高硫肥煤碳结构研究与光谱学表征

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葛涛, 李洋, Wang Meng, 陈萍, 闵凡飞, 张明旭. 高硫肥煤碳结构研究与光谱学表征[J]. 光谱学与光谱分析, 2021,41(1): 45-51.
GE Tao, LI Yang, Wang Meng, CHEN Ping, MIN Fan-fei, ZHANG Ming-xu. Spectroscopic Characterization of Carbon Structure in High Sulfur Fat Coal[J]. Spectroscopy and Spectral Analysis, 2021,41(1): 45-51.
Doi:10.3964/j.issn.1000-0593(2021)01-0045-07 复制到剪切板

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高硫肥煤碳结构研究与光谱学表征

葛涛^1,², 李洋¹, Wang Meng², 陈萍³, 闵凡飞¹, 张明旭¹

1.安徽理工大学材料科学与工程学院, 安徽淮南 232001

2.Department of Civil and Environmental Engineering, University of Houston, Houston Texas 77204, USA

3.安徽理工大学地球与环境学院, 安徽淮南 232001

作者简介: 葛涛, 1980年生, 安徽理工大学材料科学与工程学院副教授 e-mail: getao2007@163.com

收稿日期: 2019-12-09 修回日期: 2020-04-25

基金: 高校优秀青年骨干人才国外访问研修项目(gxgwfx2019013), 中国博士后科学基金项目(2018M632519), 安徽省自然科学基金项目(2008085ME144), 国家重点基础研究发展计划(973计划)项目(2014CB238901)资助

摘要

煤结构是煤化学的重要研究内容, 优质肥煤在我国属于稀缺炼焦煤种。碳是煤结构的基本骨架, 是构成煤中有机质及形成焦炭的主要元素。研究高硫肥煤中的碳结构对认知肥煤结构与性质, 提高低品质炼焦煤利用效率具有重要意义。采集并制备山东东滩(DT)和山西水峪(SY)、霍州(HZ)、高阳(GY)四个矿区的肥煤样品, 利用X-射线衍射(XRD)、傅里叶变换红外光谱(FTIR)以及 X-射线光电子能谱(XPS)对煤中碳结构进行谱学表征和联合解析, 结合煤质分析结果, 计算不同肥煤样品的碳结构参数。研究结果表明: SY, HZ, GY和DT四种肥煤的芳香度 f_a-XRD依次增大, 芳香层片的延展度 L_c和堆垛高度 L_a依次减小, 山西煤的芳香碳结构层片在排列规整度和芳香环缩合程度上强于东滩煤。 DT和GY煤中芳香烃结构主要以苯环五取代、苯环四取代和苯环三取代形式存在, SY与HZ煤中芳香结构以苯环二取代和苯环四取代为主。 DT和GY煤含有较多的支链和较高的芳环缩合度。四种肥煤中脂肪结构均是以亚甲基为主, DT, SY, HZ和GY煤的亚甲基占脂肪结构的比例分别为46.27%, 48.89%, 44.21%和41.85%, 煤中含有较多的烷基侧链。 GY与DT煤中甲基含量略高于次甲基, SY和HZ煤则相反, 这主要与不同煤样在成烃期间长脂肪族结构发生断裂的程度有关。 SY, HZ, GY和DT煤的芳碳率分别为0.83, 0.81, 0.74和0.68, 芳氢率分别为0.51, 0.43, 0.34和0.29, 煤中芳构化程度依次减小, 芳香环缩合度依次升高。 DT和HZ煤的氧化程度较高, DT煤含有较多的C—O结构, 判断DT煤中存在较多不易被热分解或不易起化学反应的非活性氧。

