What question did this study set out to answer?

This research aims to evaluate the adsorption behavior and storage capacity of CO2 in high-rank coal samples.

June 14, 2026Open Access

Adsorption Behavior and Storage Capacity Prediction of CO 2 Injection into High-Rank Coal

Key Points

This research aims to evaluate the adsorption behavior and storage capacity of CO2 in high-rank coal samples.
Conducted multi-physical field-coupled CO2 isothermal adsorption experiments on anthracite samples from the Qinshui basin.
Compared different theoretical adsorption models to select the optimal for capacity prediction.
Established estimation models for CO2 content under various states based on experimental results.
Pressure positively influences CO2 adsorption, while temperature has an inhibitory effect.
The D–A model effectively predicts CO2 adsorption in coal samples.
As burial depth increases, the proportion of free-state CO2 grows, while dissolved-state CO2 decreases.

Abstract

High Resolution Image Download MS PowerPoint Slide CO 2 geological sequestration (CCUS) serves as a critical technological pathway to achieve the strategic goal of the “dual-carbon” initiative. Coal seams characterized by dual porosity represent a favorable geological structure for storing carbon dioxide. The adsorption characteristics and storage capacity of CO 2 in the coal seam are the core indexes to evaluate the feasibility of CO 2 injection and storage. Anthracite samples from the south of the Qinshui basin were selected for multi-physical field-coupled CO 2 isothermal adsorption experiments. This study investigates the adsorption behavior of high-rank coal samples toward CO 2, compares the applicability of various theoretical adsorption models, selects the optimal one to build a storage capacity prediction model, and evaluates the CO 2 storage potential of high-rank coal seams. The results indicate that pressure has a positive effect on the adsorption of CO 2 (before reaching the supercritical state), while temperature inhibits the adsorption of CO 2 by coal samples. With the increase in water saturation, the adsorption capacity of coal samples for CO 2 gradually decreases. The theoretical model of micropore filling (the D–A model) has good applicability for predicting the adsorption of CO 2 in coal samples. On the basis of experimental results, estimation models for CO 2 content under different occurrence states and a predictive model for total storage capacity were established. The content of each CO 2 occurrence state is influenced by factors such as formation temperature, pressure, and water saturation. CO 2 is mainly stored in coal reservoirs in the form of adsorption. With increasing burial depth, the proportion of free-state CO 2 shows an increasing trend, while the content of dissolved-state CO 2 exhibits a decreasing trend. The synergistic evolution of three states determines the vertical zoning of the CO 2 storage capacity. These findings advance the understanding of storage mechanisms following CO 2 injection into high-rank coal reservoirs and provide a quantitative method for assessing the feasibility and storage potential of such injections.

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