Abstract

This study reports the template-free hydrothermal synthesis of Y zeolites, varying aluminum sources (aluminum powder and sodium aluminate), and water content in the synthesis precursor suspensions (140, 180, and 92 mol). Although all samples were crystallized at 90 °C for 4 h, significant differences in crystal size and phase purity were observed. Zeolite Y synthesized with 140 mol of water and sodium aluminate resulted in crystal sizes of 50–100 nm, while reducing the water content to 92 mol produced smaller crystals (50–80 nm) but introduced a GIS impurity phase. The zeolites were tested for CO<inf>2</inf> adsorption, revealing a direct relationship between crystal size and adsorption efficiency. Smaller crystal sizes demonstrated higher CO<inf>2</inf> adsorption capacities, with zeolites synthesized from aluminum powder outperforming those from sodium aluminate. This study highlights the critical role of synthesis conditions in tailoring the structure and performance of Y zeolites for CO<inf>2</inf> adsorption applications.