Effect of Pore Size on CO2 Adsorption Capacity over Low-Grade Carbon-Loaded Mesoporous Zeolites

This study presents a systematic approach for converting low-grade carbon derived from mining waste into functional carbon–zeolite composites with enhanced adsorption performance. To promote carbon deposition within and around zeolite frameworks, four industrially relevant zeolites, including zeolite socony mobil-5 (ZSM-5), Faujasite-type zeolite (Zeolite-Y), beta zeolite (Zeolite-β), and mordenite (MOR), were mechanically mixed with low-grade carbon under controlled stirring conditions (24 h at 250 rpm) and subsequently pyrolyzed at 800 °C. These treatments enabled a detailed assessment of structural stability and carbon–zeolite interactions. Scanning electron microscopy revealed pronounced modifications in surface morphology and carbon distribution after carbon treatment, while X-ray diffraction confirmed that the crystalline zeolite frameworks remained structurally intact despite the deposition of amorphous carbon. The adsorption performance of the resulting composites was evaluated through CO2 adsorption measurements under controlled temperature and pressure conditions, demonstrating a clear enhancement relative to the pristine zeolites. Overall, this work highlights an effective strategy for valorizing low-grade carbon waste into high-performance carbon–zeolite hybrid adsorbents and provides new mechanistic insights into framework stability, selective atom removal, and carbon–zeolite interactions in high-temperature and acidic environments.