In situ gas content is an important parameter associating coalbed methane, while the influence of pressure and temperature on methane adsorption and desorption still needs to be revealed. In this study, the molecular structure and methane adsorption capacity of anthracite coal collected from Diandong Coalfield (China) were studied based on ¹³C nuclear magnetic resonance (¹³C NMR), Fourier transform infrared spectroscopy (FT-IR), and methane isothermal adsorption experiment. The results show that the carbon skeleton of coal sample is mainly composed by aromatic carbon (72), followed by aliphatic carbon structure (14.2). Carbons connected to the oxygen atoms contribute 13.7 of the total carbons in coal molecule, and the oxygen atoms are mainly in the form of carbonyl. The 2-dimension structure and 3-dimension molecular structure of coal sample was also reconstructed. The average chemical formula of the coal molecule is C₂₀₀H₁₃₃O₂₁N₃. The experimental methane adsorption isothermal data of the coal sample under different temperatures shows that with increasing the temperature, the methane adsorption amount at each pressure decreases obviously. At 7MPa and 20C, the methane adsorption amount of the coal sample is 28.5cm³/g. Comparably, at 100C and 7MPa, the methane adsorption amount is only 15.9cm³/g, decreasing by 44. In mesopores, temperature has stronger influence on methane adsorption under higher pressure than that of lower pressure. On the contrary, in micropores, temperature has weaker effects on methane adsorption at higher pressure than that at lower pressure. The results can be beneficial for understanding methane adsorption characteristics of deep coal.

Carbon-dioxide-enhanced shale gas recovery technology has significant potential for large-scale emissions reduction and can help achieve carbon neutrality targets. Previous theoretical studies mainly focused on gas adsorption in one-dimensional pores without considering the influence from the pore geometry. This study evaluates the effects of pore shape on shale gas adsorption. The pure and competitive gas adsorption processes of CO₂ and CH₄ in nanopores were investigated using molecular simulations to improve the prediction of shale gas recovery efficiency. Meanwhile, quantitative analysis was conducted on the effects of the pore shape on the CO₂-EGR efficiency. The results indicate that the density of the adsorption layer in pores is equally distributed in the axial direction when the cone angle is zero; however, when the cone angle is greater than zero, the density of the adsorption layer decreases. Smaller cone-angle pores have stronger gas adsorption affinities, making it challenging to recover the adsorbed CH₄ during the pressure drawdown process. Concurrently, this makes the CO₂ injection method, based on competitive adsorption, efficient. For pores with larger cone angles, the volume occupied by the free gas is larger; thus, the pressure drawdown method displays relatively high recovery efficiency.

This study develops an integrated environmental–economic assessment framework to evaluate the life cycle environmental impacts and economic costs of CO₂ geological storage and produced water treatment in saline formations in China. Using a case study of a saline aquifer carbon storage project in the Ordos Basin, eight full-chain carbon capture, utilization, and storage (CCUS) scenarios were analyzed. The results indicate that environmental and cost performance are primarily influenced by technology choices across carbon capture, transport, and storage stages. The scenario employing potassium carbonate-based capture, pipeline transport, and brine reinjection after a reverse osmosis treatment (S5) achieved the most balanced outcome. Breakeven analyses under three carbon price projection models revealed that carbon price trajectories critically affect project viability, with a steadily rising carbon price enabling earlier profitability. By decoupling CCUS from power systems and focusing on unit CO₂ removal, this study provides a transparent and transferable framework to support cross-sectoral deployment. The findings offer valuable insights for policymakers aiming to design effective CCUS support mechanisms under future carbon neutrality targets.

To reduce the high energy consumption of conventional alkanolamine-based CO₂ capture, a rate-based CO₂ capture model was developed in Aspen Plus using a DETA/AEP mixed amine absorbent identified through preliminary screening experiments. The effects of key operating parameters of the absorber and stripper on system performance were systematically investigated, and the energy-saving potentials of interstage cooling, rich-solvent splitting, and their combined process were explored. The results show that the optimal operating parameters are as follows: lean-solvent temperature of 40 °C, flow rate of 150 m³/h, concentration of 35 wt.%, absorber packing height of 10 m, stripper operating pressure of 2 bar, rich-solvent feed stage at the fifth stage, and feed temperature of 105 °C. Under these optimized conditions, the model-predicted specific regeneration energy consumption of the conventional process was 6.08 GJ/t CO₂. Introducing interstage cooling at the ninth stage reduced the specific regeneration energy consumption to 5.42 GJ/t CO₂. Rich-solvent splitting, with a split ratio of 15% and hot rich-solvent feeding at the sixth stage, further reduced the value to 3.45 GJ t⁻¹ CO₂. When the two strategies were integrated, the specific regeneration energy consumption decreased to 3.38 GJ/t CO₂, corresponding to a 44.41% reduction compared with the conventional process.