Study on Adsorption Characteristics of Deep Coking Coal Based on Molecular Simulation and Experiments

Area of Science:

• Geochemistry
• Materials Science
• Chemical Engineering

Background:

• Coking coal's adsorption characteristics are crucial for understanding natural gas storage and migration.
• High temperature and pressure conditions in deep coal seams significantly alter adsorption behavior.

Purpose of the Study:

• To investigate the influence of high temperature and pressure on methane adsorption in coking coal.
• To develop and validate an isothermal adsorption model for these extreme conditions.
• To analyze the adsorption characteristics of deep coking coal using experimental and simulation methods.

Main Methods:

• Isotherm adsorption experiments were conducted on Liulin and Pingdingshan coking coal samples.
• Molecular dynamics simulations were employed to characterize adsorption behavior.
• Classical adsorption models (D-R, D-A, L-F, BET, Langmuir) were fitted to experimental data.

Main Results:

• Molecular dynamics effectively characterized deep coking coal adsorption.
• Under supercritical conditions, methane excess adsorption capacity decreased with increasing temperature.
• Excess adsorption capacity increased with pressure initially, then stabilized, and finally decreased.
• The Dubinin-Radushkevich (D-R) model provided the best fit for adsorption capacity under high temperature and pressure.

Conclusions:

• Methane adsorption in coking coal is highly sensitive to temperature, pressure, and depth.
• Adsorption capacity diminishes with increasing depth in deep coal seams.
• The D-R model is suitable for modeling methane adsorption in coking coal under high temperature and pressure.