低变质煤结构分析及其与热解焦油产率关联性研究

白 翔1,邹 达2,3,马凤云2,3,刘景梅2,3,钟 梅2,3

(1.伊犁师范大学 化学与环境科学学院,新疆 伊宁 835000;2.新疆大学 化学化工学院,新疆 乌鲁木齐 830046; 3.新疆维吾尔自治区煤炭清洁转化与化工过程重点实验室,新疆 乌鲁木齐 830046)

摘 要:通过元素分析仪和固体13C-NMR检测6种不同低阶煤的组成和结构,采用Peak-fit软件对13C-NMR谱图进行分峰拟合并半定量计算煤样中各类型有机碳含量,由Matlab数学软件分析了影响焦油产率的有机碳结构类型。结果表明:① WCW、PLQ、JJM、TCG、HG和HF煤样中亚甲基碳分别占总脂碳含量的34.41%、34.29%、34.01%、44.78%、41.62%和49.94%,说明煤样结构中脂肪碳中亚甲基碳含量较多,脂链数N均小于9,说明连接在短链上的支链,主要以脂环侧链形式存在;② HF煤样的平均亚甲基碳数Cn=2.13,其余均小于2,WCW最小,仅为1.05,说明脂肪族以短链为主,链长一般在1~3个碳;③ 影响煤焦油产率的关键因素为亚甲基碳(I2)、带质子芳碳(I4)和烷链支链化度(I7)为辅助因素;二元组合I2I4表现出良好的线性关系,三元组合I2I5(酚羟基或醚氧连碳)和I7与焦油产率的关联性最大,其④ 不同煤样中镜质组含量从26.10%增至82.10%,易断裂桥键数n与脱氢含量WH 分别从5.37增至8.17、3.24增加到5.92,交联桥键数P0越小,交联反应程度越低,易断裂桥键数n和脱氢含量WH 越大,交联桥键数P0越小,焦油特征指数Xtar越大,对焦油生成过程越有利。

关键词:低变质煤;核磁共振;热解;焦油产率

中图分类号:TQ530.2

文献标志码:A

文章编号:1006-6772(2020)04-0090-08

收稿日期:2019-11-06;责任编辑:张晓宁

DOI:10.13226/j.issn.1006-6772.19110605

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基金项目:伊犁师范大学资助项目(2017YSYY11)

作者简介:白 翔(1988—),男,新疆伊宁人,硕士研究生,主要研究方向为煤热解。E-mail:xiangzi0009@163.com。

通讯作者:钟梅,副教授。E-mail:zhongmei0504@126.com

引用格式:白翔,邹达,马凤云,等.低变质煤结构分析及其与热解焦油产率关联性研究[J].洁净煤技术,2020,26(4):90-97.

BAI Xiang,ZOU Da,MA Fengyun,et al.Structure analysis of low rank coal and its correlation with pyrolysis tar yield[J].Clean Coal Technology,2020,26(4):90-97.

Structure analysis of low rank coal and its correlation with pyrolysis tar yield

BAI Xiang1,ZOU Da2,3,MA Fengyun 2,3,LIU Jingmei2,3,ZHONG Mei2,3

(1.School of Chemistry and Environment,Yili Normal University,Yining 835000,China;2.College of Chemical and Engineering,Xinjiang University,Urumqi 830046,China;3.Xinjiang Laboratory of Coal Clean Conversion & Chemical Engineering Process Key laboratory of Autinomous Region,Urumqi 830046,China)