关键词: XRD; FTIR; XPS; 肥煤; 碳结构

中图分类号:TQ536.9 文献标志码:A

Spectroscopic Characterization of Carbon Structure in High Sulfur Fat Coal

GE Tao^1,², LI Yang¹, Wang Meng², CHEN Ping³, MIN Fan-fei¹, ZHANG Ming-xu¹

1. Department of Material Science and Engineering, Anhui University of Science and Technology, Huainan 232001, China

2. Department of Civil and Environmental Engineering, University of Houston, Houston Texas 77204, USA

3. Department of Earth and Environmental, Anhui University of Science and Technology, Huainan 232001, China

Abstract

Coal structure is an important research content of coal chemistry. High-quality fat coal is a scarce coking coal type in China. Carbon is the basic skeleton of the coal structure. Carbon is the basic skeleton of coal structure. It is the main element that forms organic matter in coal and forms coke. Study the carbon structure in high sulfur fat coal is of great significance for understanding the structure and properties of fertile coal, improving the utilization efficiency of low-quality coking coal. Collected and prepared the coal samples from Shandong Dongtan (DT), Shanxi Shuihu (SY), Huozhou (HZ), and Gaoyang (GY) mining areas. The carbon structure in coal was characterized and analyzed by XRD, FTIR and XPS. Combined with coal quality analysis results to calculate the carbon structure parameters of different coal samples. The research results show that the fa-XRD of SY, HZ, GY, DT increases sequentially. Lcand La decrease in order. The aromatic carbon structure of Shanxi coalsis stronger than Dongtan coal in arrangement regularity and aromatic ring condensation. The aromatic hydrocarbon structures in DT and GY coal exist mainly in the form of benzene ring penta-substitution, benzene ring tetra-substitution and benzene ring tri-substitution. The aromatic structure in SY and HZ coal is dominated by benzene ring disubstitution and benzene ring tetra substitution. DT and GY coals contain more branches and higher degrees of aromatic ring condensation. The fat structure of the four kinds of fat coal is dominated by methylene. The proportions of methylene groups in DT, SY, HZ, GY coal to the fat structure were 46.27%, 48.89%, 44.21%, 41.85% respectively. Coal contains more alkyl side chains. GY and DT coal have slightly higher methyl content than methine, while SY and HZ coal have the opposite. It is mainly related to the degree of fracture of the long aliphatic structure of different samples during hydrocarbon generation. The aromatic carbon ratios of SY, HZ, GY, DT coal are 0.83, 0.81, 0.74, 0.68 respectively and aromatic hydrogen ratios are 0.51, 0.43, 0.34, 0.29 respectively. The degree of aromatization in coal decreases in turn. The aromatic ring condensation degree increases in order. The oxidation degree of DT and HZ coal is high. DT coal contains C—O structure, and it is judged that there is more inactive oxygen in coal which is not easily decomposed by heat or chemical reaction.

Keyword: XRD; FTIR; XPS; Fat coal; Carbon structure

文章图片

引言

肥煤是炼焦配煤的重要煤种, 优质肥煤属于我国稀缺煤种。煤结构是煤化学的核心研究内容之一^[1], 碳作为煤结构的基本骨架, 是构成煤中有机质及形成焦炭的主要元素, 掌握高硫肥煤中碳结构特征对构建高硫肥煤大分子结构模型、认知肥煤结构与反应性, 提高煤炭利用效率、增加煤炭附加值具有重要意义。

马汝嘉等对陕西凤县无烟煤分子结构进行了表征, 认为煤芳香结构以萘、蒽和菲为主, 脂肪碳以亚甲基、次甲基、脂肪侧链和环烷烃的形式存在, 其中脂肪侧链以短链为主^[2]。安文博等在研究阜新长焰煤结构时, 发现其芳碳率较大, 芳香核缩合程度较大, 芳香结构单元排列秩序比较规则^[3]。

曾凡桂等研究了内蒙五牧场烟煤和山西成庄无烟煤的结构特征^{[4, 5]}。五牧场煤大分子结构的芳香结构单元包括苯、萘、蒽、菲, 醚键、氢化芳环以及邻位亚甲基是连接芳香结构的主要桥键。成庄煤中芳香碳以2, 3和4环结构为主, 脂肪碳主要以甲、乙基侧链及环烷烃的形式存在。

