Emerging technologies for coal mine methane mitigation with different integration strategies for effective recovery of CH4

Abstract

Low-concentration CMM (coal mine methane) (CH₄ <30%) is mostly extracted during coal mining, which discharges directly into the air from mining shafts. Herein, recent advances in CH₄ recovery from coal mine gases are summarized. Among them, studies on the use of different adsorbents (activated carbon, zeolites, and metal–organic frameworks (MOFs)) and adsorption processes are extensively reviewed for use with low-concentration CMM. MOFs demonstrate superior performance due to their tunable pore geometries and customizable surface functionalization. These characteristics enable MOFs to achieve higher CH₄ selectivity than traditional activated carbon or zeolite adsorbents. Current research focuses on scaling up these advanced MOF materials and optimizing pressure swing adsorption (PSA) processes for industrial implementation. Compared to alternative separation technologies, such as membrane separation and cryogenic distillation, PSA exhibits distinct advantages for treating low-concentration CH₄ (1–30%). PSA demonstrates better performance in both product purity and recovery rates while maintaining higher technical and economic feasibility. Future research should focus on optimizing the PSA process and integrating it with other technologies. Such developments could provide economic incentives for the widespread adoption of CH₄ recovery systems in coal mining operations.