Green synthesis of hierarchical NaY zeolite for efficient Knoevenagel condensationOA

Hierarchical aluminumrich zeolites show promising potential in the Knoevenagel condensation;however,their synthesis is hindered by high preparation cost and energy consumption.To address these issues,a green synthetic route has been developed for preparing hierarchical NaY zeolite using submolten salt(SMS)activated perlite as the sole source of silicon and aluminum.Comprehensive characterization shows that the NaY zeolite synthesized from SMS activated perlite exhibits high purity and crystallinity.This aluminum-rich NaY zeolite,with a framework SiO_(2)/Al2O3 molar ratio of approximately 4.2,features intercrystalline mesopores,a large external surface and abundant basic sites.Investigation into the crystallization process of the hierarchical NaY zeolite indicates that during the initial stage,small crystals assemble and grow on the surface of SMS activated perlite.As crystallization proceeds,the zeolite crystals rapidly grow and aggregate around the activated sample,ultimately forming a crystal-packed morphology.In the Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate,the synthesized hierarchical NaY zeolite demonstrates higher benzaldehyde conversion compared to conventional counterparts.