XRD是获取煤芳香核平面大小、堆砌高度和微晶结构的有效手段^[6], FTIR能够提供煤中芳香烃和脂肪烃结构参数, XPS对物料表面化学结构具有高度识别能力^[7]。利用XRD, FTIR和XPS分别对山东东滩(DT)及山西水峪(SY)、霍州(HZ)、高阳(GY)四个矿区肥煤进行联合解析, 获取肥煤中碳结构参数及赋存特征。

1 实验部分

1.1 样品

根据GB474— 2008制备煤样, 取200目样品密封保存。利用5E-MAG6600工业分析仪测定煤样水分、灰分和挥发分。通过Multi EA 4000元素分析仪测定样品中的C, H, N含量, 利用SDS 601智能全自动定硫仪测定样品中S的含量。煤样的工业分析和元素分析结果见表 1。

表1 煤样的工业分析和元素分析 Table 1 Industrial analysis and elemental analysis of coal samples

1.2 方法

XRD测试在岛津XRD-6000型分析仪上进行。铜靶辐射(λ =0.154 05 nm), 管压40 kV, 电流100 mA, 扫描范围2θ =10° ~80° , Ds=1° , Ss=1° , Rs=0.3mm, 扫描速度ω =3° · min^-1。

利用日本岛津IR Tracer-100型傅里叶变换红外光谱仪进行样品FTIR测试。波数范围为4 000~400 cm^-1, 分辨率为16 cm^-1, 扫描次数累加到32次。

XPS测试设备选择赛默飞世尔科技公司ESCALAB 250Xi型-X光电子能谱仪。 X射线激发源: 单色Al Kα (hν =1 486.6 eV), 功率为150 W, X射线束斑500 μ m, 结合能以C(1s)(284.8 eV)为定标标准进行校准。

XRD, FTIR和XPS谱图拟合分析软件分别是Origin9.1, Peak Fit和XPS peak。

2 结果与讨论

2.1 肥煤碳结构XRD解析

肥煤XRD谱图见图1, 煤中矿物质形成了一些峰形较尖锐且强度较大的峰。在2θ =35° 以前有一个明显的宽峰, 包括衍射角在26° 附近的002峰和19° 附近的γ 带。前者缘于芳香结构单元的平行定向, 后者则与分子中的脂肪族碳(包括脂链和脂环)结构有关。 2θ =43° 左右的低矮衍射峰属于100峰, 反映芳香环的缩合程度, 即芳香碳网层片的大小^[8]。 100峰的半高宽和对应的衍射角误差较大, 因此在拟合过程中采用去除个别影响较大的矿物峰, 并通过多次拟合求取均值的方法以减小误差。

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	图1 煤样的XRD谱图Fig.1 XRD spectrum of coal sample

对四种肥煤的002衍射峰和100衍射峰进分峰拟合, 如图2所示。分别利用布拉格方程[式(1)]和谢乐公式[式(2)和式(3)]计算层间距d₀₀₂和延展度L_a、堆垛高度L_c, 通过式(4)计算芳香度f_a-XRD。微晶结构参数计算结果见表2。

$d_{002} = λ / 2 \sin θ_{002}$ (1)

$L_{c} = 0.9 λ / (β_{002} \cos θ_{002})$ (2)

$L_{a} = 1.84 λ / (β_{100} \cos θ_{100})$ (3)

$f_{a} ⁃ XRD = I_{002} / (I_{002} + I_{γ})$ (4)

式中, λ 为入射光波长0.154 056 nm; β ₀₀₂和β ₁₀₀分别为002衍射峰和100衍射峰的拟合半峰宽; θ ₀₀₂和θ ₁₀₀分别为002衍射峰和100衍射峰的位置; I₀₀₂为002峰的峰面积, I_γ为γ 带的峰面积。

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	图2 肥煤XRD 002峰拟合谱图Fig.2 Fat coal XRD 002 peak fitting spectrum

