Synthesis, surface and crystal structure investigation of the large zeolite beta crystal

Abstract: Employing the seeded monocrystalline silicon slice (SMSS) method, we have successfully synthesized the largest zeolite beta crystals (400μm×200μm×200μm) to date. The X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), the atom force microscope (AFM), thermogravimetric (TG) and differential thermal analysis (DTA) and high-resolution transmission electron microscopy (HRTEM) characterizations were completed. The results of X-ray diffraction illustrated that the large zeolite beta presents a sequence of stacking disorder which is different from what is presented by the zeolite beta synthesized in an the alkali system. Through the optic microscopy investigation of the large zeolite beta crystals, we observed the hourglass phenomenon in the zeolite beta crystals for the first time. The FE-SEM and AFM analyses show that the surface of the large zeolite beta is formed in rugged layers. HRTEM characterization reveals the microstructure details of the large zeolite beta. Moreover, the synthesis mechanism has been discussed as a seeded growth with slowly released nutrition via gradually dissolving MSS and the crystals grow by a layer growth manner. [Copyright &y& Elsevier]