Abstract:The composition and structure of six different low-rank coal samples were determined via elemental analyzer and solid 13C-NMR apparatus.The Peak-fit software was used to analyze the 13C-NMR spectrum to semi-quantitatively calculate the ratio of different types of organic carbon in coal samples,and the influence of organic carbon types on tar yield was investigated by Matlab mathematical software.The results show that:(1) The content of methylene carbon in WCW,PLQ,JJM,TCG,HG and HF coal samples accounts for 34.41%,34.29%,34.01%,44.78%,41.62% and 49.94% of the total lipid carbon content,respectively.The content of methylene carbon in aliphatic carbon in coal sample structure is high,and the number of aliphatic chain N is less than 9,which indicates that the branched chain connected on the short chain mainly exists in the form of the alicyclic side chain.(2)The average methylene carbon number of HF coal sample is Cn=2.13,the rest are less than 2,WCW is the smallest,only 1.05,indicating that aliphatic group is mainly short chain and the chain length is generally 1-3 carbon.(3)Methylene carbon(I2) is the key factor that controls the coal tar yield,while proton aromatic carbon(I4) and proton with alkyl chain branched degree(I7) are as auxiliary factors.Binary combination of I2 and I4 show a good linear relationship with tar yield.The three-element composition of I2,I5(phenolic hydroxyl or ether oxygen carbon) and I7 has the greatest relevance of coal tar yield,and its is 0.992.(4)The vitrinite content in different coal samples increases from 26.10% to 82.10%,the number of fragile bridge bonds n and the dehydrogenation content WH increases from 5.37 to 8.17,3.24 to 5.92.The results show that the smaller the number of crosslinked bridge bonds P0 is,the lower the degree of crosslinked reaction is,the higher the number of brittle bridge bonds n and the dehydrogenation content WH is,the smaller the number of crosslinked bridge bonds P0 is,and the greater the tar characteristic index Xtar is,and the more favorable the tar generation process is.

Key words:low-rank coal;NMR;pyrolysis;tar yield

0 引 言

煤中有机大分子结构官能团的赋存状态和分布规律直接影响其热解产物 [1-3],因而研究煤的分子结构,对煤的分级分质利用和后续转化过程具有重要的指导意义[4-7]。研究人员借助NMR、FTIR等分析仪器获取煤中有机质的结构信息,用于阐明煤的结构与热解反应性之间的关联规律,结果表明煤结构中有机碳的结构类型对焦油的组成结构有重要的影响[8-13]。Furimsky等[14]基于固体核磁研究了煤阶对焦油产率的影响,发现焦油产率随煤阶升高而降低,当芳香度从57.0%增至86.0%时,与之对应的热解焦油产率从13.5%降至7.0%。Liu等[15]通过固体核磁分析了4种煤样结构,将桥头芳碳、CH2/CH3和氧接脂碳与焦油产率相关联,得到预测焦油产率的线性方程。此外,煤样经预处理后结构发生改变,对焦油产率产生重要影响[16-17]。刘鹏等[18]研究表明,煤样经水热预处理后,煤热解焦油产率增加20%左右,其原因在于水中氢在煤中发生转移,煤结构中CH2/CH3含量增加,氧接脂碳含量减少。董鹏伟等[19]发现,与内蒙古胜利褐煤原煤相比,经200 ℃和250 ℃热处理1 h后的煤样中芳香氢含量从28.02%分别减少至21.64%和22.40%,使焦油中轻油组分含量比原煤焦油提高60个百分点。此外,除煤自身有机结构对煤样的热解特性起决定外,研究者发现煤中无机矿物质对热解关联性较大,煤自身含有多种碱土金属、碱金属及过渡金属,研究结果表明这些金属对热解都具有一定的催化作用[20-23]。此外,煤中有机显微组分中镜质组、壳质组和惰质组在热解过程中相互作用,产生游离的“碎片和基团”,影响热解产物的生成[24]。一般煤岩显微组分中壳质组的烯烃和烷烃多于镜质组,且挥发分及H含量最高,惰性组最低,镜质组介于两者之间。由于多数煤层壳质体富氢的煤岩组成含量较小,因此煤中镜质组的性质和含量对煤成烃的实际贡献和对煤成油气的控制作用较显著。故在对煤热解转化过程研究中,需综合考虑煤岩组分和煤的分子结构对产物分布的影响。由此可以看出,煤结构与热解焦油产率之间的定量解释尚不完善。本文采用元素分析和固体13C-NMR分析不同镜质组含量的新疆低阶煤的组成和结构参数,利用Matlab数学专业软件,通过线性回归方法研究煤中有机质结构参数与焦油产率的关联规律,基于KO模型对醚、硫桥键数P0和易断裂桥键数n和脱氢含量WH进行量化,进而推测分子结构对焦油产率的影响。

1 试 验

1.1 煤样制备

按照镜质组变化顺序选取6种代表性煤样,其中五彩湾(WCW)和将军庙(JJM)煤样取自新疆昌吉,皮里青(PLQ)煤样取自新疆伊犁,铁厂沟(TCG)与和丰(HF)煤样取自新疆塔城,哈国K(HG)煤样来自哈萨克斯坦。将煤样磨至粒径≤74 μm,于105 ℃下干燥2 h除去水分,密封干燥保存待用。

