Synthesis And Application Of CoCrAPO-5 Molecular Sieves And Membranes

Small size and plate-like CrCoAPO-5 crystals with a high yield were firstly synthesized by conventional heating using a rapid crystallization method. During the synthesis, the morphology and size of CrCoAPO-5 could be controlled by preparation temperature, synthesis temperature and the addition of seeds. The as-synthesized CrCoAPO-5 was characterized by SEM, XRD, IR, UV-Vis, and TG etc. At the same time, we applied this method to successfully synthesize low aspect ratio of AlPO4-5 and CoAPO-5 with AFI structure, which is suitable for the synthesis of plate-like AFI type molecular sieves and it proves to be a new method for the morphology control of molecular sieves.In the performance characterization of the samples, small size and thin sheet of CrCoAPO-5 molecular sieves with shorter diffusion channels contributed to the adsorption and diffusion of object molecules in the channels, indicating the easy removal of templates, high water absorption performance and high catalytic activity of oxidation of cyclohexane. In the reaction, reaction temperature, amount of acetone, the size of the catalyst, the choice of reaction device had a certain influence on the activity of catalytic reaction.The CrCoAPO-5 membrane was synthesized on the seeded ?-Al₂O₃ substrate. A compact membrane could be abtained through secondary growth. And a highly c-oriented membrane could be recieved by epitaxial growth from oriented CoCrAPO-5 molecular sieves layer which obtained by adjusting the synthesis gel composition and synthesis time of the first-time seeded growth, and this method improved the stability of the membrane. During the synthesis, adjusting the amount of TEA and water content in the synthesis gel could effectively control the direction of crystal growth in the membrane. Reducing the preparation temperature and water content of synthetic gel could promote the intergrowth of molecular sieves in the membrane to a certain extent.