Mechanism analysis of methanol alcoholysis of Naomaohu lignite extraction residue based on model compound reaction path
-
摘要: 以淖毛湖褐煤(NL)超声辅助萃取残渣(ER)作为研究对象,在300 ℃下采用甲醇对ER进行醇解,并考察添加KOH对醇解过程的影响。通过GC-MS分析MP(未添加KOH)和MPKOH(添加KOH)两种醇解产物的组成信息。选取苯甲酸苄酯(BB)和乙酸苯酯(PA)作为ER的两种模型化合物(MER),醇解后得到产物BBP、BBPKOH、PAP和PAPKOH。结果表明,MPKOH收率高达93.39%,而MP收率仅有5.25%,说明KOH的加入明显提高了醇解产物的收率。MP中酚类化合物、酯类化合物和烷烃类化合物的相对含量分别为17.92%、34.83%和5.98%,而MPKOH中的上述三类化合物相对含量分别为38.85%、10.17%和8.71%,在KOH存在下醇解过程发生了酯交换或酯的还原反应,还伴有一定程度的烷基化反应。模型化合物醇解产物分析结果显示,BBP中以苯甲酸甲酯和苯甲醇为主,而BBPKOH中苯甲酸甲酯基本消失,且苯甲醇相对含量占91.85%;PAP中仅检测到了酚类化合物,且苯酚相对含量占87.97%,而PAPKOH中甲基取代的苯甲醚和苯酚含量高达85.64%。两种模型化合物的醇解过程均表明,未添加KOH的醇解过程主要发生酯交换或酯还原反应,添加KOH后,不但加速了上述反应,还强化了后续产物与甲醇间的烷基化反应。Abstract: Ultrasonic assisted extraction residue (ER) from Naomaohu lignite (NL) was taken as the research object. ER was subjected to methanolysis at 300 ℃, and the effect of KOH was investigated. Composition of the two alcoholysis products, MP (without KOH) and MPKOH (with KOH) was analyzed by chromatograph/mass spectrometer (GC-MS). Benzyl benzoate (BB) and phenyl acetate (PA) were selected as model compounds (MER) for ER, and the alcoholysis products (BBP, BBPKOH, PAP and PAPKOH) were obtained. Results showed that the yield of MPKOH was 93.39%, while that of MP was only 5.25%, indicating that the addition of KOH greatly improved the yield of alcoholysis product. MP consisted of phenols, esters and alkanes with the relative contents of 17.92%, 34.83% and 5.98%, respectively, while the contents of the above three compounds in MPKOH were 34.8%, 10.17% and 8.71% respectively, indicating that transesterification or ester reduction reaction occurred in the alcoholysis process with the addition of KOH accompanied by alkylation reaction. Analysis of alcoholysis products of model compounds showed that methyl benzoate and benzyl alcohol were predominant in BBP, while methyl benzoate disappeared in BBPKOH, and the relative content of benzyl alcohol accounted for 91.85%; phenols were only detected in PAP, and the relative content of phenol was 87.97%. Whereas, the content of methyl substituted anisole and phenol accounted for the largest share in PAPKOH with the contents of 85.64%. Alcoholysis process of the two model compounds showed that, without KOH, transesterification or ester reduction reaction was occurred in the alcoholysis process. And the addition of KOH not only accelerated the above reaction, but also strengthened the alkylation reaction between the subsequent products and methanol.
