30 45 60 90 O 19.60 9.17 10.11 11.74 9.58 9.96 10.28 N 0.96 1.17 1.16 1.25 1.34 1.22 1.14 St 0.24 0.17 0.17 0.23 0.26 0.21 0.16 -
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