Studies of the effect of synthesis parameters on ZSM-5 nanocrystalline material during template-hydrothermal synthesis in the presence of chelating agent

Abstract

Nanostructure ZSM-5 zeolite was synthesised via hydrothermal, chelating agent-based method from a mixture with molar composition of 1Al 2 O 3 :46SiO 2 :xTPA:5Na 2 O:1.3Trien:2500H 2 O (x = 0–5.5). The effects of crystallisation time and temperature and template type and content on the synthesised zeolite crystallinity and morphology were investigated. The final products were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Both XRD and SEM results showed that the crystallinity and particle size of the synthesised zeolite increase with increasing crystallisation time for both templates. However, twinned and intergrown crystals of ZSM-5 zeolite with very smooth surfaces were obtained with a crystallisation time of 120 h using a tetrapropylammonium hydroxide (TPAOH) template. Also, the crystallisation temperature had a strong effect on crystallinity and morphology; a highly crystalline ZSM-5 zeolite with twinned crystals was synthesised at 175 °C. Furthermore, the template content had a strong effect on the final product properties. ZSM-5 zeolite with high crystallinity and perfect particles was synthesised at a TPAOH/Si ratio of 0.058. Finally, the effect of the chelating agent (Trien) on crystallinity and morphology of the synthesised ZSM-5 was investigated. ZSM-5 zeolite was synthesised via a chelating agent-based method, with more detailed parametric studies to obtain desired properties in the final product. The effect of the chelating agent (Trien) on crystallinity and morphology of the synthesised ZSM-5 was investigated. Rough and spherical particles were synthesised in the absence of Trien . In contrast, twinned and intergrown shaped crystals with very smooth surfaces were obtained after 120 h of crystallisation at 175 °C in the presence of Trien. ► Nanostructure ZSM-5 zeolite was synthesised via hydrothermal method. ► Trien was used as chelating agent for ZSM-5 zeolite synthesis. ► The effects of synthesis parameters on the zeolite structure were investigated. ► The presence of Trien resulted in the synthesis of twinned and intergrown crystals. ► Rough and spherical particles were synthesised in the absence of Trien.