Modulating Acidic Oxygen-Containing Functional Groups on Coal-Based Activated Carbon to Enhanced Methane Adsorption...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Efficient methane capture from coal mine gas is crucial for safety and energy recovery.
• Pressure swing adsorption (PSA) is a key technology for gas separation and purification.
• Adsorbent properties significantly influence PSA efficiency for low-concentration gas streams.

Purpose of the Study:

• To investigate the synergistic effects of pore architecture and surface chemistry on methane adsorption.
• To develop an optimized coal-based activated carbon for enhanced methane enrichment.
• To elucidate the adsorption mechanism and diffusion kinetics.

Main Methods:

• Coal-based activated carbon was modified using preoxidation and controlled KOH activation.
• Characterization of pore structure and surface chemistry (e.g., CH2/CH3 ratio, oxygen-containing groups).
• Methane adsorption isotherms and kinetic studies were performed to analyze adsorption capacity and diffusion.

Main Results:

• An optimal carbon to alkali ratio (1:4) yielded a micropore- and small mesopore-dominated structure (91.26% pore volume).
• Surface modification enhanced physisorption potential and methane affinity via oxygen-containing groups.
• A two-stage diffusion mechanism was identified, with boundary layer transfer and micropore diffusion.

Conclusions:

• Synergistic modulation of pore and surface properties is vital for high-performance adsorbents.
• The developed activated carbon shows significant potential for efficient methane capture and separation from coal mine gas.
• Understanding diffusion mechanisms is key to optimizing PSA processes.