Quantitative Analysis of Pore Structure and Its Impact on Methane Adsorption Capacity of Coal

Abstract

Better understanding of the storage and transportation characteristics of methane in coal seams is important to further develop and utilize the methane resources in the coalbed. This study is devoted to investigating the relationship between methane adsorption performance and pore structure by analyzing twelve coal samples derived from the typical methane-rich coalbeds in China. To eliminate the influence of inorganic components such as ash in different coal samples, a specific fixed-bed reactor with internals was employed for the coal treatment. Based on N2/CO2 adsorption analysis at low-pressure condition, the pores in coal were classified into three types in this study: ultra-micropore (pore width < 1 nm), micropore (1 nm < pore width < 2 nm) and mesopores (2 nm < pore width < 50 nm). According to the Langmuir equation, the Langmuir volume (VL) and Langmuir pressure (PL) were calculated to characterize the high-pressure adsorption of methane, and the influence of methane adsorption associated parameters was evaluated. The results indicate that N2-pore size distributions (1–50 nm) varied a lot among samples, suggesting the significant heterogeneity of pore structure among samples. Estimated by the FHH model, pore surface fractal dimension (D1) and spatial geometry fractal dimension (D2) were, respectively, ranging in 2.059–2.808 and 2.649–2.852, which indicated that the more irregular surface, namely more inhomogeneous pore structures, resulted in the more surface area and stronger adsorption capability. By grey relational analysis (GRA), the importance of the pore structure factors on methane adsorption was identified, as an order from the most important to the least: ultra-micropore volume (0.9085) > ultra-micropore surface area (0.8976) > fractal dimension D1 (0.8862) > N2-BET surface area (0.7915) > micropore volume (0.5035) > micropore surface area (0.5006). This study shows the influence of parameters of pore structure on methane adsorption of coal and clarifies the order importance of these parameters by the GRA method.

This is a preview of subscription content, access via your institution.

Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
Figure 10

References

  1. Behar, F., & Hatcher, P. G. (1995). Artificial coalification of a fossil wood from brown coal by confined system pyrolysis. Energy & Fuels, 9(6), 984–994.

    Google Scholar 

  2. Bustin, R. M., & Clarkson, C. R. (1998). Geological controls on coalbed methane reservoir capacity and gas content. International Journal of Coal Geology, 38(1–2), 3–26.

    Google Scholar 

  3. Cai, Y., Liu, D., Pan, Z., Yao, Y., Li, J., & Qiu, Y. (2013). Pore structure and its impact on CH4 adsorption capacity and flow capability of bituminous and subbituminous coals from Northeast China. Fuel, 103, 258–268.

    Google Scholar 

  4. Clarkson, C. R., & Marc Bustin, R. (1996). Variation in micropore capacity and size distribution with composition in bituminous coal of the Western Canadian Sedimentary Basin. Fuel, 75(13), 1483–1498.

    Google Scholar 

  5. Clarkson, C. R., Solano, N., Bustin, R. M., Bustin, A. M. M., Chalmers, G. R. L., He, L., et al. (2013). Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion. Fuel, 103, 606–616.

    Google Scholar 

  6. De Jonge, H., & Mittelmeijer-Hazeleger, M. C. (1996). Adsorption of CO2 and N2 on Soil Organic Matter: Nature of Porosity, Surface Area, and Diffusion Mechanisms. Environmental Science and Technology, 30(2), 408–413.

    Google Scholar 

  7. Everett, D. H. (1972). Manual of symbols and terminology for physicochemical quantities and units, appendix II: definitions, terminology and symbols in colloid and surface chemistry. Pure and Applied Chemistry, 31(4), 577–638.

    Google Scholar 

  8. Fan, J., Liu, P., Li, J., & Jiang, D. (2020). A coupled methane/air flow model for coal gas drainage: model development and finite-difference solution. Process Safety and Environmental Protection, 141, 288–304.

    Google Scholar 

  9. Genty, C., Jensen, J. L., & Ahr, W. M. (2007). Distinguishing carbonate reservoir pore facies with nuclear magnetic resonance measurements. Natural Resources Research, 16(1), 45–54.

    Google Scholar 

  10. Gorbaty, M. L., Mraw, S. C., Gethner, J. S., & Brenner, D. (1986). Coal physical structure: porous rock and macromolecular network. Fuel Processing Technology, 12, 31–49.

    Google Scholar 

  11. Hao, S., Wen, J., Yu, X., & Chu, W. (2013). Effect of the surface oxygen groups on methane adsorption on coals. Applied Surface Science, 264, 433–442.

    Google Scholar 

  12. Harris, L., & Yust, C. (1976). Transmission electron microscope observations of porosity in coal. Fuel, 55(3), 233–236.