1.2 煤样分析

煤样的工业分析根据国标GB-T 212—2001测定,其元素含量由元素分析仪测试(Thermo Flash EA-1112,Thermo-Finnegan Corporation),结果见表1。可以看出,HG煤样的挥发分最高,为54.05%,WCW煤样挥发分最低,仅为32.72%,HF煤样的H/C最大,为0.98,PLQ的H/C仅为0.44。

表1 煤样的工业分析和元素分析

Table 1 Proximate and ultimate analysis of coal samples

煤样工业分析/%MadAdVdafFCd元素分析/%CdafHdafOdafNdafStH/C煤岩组分/%VitrineInertiniteExiniteWCW10.314.1432.7267.378.283.5816.990.610.540.5526.173.30.6PLQ22.384.7830.0169.9979.522.9016.790.710.080.4438.158.71.8JJM5.423.9334.4965.5178.674.4614.950.980.950.6866.732.40.6TCG5.207.9143.7356.3077.024.8215.751.011.400.7571.826.91.2HG16.8013.5154.0545.9573.315.1819.700.910.990.8577.213.90.4HF5.2215.1445.4254.5877.086.2915.081.270.270.9882.18.84.4

煤样固体核磁采用Varian Ino va-400(美国Varian公司)超导核磁共振谱测定,固体双共振探头,转速为5 kHz,共振频率为100.38 MHz,循环延迟时间6 s,碳氢交叉极化接触时间2 ms,数据扫描采集共计9 000。

2 试验结果与讨论

2.1 煤样的13C-NMR结构分析

图1为各煤样的13C-NMR谱图。可以看出,各煤样的谱型相似。根据文献将煤中碳的类型分为脂肪碳区(δ=0~90)、芳香碳区(δ=90~160)和羰基碳区(δ=160~220)组成[25]。6种煤样脂碳区的峰强度为:WCW<PLQ<JJM <TCG<HG<HF;而芳碳区的峰强度呈相反趋势,羧基碳则无明显变化。为解析各煤样中碳结构的分布情况,结合碳结构的化学位移归属,利用Peak-Fit软件对谱图进行分峰拟合处理[26],从而获得煤样各类型碳结构的初始分布,结果见表2。对各结构参数进行归一化处理,得到煤中脂肪族和芳碳族、羰基碳结构参数,见表3和4。

图1 煤样的13C-NMR曲线
Fig.1 13C-NMR curves of coal samples

表2 6种煤样的核磁分析结果

Table 2 Curve-fitted 13C-NMR data for 6 coal samples

Carbon functionalityLocationTypical chemicalshift δRelative content/%WCWPLQJJMTCGHGHFAliphatic methyl14~161.021.161.361.071.191.38Aromatic methyl16~223.163.744.364.064.204.79Aliphatic C(2) Carbon Methylene22~367.878.829.7615.114.7216.89Methine and quaternary carbon36~504.414.835.296.937.206.56Oxy-methylene50~601.861.972.072.472.80.2.39Oxy-methine60~701.541.591.641.141.691.41Oxy-quaternary70~903.013.614.222.953.572.56Ortho-oxyaromatic protonated100~12927.0528.2329.4427.1421.5319.60Aromatic protonated129~13711.8911.4710.8610.458.248.69Aromatic branched137~14810.4910.049.5910.2410.1510.2Oxy-Aromatic carbon148~16511.9510.769.5610.4311.1911.06Carboxyl165~18813.1811.9810.722.037.018.87Carbonyl188~2202.583.384.235.985.514.62

由图1可知,在脂碳区,δ在14、23处出现肩峰,分别归属为脂肪链上的终端—CH3和芳环上的—CH3;各煤样谱图中最高峰均出现在δ=22~36范围内,峰值约为29,说明—CH2的共振信号最强,其含量在脂肪区最多;在δ=36~50,6种煤样均有较弱的共振信号,可归属于次甲基碳或季碳;δ=50~90的化学位移区间,也有弱氧接脂碳的共振信号,表明6种煤样中氧接脂碳数量较少。

