The Preparation and Characterization of Several Metal Phosphate Catalysts

Metal phosphates have been widely used as catalysts in many organic reactions for their acid-base and redox properties^[1,2]. Their structure and properties are affected greatly by the preparation method^[2-5]. AlPO₄ is one of the most important metal phosphates. There are many different phases of AlPO₄) that is, amorphous, crystalline and molecular sieve. The usual methods of preparation of AlPO₄ are described elsewhere^[1,3], i.e. gelification of a mixture of an aluminum salt (chloride, nitrate etc.) with orthophosphoric acid (or NaH₂PO₄) in the presence of a base. Ammonia, ethylene oxide, and propylene oxide are used as base mostly.