表2 肥煤XRD解析碳结构参数 Table 2 XRD structural parameters of coal sample

石墨特征峰的2θ ₀₀₂衍射角为26° , 芳香结构单元层间距d₀₀₂为0.34 nm^[9]。四种肥煤的d₀₀₂都与石墨接近, 具有类似石墨的结构特征。但是碳的堆垛排列程度远不及石墨的整齐, 表明煤中存在较多的脂肪侧链。 γ 带使得DT煤XRD谱图的不对称性明显高于SY, HZ和GY煤, 说明DT煤中存在较多的脂肪碳结构, DT煤变质程度比SY, HZ, GY煤低。 SY, HZ, GY煤的L_c, L_a和f_a-XRD均大于DT煤, 则表明山西煤的芳香碳结构层片排列规整度和芳香环缩合程度都强于DT煤。

2.2 肥煤碳结构FTIR解析

图3为肥煤FTIR吸光度(Absorbance)-波数(Wave number)谱图。

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	图3 煤样的FTIR谱图Fig.3 FTIR spectrum of coal sample

2.2.1 芳香烃结构

煤中芳香烃结构FTIR的拟合特征峰不超过6个^[10]。肥煤芳香烃结构拟合谱见图4, 特征峰结构及相对含量见表3。 DT和GY煤中芳香烃结构主要以苯环五取代、苯环四取代和苯环三取代形式存在。其中, DT煤中苯环四取代含量达到56.87%, GY煤中则是苯环五取代含量最高。 SY与HZ煤中芳香结构以苯环二取代和苯环四取代为主。 DT和GY煤含有较多的支链和较高的芳环缩合度。

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	图4 芳香结构FTIR拟合谱图Fig.4 FTIR fitting spectrum of aromatic structure

表3 芳香结构FTIR解析参数 Table 3 Parameters of FTIR of aromatic structure

2.2.2 脂肪碳结构

煤中脂肪结构的FTIR拟合峰一般为6~9个^[11]。肥煤脂肪烃结构拟合谱见图5, 特征峰结构归属及相对含量见表5。四种煤中脂肪结构均是以亚甲基为主。 DT, SY, HZ和GY煤的亚甲基占脂肪结构的比例分别为46.27%, 48.89%, 44.21%和41.85%。表明煤中含有较多的烷基侧链, 与XRD的分析结果一致。 GY与DT煤中甲基含量略高于次甲基, SY和HZ煤则相反, 主要与不同煤样在成烃期间长脂肪族结构发生断裂的程度有关。

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	图5 脂肪结构FTIR拟合谱图Fig.5 FTIR fitting spectrum of aliphatic structure

表4 芳香结构FTIR拟合参数 Table 4 Parameters of FTIR of aliphatic structure

表5 煤样的FTIR结构参数 Table 5 XRD structural parameters of coal sample

煤样	$f_{ar}^{H}$	$f_{ar}^{C}$	CH₃/CH₂
DT	0.29	0.68	0.66
SY	0.51	0.83	0.51
HZ	0.43	0.81	0.61
GY	0.34	0.74	0.71

表5 煤样的FTIR结构参数 Table 5 XRD structural parameters of coal sample

2.2.3 肥煤结构参数

分析煤结构时, 近似认为煤中氢只有芳香氢和脂肪氢两种形式存在, 根据煤中芳香烃和脂肪烃结构的 FTIR 解析结果及元素分析数据, 利用式(5), 式(6)和式(7)计算煤结构参数^[12], 见表5。

$f_{ar}^{H} = (\frac{I_{700 ~ 900}}{I_{700 ~ 900} + I_{2800 ~ 3000}})$ (5)

$f_{ar}^{C} = 1 - \frac{C_{al}}{C} = 1 - (1 - f_{ar}^{H}) \times \frac{H}{C} \div \frac{H_{al}}{C_{al}}$ (6)

$C H_{3} / C H_{2} = I_{C H_{3}} / I_{C H_{2}}$ (7)