表3为各煤样中脂碳的分布情况。可以看出,煤样中脂碳率在22.86%~37.47%,其中WCW最低。WCW、PLQ、JJM、TCG、HG和HF煤样中亚甲基碳分别占总脂碳含量的34.41%、34.29%、34.01%、44.78%、41.62%和49.94%,说明脂碳中亚甲基碳含量较多。HF煤样的平均亚甲基碳数Cn=2.13,其余均小于2,WCW最小,仅为1.05,说明脂肪族以短链为主,链长一般在1~3个碳之间。WCW、PLQ、JJM、TCG、HG和HF煤样中脂链的支链化度Bi分别为19.28%、18.78%、18.43%、20.55%、20.35%和18.23%,且脂链数N均小于9,说明连接在短链上的支链,主要以脂环侧链形式存在,HG煤样的支链化度Bi较HF高,说明该煤样更易于生成气体产物。

δ=0~25、45~90和165~220处,均存在气潜力碳,其中δ=0~25为脂甲基碳的化学位移,热解时主要产生CH4等烷烃气体。由表3可知,各煤样中脂甲基碳含量在4.18%~6.17%。δ=45~90为氧接脂碳,主要包含醇、醚和含氧杂环等结构,WCW、PLQ、JJM、TCG、HG和HF煤样的值分别为6.41%、7.17%、7.93%、6.65%、6.36%和8.06%。

表3 煤样中脂肪族碳计算结果

Table 3 Calculation results of aliphatic carbon in coal samples

煤样falf*alfMalfHalfOalCnNBiWCW22.8634.414.187.876.411.057.4819.28PLQ24.6034.294.908.827.171.257.0518.78JJM25.6034.015.029.767.931.476.6318.43TCG33.7344.785.1315.106.561.878.0720.55HG35.4041.625.3914.728.061.867.9520.35HF37.4746.946.1716.896.362.137.8918.23

注:fal为脂碳率;为亚甲基占脂碳之比;为脂甲基碳;为亚甲基碳;为氧接脂碳;Cn为平均亚甲基碳数;N为脂链数;Bi为烷链支链化度。

表4为各煤样中芳碳的分布情况。WCW、PLQ、JJM、TCG、HG和HF的芳碳率呈递减趋势,由61.38%降至从11.89%降至8.24%,说明煤样的芳构化程度逐渐降低,芳香稠环减少。其值反映了多环的连接方式,WCW、PLQ、JJM、TCG、HG和HF的XBP值分别为24.03%、22.39%、22.35%、21.86%、19.22%和21.27%,均小于33%,说明6个煤样结构中芳环均以迫位缩合为主[27-28]

由表4可知,6个煤样的在9.56%~11.95%,说明煤样中部分氧直接与苯环相连形成酚羟基或醚氧基团。

表4 6个煤样中芳族碳分布参数

Table 4 Distribution parameters of aromatic carbon in six kinds of coal samples

煤样fafHafNafSafBafCPafPafCaXBPβWCW61.3827.0534.3310.4911.8949.4911.9515.7624.0341.71PLQ60.0528.2332.2710.0410.4749.0310.7615.3623.3940.87JJM59.4529.4430.019.5910.8648.599.5614.9522.3539.55TCG58.2627.1431.1210.2410.4547.8110.438.0121.8642.45HG51.1121.5329.5810.158.2442.8711.1913.4919.2249.97HF50.0119.6029.9510.28.6940.8611.0612.5221.2752.57

注:fa为芳环碳;为质子化芳碳;为非质子化芳碳;为烷基取代碳;为芳香桥碳;为周碳;为酚羟基或醚氧连碳;为羰基碳;β为芳环取代度;XBP为芳香的桥碳与周碳之比。

从图1可以看出,δ在165~220区间的共振信号明显比脂肪区和芳碳区弱,结合表4可知,煤样中羧基碳(δ=165~188)和醛、酮碳(δ=188~220)含量相对较少,且WCW>HF>PLQ>HG>JJM>TCG。

2.2 煤样结构对焦油产率影响因素

基于Matlab软件编程,通过多元线性回归将煤样的化学结构参数I1I7与煤热解焦油产率Y相关联,拟合结果见表5。线性回归中,添加有效的函数变量可增大拟合度R2,但未扣除参数变量个数的增加对其数值的影响。由于排除了变量个数对拟合关系的影响,其数值仅反映拟合线性方程拟合优度大小,使不同参数变量的优合度具有可比性。因此,将优合度作为判断原煤结构与其热解焦油产率关联性的依据。

