A series of SAPO⁃34 molecular sieves with different crystallization time were synthesized by hydrothermal method using pseudo⁃boehmite, silica sol and phosphoric acid as raw materials, TEA & TEABr as template. The crystal structure and physicochemical properties of the synthesized SAPO⁃34 molecular sieve were characterized by XRD, SEM and NH3⁃TPD. The catalytic activity of MTO was evaluated in a fixed bed reactor. The results showed that pure phase lamellar SAPO⁃34 molecular sieves were synthesized under different crystallization time. The longer the crystallization time was, the higher the crystallinity was, the greater the lamellar thickness was, and the more the acid centers were. At 450 ℃, 2 h-1, 0.2 MPa, crystallization time 72 h, the SAPO⁃34 molecular sieve had the best MTO catalytic activity with a single⁃pass lifetime 360 min and yield of diene 86.8%.

Composite oxides are of great interest to researchers due to their excellent physicochemical properties, while zirconium⁃containing composite oxides are used in catalytic hydrodesulfurization, dearomatization, gas phase Beckmann rearrangement reactions of cyclohexanone oximes, and removal of organic contaminants that have wide range of applications. This article reviews the three main preparation methods for zirconium⁃containing composite oxide catalysts (sol⁃gel method, hydrothermal synthesis method, co⁃precipitation method) as well as the defects and advantages of these three methods. Some other preparation methods are also briefly introduced.