Effects of K+, Ca2+ and Fe3+ on the distribution, structure and quality of the pyrolysis products of Hefeng coal
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摘要: 将K+、Ca2+、Fe3+的硝酸盐用于处理脱灰和丰煤样（K-DC、Ca-DC和Fe-DC），在热重分析仪中考察了处理煤样的失重特征和气体逸出规律。结果表明，处理煤样的总失重率减少，CO2和H2的浓度较原煤（DC）的高。通过固定床研究了处理煤样热解过程中产物的分配规律，采用元素分析、FT-IR、模拟蒸馏和GC-MS等分析了半焦的结构特征和焦油的组成与品质。结果表明，与DC相比，处理煤样的半焦和气体产率增加，焦油产率降低，相应半焦的不饱和度和缩合程度降低。在各金属组分的作用下，焦油中的轻质组分分率增加，其中，Fe3+的作用最为显著，其值增加了22.4%。GCMS结果表明，长链烷烃含量高达70%，是焦油组分重的主要原因，K和Fe组分可促进其分解。Abstract: The nitrate solution of K+, Ca2+ and Fe3+ was used to treat Hefeng demineralized coal (DC) separately. The weight loss and gas evolution of coal samples were studied by thermogravimetric analyzer. It is found that the total weight loss of treated coal samples decreases, while the concentration of CO2 and H2 increases for treated samples. Then the distribution variation of products during the pyrolysis process of treated coal samples were investigated in a fixed bed reactor together with the analyses of elemental analysis, FT-IR, simulated distillation and GC-MS. The results indicate that the char and gas yields of treated coal samples rise, while the tar yields decline. The unsaturation and condensation of corresponded char samples exhibit a decreasing tendency. Under the action of these metal components, the percentage of light component in the tar increases, especially by 22.4% due to the effect of iron species. GC-MS analysis exhibits that long chain alkanes occupy about 70% of the total relatively, leading to the high content of heavy component in tar, which can be catalytically cracked by K and Fe species.
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Key words:
- demineralized coal /
- metal ion /
- catalytic pyrolysis /
- char structure /
- tar quality
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图 1 热解装置流程示意图
1: nitrogen; 2: mass flowmeter; 3: thermocouple; 4: electric furnace; 5: reactor; 6: condenser; 7: washing bottle; 8: wet gas meter; 9: U-type drying tube; 10: online mass spectrometer; 11: gas bag
Figure 1 Schematic of coal pyrolysis setup
图 2 煤样的SEM照片((a)-(d))及EDS谱图(e)
Figure 2 SEM ((a)-(d)) and EDS (e) images of coal samples
图 4 煤样热解过程中气体的逸出规律
Figure 4 Evolution curves of gas during the pyrolysis process of coal samples
图 5 处理煤样的热解产物分布(a)及各气体组分产率(b)
Figure 5 Products distribution (a) and the yield of each gas (b) during the pyrolysis of treated coal samples
图 6 半焦的Raman谱图(a)和峰拟合示意图(b)
Figure 6 Raman spectra of char samples (a) and the schematic graph of fitting curves(b)
图 9 各煤样热解焦油的GC-MS谱图
Figure 9 GC-MS spectra of pyrolysis tars from treated coal samples
表 1 煤样分析
Table 1 Analyses of coal samples
Coal sample Proximate analysis w/% Ultimate analysis wdaf/% H/C Ad Vdaf FCdaf* C H O* N S Raw coal 15.14 45.42 54.58 77.08 6.29 15.09 1.27 0.27 0.98 DC 1.69 43.56 56.44 71.84 5.64 20.79 1.50 0.23 0.94 *：by difference 
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表 2 半焦的元素分析
Table 2 Ultimate analysis of char samples
Sample Ultimate analysis w/% H/C (molar ratio) Degree of unsaturation Ω C H N O* S DC-char 83.34 2.49 2.08 11.85 0.24 0.359 11.53 K-DC-char 81.02 2.49 2.10 14.16 0.23 0.369 11.16 Ca-DC-char 79.86 2.66 2.14 15.14 0.20 0.400 10.80 Fe-DC-char 82.37 2.50 2.46 12.41 0.26 0.364 11.00 *: by difference