    Google Scholar 

  13. Hu, E., Zeng, X., Wang, F., Li, Y., Yi, X., & Fu, X. (2017). Effects of metallic heating plates on coal pyrolysis behavior in a fixed-bed reactor enhanced with internals. Energy & Fuels, 31(3), 2716–2721.

    Google Scholar 

  14. Jagiello, J., Ania, C., Parra, J. B., & Cook, C. (2015). Dual gas analysis of microporous carbons using 2D-NLDFT heterogeneous surface model and combined adsorption data of N2 and CO2. Carbon, 91, 330–337.

    Google Scholar 

  15. Landais, P. (1991). Assessment of coal potential evolution by experimental simulation of natural coalification. Organic Geochemistry, 17(6), 705–710.

    Google Scholar 

  16. Langmuir, I. (1918). The adsorption of gases on plane surfaces of glass, mica and platinum. Journal of the American Chemical Society, 40(9), 1361–1403.

    Google Scholar 

  17. Levy, J. H., Day, S. J., & Killingley, J. S. (1997). Methane capacities of Bowen Basin coals related to coal properties. Fuel, 76(9), 813–819.

    Google Scholar 

  18. Li, X., Li, Z., Wang, E., Liang, Y., Li, B., & Liu, Y. (2018). Pattern recognition of mine microseismic (MS) and blasting events based on wave fractal features. Fractals, 26(03), 1850029. https://doi.org/10.1142/s0218348x18500299.

    Article  Google Scholar 

  19. Liu, X., & He, X. (2017). Effect of pore characteristics on coalbed methane adsorption in middle-high rank coals. Adsorption, 23(1), 3–12.

    Google Scholar 

  20. Liu, S., Li, X., Wang, D., Wu, M., Yin, G., & Li, M. (2019). Mechanical and acoustic emission characteristics of coal at temperature impact. Natural Resources Research, 4, 1–18.

    Google Scholar 

  21. Liu, X., & Nie, B. (2016). Fractal characteristics of coal samples utilizing image analysis and gas adsorption. Fuel, 182, 314–322.

    Google Scholar 

  22. Macuda, J., Baran, P., & Wagner, M. (2020). Evaluation of the presence of methane in złoczew lignite comparison with other lignite deposits in Poland. Natural Resources Research. https://doi.org/10.1007/s11053-020-09691-7.

    Article  Google Scholar 

  23. Mahajan, O. P. (1991). CO2 surface area of coals: The 25-year paradox. Carbon, 29(6), 735–742.

    Google Scholar 

  24. Mastalerz, M., Drobniak, A., & Rupp, J. (2008). Meso-and micropore characteristics of coal lithotypes: implications for CO2 adsorption. Energy & Fuels, 22(6), 4049–4061.

    Google Scholar 

  25. Mastalerz, M., Gluskoter, H., & Rupp, J. (2004). Carbon dioxide and methane sorption in high volatile bituminous coals from Indiana, USA. International Journal of Coal Geology, 60(1), 43–55.

    Google Scholar 

  26. Mastalerz, M., He, L., Melnichenko, Y. B., & Rupp, J. A. (2012). Porosity of coal and shale: insights from gas adsorption and SANS/USANS techniques. Energy & Fuels, 26(8), 5109–5120.

    Google Scholar 

  27. Matranga, K. R., Myers, A. L., & Glandt, E. D. (1992). Storage of natural gas by adsorption on activated carbon. Chemical Engineering Science, 47(7), 1569–1579.

    Google Scholar 

  28. Nelabhotla, D. M., Jayaraman, T. V., Asghar, K., & Das, D. (2016). The optimization of chemical mechanical planarization process-parameters of c-plane gallium-nitride using Taguchi method and grey relational analysis. Materials and Design, 104, 392–403.

    Google Scholar 

  29. Nguyen, T. X., & Bhatia, S. K. (2007). Pore accessibility of N2 and Ar in disordered nanoporous solids: theory and experiment. Adsorption, 13(3–4), 307–314.

    Google Scholar 

  30. Nie, B., Liu, X., Yang, L., Meng, J., & Li, X. (2015). Pore structure characterization of different rank coals using gas adsorption and scanning electron microscopy. Fuel, 158, 908–917.

    Google Scholar 

  31. Okolo, G. N., Everson, R. C., Neomagus, H. W. J. P., Roberts, M. J., & Sakurovs, R. (2015). Comparing the porosity and surface areas of coal as measured by gas adsorption, mercury intrusion and SAXS techniques. Fuel, 141, 293–304.

