Influence of coal rank on CPSD in low-temperature N2 adsorption

doi:10.16265/j.cnki.issn1003-3033.2022.04.008

Abstract

Abstract:

In order to study coal adsorption theory and adsorption mechanism of coalbed methane, six coal samples of different ranks were selected for low-temperature N₂ adsorption experiments to explore CPSD of filled N₂ molecules in coals. Then, experimental isotherm characteristics were analyzed through density functional theory (DFT) and theory of volume filling of micropore (TVFM), and critical filling pressure (CFP) and CPSD for micropore fillings were obtained. Finally, relative pressure segmentation method was used to verify the results by fitting of Langmuir equation-Dubinin-Astakhov (D-A) equation-Brunauer-Emmet-Teller (BET) equation. The results show that N₂ adsorption/desorption isotherm of coal samples, from low to high rank, transitions from type II to type I. And proportion of N₂ molecules present in forms of micropore filling and monolayer adsorption in low-rank coals is greater than that of high-rank ones. CPSD decreases first and then increases as coal rank goes from low to high. The higher the rank is, the smaller CPSD range of 6 coal samples will be, which is between 1.61-2.19 nm.

Key words: coal rank, low-temperature N₂, adsorption experiment, critical filling pore size distribution (CPSD), micropore filling, pore structure

HONG Lin, WANG Wenjing, GAO Dameng, GUO Yingchao, MA Honghai. Influence of coal rank on CPSD in low-temperature N₂ adsorption[J]. China Safety Science Journal, 2022, 32(4): 51-58.

