Simple, efficient syntheses of zeolite ZSM-11 (MEL) at temperatures below 100 °C using very dense gels

The synthesis of pure phase ZSM-11 (MEL) at temperatures below 100 °C has been achieved using extremely dense gels with minimal water contents. Both hydroxide and fluoride routes were investigated using N,N-diethyl-3,5-dimethylpiperidinium and 2,2-diethoxyethyltrimethylammonium based templates. Highly crystalline materials were successfully synthesised within relatively short reaction times using a wide range of reaction conditions. The syntheses are shown to be not as efficient as the related ZSM-5 (MFI) materials, suggesting that the structure directing power of the template molecules is critical for low temperature reactions.

Graphical abstractDense gel syntheses of phase pure MEL at temperatures below 100 °C with crystallisation times similar to conventional syntheses at much higher temperatures.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis of high-silica zeolites below 100 °C using very dense gels with both hydroxide and fluoride ions as mineralisers. ► Very high quality MEL zeolites prepared at 90 °C in 7–14 days in high yield. ► Simple reactions using non-pressurised equipment.