-
Key words:
- lignite residue /
- model compound /
- alcoholysis /
- GC-MS
-
Proximate analysis w/% Ultimate analysis wdaf/% Raito Mad Ad Vdaf C H N S O* H/C O/C 7.12 10.49 49.20 71.89 5.17 0.88 0.74 21.32 0.86 0.22 *: by difference 表 2 MP中检测到的化合物
Table 2 Compounds detected in MP
Peak Compound RC/% 1 methyl pentanoate 3.18 5 N-propylacetamide 0.57 7 5-(propan-2-ylidene)cyclopenta-1,3-diene 0.17 10 dodecanamine 0.08 11 N-isopropyl-3-phenylpropanamide 0.24 20 undecane 5.98 26 2-methylpropan-1-amine 0.11 34 5-methoxy-2,3,4-trimethylphenol 0.65 39 3-(tert-butyl)-4-methoxyphenol 9.64 40 dimethyl isophthalate 0.57 42 N1,N1-diethylbenzene-1,4-diamine 7.45 44 dimethyl nonanedioate 3.92 46 dimethyl decanedioate 5.66 52 2-propionylbenzoic acid 5.14 53 1-octylcyclohex-1-ene 12.89 54 methyl palmitate 5.79 56 methyl stearate 3.61 58 2,2'-methylenebis(6-tert-butyl-4-methylphenol) 7.63 59 methyl 11-docosenoate 6.83 61 methyl lignocerate 9.29 62 2-ethylacridine 10.62 表 3 MPKOH中检测到的化合物
Table 3 Compounds detected in MPKOH
Peak Compound RC/% 2 L-homoserine 1.70 3 2,4-dimethylpentan-3-ol 2.74 4 (methylsulfinyl)methane 0.88 6 5-methyl-2-phenyl-1H-indole 0.52 8 ethyl 2-(benzo[d][1,3]dioxol-5-yl)acetate 0.41 9 2-((dimethylamino)methyl)-6-methoxyphenol 0.30 12 2-methylcyclohexan-1-ol 0.54 13 4-(1-methylpiperidin-4-yl)benzene-1,2-diol 0.26 14 2,6-dimethylocta-2,4,6-triene 0.43 15 piperidin-3-ol 0.43 16 1,3-dioxolane 0.03 17 1,1,3,3-tetramethylguanidine 1.24 18 butyraldehyde 0.45 19 acrylamide 0.76 20 undecane 2.79 21 N1-(3-aminopropyl)propane-1,3-diamine 0.88 22 2-butyloctan-1-ol 0.77 23 2,6-dimethylphenol 0.75 24 2,3,4,6-tetramethylphenol 3.90 25 3,3-dimethylpiperidine 0.84 27 2,3,5-trimethylphenol 9.65 28 (2,2-dimethylpropylidene)cyclohexane 0.93 29 2-(tert-butyl)-6-methylphenol 1.89 30 1-butyl-4-ethylbenzene 1.45 31 2-isopropyl-5-methylphenol 2.39 32 2-ethyl-4,5-dimethylphenol 1.86 33 N1,N1-diethylbenzene-1,4-diamine 5.26 35 2-(1-hydroxybut-2-en-1-ylidene) cyclohexan-1-one 1.31 36 1-(2-hydroxy-5-methylphenyl)ethan-1-one 5.12 37 3-methoxy-2,5,6-trimethyl-phenol 0.26 38 2-(tert-butyl)-4,6-dimethylphenol 11.67 39 2-(tert-butyl)-4-methoxyphenol 9.21 41 2,2-dimethyl-2,3-dihydrobenzofuran-3,7-diol 6.40 43 icosane 4.62 45 2-(hexadecyloxy)ethan-1-ol 0.19 47 tridecane 1.00 48 2-octyldodecan-1-ol 0.44 49 heptadec-15-enal 0.57 50 undecane 0.18 51 octadecane 0.12 55 2-hydroxycyclopentadecan-1-one 2.49 57 bis(2-ethylhexyl) adipate 9.76 58 6,6'-methylenebis(2-(tert-butyl)-4-methylphenol) 2.46 60 4-(2-aminopropyl)phenol 0.20 表 4 BBP和BBPKOH中GC-MS检测到的化合物
Table 4 Compounds detected in BBP and BBPKOH
Compound RC/% BBP BBPKOH Benzaldehyde 2.66 3.05 (Methoxymethyl)benzene 0.49 1.68 Phenylmethanol 38.19 91.85 Methyl benzoate 51.63 2.20 (Dimethoxymethyl)benzene 3.59 0.61 1,2-diphenylethane 2.64 1,2-diphenylethene 0.14 Benzyl benzoate 0.66 Cyclohexylmethanol 0.55 m-tolylmethanol 0.06 表 5 PAP中GC-MS检测到的化合物