式中, $f_{ar}^{H}$ 为煤的芳氢率, I为波数区间内吸收峰面积; $f_{ar}^{C}$ 为煤的芳碳率, 又称碳芳香度, H/C是煤中氢碳原子比, H_al/C_al为脂肪族中的氢碳原子比, 一般用经验值 1.8; CH₃/CH₂为支链长度。

SY, HZ, GY和DT煤的芳碳率逐渐降低, 四种肥煤的芳构化程度依次减小, 与XRD分析结果一致。但是, XRD解析的芳香度明显小于FTIR分析结果, 这是因为在利用XRD结构参数计算芳香度时, 只考虑了002峰的面积, 是仅限于构成002面网内芳碳原子的百分含量^[13]。 SY, HZ, GY和DT煤的芳氢率也是依次降低的, 这在煤中芳香结构分析中可以找到合理的解释。一方面是因为煤中脂肪族的芳构化程度不同, 芳氢率随芳构化程度升高而增大; 另一方面煤中发生的芳环缩聚反应不一致, 芳环缩聚程度越高其芳氢率越低。

2.3 肥煤碳结构XPS解析

煤样XPS全谱如图6所示。

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	图6 煤样的XPS谱图Fig.6 XPS spectrum of coal sample

煤的XPS碳谱一般会出现三到四个解叠峰, 对应特征结构包括COO^-, C— O, C— H以及C— C^[14]。肥煤XPS的C(1s)拟合谱见图7, 各结构及其相对含量见表6。

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	图7 肥煤XPS[C(1s)]拟合谱图Fig.7 Fatcoal XPS [C(1s)] fitting spectrum

表6 煤样XPS的C(1s)拟合结构及相对含量 Table 6 XPS spectral for C(1s) fitting and relative content of coal sample XPS

SY, HZ, GY和DT煤芳构碳含量依次为80.72%, 79.56%, 77.00%和66.64%。与FTIR分析结果相差不大。 DT和HZ煤出现了羧基的拟合特征峰, 表明两种煤样的氧化程度较高。 DT煤含有较多的C— O结构, 元素分析结果显示DT煤中氧含量较高, 推断东滩煤中有较多不易被热分解或不易起化学反应的非活性氧存在。

3 结论

(1)DT煤样的XRD谱图不对称性高于其他煤样, SY, HZ, GY和DT煤样的f_a-XRD依次增大, L_c和L_a依次减小, 山西煤变质程度、芳香碳结构层片在排列规整度和芳香环缩合程度均高于DT煤。

(2)DT和GY煤中芳香烃结构主要以苯环五取代、苯环四取代和苯环三取代形式存在, SY与HZ煤中芳香结构以苯环二取代和苯环四取代为主。 DT和GY煤含有较多的支链和较高的芳环缩合度。

(3)四种肥煤中脂肪结构均是以亚甲基为主, 煤中含有较多的烷基侧链。 GY与DT煤中甲基含量略高于次甲基, SY和HZ煤则相反, 主要与不同煤样在成烃期间长脂肪族结构发生断裂的程度有关。

(4)SY, HZ, GY和DT煤的芳碳率和芳氢率均依次降低, 煤中芳构化程度依次减小, 芳香环缩合度依次升高。

(5)DT和HZ煤的氧化程度较高。 DT煤含有较多的C— O结构, 判断DT煤中有较多不易被热分解或不易起化学反应的非活性氧存在。

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[7]	Valentine A, ChanturiyaI, Zh. Bunin, et al. Minerals Engineering, 2019, 143: 1. [本文引用:1]
[8]	ZHAO Hong-yu, LI Yu-huan, SHU Yuan-feng, et al(赵洪宇, 李玉环, 舒元锋, 等). Coal Science and Technology(煤炭科学技术), 2016, 44(3): 177. [本文引用:1]
[9]	Baysal M, Yurum A, Yildiz B, et al. International Journal of Coal Geology, 2016, 163: 166. [本文引用:1]
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[12]	Chen X, Zhao Y, Liu L, et al. Journal of Analytical and Applied Pyrolysis, 2018, 130: 294. [本文引用:1]
[13]	Zhou Y, Albijanic B, Wang Y L, et al. Energy Sources, Part A, 2018, 40(12): 1559. [本文引用:1]
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2018

0.0

... 煤结构是煤化学的核心研究内容之一^[1], 碳作为煤结构的基本骨架, 是构成煤中有机质及形成焦炭的主要元素, 掌握高硫肥煤中碳结构特征对构建高硫肥煤大分子结构模型、认知肥煤结构与反应性, 提高煤炭利用效率、增加煤炭附加值具有重要意义 ...