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表 3 半焦Raman光谱分峰面积比
Table 3 Curve fitting peak area ratio of char samples
Sample Peak area ratio/% IG/ ID3 ID1/ Iall ID2/ Iall ID3/ Iall ID4/ Iall IG/ Iall DC-char 65.52 5.13 7.01 2.16 20.17 2.88 K-DC-char 63.12 4.16 11.34 2.88 18.49 1.63 Ca-DC-char 65.46 3.87 8.58 3.27 18.82 2.19 Fe-DC-char 66.84 4.15 9.25 2.17 17.59 1.90
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表 4 焦油的模拟蒸馏分析
Table 4 Simulating distillate fractions of tar samples
Sample Fraction w/% light oil(< 170 ℃) phenol oil(170-210 ℃) naphthalene oil(210-230 ℃) wash oil(230-280 ℃) anthracene oil(280-360 ℃) pitch(> 360 ℃) DC 1.8 8.6 5.5 13.8 21.1 49.2 K-DC 1.0 10.0 6.0 15.1 22.2 45.7 Ca-DC 1.6 9.4 6.2 16.0 22.7 44.1 Fe-DC 2.8 12.4 6.9 16.1 23.6 38.2
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表 5 焦油中各主要组分的GC-MS谱图鉴定
Table 5 Identification of major peaks in GC-MS spectrum of tar
Peak Compound Peak Compound 1 heptane 44, 69 1-tetradecene 2 2, 6-dimethyl-2, 4-heptdiene 45, 48 1-methyl-naphthalene 3 ethylbenzene 46 tridecane 4 1, 1-dimethyl-2-pentayl-cyclopropane 47 7- hexadecene 5, 7 o-xylene 49 [3-(2-cyclohexylethyl)-6-cyclopentylhexyl]-benzene 6 1-nonene 50 heptyl-benzene 8 nonane 51, 57 1-pentadecene 9 4-nonene 52 3-tetradecene 10 2-methyl-1-octanol 53 tetradecane 11 3-ethyl-2-methyl-1-heptane 54 5-tetradecene 12 4, 5-dimethyl-octane 55 1, 2-dimethyl-naphthalene 13 propylbenzene 56, 68 heneicosane 14 1-ethyl-3-methyl-benzene 58 pentadecane 15 5-methyl-undecane 59 1, 2, 3, 4-tetrahydro-5, 6, 7, 8-tetramethyl-naphthalene 16, 19, 23 1, 3, 5-trimethyl-benzene 60, 63 1-heptadecene 17 1-ethyl-2-methyl-benzene 61 hexadecane 18 1-decene 62 hexadecamethyl-cyclooctasiloxane 20 2, 4, 6-trimethyl-octane 64 heptadecane 21 1- ethyl-2-phenyl-cyclopropane 65 1-octadecene 22 2-dodecene 66 octadecane 24 1-ethyl-2-(1-methylethyl)-benzene 67 1-heneicosanol 25 indane 70, 78 n-tetracosanol-1 26 butyl-benzene 71 tetracosane 27 2-methyl-phenol 72, 74, 83 1-heptacosanol 28 1-methyl-4-propyl-benzene 73, 77 pentacosane 29 3-methyl-phenol 75 hexacosane 30 nonyl-cyclopropane 76, 85 1-octacosanol 31 undecane 79 octacosane 32 1-hexyl-2-propyl-cis-cyclopropane 80 carbonic acid, ethyl octadecyl ester 33 3-phenyl-2-propenal 81 1-octacosanol 34 2-ethyl-phenol 82 nonacotane 35 1H-indene 84, 89 triacontane 37 1-methylindene 86 hentriacontane 38 3, 4-dimethyl-phenol 87 dotriacontane 39 naphthalene 88 1-hentetracontanol 40 nonyl-cyclopropane 90 tetracontane 41 dodecane 91 diploptene 42 5-tetradecene 92 acetate lupan-3-ol 43 2, 5-dimethyl-undecane 93, 94 15-isobutyl-(13.alpha.H)-isocopalane
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表 6 各处理煤样热解焦油的成分分析
Table 6 Compositions of pyrolysis tar from treated coal samples
Component Relative content w/% DC K-DC Ca-DC Fe-DC Aliphatic hydrocarbons 69.00 70.44 70.00 69.99 b.p. above 300 ℃ 46.80 33.07 40.42 35.98 Aromatic hydrocarbons： 16.22 20.40 13.96 20.04 Benzenes 7.21 11.83 7.27 11.08 Phenols 5.67 4.86 1.77 4.79 Naphthalenes 1.92 2.27 3.58 2.35 Indenes 1.42 1.44 1.07 1.82 Oxygen containing compounds beyond phenol derivatives 14.78 9.16 16.04 9.97
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