Performance evaluation of amine-modified binder-free zeolite Y for CH4/N2 separation

Methane is the second most significant greenhouse gas after carbon dioxide, and the development of efficient methane/nitrogen separation materials is crucial for recovering methane from low-concentration anthropogenic sources. In this study, a novel adsorbent, CHY, was developed using binder-free Y zeolite (BF-Y-Z) as the precursor, modified by incorporating CH + ions through ion exchange. Characterization results confirmed the successful introduction of CH + ions without altering the zeolite's FAU-type framework structure. The adsorption performance of CHY was systematically evaluated, demonstrating good CH 4 uptake and CH 4 /N 2 separation capability. According to IAST model calculations, CHY exhibited a CH 4 /N 2 selectivity of 4.1 at 303 K and 100 kPa, which represents a significant improvement over the unmodified BF-Y-Z. A single-column breakthrough experiment revealed a dynamic CH 4 adsorption capacity of 0.21 mmol/g at 303 K, indicating CHY's effective CH 4 capture performance in flowing binary gas systems. A four-column vacuum swing adsorption (VSA) cycle was established to investigate the influence of gas flow rate, adsorption time, and desorption time on methane purity and recovery. Under optimal conditions (gas flow rate of 0.4 L/min, adsorption time of 100 s, and desorption time of 120 s), CHY achieved a methane purity of 65% and a recovery rate of 75%. These results highlight CHY's excellent separation efficiency and cyclic stability, suggesting its strong potential for practical methane/nitrogen separation applications.