Direct liquefaction behavior of Shenhua coal under CO containing atmosphere
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摘要: 在CO或合成气气氛下进行煤直接液化有利于降低制氢成本。本文通过对比CO、H2、N2三种气氛下的液化行为，探究了CO对神华上湾煤液化过程的影响，并进一步研究不同CO/H2比以及催化剂对合成气条件下液化过程的影响。结果显示，在CO气氛下煤直接液化的油产率达到43.1%，比H2气氛中低4.2%，但比N2气氛下高10.2%，添加神华863催化剂后液化效果得到进一步的提升，表明CO在液化过程中可通过水煤气变换反应和CO与煤有机结构间的反应促进煤液化。对液化产物进行GC-MS、FI-TR等分析发现，CO使液化油中苯系物、脂肪烃与含氧化合物同时增多，对液化残渣中官能团与自由基浓度的影响不明显。在CO+H2合成气下的实验结果表明，在20%CO的合成气中煤液化具有最高的油产率，达到57.4%；适当提高煤的含水量能够提升液化效果；神华863催化剂对液化过程与水煤气变换反应均具有良好的催化作用。研究工作为煤在合成气下的直接液化提供理论基础。Abstract: Direct coal liquefaction (DCL) under CO or syngas atmosphere is beneficial to reduce the cost of hydrogen production. In this paper, the effects of CO on the liquefaction process of Shangwan coal were investigated by comparing the liquefaction behavior in three atmospheres of CO, H2, and N2. Then, the effects of different CO/H2 ratios and catalysts on the liquefaction process in syngas were investigated. The results indicated that the oil yield under the CO atmosphere reached 43.1%, which was 4.2% lower than that under H2, but 10.2% higher than that under N2. The liquefaction performance was further improved by adding the Shenhua 863 catalyst. It is analyzed that CO promoted liquefaction in two ways: water-gas shift reaction and the reaction between CO and organic structures of coal. Through the characterization of the products by GC-MS and FI-TR, it was found that CO makes the benzenes, aliphatics, and oxygen-containing compounds in liquefied oil simultaneously increased, the effect on functional groups and free radicals concentration in the solid products was not obvious. The experimental results under syngas showed that the highest oil yield, 57.4%, can be obtained in DCL with 20%CO syngas, and further improved by increasing the moisture content of coal appropriately. In addition, it was found that the Shenhua 863 catalyst has a good catalytic effect on the liquefaction process and also water-gas shift reaction. The research work provides a theoretical basis for the direct liquefaction of coal under syngas.
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Key words:
- Direct coal liquefaction /
- hydrogen-rich atmosphere /
- syngas /
- water-gas shift reaction
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图 1 实验设备及产物分离流程示意图
Figure 1 Schematic diagram of experimental equipment and product separation procedure
图 2 不同气氛下催化与非催化液化的气液固产物产率和氢耗分布
Figure 2 Product yields and hydrogen consumption distribution of catalytic and non-catalytic liquefaction under different atmospheres
(a): Product yields; (b): Hydrogen consumption distribution.
图 3 不同气氛下催化与非催化液化的水产率和CO消耗分布
Figure 3 Water yield and CO consumption distribution of catalytic and non-catalytic liquefaction under different atmospheres
(a): variation amount of water; (b): CO consumption distribution.
图 4 不同气氛下液化油的GC-MS结果
Figure 4 GC-MS results of liquefaction oil under different atmospheres
图 5 不同气氛下煤液化产生的沥青烯和液化残渣的FT-IR谱图
Figure 5 FT-IR spectra of asphaltene and liquefaction residue under different atmospheres
(a): asphaltene; (b): liquefaction residue.
图 6 不同气氛下煤液化产生的沥青烯和液化残渣的总自由基浓度和g值
Figure 6 Total radical concentrations and g value of asphaltene and liquefaction residue under different atmospheres
(a): total radical concentrations; (b): g value.