Table 5 Compounds detected in PAP
Retention time /min Compound RC /% 5.626 phenol 87.97 7.017 o-cresol 5.25 8.279 2,6-dimethylphenol 0.31 9.037 2-hydroxybenzyl alcohol 0.88 28.63 2,2'-methylenebis-phenol 5.59 表 6 PAPKOH中检测到的化合物
Table 6 Compounds detected in PAPKOH
Peak Compound RC/% 1 anisole 6.67 2 1-methoxy-2-methylbenzene 1.79 3 1-methoxy-4-methylbenzene 4.66 4 o-cresol 0.11 5 2-methoxy-1,3-dimethylbenzene 0.52 6 p-cresol 0.14 7 1-methoxy-2,4-dimethylbenzene 10.23 8 3,5-dimethylphenol 7.32 9 2-methoxy-1,3,5-trimethylbenzene 9.44 10 2,3,6-trimethylphenol 52.51 11 thymol 0.09 12 (4-(tert-butyl)phenyl)methanol 0.17 13 1-(2-hydroxy-4,5-dimethylphenyl)ethan-1-one 0.08 14 2-allyl-4-methylphenol 0.13 15 2-ethyl-4,5-dimethylphenol 0.93 16 2-isopropyl-5-methylphenol 0.43 17 1-(2,3,4-trimethylphenyl)ethan-1-one 0.07 18 2-methyl-6-propylphenol 0.01 19 methyl 2-hydroxy-5-methylbenzoate 0.12 20 2-methyl-4-propylphenol 0.04 21 2-(2-methoxy-5-methylphenyl)propanal 0.04 22 5-propylbenzo[d][1,3]dioxole 0.23 23 1-(sec-butyl)-4-methoxybenzene 0.20 24 4-methyl-2-(pent-3-yn-2-yl)phenol 0.06 25 1,2,3,4,5,6-hexamethylbenzene 0.10 26 1,5,7-trimethyl-1,2,3,4-tetrahydronaphthalene 0.02 27 4-(methoxymethyl)-2,6-dimethylphenol 0.39 28 1-(benzo[d][1,3]dioxol-5-yl)propan-2-one 0.04 29 9H-xanthene-9-carboxylic acid 0.23 30 9H-xanthene 0.54 31 9,9-dimethyl-9H-fluoren-3-ol 0.09 32 phenyl(o-tolyl)methanone 0.30 33 (2,5-dimethylphenyl)(phenyl)methanone 0.27 34 9H-xanthen-9-one 0.05 35 1-methoxy-2-(4-methoxybenzyl)benzene 0.19 36 4,4'-dimethoxy-2,2'-dimethyl-1,1'-biphenyl 0.17 37 methyl 2-phenoxybenzoate 0.04 38 2,2'-(propane-2,2-diyl)bis(methoxybenzene) 0.57 39 4,4'-methylenebis(2,6-dimethylphenol) 0.03 40 4-(methoxycarbonyl)benzyl 4-methylbenzoate 0.39 41 4,4'-methylenebis(2,6-dimethylphenol) 0.25 42 1,2-bis(4-methoxyphenyl)ethan-1-one 0.19 43 3-hydroxy-2-(4-methylbenzoyl)phenyl 2-methoxybenzoate 0.04 44 1-(phenylethynyl)-4-styrylbenzene 0.10 表 7 PAPKOH中检测到的化合物
Table 7 Compounds detected in PAPKOH
Peak Composition Structure RC/% Peak Composition Structure RC/% 1 anisole 6.67 10 2,3,6-trimethylphenol 52.51 2 1-methoxy-2-methylbenzene 1.79 11 thymol 0.09 3 1-methoxy-4-methylbenzene 4.66 14 2-allyl-4-methylphenol 0.13 4 o-cresol 0.11 15 2-ethyl-4,5-dimethylphenol 0.93 5 2-methoxy-1,3-dimethylbenzene 0.52 16 2-isopropyl-5-methylphenol 0.43 6 p-cresol 0.14 18 2-methyl-6-propylphenol 0.01 7 1-methoxy-2,4-dimethylbenzene 10.23 20 2-methyl-4-propylphenol 0.04 8 3,5-dimethylphenol 7.32 24 4-methyl-2-(pent-3-yn-2-yl) phenol 0.06 -
