Effect of Fe modified Zr-based montmorillonites on the pyrolysis behavior of Xinjiang Hefeng coal
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摘要: 采用机械球磨法制备不同Fe盐改性Zr基蒙脱土催化剂，通过X射线衍射仪（XRD）、物理吸附仪（BET）、化学吸附仪（NH3-TPD、H2-TPR）和X射线光电子能谱仪（XPS）分析其组成和结构。结果表明，与24ZrAM相比，以FeCl3·6H2O和FeCl2·4H2O为铁源时，3Cl−-24ZrAM和2Cl−-24ZrAM中生成了Fe–O–Zr结构。Fe的硫酸盐存在时，催化剂的比表面积显著减小。引入Fe后，催化剂的总酸量均降低，3Cl−-24ZrAM的酸量与强酸强度最高。H2-TPR显示，3Cl−-24ZrAM、2Cl−-24ZrAM和
$3{\rm{NO}}_3^ - $ -24ZrAM中Fe2O3还原为Fe3O4的温度均低于500 ℃。在固定床反应器中考察了催化剂对新疆和丰煤热解行为及含不同桥键模型化合物的断键机制的影响。与24ZrAM相比，不同Fe源改性蒙脱土均能降低焦油中沥青的质量分数，其中，3Cl−-24ZrAM的裂解活性最高，轻质焦油分率增加至63%，比24ZrAM提高了18.9%，轻油和酚油质量分数分别为24ZrAM的1.3倍和1.4倍，长链烃含量进一步降低，降幅为0.7%。引入Fe后，苄基苯基醚（BPE）、联苄和联苯的转化率分别比24ZrAM提高了5%、1.6%和43.9%。-
关键词:
- Fe改性Zr基蒙脱土 /
- 新疆和丰煤 /
- 模型化合物 /
- 催化热解 /
- 焦油品质
Abstract: A serial of Fe modified Zr-based montmorillonites were prepared by mechanical ball milling and their characteristics were depicted by X-ray diffractometer (XRD), N2 adsorption-desorption instrument (BET), temperature-programmed desorption of ammonia (NH3-TPD, H2-TPD), X-ray photoelectron spectrometer (XPS). The results show that compared with 24ZrAM, when FeCl3·6H2O and FeCl2·4H2O are used as iron sources, Fe–O–Zr structure appears on the 3Cl−-24ZrAM and 2Cl−-24ZrAM catalysts. In the presence of Fe sulfate, the specific surface area of the catalysts decreases markedly. With the introducing of Fe, the total acid content of catalysts reduces. Wherein, 3Cl−-24ZrAM has the highest acid content and strongest acid strength. H2-TPR shows that the temperature for Fe2O3 reduced to Fe3O4 in 3Cl−-24ZrAM, 2Cl−-24ZrAM and$3{\rm{NO}}_3^ - $ -24ZrAM is lower than 500 ℃. Then, the effect of catalysts on the pyrolysis behavior of Xinjiang Hefeng coal and the bridge bond cleavage mechanism of different model compounds were investigated in a fixed bed reactor. It is noted that compared with 24ZrAM, the fraction of coal tar pitch all declines under the action of Fe species. Among them, 3Cl−-24ZrAM has the highest cracking activity with the light tar fraction of 63%, which is 18.9% higher than that of 24ZrAM. Meanwhile, the content of light oil and phenol oil are 1.3 times and 1.4 times higher than that of 24ZrAM, respectively. As for long-chain hydrocarbons, a further decline by 0.7% is observed. In addition, the conversion rates of benzyl phenyl ether (BPE), dibenzyl and biphenyl increase by 5%, 1.6% and 43.9%, respectively. -
图 2 催化剂的XRD 谱图：Fe 盐(a)，Fe 盐与24Zr (b)和Fe盐与24ZrAM(c)
Figure 2 XRD spectra of different catalysts: Fe salts (a), Fe-24Zr (b) and Fe-24ZrAM (c)
图 3 催化剂的 N2吸附-脱附等温曲线（a）和孔径分布（b）
Figure 3 N2 adsorption-desorption isotherms (a) and pore size distributions of catalysts (b)
图 4 催化剂的H2-TPR 谱图：Fe 盐(a)，Fe 盐与24Zr (b)和Fe盐与24ZrAM(c)
Figure 4 H2-TPR profiles of different catalysts: Fe salts (a), Fe-24Zr (b) and Fe-24ZrAM (c)
图 5 催化剂的NH3-TPD谱图（a）NH3-TPD高斯拟合（b）
Figure 5 NH3-TPD profiles of catalysts (a) and Gaussian fitting results of NH3-TPD (b)
图 6 催化剂对和丰煤产物分布（a）与气体组成（b）的影响
Figure 6 Products distribution (a) and gas components (b) from Hefeng coal pyrolysis over catalysts
图 7 焦油的馏程分布（a）与产率（b）
Figure 7 Simulated distillate fractions (a) and yields (b) of tar
表 1 煤样分析
Table 1 Analysis of coal samples
Sample Proximate analysis w/% Ultimate analysis wdaf/% Ad Vdaf FCdaf* C H O* N S Raw coal 22.83 47.47 52.53 72.06 5.64 19.07 3.00 0.23 DC 1.10 44.98 55.02 61.17 4.93 30.86 2.83 0.21 *: by difference 
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表 2 催化剂的孔结构特征和Fe2O3的粒径
Table 2 Pore structure characteristics of the catalysts and crystallize size of Fe2O3
Sample BET surface area/(m2·g−1) Pore volume/(cm3·g−1) Average pore size/nm Crystallize size/nm 24ZrAM 93 0.12 6.58 ${\rm{3SO}}_4^{2 - } $-24ZrAM 28 0.13 16.75 8.7 3Cl−-24ZrAM 108 0.13 6.19 6.2 ${\rm{SO}}_4^{2 - }$-24ZrAM 56 0.16 11.55 10.2 2Cl−-24ZrAM 117 0.15 6.40 9.5 ${\rm{3NO}}_3^ - $-24ZrAM 94 0.16 7.07 5.2
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表 3 联苄热解产物分布
Table 3 Distribution of bibenzyl pyrolysis products
Sample Monomer aromatics content /% Dimeric aromatics content /% BTX styrene other
alkylbenzenesbiphenyl propane-1,2-
diyldibenzene1,3-diphenylpropane stilbene others Blank 3.7 0.4 0.7 13.2 34.1 30.3 15.7 1.9 24ZrAM 4.0 0.4 11.3 11.8 22.2 23.0 12.1 12.5 3Cl−-24ZrAM 7.3 3.0 19.1 24.9 14.9 16.4 3.8 10.6
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表 4 联苯热解产物分布
Table 4 Distribution of biphenyl pyrolysis products
Sample Monomer aromatics content/% Dimeric aromatics content/% BTX other
alkylbenzenesnaphthalene 2-methyl-1,1’-
biphenyl4-methyl-1,1’-
biphenylbibenzyl others Blank 8.1 − 12.7 4.8 15.4 48.3 10.7 24ZrAM 1.1 1.8 0.4 36.2 42.7 1.5 16.3 3Cl−-24ZrAM 4.3 1.7 0.4 32.2 41.8 3.4 16.2
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