Exploration of Capturing CO₂ from Flue Gas by Calcite Slit‐Nanopores: A Computational Investigation

Abstract

Capturing CO2 from flue gas is recognized as a key process to improve the environment, therefore, developing a new cost‐effective sorbent is crucial. In this study, the calcite slit‐nanopores with various pore sizes ranging from ∼5 Å to ∼30 Å were constructed, the grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulation methods were used to examine the microscopic behaviors of CO2 and N2 in calcite slit‐nanopores. Diverse adsorption layer structures for CO2 and N2 molecules as single component in calcite slit‐nanopores are found as the pore size changing, of which the CO2 represents a transformation from single adsorption layer to five adsorption layers, while N2 represents a variation from single adsorption layer to three adsorption layers. Meantime, different adsorption orientations of CO2 and N2 molecules adsorbed close onto the calcite pore surface are also found. Moreover, strong competitive adsorption of CO2 over N2 is found due to the different interactions between CO2 and N2 molecules with the calcite pore surface, the capacity of competitive adsorption decreases with the pore size increasing. The self‐diffusion and isosteric heat of CO2 and N2 molecules in calcite slit‐nanopores are also examined to demonstrate the different adsorption intensities of gases in calcite slit‐nanopores. This work demonstrates the detailed microscopic behaviors of CO2 and N2 molecules in calcite slit‐nanopores, which not only enriches the theoretical knowledge about gases adsorption in calcite slit‐nanopores, but also gives out the feasibility of capturing CO2 from flue gas by calcite‐based substances.

Exploring the Role of Inorganic and Organic Interfaces on CO2 and CH4 Partitioning: Case Study of Silica, Illite, Calcite, and Kerogen Nanopores on Gas Adsorption and Nanoscale Transport Behaviors

“…The higher adsorption affinity of CO 2 and CH 4 on calcite is driven by the interaction with the calcium ion (Ca 2+ ) . The CO 2 molecule resides closer to Ca 2+ than CH 4 as the distance between the oxygen atom in CO 2 and Ca 2+ is about 1.95 ± 0.03 Å compared to 2.05 ± 0.04 Å for CH 4 .…”

Study of Adsorption Characteristics of CO2, O2, and N2 in Coal Micropores and Mesopores at Normal Pressure

“…In order to further study the adsorption capacity of pores for CO 2 , O 2 , and N 2 , the microscopic diffusion characteristics of the gas were studied using the self-diffusion coefficient ( D S ). The formula for calculating the self-diffusion coefficient is as follows: where r i ( t ) is the position of molecule when the time is t , and r i (0) is the initial position.…”

Adsorption Kinetics of CO2 on a Reconstructed Calcite Surface: An Experiment-Simulation Collaborative Method

“…The Forcite module of Materials Studio and the COMPASS force field , were employed to simulate CO 2 –calcite interface adsorption. This is the first ab initio force field and has been validated to be capable of accurately predicting structural and thermophysical properties for a broad range of organic and inorganic substances, , such as N 2 , CO 2 , and calcite. ,,, The COMPASS force field consists of bonded and nonbonded interactions. Bonded interactions include bond stretching, angular bending, dihedral angle torsion, out-of-plane interactions, and cross terms.…”

“…Calcite is one of the most important minerals in nature. The calcite surface and CO 2 adsorbed interface are extensive involved in a variety of biological and energy industrial processes under various conditions such as biomineralization, geosequestration of CO 2 , enhanced oil recovery, , and flue gas separation . Under complex conditions, it is difficult to study CO 2 adsorption on a calcite surface by traditional experimental methods. , Most studies have been based on molecular dynamics (MD) simulation methods to provide thermodynamic feasibility.…”

“…Tao et al reported the effect of various temperatures on the interface adsorption behavior of CO 2 molecules. In particular, the calcite surface can also be used to achieve CO 2 capture from flue gas . Given that calcite is an abundant and widely distributed mineral on Earth, calcite-based substances are a promising alternative to replace other materials and thus to weaken the greenhouse effect.…”