Selection of coals of different maturities for CO2 Storage by modelling of CH4 and CO2 adsorption isotherms

Abstract

International audienceCO2 injection in unmineable coal seams could be one interesting option for both storage and methane recovery processes. The objective of this study is to compare and model pure gas sorption isotherms (CO2 and CH4) for well-characterised coals of different maturities to determine the most suitable coal for CO2 storage. Carbon dioxide and methane adsorption on several coals have been investigated using a gravimetric adsorption method. The experiments were carried out using both CO2 and CH4 pure gases at 25 °C from 0.1 to 5 MPa (1 to 50 bar). The experimental results were fitted using Temkin's approach but also with the corrected Langmuir's and the corrected Tóth's equations. The two last approaches are more accurate from a thermodynamical point of view, and have the advantage of taking into account the fact that experimental data (isotherms) correspond to excess adsorption capacities. These approaches allow better quantification of the adsorbed gas. Determined CO2 adsorption capacities are from 0.5 to 2 mmol/g of dry coal. Modelling provides also the affinity parameters of the two gases for the different coals. We have shown these parameters determined with adsorption models could be used for classification and first selection of coals for CO2 storage. The affinity ratio ranges from a value close to 1 for immature coals to 41 for high rank coals like anthracites. This ratio allows selecting coals having high CO2 adsorption capacities. In our case, the modelling study of a significant number of coals from various ranks shows that anthracites seem to have the highest CO2 storage capacities. Our study provides high quality affinity parameters and values of CO2 and CH4 adsorption capacities on various coals for the future modelling of CO2 injection in coal seams

Assessing CO2 Adsorption Capacities onto Shales Through Gravimetric Experiments: A First Step in the Feasibility Study of Coupling “Fracking” with Carbon Storage

“…Adsorbed CO 2 quantities are lower than those observed for coal samples. At 298 K and 5 MPa, the adsorbed CO 2 quantity onto shale is about 0.3 mmol/g, where as it is between 0.45 to 2.0 mmol/g onto raw coal, depending the coal sample [3]. The results are not the same for the 2 shale samples, which is not surprising because the samples do not have the same mineral composition.…”

Fractal Characteristics of Nanoscale Pores in Shale and Its Implications on Methane Adsorption Capacity

“…1 One important reason is that pores in shales are composed of different pore types, such as clay, organic, and carbonate pores. 13,46 Clay and organic pores are usually considered the major contributors to the nanoscale pores in shale and consequently control methane adsorption capacity. 19,[47][48][49] Considering the significant differences between organic and clay pores, it is necessary to discuss the fractal characteristics of each.…”

Study of the Effect of Functionalization of Carbon Nanotubes on Gas Separation

“…Two of the most common adsorption models, the Langmuir (Garnier et al, 2011) and Sips (Foo et al, 2010) isotherms, were used to correlate the experimental data of CO 2 and CH 4 adsorption on MWCNT and N-MWCNT at 298 K. The values of model parameters are given in Table 3. The Langmuir isotherm corresponds to homogeneous adsorbent surfaces (Purna Chandra Rao et al, 2006).…”