Synthesis and Characterization of Higha2silica SAPO-5 from Metakolin

Higha2silica silicoaluminophosphate (SAPO-5) molecular sieves were hydrothermally synthesized using metakaoline with a certain activity as the silicon and aluminum sources, phosphoric acid as the phosphorus source and triethanolamine combined with cetyltrimethylammonium bromide (CTMABr) as the template agents. The sample was characterized by means of X-ray diffraction spectroscope (XRD), Infrared spectrum (IR), scanning electron microscope (SEM) and 29Si, 27Al MAS-NMR and X-ray photoelectron spectroscope (XPS), temperaturea2programmed desorption of adsorbed NH3. The results show that the crystallization of the SAPO-5 can be promoted by the addition of CTMABr. The synthesized SAPO-5 reveals pillara2like morphology with dimension of 20| | | . The local environment of Si and Al changs greatly after reaction and many foura2coordinated structures such as Al(OP)4 and Si(AlO)4 are produced with the Si/Al ratio of 0.56. The acidity amount of the product is 0.578mmol/g and the ratio of the strong acid sites to the weak acid sites is 0.684.