低阶粉煤催化微波热解制备含碳纳米管的高附加值改性兰炭末

doi:10.11949/0438-1157.20230132

化工学报 ›› 2023, Vol. 74 ›› Issue (9): 3956-3967.DOI: 10.11949/0438-1157.20230132

• 材料化学工程与纳米技术 • 上一篇下一篇

低阶粉煤催化微波热解制备含碳纳米管的高附加值改性兰炭末

吴雷¹^,²(), 刘姣¹(), 李长聪¹, 周军¹^,²(), 叶干¹, 刘田田¹, 朱瑞玉¹, 张秋利¹^,², 宋永辉²^,³

^1.西安建筑科技大学化学与化工学院，陕西西安 710055
^2.陕西省黄金与资源重点实验室，陕西西安 710055
^3.西安建筑科技大学冶金工程学院，陕西西安 710055

收稿日期:2023-02-21 修回日期:2023-05-02 出版日期:2023-09-25 发布日期:2023-11-20
通讯作者: 周军
作者简介:吴雷（1988—），男，博士，工程师，wulei@xauat.edu.cn
刘姣（1997—），女，硕士研究生，liujiao@xauat.edu.cn
基金资助:
陕西省创新能力支撑计划项目(2020TD-028);陕西省教育厅服务地方专项项目(22JC045);陕西省教育厅科研计划项目一般专项项目(22JK0278);榆林市科技计划项目(CXY-2020-058);西安市碑林区科技计划项目(GX2133);西安建筑科技大学科技基金项目(ZR21065)

Catalytic microwave pyrolysis of low-rank pulverized coal for preparation of high value-added modified bluecoke powders containing carbon nanotubes

Lei WU¹^,²(), Jiao LIU¹(), Changcong LI¹, Jun ZHOU¹^,²(), Gan YE¹, Tiantian LIU¹, Ruiyu ZHU¹, Qiuli ZHANG¹^,², Yonghui SONG²^,³

^1.School of Chemistry and Chemical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, Shaanxi, China
^2.Key Laboratory of Gold and Resources of Shaanxi Province, Xi’an 710055, Shaanxi, China
^3.School of Metallurgical Engineering, Xi’an University of Architecture and Technology, Xi’an 710055, Shaanxi, China

Received:2023-02-21 Revised:2023-05-02 Online:2023-09-25 Published:2023-11-20
Contact: Jun ZHOU

摘要/Abstract

摘要：

由于兰炭末粒径小、挥发分低等原因限制了其在工业生产中大规模利用。因此，兰炭末高附加值改性制备是当前极具吸引力和前景的研究课题。通过KOH协助微波热解低阶粉煤制备了含有碳纳米管的高附加值改性兰炭末，研究了KOH添加量（碱碳比）对改性兰炭末的形貌和结构、石墨化度、微晶结构和碳纳米管（CNTs）含量的影响，推测了改性兰炭末中碳纳米管的生成机制。结果表明：当碱碳比为1.0时，改性兰炭末中生成了直径在30~50 nm，长度约为几十微米的碳纳米管，其含量为3.01%（质量）。随着碱碳比增加，K的刻蚀和原煤所含矿物质产生的Fe₃C对碳纳米管的生成具有促进作用，改性兰炭末的有序性有所增强，石墨层间距的交互作用增强，Raman光谱中出现碳纳米管的标志特征峰G′，表明生成了含有碳纳米管的高附加值改性兰炭末。此外，FT-IR光谱中改性兰炭末中的C—C、C—H和醚键C—O—C结构强度明显减弱。这种现象的产生可能有两方面原因：一是这些碳结构在催化剂的作用下成为了碳纳米管直接生成的固相碳源；二是这些碳结构热分解释放出CO和CH₄，这些气体可作为碳纳米管的气相碳源。高附加值改性兰炭末中碳纳米管的生成可能是 “顶端生成”模型和“粒-线-管生成”模型共同作用的结果。

关键词: 碳纳米管, 生长机制, 催化微波热解, 改性兰炭末, 低阶粉煤

Abstract:

The limitation of large-scale utilization of bluecoke powders in industrial production due to their small particle size and low volatiles, and their preparation through high value-added modification therefore is an attractive and promising research subject for now. In this study, the high value-added modified bluecoke powders containing carbon nanotubes were prepared by KOH-assisted microwave pyrolysis of low-rank pulverized coal. The effects of KOH addition (alkali-carbon ratio) on the morphological structure, graphitization, microcrystalline structure and carbon nanotubes content of the modified bluecoke powders were investigated, and the generation mechanism of carbon nanotubes in the modified bluecoke powders was speculated. The results showed that carbon nanotubes with diameters of 30—50 nm and lengths of several tens of micrometers were produced in the modified bluecoke powders at the alkali-carbon ratio of 1.0, and the content was about 3.01%(mass). With the increment of the alkali-carbon ratio, the formation of carbon nanotubes was promoted by the etching of K and Fe₃C produced from minerals in the raw coal, meanwhile the ordering of modified bluecoke powders and the interaction of graphite layer spacing were enhanced. The characteristic peak G' in the Raman spectra of carbon nanotubes was found that indicated the high value-added modified bluecoke powders containing carbon nanotubes were successfully produced. In addition, the intensities of C—C, C—H and ether bonded C—O—C structures in FT-IR spectra of the modified bluecoke powders were significantly weakened. This phenomenon was caused by two potential reasons. On the one hand, these carbon structures became the direct solid-phase carbon source of carbon nanotube with the presence of catalysts. On the other hand, the thermal decomposition of these carbon structures released CO and CH₄, which could be used as the gas-phase carbon source for carbon nanotubes. The formation of carbon nanotubes in the high value-added modified bluecoke powders may be the result of the joint action of the “top formation” model and the “particle-wire-tube formation” model.