Figures/Tables 10

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References 23

[1]	洪林. 碳材料孔隙吸附性能及突出煤孔隙特征研究[D]. 葫芦岛: 辽宁工程技术大学, 2014.
	HONG Lin. Research on the adsorptivity of pore in caron materials and the porosity character of outbust coal[D]. Huludao: Liaoning Technical University, 2014.
[2]	刘佳佳, 胡建敏, 杨明, 等. 不同层理高阶煤孔隙特征的核磁共振试验[J]. 中国安全科学学报, 2021, 31(9):83-89. doi: 10.16265/j.cnki.issn1003-3033.2021.09.012
	LIU Jiajia, HU Jianmin, YANG Ming, et al. Nuclear magnetic resonance experimental study on pore characteristics of high rank coal with different bedding[J]. China Safety Science Journal, 2021, 31(9):83-89. doi: 10.16265/j.cnki.issn1003-3033.2021.09.012
[3]	赵迪斐, 卢琪荣, 郭英海, 等. 煤层气储层孔隙纳米尺度表征的研究进展与展望:精细、量化与机理耦合[J]. 非常规油气, 2020, 7(1):108-118,100.
	ZHAO Difei, LU Qirong, GUO Yinghai, et al. Research progress and prospects of pore nano scale characterization of coalbed methane reservoir: accurate characterization, quantification and mechanism coupling[J]. Unconventional Oil & Gas, 2020, 7(1):108-188,100.
[4]	李阳, 张玉贵, 张浪, 等. 基于压汞、低温N₂吸附和CO₂吸附的构造煤孔隙结构表征[J]. 煤炭学报, 2019, 44(4):1188-1196.
	LI Yang, ZHANG Yugui, ZHANG Lang, et al. Characterization on pore structure of tectonic coals based on the method of mercury intrusion, carbon dioxide adsorption and nitrogen adsorption[J]. Journal of China Coal Society, 2019, 44(4):1188-1196.
[5]	THOMMES M, MORLAY C, AHMAD R, et al. Assessing surface chemistry and pore structure of active carbons by a combination of physisorption (H₂O, Ar, N₂, CO₂), XPS and TPD-MS[J]. Adsorption, 2011, 17(3):653-661. doi: 10.1007/s10450-011-9360-4
[6]	XIONG Qingrong, LI Kang, YANG Diansen, et al. Characterizing coal pore space by gas adsorption, mercury intrusion, FIB-SEM and μ-CT[J]. Environmental Earth Sciences, 2020, 79(10):209-224. doi: 10.1007/s12665-020-08950-3
[7]	闫江伟, 薄增钦, 杨亚磊. 纳米级孔隙对构造煤吸附瓦斯能力的影响[J]. 中国安全科学学报, 2018, 28(10):131-136. doi: 10.16265/j.cnki.issn1003-3033.2018.10.022
	YAN Jiangwei, BO Zengqin, YANG Yalei. Influence of nanoscale pore on gas adsorption capacity of deformed coal[J]. China Safety Science Journal, 2018, 28(10):131-136. doi: 10.16265/j.cnki.issn1003-3033.2018.10.022
[8]	洪林, 高大猛, 王继仁, 等. 低温低压下煤微孔吸附特性研究[J]. 中国安全科学学报, 2018, 28(12):77-82. doi: 10.16265/j.cnki.issn1003-3033.2018.12.013
	HONG Lin, GAO Dameng, WANG Jiren, et al. Adsorption characteristics of micropores in coal at low temperature and pressure[J]. China Safety Science Journal, 2018, 28(12):77-82. doi: 10.16265/j.cnki.issn1003-3033.2018.12.013
[9]	近藤精一, 石川达雄, 安部郁夫. 吸附科学(原著第2版)[M].李国希,译. 北京: 化学工业出版社, 2006: 40-93.
[10]	GIL A. Analysis of the micropore structure of various microporous materials from nitrogen adsorption at 77 K[J]. Adsorption, 1998, 4(3/4):197-206. doi: 10.1023/A:1008821430432
[11]	GHOSAL R, SMITH D M. Micropore characterization using the Dubinin-Astakhov equation to analyze high pressure CO₂(273 K) adsorption data[J]. Journal of Porous Material, 1996, 3(4):247-255. doi: 10.1007/BF01137914
[12]	WU Fengchin, WU Pinhsueh, TSENG Ruling, et al. Description of gas adsorption isotherms on activated carbons with heterogeneous micropores using the Dubinin-Astakhov equation[J]. Journal of the Taiwan Institute of Chemical Engineers, 2014, 45(4):1757-1763. doi: 10.1016/j.jtice.2014.01.016
[13]	SHKOLIN A V, FOMKIN A A. Theory of volume filling of micropores applied to the description of methane adsorption on the microporous carbon adsorbent AUK[J]. Russian Chemical Bulletin, 2009, 58(4):717-721. doi: 10.1007/s11172-009-0083-6
[14]	程远平, 胡彪. 微孔填充—煤中甲烷的主要赋存形式[J]. 煤炭学报, 2021, 46(9):2933-2948.
	CHENG Yuanping, HU Biao. Main occurrence form of methane in coal: micropore filling[J]. Journal of China Coal Society, 2021, 46(9):2933-2948.
[15]	POLYAKOV N S, PETUKHOVA G A. Extension of the theory of volume filling of micropores to adsorption in supermicropores[J]. Adsorption, 2005, 11(3/4):357-362. doi: 10.1007/s10450-005-5424-7
[16]	BALZER C, CIMINO R T, GOR G Y, et al. Deformation of microporous carbons during N₂, Ar, and CO₂ adsorption: insight from the density functional theory[J]. Langmuir, 2016, 32(32):8265-8274. doi: 10.1021/acs.langmuir.6b02036
[17]	NAKAI K, NAKADA Y, HAKUMAN M, et al. High resolution N₂ adsorption isotherms at 77.4 K and 87.3 K by carbon blacks and activated carbon fibers-analysis of porous texture of activated carbon fibers by alS1as-method[J]. Journal of Colloid and Interface Science, 2012, 367(1):383-393. doi: 10.1016/j.jcis.2011.10.061
[18]	AN Fenghua, CHENG Yuanping, WU Dongmei, et al. The effect of small micropores on methane adsorption of coals from Northern China[J]. Adsorption, 2012, 19(1):83-90. doi: 10.1007/s10450-012-9421-3
[19]	陈刘瑜, 李希建, 沈仲辉, 等. 贵州北部突出煤的孔隙结构及分形特征研究[J]. 中国安全科学学报, 2020, 30(2):66-72. doi: 10.16265/j.cnki.issn1003-3033.2020.02.011
	CHEN Liuyu, LI Xijian, SHEN Zhonghui, et al. Pore structure and fractal characteristics of outburst coal in northern Guizhou[J]. China Safety Science Journal, 2020, 30(2):66-72. doi: 10.16265/j.cnki.issn1003-3033.2020.02.011
[20]	GB/T 474—2008, 煤样的制备方法[S].
	GB/T 474-2008, Method for preparation of coal sample[S].
[21]	GB/T 212—2008, 煤的工业分析方法[S].
	GB/T 212-2008, Proximate analysis of coal[S].
[22]	EMMETT P H, BRUNAUER S. Accumulation of alkali promoters on surfaces of iron synthetic ammonia catalysts[J]. Journal of the American Chemical Society, 2002, 59(2):310-315. doi: 10.1021/ja01281a026
[23]	张哲泠, 杨正红. 微介孔材料物理吸附准确性分析的理论与实践[J]. 催化学报, 2013, 34(10):1797-1810.
	ZHANG Zheling, YANG Zhenghong. Theoretical and practical discussion of measurement accuracy for physisorption with micro- and mesoporous materials[J]. Chinese Journal of Catalysis, 2013, 34(10):1797-1810. doi: 10.1016/S1872-2067(12)60601-9

