Comparative Studies Of Different Crystallization Routes To Realize The Synthesis Of Aluminophosphate (Or Silicoaluminophosphate) Efficiently And Controllably

As an important solid acid catalyst,(silicon)aluminumphosphate molecular is the focus of researchers,and aluminum phosphate molecular sieve is an important way to study the mechanism of molecular sieve crystallization.Therefore,it is of great significance to synthesize and analyze the crystallization mechanism of(silicon)aluminumphosphate molecular sieve by high efficiency control.This dissertation systematically investigated the optimal synthesis route of the(silicon)aluminumphosphate molecular sieve and the application of the CoSAPO-5 catalyst in the air epoxidation of ?-pinene.According to the research system,it is divided into two aspects AlPO-n and SAPOs.Controllable synthesis of AlPO-n:Comparing static,rotational,horizontal stirring and microwave hydrothermal methods,the crystallization efficiencies of AlPO4-5 molecular sieves are greatly improved under rotating hydrothermal conditions at a rotation speed of 60 rpm.Crystallization of AlPO4-5 molecular sieves with high crystallinity can be achieved in 10 minutes.Through various characterizations,it has been proved that the 4-membered ring of the basic structural unit is already present at the time of preparing the gel,and the transition from the amorphous phase to the ordered crystal in the rotation synthesis takes place within only 2 minutes.AlPO4-11 molecular sieve can obtain the pure phase of AlPO4-11 at the fastest speed of 100 rpm.The fastest crystallization time is 40 minutes.At the same time,the effects of different crystallization modes on the morphology of the samples were investigated.It was found that the rotating hydrothermal crystallization mode promoted the synthesis of a highly uniform microcrystalline zeolite with a length of 1?m and a width of 0.5 ?m.At the same time,through a series of characterizations,the crystallization mechanism of AlPO4-11 molecular sieve was explored.Controllable synthesis and catalytic application of SAPOs:Through the comparative study of different crystallization modes,the optimal route for the synthesis of SAPO-5 molecular sieve was determined.Then,through the ion exchange of the SAPO-5 molecular sieve precursor,a CoSAPO-5 molecular sieve catalyst was prepared and used in the air epoxidation reaction of a-pinene to exhibit excellent catalytic activity.Catalyst cycling studies have shown that the catalyst is a stable,heterogeneous catalyst that can be used repeatedly.