表5 13C-NMR参数与热解焦油产率Y相关性多元线性回归分析

Table 5 Multiple linear regression analysis on the relationship between 13C-NMR parameters and tar yield Y value

NO.Independent variables xi(i=1,2,3)R2adjx1x2x3NO.Independent variables xi,(i=1,2,3)R2adjx1x2x3E1I10.499E31I1I2I50.868E2I20.700E32I1I2I60.905E3I30.305E33I1I2I70.795E4I40.685E34I1I3I40.019E5I5-0.110E35I1I3I50.838E6I60.154E36I1I3I60.873E7I7-0.224E37I1I3I70.329E8I1I20.699E38I1I4I50.769E9I1I30.342E39I1I4I60.908E10I1I40.334E40I1I4I70.758E11I1I50.844E41I1I5I60.971E12I1I60.915E42I1I5I70.767E13I1I70.372E43I1I6I70.889E14I2I30.609E44I2I3I40.906E15I2I40.906E45I2I3I50.418E16I2I50.602E46I2I3I60.418E17I2I60.606E47I2I3I70.778E18I2I70.850E48I2I4I50.860E19I3I40.199E49I2I4I60.871E20I3I50.147E50I2I4I70.864E21I3I60.559E51I2I5I60.417E22I3I70.104E52I2I5I70.992E23I4I5-0.009E53I2I6I70.816E24I4I6-0.618E54I3I4I50.064E25I4I7-0.515E55I3I4I60.966E26I5I60.073E56I3I4I70.107E27I5I7-0.501E57I4I5I6-0.359E28I6I7-0.521E58I4I5I7-0.125E29I1I2I30.660E59I5I6I7-0.327E30I1I2I40.879

注:I1为脂甲基碳为亚甲基碳为非质子化芳碳为质子化芳碳为酚羟基或醚氧连碳为羰基碳为烷链支链化度(Bi)。

通过表5中一次变量的线性方程Y=f(x1)的拟合结果可知(E1E7),I2与焦油产率Y的线性优合度最大,为0.700。原煤中亚甲基碳的主要存在形式有:独立的长链烷烃和烯烃、链接在某种官能团上的脂肪链、以取代基形式链接在官能团的侧链、结构单元之间的桥键,且脂肪碳-碳键裂解是煤焦油产生的主要来源,因此,I2是影响煤焦油产率的首要因素,其他官能团可能存在正协同或负协同作用。

I2作为固定变量,分别引入I1I3I4I5I6I7作为第二参考变量,按照方程Y=f(x1,x2)进行二元线性回归(表5中E8E14E15E16E17E18)。可见,I4I7加入后增大,分别从E2的0.700增至E15的0.906和E18的0.850。说明I4I7I2有正协同作用,并且I4的协同效应大于I7I1I3I5I6的加入均使减小,减小幅度依次为I5>I6>I3>I1。由此推断I4I7是影响煤焦油产率的辅助因素,对I2的拟合线性方程起修正作用。通过二元线性回归得到

Y=1.696I2+0.757I4-34.94,

Y=1.517I2-2.413I4+36.29。

I2I4作为固定变量,分别引入I1I3I5I6(表7中E30E44E48E49E55)作为第3个参变量进行三元线性回归。I1I5I6分别加入方程Y=f(x1,x2,x3)时,E15从0.906分别降至0.879(E30)、0.860(E48)和0.871(E49);添加I3后,E44E15相等,为0.906。由此可推断,变量I1I3I5I6对方程Y=f(x1,x2)无修正作用。煤热解过程中,弱桥键首先断裂,生成自由基碎片,自由基之间的反应活泼,I4表示带质子芳碳提供的氢自由基可稳定热解产生的自由基,从而减少自由基之间的缩合反应。但若没有足够的氢与自由基饱和时,自由基之间发生相互聚合形成半焦。因此,以I2为主、I4为辅的二元线性结构组合,在表达形式上更简单,易于操作和应用,可作为一组较为合理的关联焦油产率的辅助方案。

I7替代I4I2I7作为2个固定变量,引入I1I3I5I6作为第3个参变量进行三元线性回归(表5中E33E47E52E53),可见,I1I3I6均使减小,与E18相比分别减少了6.49%、8.48%和4.02%;而I5的加入使E18的0.850增至E52的0.992,增加了16.78%。由表5还可以看到,在E1E59范围内,I2I5I7的组合与焦油产率的关联性最大,说明在煤热解生成焦油的过程中,焦油产率除了受缩合反应的影响,更受制于交联反应,I5代表的—C—O—桥键易断裂发生交联反应,其控制热解焦油生成的过程,从而影响最终焦油产率。

