Influence of pore-functional group synergy on gas adsorption in coals with different metamorphic degrees

doi:10.16265/j.cnki.issn1003-3033.2026.07.0402

Abstract

Abstract:

To investigate the intrinsic relationship between pore structure, surface functional groups, and adsorption characteristics of O₂, N₂, and CO₂ in coals with different metamorphic degrees, four coal samples including long-flame coal, gas coal, bituminous coal, and anthracite were selected. The microscopic structures were characterized using low-temperature N₂/CO₂ adsorption, mercury intrusion porosimetry, the Frenkel-Halsey-Hill (FHH) fractal model, and Fourier Transform Infrared Spectroscopy (FTIR). Adsorption experiments of O₂, N₂, and CO₂ were conducted at 20, 30, and 40 ℃ under 0.1-1.0 MPa. The results indicate that micropore volume and specific surface area exhibit a non-monotonic evolution of "decrease-increase-decrease" with increasing coal rank, with bituminous coal (YCW) showing the most developed micropores and highest fractal dimension (2.68). Oxygen-containing functional groups decrease while aromaticity increases with coalification. The adsorption of non-polar gases (O₂, N₂) is strictly controlled by micropore volume, following the order YCW>XT>DX>TX, whereas the adsorption of polar gas (CO₂) is governed by the synergistic "pore-functional group" effect, yielding a distinct order of YCW>TX>XT>DX. All three gases undergo physical adsorption, with isosteric heats following CO₂>O₂>N₂.

Key words: pore structure, fractal dimension, functional group characteristics, gas adsorption, isosteric heat of adsorption, coal metamorphic degree

CLC Number:

X937
TD752.2

Wu Chunlei, Shi Bobo, Li Jia, Xue Yong. Influence of pore-functional group synergy on gas adsorption in coals with different metamorphic degrees[J]. China Safety Science Journal, 2026, 36(7): 135-143.

Figures/Tables 12

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煤样	工业分析
煤样	M_ad	A_ad	V_daf	FC_ad
DX	6.68	10.97	45.96	36.39
TX	1.27	13.05	34.56	51.12
YCW	7.56	4.40	27.76	60.28
XT	2.16	11.64	4.68	81.52

煤样	总孔容 V/(cm³/g)	微孔孔容 V₁/(cm³/g)	(V₁/V)/ %	小孔孔容 V₂/(cm³/g)	中孔孔容 V₃/(cm³/g)	总孔比表面积 S/(m²/g)	微孔比表面积 S₁/(m²/g)	(S₁/S)/ %
DX	0. 131 7	0. 100 3	76.158	0. 026 6	0. 003 9	215.862	214.374	99.311
TX	0. 124 8	0. 093 6	75.000	0. 027 5	0. 003 3	155.532	154.288	99.200
YCW	0. 183 0	0. 136 0	74.317	0. 038 5	0. 007 1	301.098	299.256	99.388
XT	0. 131 5	0. 100 1	76.122	0. 026 8	0. 003 9	232.196	230.242	99.158

煤样	煤种	拟合斜率A	分形维数D	决定系数r²
DX	长焰煤	-0. 412 5	2. 587 5	0. 982 3
TX	气煤	-0. 489 2	2. 510 8	0. 975 6
YCW	烟煤	-0. 315 6	2. 684 4	0. 990 1
XT	无烟煤	-0. 453 4	2. 546 6	0. 986 7

煤样	I₃₄₀₀/ I₁₆₀₀	I₂₉₂₀/ I₁₆₀₀	I₁₇₀₀/ I₁₆₀₀	I₁₁₀₀/ I₁₆₀₀	I₈₅₀/ I₁₆₀₀	芳香度 f_a
DX	1.85	2.12	0.68	1.24	0.45	0.32
TX	1.23	1.45	0.35	0.89	0.62	0.48
YCW	1.56	1.78	0.42	1.08	0.71	0.41
XT	0.45	0.38	0.12	0.34	0.89	0.78

煤样	温度/ ℃	N₂			CO₂			O₂
煤样	温度/ ℃	V_L/ (cm³/g)	P_L/ MPa	r²	V_L/ (cm³/g)	P_L/ MPa	r²	V_L/ (cm³/g)	P_L/ MPa	r²
DX	20	12.691	2.640	0. 999 1	13.647	0.042	0. 939 0	16.947	1.532	0. 999 5
	30	11.596	3.745	0. 998 0	13.311	0.050	0. 958 3	15.748	1.705	0. 999 3
	40	10.700	3.894	0. 998 3	12.668	0.053	0. 960 5	15.072	2.274	0. 999 5
TX	20	12.023	0.919	0. 998 9	26.981	0.034	0. 924 3	13.158	1.023	0. 997 5
	30	10.142	2.376	0. 998 8	26.019	0.042	0. 974 1	12.681	1.375	0. 998 0
	40	9.579	3.594	0. 999 0	25.342	0.063	0. 985 8	11.879	1.517	0. 992 1
YCW	20	17.382	0.590	0. 998 8	28.355	0.049	0. 974 9	21.691	0.489	0. 996 3
	30	16.724	0.635	0. 998 6	26.976	0.058	0. 981 2	21.365	0.711	0. 998 0
	40	15.800	0.813	0. 998 7	26.555	0.082	0. 994 4	20.519	0.723	0. 997 5
XT	20	15.424	1.741	0. 998 1	16.284	0.050	0. 952 9	19.425	1.565	0. 999 3
	30	14.568	2.158	0. 999 4	15.626	0.062	0. 981 5	18.947	1.900	0. 999 4
	40	13.839	2.482	0. 998 7	15.021	0.078	0. 993 5	18.291	2.108	0. 999 1