Synthesis And Characterization Of Cobalt Phosphate Molecular Sieve

Molecular sieve is a kind of aluminosilicate compounds, who has uniformitychannel structure、larger internal surface area and high activity. In1982, Wilson andFlanigen of the union carbide （U.C.C） compound AlPO4-n molecular sieve for the firsttime. It is made up of PO4and AlO4tetrahedron, it has broken the traditional conceptwith molecular sieve composes of the SiO4and AlO4tetrahedron.Then peoplesynthesize a series of derivatives, introducing some heteroatom such as （Fe、Co、Zn、Cr） formed the phosphate molecular sieve containing heteroatom,for exampleCoAPO-5、FeAPO-5etc or phosphate molecular sieve such as Zn3（PO4）2、Mn3（PO4）2、CePO4etc. Because of transition metals has underfill valence orbit、higher activity、light、electric、magnetic and other properties. Therefore the synthesis and research of thetransition metal phosphate molecular sieve has become a hot spot. The experiment willintroduce the eighth group transition metal element Co in order to synthesis cobaltphosphate, then study on the synthesis conditions and a series of characterization.We synthesize cobalt phosphate molecular sieve under certain mole ratio.Thenstudy some factors influence on the synthesis cobalt phosphate such as cobalt source、template species、template dosage、pH value、water quantity、crystallization time、crystallization temperature、aging time、feeding order etc.On this basis, we study theroasting temperature and roasting time influence on the cobalt phosphate molecularsieve skeleton.The experimental results show that cobalt source is the key of synthesisof cobalt phosphate molecular sieve,pH main influence precursor generation of cobaltphosphate molecular sieve.Crystallization time and crystallization temperatureinfluence nucleation and growth rate of the crystalloid.Different crystallizationtemperature lead to crystal structure and crystal form various finally. The purpose ofthe roasting is removal the water and triethylamine,the over high temperature makemolecular sieve skeleton to collapse,the low temperature is not enough to removetotally.Therefore, suitable roasting temperature and roasting time decide the finalphysical and chemical properties of cobalt phosphate molecular sieve.The experimentcondition is n（P₂O₅）:n（Et₃N）:n（H₂O）:n（CoO）=2:3:320:1（molar ratio）,crystallization time is36h,crystallization temperature180℃, pHis in the range of4.25⁵.04,we havesuccessfully synthesized cobalt phosphate molecular sieve by the hydrothermalcrystallization method.By means of XRD、 FT-IR、 UV-Vis、 TPD、 BET etccharacterization methods study the acid、adsorbability、redox property、thermal stability.The experiment with n-butanol and acetic acid esterification is used to the probereaction for investigation catalytic performance of cobalt phosphate molecular sieve.Theexperiment results show that the maximum acetic acid conversion is87.29%, it hasproved that cobalt phosphate molecular sieve has high catalytic activity.