图 7 原煤以及不同反应条件下液化残渣的EPR谱图
Figure 7 EPR spectra and fitted sub-curve of SW and its liquefaction residue under different reaction conditions
图 8 不同CO/H2比例合成气气氛下的液化结果
Figure 8 Liquefaction results under different CO/H2 ratios of syngas
(a): product yields; (b): hydrogen consumption distribution; (c): CO consumption distribution; (d): CO and THN conversion.
图 9 添加水量对上湾煤在20% CO合成气下液化的影响
Figure 9 Effect of water addition on DCL
(a): product yield; (b): gas consumption and XCO.
图 10 催化剂对上湾煤在20%CO合成气下液化的影响
Figure 10 Effect of catalyst on SW DCL
(a): product yield; (b): gas consumption and XCO; (c): water yield.
表 1 上湾煤及神华铁基催化剂工业分析和元素分析
Table 1 Proximate and ultimate analyses of SW and iron-based catalyst
Sample Proximate analysis/% Ultimate analysis/%, daf Mad Ad Vdaf C H N S O* SW 1.30 5.54 37.04 71.91 4.95 0.99 0.36 21.79 Fe catalyst 3.96 13.12 37.40 − − − − − * by difference 
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表 2 不同实验条件下的CO2产率*
Table 2 Yield of CO2 under different conditions
Run Catalyst Atmosphere YCO2 (mmol/g) 1 None N2 0.68 2 None N2 0.69 3 None H2 0.60 4 None H2 0.63 5 1%Fe N2 0.75 6 1%Fe N2 0.66 7 1%Fe H2 0.57 8 1%Fe H2 0.59 * Experiments at same conditions except for the catalyst and atmosphere, each condition repeated twice.
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表 3 原煤及不同气氛下液化反应后残渣的EPR谱图拟合结果
Table 3 Fitted results of EPR spectra of SW and liquefaction residue under different atmospheres
Sample Fitted curve g value Line width(Gauss) Line shape Radical concentration(spins/g×1018) SW Sub-curve-1 2.00513 9.20 G/L 5.09 Sub-curve-2 2.00540 5.45 G/L 6.75 N2 Sub-curve-1 2.00474 3.25 Gauss 12.17 Sub-curve-2 2.00369 12.50 G/L 8.41 Sub-curve-3 2.00467 6.84 Lorenz 7 .38 N2-Fe Sub-curve-1 2.00476 2.92 Gauss 8.44 Sub-curve-2 2.00408 11.10 G/L 10.56 Sub-curve-3 2.00474 6.24 Lorenz 6.80 H2 Sub-curve-1 2.00495 3.06 Gauss 7.87 Sub-curve-2 2.00433 11.24 G/L 7.55 Sub-curve-3 2.00490 6.27 Lorenz 4.54 H2-Fe Sub-curve-1 2.00490 11.64 Gauss 6.92 Sub-curve-2 2.00367 36.70 G/L 5.16 Sub-curve-3 2.00478 6.80 Lorenz 4.09 CO Sub-curve-1 2.00483 3.03 Gauss 10.09 Sub-curve-2 2.00412 11.36 G/L 11.07 Sub-curve-3 2.00479 6.37 Lorenz 7.47 CO-Fe Sub-curve-1 2.00496 11.63 Gauss 8.41 Sub-curve-2 2.00427 6.58 G/L 8.88 Sub-curve-3 2.00493 25.36 Lorenz 5.69
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表 4 不同充压比合成气的色谱测量值
Table 4 Chromatographic measurements of reaction gas
Syngas* Initial CO pressure
(MPa)Measured volume
fraction of gas
(%)CO H2 20% CO 1.2 25.16 74.84 40% CO 2.4 44.55 55.45 60% CO 3.6 63.27 36.73 80% CO 4.8 80.85 19.15 * Fill the reactor with CO at the specified pressure, and then fill the reactor pressure with H2 to 6 MPa
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