2019

0.0

... 马汝嘉等对陕西凤县无烟煤分子结构进行了表征, 认为煤芳香结构以萘、蒽和菲为主, 脂肪碳以亚甲基、次甲基、脂肪侧链和环烷烃的形式存在, 其中脂肪侧链以短链为主^[2] ...

2018

0.0

... 安文博等在研究阜新长焰煤结构时, 发现其芳碳率较大, 芳香核缩合程度较大, 芳香结构单元排列秩序比较规则^[3] ...

2013

0.0

ZHANG

, ZENG

Fan-gui

, XIANG

Jian-hua

(张莉, 曾凡桂, 相建华). Journal of Fuel Chemistry and Technology(燃料化学学报), 2013, 41(11): 1294.

Based on the results of proximate analysis, elemental analysis, 13 C-NMR, FT-IR and XPS results, the structure model of the raw coal in coal seam 11 of Wumuchang district, Yimin Basin of Hulun Buir, Inner Mongolia was built using ACD/lab software. The 13 C-NMR predicting software ACD/CNMR predictor was used to modify the structure. The macromolecule structure model which coincides with the nuclear magnetic resonance map is achieved. The characteristics of structures of macromolecules are as follows. Benzene, naphthalene, anthracene and phenanthrene are aromatic constitutional units, the quantities are 1, 2, 2, 1 respectively. Ether linkages, hydrogen aromatic rings and ortho methylene are bridges connecting aromatic units. Oxygen atoms exist in forms of phenolic hydroxyl groups, the quantities are 7, 3, 2 respectively. Nitrogen atoms exist in forms of pyridine and pyrrole. Methyl and short fatty chains are distributed in the edges of aromatic rings. The coal structure is compared with lignite in nearby mining area and Shendong long flame coal with similar metamorphic grade. In the environment of high temperature and low pressure, oxygen containing functional groups are lost rapidly in the process of thermal revolution, leading to the formation of short chain aliphatic groups. The environment of low pressure during thermal revolution is benefit with escape of micro molecules, leading to the aggregation of free radicals, so that large aromatic structure units are formed. However, due to the steric effect caused by the linear chain aliphatic groups, the orientation arrangement of aromatic structure units is not favored, leading to the phenomenon that the maturation of chemical components occurs before that of coal structure.

Key Laboratory of Coal Science & Technology, Ministry of Education & Shanxi Province, Department of Earth Science & Engineering, Taiyuan University of Technology, Taiyuan 030024, China

在对内蒙古自治区呼伦贝尔市伊敏盆地五牧场区11号煤层原煤工业分析、元素分析、 13 C-NMR、FT-IR、XPS等分析基础上,获得了煤大分子结构中碳骨架信息、脂肪结构以及含氧官能团类型及比例、氮原子的存在形式和比例等结构信息。以此为基础,构建了煤的大分子结构模型,并应用 13 C-NMR预测软件ACD/CNMR predictor 对其进行了修正, 获得与实验核磁共振谱图吻合较好的大分子结构模型。大分子结构的芳香结构单元以苯、萘、蒽、菲为芳香结构单元,数量分别是1、2、2、1,醚键、氢化芳环以及邻位亚甲基作为连接芳香结构的主要桥键;氧原子以酚羟基、羰基、羧基的形式存在,数量分别是7、3、2;氮原子分别以吡啶和吡咯的形式存在,甲基和脂肪短链分布在芳香单元的边缘。与相邻矿区的褐煤及相近变质程度的神东长焰煤的比较发现,其形成机制主要是在高温低压环境下,热演化过程中快速失去各种含氧官能团,导致短链脂肪类物质的形成,而低压环境则有利于热演化过程中形成的各种小分子物质逸散导致自由基的缩聚,形成较大的芳香结构单元,但是直链脂肪类物质的存在具有位阻效应,不利于芳香结构单元的定向排列,导致所谓的"化学成分成熟超前于其结构成熟"现象。