2.3 煤样结构参数与焦油产率的关联性分析

原煤结构中—C—C—和—C—O—桥键,可通过固体核磁间接测定,但—O—和—S—桥键数较难获得。因此,KO等[29]将煤结构与焦油生成特征相关联,推测得到焦油最大产率的经验公式(式(1)~(5))。通过测定煤中O和So元素含量,进而计算出交联反应的桥键数P0。此外,由煤结构中脂肪碳含量可推测出易断裂桥键数n,脱氢含量WH由经验公式得出。

焦油生成特征数XTAR计算公式为

(1)

(2)

(3)

(3)

(4)

[OH]=33.2-0.35[C][30]

式中,n为易断裂桥键数;P0为交联桥键数;WH为脱氢含量;[So]近似采用St全硫含量;[C]、[O]和[H]为煤中干燥无灰基C、O、H元素含量;[OH]为羟基含量。

将式(2)~(4)代入式(1)得

(5)

各煤样的模型参数计算结果见表6。煤中桥键主要由亚甲基碳、醚键和硫醚键组成。热解过程中,醚键和硫醚键易发生交联反应,使焦油产率降低。相关研究认为[31-32],交联反应除了控制焦油产率外,还决定其分子量分布,P0越小,说明在热转化过程中受交联反应的影响越小,即有利于煤热解生成焦油。热解过程中煤样自身可提供氢自由基来稳定桥键断裂产生的自由基,抑制自由基相互结合成半焦,故脱氢量WH值越大,越利于生成焦油分子。由表6可以看出,HF的脱氢含量WH值最大,为5.92,说明该煤样自身可提供的氢自由基最多,焦油生成潜力最大。

由表6可知,随镜质组含量增大,煤样的易断裂桥键数n从5.37增至8.17,说明煤样热解生成焦油前驱体的能力逐渐增强,同时印证了HF煤样结构中,亚甲基碳含量最多。将结构参数与焦油特征指参数XTAR相关联(式(5)),可见,XTAR不仅与煤样大分子网络中的弱桥键(—CH2—CH3、—CH2—、—CH2—O—、—O—和—S—)含量密切相关,而且还受制于体系自身可提供的氢自由基浓度和交联桥键数。HF煤样的XTAR为50.93,PLQ煤样仅为14.20,初步判定相同热解条件下,HF煤样的焦油产率最高,PLQ煤样最低。

表6 煤样热解模型输入参数

Table 6 Input parameters of the pyrolysis model of coal samples

煤样镜质组含量/%P0[OH]WHnXTARWCW26.11.085.803.245.3716.12PLQ38.11.055.372.585.7814.20JJM66.70.965.674.135.9325.41TCG71.81.026.244.455.9625.90HG77.11.267.544.747.2027.09HF82.10.956.225.928.1750.93

煤样XTAR与格金焦油产率随镜质组含量的变化如图2所示。可以看出,随镜质组含量增加,Xtar与煤样的格金焦油产率均逐渐增加。虽HG和HF煤样的挥发分产率为54.05%和45.42%,但两者的焦油产率分别为11.83%和15.8%,这是由于HG煤样的交联程度P0最高,易生成H2O和CO2,且支链化度Bi较HF煤样高,在热解过程中易生成气体。

图2 煤样的最大焦油产率预测
Fig.2 Prediction of maximum tar yield of coal samples

3 结 论

1)煤样结构中脂肪链以短链为主,链长一般在1~3个碳,支链化度在18%~20%,连接在短链上的支链主要以脂环侧链形式存在,其煤样结构中芳环的缩合程度较高,且均以迫位缩合为主。

2)亚甲基碳是影响煤焦油产率的首要因素,带质子芳碳和烷链支链化度为辅助因素,3者决定焦油的生成潜力,而氧接脂碳(I5和I6)影响焦油的最终产率。

3) 不同煤样镜质组含量从26.10%增至82.10%时,易断裂桥键数n与脱氢含量WH分别从5.37增至8.17、3.24增到5.92;交联桥键数P0越小,交联反应程度越低,HF煤样的焦油产率最高,为18.5%。

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