Seed-directed synthesis of KFI zeolites without organic agents, fluoride, or Sr2+/Cs+ for CO2 adsorption

This study presents a seed-directed method for synthesizing KFI zeolites without using organic structure-directing agents (OSDA), fluoride, and Sr 2+ /Cs + mineralizers. The crystallization behavior of KFI zeolites was studied concerning gel composition, temperature and duration. High-crystallinity cubic KFI zeolites were synthesized under optimized conditions (gel composition: 8.1–9.0 SiO 2 : 0.9 Al 2 O 3 : 2 K 2 O: 450 H 2 O, 150 °C for 20 h). Adsorption analyses show that KFI zeolites synthesized at SiO 2 /Al 2 O 3 ratio of 10 have excellent CO 2 uptake of 3.15 mmol/g and CO 2 /CH 4 ideal selectivity of 4.6 at P/P 0 = 1.0, indicating their potential for pressure swing adsorption.