A Study on the Effect of Coal Metamorphism on the Adsorption Characteristics of a Binary Component System: CO₂ and N₂

Abstract

At present, there is little research on the multicomponent gas adsorption characteristics of coal with different metamorphisms. In this study, DH (low metamorphism), FGZ (medium metamorphism), and DSC (high metamorphism) coal samples were selected as the microscopic research objects, and the molecular models of them were constructed by means of elemental analysis, 13C NMR, and X-ray. The adsorption characteristics of coal with different metamorphisms under the binary component system (CO2 and N2) were explored by experiments and simulations at 298 K and 1000 kPa. The results showed that in the binary component system gas environment, the adsorption strength of CO2 is stronger than that of N2. DH has the highest isosteric heat of adsorption, and the adsorption strengths of CO2 and N2 is stronger than that for FGZ and DSC. The adsorption amounts of CO2 and N2 by three coal molecules are ranked as DH > FGZ > DSC. The sequence of adsorption selectivity of CO2/N2 is DH > FGZ > DSC > 1, which demonstrates the stronger competitiveness of CO2 than N2. The adsorption selectivity of CO2/N2 for DH is stronger than that for DSC. However, with the increase of the CO2 component, the adsorption selectivity of CO2/N2 for DH has a great influence, while DSC is relatively stable. The simulation results display a good agreement with the experimental results. The research can improve the accuracy and efficiency of inert injection measures and has guiding significance for the prevention and control of coal spontaneous combustion accidents by inert injection.

Adsorption Factors in Enhanced Coal Bed Methane Recovery: A Review

“…The desorption of methane is enhanced in the case that the mixed gas has a CO 2 concentration of less than 10%. Increasing the proportion of CO 2 increases the probability of adsorption while decreasing the desorption of methane [99]. The adsorption selectivity obtainable from a mixed gas injection may be calculated as [99]…”

“…Modern techniques, such as Fourier transform infrared (FTIR) Raman, and 13 C NMR spectroscopies as well as X-ray diffraction have been applied to the analysis of coal [99]. Low-rank coals have been determined to be primarily composed of oxygen-containing functional groups [49] while medium-rank coals with lower volatile matter content exhibit a high degree of aromatization and lower amount of oxygen-containing functional and aliphatic compounds [127].…”

“…High-rank coals contain some oxygen-based functional groups [49]. 13 C NMR can be used to elucidate the macro-molecular structure of coal [99]. Such studies have indicated that lignite exhibits decarboxylation and dehydration, bituminous coals show decarboxylation and hydrogen disproportionation and anthracite contains aromatic rings and shows dehydrogenization (Figure 6).…”

“…Such studies have indicated that lignite exhibits decarboxylation and dehydration, bituminous coals show decarboxylation and hydrogen disproportionation and anthracite contains aromatic rings and shows dehydrogenization (Figure 6). The 13 C NMR is data can be processed using the equation [99].…”

“…Gases 2022, 2, FOR PEER REVIEW 12 coals show decarboxylation and hydrogen disproportionation and anthracite contains aromatic rings and shows dehydrogenization (Figure 6). The 13 C NMR is data can be processed using the equation [99].…”