煤样	煤矿	分类	水分	灰分	挥发分	固定碳
S₁	蒲河	褐煤	16.84	11.59	34.72	36.86
S₂	准格尔	长焰煤	5.21	14.20	24.93	55.67
S₃	小凌河	气煤	2.14	26.06	29.63	42.17
S₄	鹤岗	1/3焦煤	1.62	6.78	33.08	58.52
S₅	常村	贫煤	1.25	9.17	13.24	76.34
S₆	余吾	无烟煤	1.46	9.78	10.55	78.21

煤样	等温线类型	滞后环类型	孔隙形状	P/P₀ (B点)	Q_B占总吸附量比例/%
S₁	Ⅱb	H2	墨水瓶孔	0.098 86	31.24
S₂		H3	非均匀狭缝孔	0.060 05	13.70
S₃			非均匀狭缝孔	0.043 09	13.34
S₄			0.062 26		11.77
S₅	Ⅰb	H4	均匀且狭窄的狭缝孔	0.110 94	19.57
S₆	Ⅰb	H4	均匀且狭窄的狭缝孔	0.160 89	11.52

煤样	CFP(P/P₀)	CPSD/nm	D-A指数
S₁	8.0×10^-4~0.033 9	1.73~2.19	1.362 0
S₂	5.5×10^-4~0.030 2	1.70~2.17	1.534 3
S₃	2.4×10^-4~0.010 0	1.64~1.99	1.532 4
S₄	1.4×10^-4~0.010 4	1.61~2.00	1.833 0
S₅	5.0×10^-4~0.010 6	1.69~2.00	2.544 4
S₆	8.4×10^-4~0.010 7	1.73~2.01	2.437 5

煤样	P/P₀	R²		P/P₀	R²
煤样	P/P₀	D-A	Langmuir	P/P₀	D-A	Langmuir	BET
S₁	8.0×10^-4~0.033 9	0.999 21	0.994 2	0.033 9~0.302 1	0.967 46	0.985 22	0.999 76
S₂	5.5×10^-4~0.030 2	0.999 45	0.994 02	0.030 2~0.302 35	0.951 76	0.985 47	0.999 54
S₃	2.4×10^-4~0.010 0	0.999 80	0.996 19	0.010 0~0.321 4	0.890 9	0.970 82	0.999 72
S₄	1.4×10^-4~0.010 4	0.998 83	0.995 03	0.010 4~0.300 2	0.874 45	0.982 49	0.999 56
S₅	5.0×10^-4~0.010 2	0.999 28	0.998 65	0.010 2~0.321 2	0.984 32	0.999 87	0.990 27
S₆	8.4×10^-4~0.010 7	0.998 63	0.997 72	0.010 7~0.321 5	0.934 71	0.998 55	0.984 62

Influence of coal rank on CPSD in low-temperature N₂ adsorption

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