Preparation And Performance Of Phosphotungstate Catalysts

As a kind of polynuclear inorganic macromolecule compound containing oxo bridge,heterpoly acid were the oxygenic polyatomic acid that coordinated with center atom(P,Si,As,Ge etc.) and coordinating atom(Mo,V,W etc.).There are five species such as Keggin,Dawson,Anderson,Waugh,Silverton in heterpoly acid assorting by structure of anions.The heterpoly acids have such unique cage structures that are similar with liquid phase.So catalysis can carry from not only the teeth outwards but also in the body and heterpoly acid have good catalyzed activity and selectivity.The heterpoly acid can catalyst as acid catalysis and oxidization.Furthermore heterpoly acid are provided with photoelectricity catalysis and polymerization retardor.It is one kind of ideal catalyst therefore.The three kind of phosphotungstate were prepared by different of diphenylamine,ammonium oxalate and 8-hydroxyquinoline with phosphotungstic acid(HPA)via double reaction.IR and UV analysis indicated that the compounds kept entire Keggin structure,then the coordination of N-H have strengthened the M-Ob-M bond and M-O_c-M bond;TG analysis indicated that the introduction of N element have improved the stability of water of hydration;XRD analysis indicated that the conclusion is corrected.It is the esterification of acetic acid and n-octanol as probe reaction to test the catalysis of phosphotungstate-diphenylamine and ammonium oxalate-phosphotungstate.The result indicated that the hosphotungstate had the best catalysis when the reaction temperature is 110℃,the molar ratio of octanol to acetic acid is 1:1.4,reaction time is 3.5 hours,the amount of catalyst is 0.4g,the yield of octyl acetate is over 90%.the catalyst may reuse and did not cause second pollution to the environment.It has studied electrochemistry behavior of[(C₆H₅)₂NH₂]₃[PW₁₂O₄₀] 4H₂/PVA laminated film by cyclic voltammetric measurernents(CV).The result indicated that the constitutive property is stable,it has the good oxidized reducibility and the obvious electrocatalysis to ClO₄^-.We evaluate photocatalysis activity by using the ammonium oxalate- phosphotungstate to degradation Rodamine B.The result show:the phosphotungstate have good photocatalysis activity and degrade Rodamine B obviously.The catalyst can use repetitively after simple treatment.So the catalyst may use widely in practice.It is the esterification of acetic acid and n-butanol as probe reaction to test the catalysis of phosphotungstate-8-hydroxyquinoline.The result indicated that the phosphotungstate had the best catalysis when the reaction temperature is 98℃,the molar ratio of butanol to acetic acid is 1:1.4,reaction time is 3.5 hours,the amount of catalyst is 0.4g,the yield of butanol acetate is 90.6%.the phosphotungstate may use repetitive and have no pollution to environment.That's good for industrialization.