... 曾凡桂等研究了内蒙五牧场烟煤和山西成庄无烟煤的结构特征^[4,5] ...

2013

0.0

XIANG

Jian-hua

, ZENG

Fan-gui

, LI

Bin

, et al(相建华, 曾凡桂, 李彬, 等). Journal of Fuel Chemistry and Technology(燃料化学学报), 2013, 41(4): 391.

The macromolecular structure model of Chengzhuang coal was constructed based on the results of proximate and ultimate analysis, 13 C-NMR spectrum and XPS spectrum. In the model the numbers of rings in polycyclic aromatic hydrocarbon were distributed between 1 and 5. The aliphatic C atoms existed in the forms of -CH 3 ,-CH 2 - and cycloalkanes. 9 atoms of O were in the form of C=O, while one in the form of -OH and another one in the form of -O-. 2 atoms of N were in pyrrole, while S atom did not appear in the model because its concentration was lower than 1%. Molecular mechanics (MM) and molecular dynamics (MD) was adopted to simulate the energy-minimum conformation of the model and the results showed that the aromatic layers tended to be parallel by intramolecular or intermolecular π-π interaction and the latter should be one of the main contributors for the short-range ordering of high-rank coal structure. The van der waals energy and hydrogen bond energy contributed to the energy-minimum conformation.

Key Laboratory of Coal Science & Technology, Ministry of Education & Shanxi Province, Department of Earth Science & Engineering, Taiyuan University of Technology, Taiyuan 030024, China

利用晋城矿区成庄矿煤的工业分析、元素分析、 13 C-NMR、XPS等实验结果,构建了其大分子结构模型.模型中,芳香碳以2、3、4环结构为主,最大环数达五个;脂肪碳以甲、乙基侧链及环烷烃的形式存在.九个氧原子分别以七个羰基(主要为醌基)、一个羟基及一个醚氧的型式存在;两个氮原子以吡咯的形式存在.硫原子含量很低,在模型构建中没有体现.采用分子力学(MM)和分子动力学(MD)方法,对成庄煤结构模型进行能量最小化模拟.结果表明,分子内及分子间芳香层片之间的π-π相互作用,使其以近似平行的方式排列;高煤级煤结构中,短程有序的原因主要是分子间芳香层片的定向排列.分子间的氢键能及范德华能使结构达到最稳构型.

... 曾凡桂等研究了内蒙五牧场烟煤和山西成庄无烟煤的结构特征^[4,5] ...

2013

0.0

... XRD是获取煤芳香核平面大小、堆砌高度和微晶结构的有效手段^[6], FTIR能够提供煤中芳香烃和脂肪烃结构参数, XPS对物料表面化学结构具有高度识别能力^[7] ...

2019

0.0

2016

0.0

ZHAO

Hong-yu

, LI

Yu-huan

, SHU

Yuan-feng

, et al(赵洪宇, 李玉环, 舒元锋, 等). Coal Science and Technology(煤炭科学技术), 2016, 44(3): 177.

