Abstract
In this paper, we optimized the fluorine route in hydrothermal conditions under atmospheric pressurefor the synthesis of ZSM-5 crystals of controlled size. Several experimental parameters were varied forobtaining particles in the nanoscale range in the shortest time with the highest crystalline as well astextural properties. The 100% crystalline ZSM-5 crystals were obtained for a temperature of reaction of100◦C and a crystallization time of 7 days. The concentration of the organic template was found to greatlyinfluence the crystallization process. XRD showed that the best result was obtained for a TPABr/SiO2ratioof 0.4. Below this ratio, a slowdown of the crystallization process was observed. The increase of the molarratio template/silica above 0.4 induced an unfavourable increase of the alkalinity of the mixture. Thisresulted in a decrease of the crystal growth and consequently a decrease of the size of the zeolite crystals.In these conditions, the average diameter of the crystals was extended from 20 to 47 nm. Beyond 20 h, the ageing time had a little effect on the crystallinity of the final products, whereas the crystal size wasconsiderably reduced from 52 nm to less than 25 nm when the ageing time was increased from 20 to 44 h.