Crystal growth study of nanosized K-MER zeolite from bamboo leaves ash and its catalytic behaviour in Knoevenagel condensation of benzaldehyde with ethyl cyanoacetate

Abstract

A detailed study on the formation of nanosized K-MER zeolite from a template-free hydrogel system is reported. By using a new recipe and bamboo leave ash (BLA) as a reactive silica source, the K-MER zeolite crystallization time has been shortened from 15 days to 6 h at 180 °C, enabling the investigation of induction, nucleation and crystal growth of nanoscale K-MER zeolite using spectroscopy and microscopy techniques. The resulting zeolite nanorods ((45.1 ± 14.5 nm length) × (3.9 ± 1.9 nm width)) have a Si/Al ratio of 2.31 and they tend to assemble in parallel forming bulkier bundle-like secondary structure ((728 ± 171 nm length) × (251 ± 49 nm width). The nanocrystals (84.3% conversion and yield, 100% selective to ethyl 2-cyano-3-phenylacrylate (ECP)) show better catalytic performance than other homogeneous base catalysts (92–99% conversion, 82–84% yield) in Knoevenagel reaction of benzaldehyde and ethyl cyanoacetate under non-microwave instant heating condition, thus offering an eco-friendly approach for synthesizing highly selective solid base catalyst for synthesizing pure fine chemicals.