In order to explore the effect of calcium oxide on the catalytic pyrolysis characteristics of different rank coals,the changes of the pyrolysis products distribution and the char structure were analyzed based on Inner Mongolia Xilinguole lignite and Ningxia Shizuishan anthracite were carried out with a fixed bed reactorBy means of X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR),the variance of microcrystalline structure,aliphatic structure,aromatization and oxygen-enriched efficiency of char prepared by pyrolysis of lignite and anthracite under different temperatures before and after addition of calcium oxide were investigatedThe research results showed that the H 2 cumulative yield of 2%CaO added in ingnite at 900 ℃ was the largest,reaching 39.11 mL/g.The CO cumulative yield of coal sample with calcium oxide was greater than that of without calcium oxide in high temperature pyrolysis stage.Compared with the addition of calcium oxide,the temperature had a greater influence on the aromatic layer spacing and the diameter of the aromatic layer The value of lignite char aromatic layer stack height and the layer number increased gradually with the adding of calcium oxide at 900 ℃,but anthracite char was on the contrary.The structural deviation degree of graphitization of the microcrystalline structure of char prepared by pyrolysis of lignite and anthracite with the addition of calcium oxide was higher than that of the char without the addition of calcium oxide.The aliphatic structure,aromatization and oxygen-enriched efficiency infrared structure parameters of lignite char was generally higher than that of anthracite charAt high temperature,the degree of the condensation reaction was increased,and the conversion rate of the char was enhanced with the addition of CaO,which led to the aromatization parameters increased.The C=O groups content in raw coal was rare,and the C=O groups was generated through reaction between the calcium oxide promoted aromatic ring cracking under high temperature and CO 2 ,which led to oxygen-enriched efficiency in char increased gradually.

1School of Chemical and Environmental Engineering,China University of Mining & Technology (Beijing),Beijing100083,China;2College of Energy and Power Engineering,Inner Mongolia University of Technology,Hohhot010051,China

为研究CaO对不同变质程度煤在催化热解过程中的作用规律，以锡林郭勒褐煤和宁夏石嘴山无烟煤为研究对象，利用实验室小型固定床反应器，研究了CaO对褐煤和无烟煤热解特性及煤焦结构的影响，运用X射线衍射(XRD)及傅里叶红外光谱(FT-IR)对比研究了不同温度下褐煤、无烟煤添加CaO前后热解半焦微晶结构以及脂肪结构、芳构化、富氧程度等红外结构参数的变化规律。试验结果表明：在900 ℃时，添加质量分数2%CaO的褐煤煤样H 2 累积产率最大，达39.11 mL/g；添加CaO后煤样在高温热解阶段生成CO的累积产率大于未添加CaO煤样的量。与加入CaO相比，温度对芳香层片间距和芳香层片直径影响更大；热解温度为900 ℃时，随着CaO的加入，褐煤半焦芳香层片堆积高度和晶层数逐渐增大；而对于无烟煤半焦来说，则与之相反；加入CaO的褐煤和无烟煤热解半焦的微晶结构偏离石墨化程度大于未加入CaO的热解半焦。褐煤半焦的脂肪结构、芳构化、富氧程度等红外结构参数普遍高于无烟煤半焦。高温时，缩合反应程度增大，CaO促进半焦的转化率提高，导致芳构化参数变大；原煤中C=O基团很少，高温下通过CaO促进芳环裂解和CO 2 反应生成C=O基团，进而导致半焦中富氧程度呈升高趋势。

... 左右的低矮衍射峰属于100峰, 反映芳香环的缩合程度, 即芳香碳网层片的大小^[8] ...

2016

0.0

... 34 nm^[9] ...

2019

0.0

... 煤中芳香烃结构FTIR的拟合特征峰不超过6个^[10] ...

2017

0.0

... 煤中脂肪结构的FTIR拟合峰一般为6~9个^[11] ...

2018

0.0

... 分析煤结构时, 近似认为煤中氢只有芳香氢和脂肪氢两种形式存在, 根据煤中芳香烃和脂肪烃结构的 FTIR 解析结果及元素分析数据, 利用式(5), 式(6)和式(7)计算煤结构参数^[12], 见表5 ...

2018

0.0

... 但是, XRD解析的芳香度明显小于FTIR分析结果, 这是因为在利用XRD结构参数计算芳香度时, 只考虑了002峰的面积, 是仅限于构成002面网内芳碳原子的百分含量^[13] ...

2016

0.0

... C^[14] ...