Synthesis, Characterization And Catatytic Properties Of Microporous Aluminophosphate Sieves

Microporous materials with high specific surface area, uniformity pore size distributions and high hydrothermal stability, therefore were used widely in many fields, such as adsorption and separation, ion exchange and host-guest chemistry. In the catalytic industry, they can also be used as catalysts and catalyst carriers. Since people the first time found the natural zeolite structure of porous materials, the synthesis and applications of microporous materials obtained a series of great achievements. Early studies on natural zeolite were mainly on the structure and nature of knowledge . Researchers found a lot of different structure materials. During 1940s chemist of zeolite the first time imitated the vegatl environment of natural zeolites and synthesized low Si-Al ratio of zeolites under the hydrothermal conditions. In the early 1980s the researchers successfully synthesized a new family of molecular sieve - aluminophosphate molecular sieve, which is not a class of porous silicon compounds. It was an important milestone in the history of the microporous material development .The frameworks of AlPO4-n family are the same amount of aluminum from tetrahedral oxygen tetrahedron composed of oxygen and phosphorus, so its crystal skeleton is neutral which have non-acid centers in the surface and only weak catalytic properties. In the aluminophosphate molecular sieve,the oxygen from the aluminum phosphate composition interconnected skeleton, which in addition to aluminum ion tetrahedral coordination with oxygen. The oxygens are five-coordinate structure of hexa-coordinate, so the structure with a large range of adjustable quality. The appearance of aluminophosphate molecular sieves has greatly enriched the microporous materials at the chemical composition and skeletal structure. Scientific personnel who research in the synthesis of such materials started a lot of work,they found that it needs the participation of the template in the synthesis process before the formation of pore structure. APO-5 molecular sieve which has a AFI skeleton structure is one of the most representative material, as many as 85 kinds of organic compounds can be synthesized as a template to get the material. Because of its neutral framework, the material of the skeleton structure could be changed by adding different metal, which has been widely concern.In this paper we hydrothermaly synthesize that possess AFI framework molecular sieves by useing diquaternary ammonium as SDA and characterized their structures by spectroscopy methods.The catalytic property is evaluated in the selective O-methylation of catechol. From above research,the detailed results is as follows:1 APO-5 materials are synthesized by diquaternary ammonium and we check the impact of different aluminium sources .The framework of molecular sieves are very steady when isopropylate aluminum as the aluminium source without adding HF.The framework collapse after be calcined when aluminum hydroxide as aluminium source. The structure is dense after phosphite as phosphorus source. The phases of material are weakening after increase water content.When the P / Al≠1, there are a few other phases in the molecular sieves. We try to enhance the synthesis of diquaternary ammonium phosphate of aluminum materials through different synthesis methods.2 We add Mg or Si to the initial gel in order to form acid-base centers. In this part of experiment, we use isopropanol aluminuml as the aluminum source of aluminum without adding HF.As the Mg / Al is lower than 0.1, the crystal exist AFI phase steadily, when Mg / Al higher than 0.1, the crystal generate other phase. It needs to add HF in order to maintain the structure of crystalline phase alumina aluminum source when alumina as aluminum source. Later we dop the Ti or Sn to the gel. The results show that two atoms can access to the skeleton very well. 3 We simply synthesize different transition metal zeolites by changing the temperature and amount of template. The material which have Co or Mn can easily form AFI structure and Fe or Cr is more difficult to enter the framework. We can note that there are some flaws when diquaternary ammonium in guiding the transition metal to form microporous material.4 We evaluate catalytic property of the materials that are synthesized by Et3N in the O-methylation of catechol.These material display a certain degree of reactivity and this can explain the existence of acid-base center in the molecularsieves and also evaluate catalytic property of the materials that are synthesized by diquaternary ammonium in the Oxidation of Cyclohexane.5 We change the two-branched-chain structure of diquaternary ammonium, and used these organic compounds as templates to synthesize aluminophosphate microporous molecular sieves.