    Google Scholar 

  32. Shen, J., Sulkowski, J., Beckner, M., & Dailly, A. (2015). Effects of textural and surface characteristics of metal-organic frameworks on the methane adsorption for natural gas vehicular application. Microporous and Mesoporous Materials, 212, 80–90.

    Google Scholar 

  33. Sun, W., Feng, Y., Jiang, C., & Chu, W. (2015). Fractal characterization and methane adsorption features of coal particles taken from shallow and deep coalmine layers. Fuel, 155, 7–13.

    Google Scholar 

  34. Thommes, M. (2010). Physical adsorption characterization of nanoporous materials. Chemie Ingenieur Technik, 82(7), 1059–1073.

    Google Scholar 

  35. Walker, P. L., & Mahajan, O. P. (1993). Pore structure in coals. Energy & Fuels, 7(4), 559–560.

    Google Scholar 

  36. Wang, Y., Zhu, Y., Liu, S., & Zhang, R. (2016). Pore characterization and its impact on methane adsorption capacity for organic-rich marine shales. Fuel, 181, 227–237.

    Google Scholar 

  37. Xu, S., Han, Z., Wu, R., Cheng, J., & Xu, G. (2018a). Correlating micro/meso pore evolution and chemical structure variation in a mild thermal treatment of a subbituminite. RSC Advances, 8(18), 9754–9761.

    Google Scholar 

  38. Xu, S., Lai, D., Zeng, X., Zhang, L., Han, Z., Cheng, J., et al. (2018b). Pyrolysis characteristics of waste tire particles in fixed-bed reactor with internals. Carbon Resources Conversion, 1(3), 228–237.

    Google Scholar 

  39. Xu, G., Yang, Y.-P., Lu, S.-Y., Li, L., & Song, X. (2011). Comprehensive evaluation of coal-fired power plants based on grey relational analysis and analytic hierarchy process. Energy Policy, 39(5), 2343–2351.

    Google Scholar 

  40. Xu, S., Zeng, X., Han, Z., Cheng, J., Wu, R., Chen, Z., et al. (2019). Quick pyrolysis of a massive coal sample via rapid infrared heating. Applied Energy, 242, 732–740.

    Google Scholar 

  41. Yang, R. T., & Saunders, J. T. (1985). Adsorption of gases on coals and heat treated coals at elevated temperature and pressure. Fuel, 64(5), 616–620.

    Google Scholar 

  42. Yao, Y., Liu, D., Tang, D., Tang, S., & Huang, W. (2008). Fractal characterization of adsorption-pores of coals from North China: An investigation on CH4 adsorption capacity of coals. International Journal of Coal Geology, 73(1), 27–42.

    Google Scholar 

  43. Yao, Y., Liu, D., & Xie, S. (2014). Quantitative characterization of methane adsorption on coal using a low-field NMR relaxation method. International Journal of Coal Geology, 131, 32–40.

    Google Scholar 

  44. Zhang, Y., Lebedev, M., Smith, G., Jing, Y., Busch, A., & Iglauer, S. (2019a). Nano-mechanical properties and pore-scale characterization of different rank coals. Natural Resources Research, 29(3), 1787–1800.

    Google Scholar 

  45. Zhang, K., Wang, L., Cheng, Y., Li, W., Kan, J., Tu, Q., et al. (2019b). Geological control of fold structure on gas occurrence and its implication for coalbed gas outburst: case study in the qinan coal mine, huaibei coalfield. China. Natural Resources Research, 29(2), 1375–1395.

    Google Scholar 

  46. Zhao, Y., Liu, S., Elsworth, D., Jiang, Y., & Zhu, J. (2014). Pore structure characterization of coal by synchrotron small-angle X-ray scattering and transmission electron microscopy. Energy & Fuels, 28(6), 3704–3711.

    Google Scholar 

  47. Zuo, W. E. J., Liu, X., Peng, Q., Deng, Y., & Zhu, H. (2016). Orthogonal experimental design and fuzzy grey relational analysis for emitter efficiency of the micro-cylindrical combustor with a step. Applied Thermal Engineering, 103, 945–951.

    Google Scholar 

Download references

Acknowledgments

The study was financially supported by National Science and Technology Major Project of China (2016ZX05040-003). We thank Doctor Nie Fan for his linguistic assistance during the revise of this manuscript.

Author information

Affiliations

Authors

Corresponding authors

Correspondence to Erfeng Hu or Xingchun Li.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Xu, S., Hu, E., Li, X. et al. Quantitative Analysis of Pore Structure and Its Impact on Methane Adsorption Capacity of Coal. Nat Resour Res 30, 605–620 (2021). https://doi.org/10.1007/s11053-020-09723-2

Download citation

Keywords

  • Methane adsorption
  • Pore structure
  • Modified coal
  • Fractal dimension
  • Grey relational analysis