[1] WU J H, LIU J Z, ZHANG X, WANG Z H, ZHOU J H, CEN K F. Chemical and structural changes in Ximeng lignite and its carbon migration during hydrothermal dewatering[J]. Fuel,2015,148:139−144. doi: 10.1016/j.fuel.2015.01.102 [2] LI Z K, WEI X Y, YAN H L, ZONG Z M. Insight into the structural features of Zhaotong lignite using multiple techniques[J]. Fuel,2015,153:176−182. doi: 10.1016/j.fuel.2015.02.117 [3] CONG X S, ZONG Z M, ZHOU Y, LI M, WANG W L, LI F G, ZHOU J, FAN X, ZHAO Y P, WEI X Y. Isolation and identification of 3-ethyl-8-methyl-2, 3-dihydro-1 H-cyclopenta [a] chrysene from Shengli lignite[J]. Energy Fuels,2014,28(10):6694−6697. doi: 10.1021/ef402403y [4] LU H Y, Wei X Y, YU R, PENG Y L, QI X Z, QIE L M, WEI Q, LV J, ZHONG Z M, ZHAO W, ZHAO Y P, NI Z H, WU L. Sequential thermal dissolution of Huolinguole lignite in methanol and ethanol[J]. Energy Fuels,2011,25(6):2741−2745. doi: 10.1021/ef101734f [5] YU X Y, WEI X Y, LI Z K, ZANG D D, ZONG Z M. Two-step depolymerization of Zhaotong lignite in ethanol[J]. Fuel,2017,196(15):391−397. [6] LIU F J, WEI X Y, ZHU Y, GUI J, WANG Y G, FAN X, ZHAO Y P, ZONG Z M, ZHAO W. Investigation on structural features of Shengli lignite through oxidation under mild conditions[J]. Fuel,2013,109:316−324. doi: 10.1016/j.fuel.2013.01.020 [7] ROSS D S, BLESSING J E. Alcohols as H-donor media in coal conversion. 2. Base-promoted H-donation to coal by methyl alcohol[J]. Fuel,1979,58(6):438−442. doi: 10.1016/0016-2361(79)90085-1 [8] LI S, ZONG Z M, LI Z K, WANG S K, YANG Z, XU M L, SHI C, WEI X Y, WANG Y G. Sequential thermal dissolution and alkanolyses of extraction residue from Xinghe lignite[J]. Fuel Process Technol,2017,167:425−430. doi: 10.1016/j.fuproc.2017.07.025 [9] LI Z K, ZONG Z M, YANG Z S, YAN H L, FAN X, WEI X Y. Sequential thermal dissolution of Geting bituminous coal in low-boiling point solvents[J]. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects,2014,36(23):2579−2586. doi: 10.1080/15567036.2013.869639 [10] PAN C X, WEI X Y, SHUI H F, WANG Z C, GAO J, WEI C, GAO X Z, ZONG Z M. Investigation on the macromolecular network structure of Xianfeng lignite by a new two-step depolymerization[J]. Fuel,2013,109:49−53. doi: 10.1016/j.fuel.2012.11.059 [11] LEI Z P, LIU M X, SHUI H F, WANG Z C, WEI X Y. Study on the liquefaction of Shengli lignite with NaOH/methanol[J]. Fuel Process Technol,2010,91(7):783−788. doi: 10.1016/j.fuproc.2010.02.014 [12] LIU F J, WEI X Y, LI W T, GUI J, LI P, WANG Y G, XIE R L, ZONG Z M. Methanolysis of extraction residue from Xianfeng lignite with NaOH and product characterizations with different spectrometries[J]. Fuel Process Technol,2015,136:8−16. doi: 10.1016/j.fuproc.2014.07.012 [13] LI S, ZONG Z M, WANG S K, XU M L, WEI X Y, LIU F J. Compositional features of the extracts from the methanolysis of Xilingol No. 6 lignite[J]. Fuel,2019,246:516−520. doi: 10.1016/j.fuel.2018.11.133 [14] 毛凯敏, 莫文龙, 马凤云, 马亚亚, 王越, 魏贤勇, 樊星. 淖毛湖褐煤分级萃取可溶有机质的组成结构特征及萃余残渣的热转化性能[J]. 