Key words: carbon nanotubes, growth mechanism, catalytic microwave pyrolysis, modified bluecoke powders, low-rank pulverized coal

中图分类号:

TQ 536.9

吴雷, 刘姣, 李长聪, 周军, 叶干, 刘田田, 朱瑞玉, 张秋利, 宋永辉. 低阶粉煤催化微波热解制备含碳纳米管的高附加值改性兰炭末[J]. 化工学报, 2023, 74(9): 3956-3967.

Lei WU, Jiao LIU, Changcong LI, Jun ZHOU, Gan YE, Tiantian LIU, Ruiyu ZHU, Qiuli ZHANG, Yonghui SONG. Catalytic microwave pyrolysis of low-rank pulverized coal for preparation of high value-added modified bluecoke powders containing carbon nanotubes[J]. CIESC Journal, 2023, 74(9): 3956-3967.

图/表 12

表1 原煤的工业和元素分析

Table 1 Proximate and elemental analysis of raw coal

Sample	Industrial analysis/%(mass)				Elemental analysis/%(mass)
Sample	FC_ad.	M_ad.	A_ad.	V_daf.	C_daf.	H_daf.	O_daf.	N_daf.	S_daf.
coal	54.68	6.71	10.85	34.26	81.84	4.23	9.87	0.95	3.11

表2 原煤的灰分分析

Table 2 Ash analysis of raw coal

Composition	Content/%(mass)
Fe₂O₃	29.89
Al₂O₃	7.25
CaO	25.29
MgO	1.36
SiO₂	12.01
K₂O	0.08
Na₂O	0.12

图1 微波热解低阶煤制备富含碳纳米管的兰炭末的示意图

Fig.1 Schematic diagram of the preparation of carbon nanotube-rich bluecoke powders using microwave pyrolysis of low-rank coal

图2 不同碱碳比下改性兰炭末的微观形貌图(SEM)

Fig.2 Microscopic morphology of modified bluecoke powders at different alkali-carbon ratios (SEM)

图3 改性兰炭末SC-1.0的TEM图

Fig.3 TEM images of modified bluecoke powders SC-1.0 (TEM)

图4 不同碱碳比下改性兰炭末的XRD谱图

Fig.4 XRD patterns of modified bluecoke powders at different alkali-carbon ratio

图5 不同碱碳比下改性兰炭末的FT-IR谱图

Fig.5 FT-IR spectra of modified bluecoke powders at different alkali-carbon ratio

图6 不同碱碳比下改性兰炭末的Raman谱图

Fig.6 Raman spectra of modified bluecoke powders at different alkali-carbon ratio

图7 不同碱碳比下改性兰炭末的Raman谱图分峰拟合结果

Fig.7 Splitting results of Raman spectra for modified bluecoke powders at different alkali-carbon ratios

表3 不同碱碳比下改性兰炭末的Raman谱图分峰拟合参数

Table 3 Raman spectral fitting parameters for modified bluecoke powders at different alkali-carbon ratios

Samples	I_D1/I_G	I_D2/I_G	I_D3/I_G	I_D4/I_G	I_G/I_All
SC-0	2.145	0.284	1.519	0.543	0.151
SC-0.4	2.206	0.215	1.489	0.434	0.130
SC-0.6	1.228	0.252	1.884	0.352	0.168
SC-0.8	1.156	0.174	1.279	0.774	0.245
SC-1.0	1.152	0.135	0.791	0.324	0.247
SC-1.2	1.181	0.230	0.829	0.274	0.222
CNT	1.150	0.154	1.390	0.266	0.240

图8 不同碱碳比下改性兰炭末的热失重图

Fig.8 Thermal mass loss diagram of modified bluecoke powders at different alkali-carbon ratios

图9 KOH协助低阶煤微波热解所得兰炭末中碳纳米管的生成机制

Fig.9 Generation mechanism of carbon nanotube in bluecoke powders obtained by KOH-assisted microwave pyrolysis of low-rank coal

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低阶粉煤催化微波热解制备含碳纳米管的高附加值改性兰炭末

Catalytic microwave pyrolysis of low-rank pulverized coal for preparation of high value-added modified bluecoke powders containing carbon nanotubes

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