Molecular simulation of C2H4/CO2/N2/O2 adsorption characteristics in lignite and anthracite

As an index gas of spontaneous combustion, C2H4 has been used in several coal mines, but its adsorption on residual coal during the process from generation to sampling has an impact on evaluation. The molecular structure models of lignite and anthracite were constructed through molecular mechanics and dynamics, and the Grand Canonical Monte Carlo systems were used to simulate the adsorption of C2H4 and other common gases on lignite and anthracite at temperatures of 288.15-318.15 K. The order of adsorption capacity was CO2 > C2H4 > O-2 > N-2 in the lignite and anthracite molecular models within the low-pressure zone. When the pressure increases, the adsorption capacity of O-2 and N-2 exceeded that of C2H4. The C2H4 and CO2 have similar and concentrated adsorption sites, and it is easier to reach the limit adsorption capacity; O-2 and N-2 have similar adsorption sites, the number of sites is much more than that of C2H4 and CO2, and their limit adsorption capacities are larger than those of C2H4 and CO2. When C2H4 is monitored in a goaf, its concentration is not quite accurate because of the adsorption of residual coal, which is different from the detected temperature of the C2H4 concentration obtained from the experiment. This is of great significance to further experiments and more on-site data statistics to fix the problem for coal mines. (C) 2021 Author(s).

Automated summary

The study found that in the low-pressure zone, lignite and anthracite have a strong adsorption capacity for C2H4, which gradually weakens with increasing pressure; C2H4 and CO2 have similar and concentrated adsorption sites, while O2 and N2 have more adsorption sites and larger adsorption capacities.