Pores size distribution (PSD) and surface area (SA) analysis are so important for the description of porous materials, so selection of different pore characterization methods is emphasized, especially nondestruction methods. In this study, N₂, H₂O, CO₂, and Hg were utilized as molecular probes to estimate the PSD in Shengli lignite (SL). In the N₂ adsorption, traditional degassed sample and wet samples freezing by liquid N₂ were combined to obtain the PSD and moisture distribution in SL. The pores of degassed samples were mainly located in the range of 5–100 nm, and most of the moisture was in the larger macropores in the range of 26–100 nm, peaking at 37 nm. We used two methods of H₂O as molecular probe: H₂O dynamic adsorption and low-field nuclear magnetic resonance (LFNMR). The saturation concentration of H₂O in the pore of SL was 0.29 cm³/g from H₂O adsorption, and the pores located in the range of 1–154 nm and peaked at 42.4 nm from LFNMR. The comparison and combination of different molecule probes were also presented. The surface area (SA) from CO₂ adsorption was the most credible because of the good monolayer adsorption of CO₂ in the micropores. N₂ and CO₂ adsorption would lead to an underestimation of the mesopore and micropore volume, and LFNMR has the most potential for PSD analysis owing to the high accuracy of the equipment and the nondestructive sample (without predrying process).

中文翻译：

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利用Hg，H ₂ O，CO ₂和N ₂作为分子探针估算褐煤中的孔隙分布

孔尺寸分布（PSD）和表面积（SA）分析对于描述多孔材料非常重要，因此强调选择不同的孔表征方法，尤其是非破坏性方法。在这项研究中，N ₂，H ₂ O，CO ₂和Hg被用作分子探针来估计胜利褐煤（SL）中的PSD。在N ₂吸附中，将传统的脱气样品和由液体N ₂冷冻的湿样品结合在一起，得到PSD和SL中的水分分布。脱气样品的孔主要位于5–100 nm范围内，并且大多数水分位于26–100 nm范围内的较大大孔中，并在37 nm处达到峰值。我们使用了H _2的两种方法O作为分子探针：H ₂ O动态吸附和低场核磁共振（LFNMR）。从H ₂ O吸附开始，SL孔中H ₂ O的饱和浓度为0.29 cm ³ / g，根据LFNMR，孔位于1–154 nm的范围内，并在42.4 nm达到峰值。还介绍了不同分子探针的比较和组合。由于CO ₂在微孔中良好的单层吸附，因此最可靠的是CO ₂吸附的表面积（SA）。N ₂和CO ₂ 吸附会导致低估中孔和微孔的体积，由于设备和非破坏性样品的高精度（无预干燥过程），LFNMR具有最大的PSD分析潜力。