燃料化学学报,2021,49(10):1389−1401. doi: 10.1016/S1872-5813(21)60117-2(MAO Kai-min, MO Wen-long, MA Feng-yun, MA Ya-ya, WANG Yue, WEI Xian-yong, FAN Xing. Composition and structure characteristics of soluble organic matter from Naomaohu lignite by sequential extraction and thermal conversion performance of the corresponding residue[J]. J Fuel Chem Technol,2021,49(10):1389−1401. doi: 10.1016/S1872-5813(21)60117-2 [15] XU M L, WEI X Y, YU X Y, LIU F J, WU Q C, LI S, WANG S K, LIU G H, LIU Z Q, GUO X H, ZHANG Y Y, ZONG Z M. Insight into molecular compositions of soluble species from sequential thermal dissolution of Liuhuanggou bituminous coal and its extraction residue[J]. Fuel,2019,253:762−771. doi: 10.1016/j.fuel.2019.05.045 [16] GAO Y, WEI X Y, LI Y J, BAI J J, KANG Y H, LIU G H, MA X R, LI X, LU C Y, BAI H C, ZONG Z M. Investigation on the composition of soluble portions from the extraction residue of Hanglaiwan subbituminous coal by thermal dissolution and alkanolyses[J]. Fuel,2021,306:121747. doi: 10.1016/j.fuel.2021.121747 [17] 夏同成, 魏贤勇, 刘卫兵, 卿宇, 路瑶, 宗志敏, 许斌, 王世杰, 李春启. 锡林浩特褐煤的超临界甲醇解研究[J]. 武汉科技大学学报,2009,32(6):627−630.XIA Tong-cheng, WEI Xian-yong, LIU Wei-bing, QinYu, LU Yao, Zong Zhi-ming, XU Bing, WANG Shi-jie, LI Chong-qi. Supercritical methanolysis of Xilinhaote lignite[J]. J Wuhan Univ Sci Technol,2009,32(6):627−630. [18] KANG Y H, WEI X Y, ZHAN X Q, LI Y J, LIU G H, MA X R, LI X, BAI H C, LI Z N, YAN H J, ZONG Z M. Deep catalytic hydroconversion of straw-derived bio-oil to alkanes over mesoporous zeolite Y supported nickel nanoparticles[J]. Renewable Energy,2021,173:876−885. doi: 10.1016/j.renene.2021.04.003 [19] 李白雪, 薛锋, 王建, 丁恩勇. 聚碳酸酯在乙二醇中的可控醇解[J]. 塑料工业,2015,43(3):127−131. doi: 10.3969/j.issn.1005-5770.2015.03.022LI Bai-xue, XUE Feng, WANG Jian, Ding En-yong. Controllable glycolysis of polycarbonate in ethylene glycol[J]. China Plastics Ind,2015,43(3):127−131. doi: 10.3969/j.issn.1005-5770.2015.03.022 [20] YIN J N, LIN X C, WANG C H, DAI J Z, WANG Y G, XU Z G. Identification of the transformation features of heteroatomic compounds in a low rank coal by combining thermal extraction and various analytical approaches[J]. Fuel,2020,270:117480. doi: 10.1016/j.fuel.2020.117480 [21] SHUI H F, MA X Q, YANG L, SHUI T, PAN C X, WANG Z C, LEI Z P, REN S B, KANG S G, CHARLES XU C B. Thermolysis of biomass-related model compounds and its promotion on the thermal dissolution of coal[J]. J Energy Ins,2017,90(3):418−423. doi: 10.1016/j.joei.2016.04.001 [22] WANG T M, ZONG Z M, LIU F J, LUI C, LV J H, JING L, ZANG D D, QU M, GUI J, LIU X X, WEI X Y, WEI Z H, LI Y. Investigation on compositional and structural features of Xianfeng lignite through sequential thermal dissolution[J]. Fuel Process Technol,2015,138:125−132. doi: 10.1016/j.fuproc.2015.04.029 [23] MONDRAGON F, ITOH H, OUCHI K. Solubility increase of coal by alkylation with various alcohols[J]. Fuel,1982,61(11):1131−1134. doi: 10.1016/0016-2361(82)90198-3 [24] GAO H S, ZONG Z M, TENG D G, LI J H, WEI X Y, GUO Q J, ZHAO T S, BAI H C, KANG Y H. Catalytic o-methylation of phenols and its application in converting crude phenols in a low-temperature coal tar to mesitol and durenol[J]. Fuel,2021,288:119681. doi: 10.1016/j.fuel.2020.119681