Synthesis And Characterization Of Phosphate Molecular Sieves In Triethylamine, Ethylene Diamine, Pyridine Vapor Systems

Phosphate molecular sieves are one of the most important porous materials. Preparation of new framework phosphate molecular sieves as well as the development of new synthetic ways are becoming the central topic of micro-porous materials chemistry.For a long time,phosphate molecular sieves are normally synthesized by hydro-thermal and solvent-thermal methods whereas seldom by vapor-phase transport method(VPT).In this article,we reported the synthesis of metal phosphate molecular sieves by using VPT method.Triethylamine,ethylene diamine and pyridine were chosen as structure-directing agent and steam sources,which were readily vaporized and commonly used as structure-directing agents.The typical sample were characterized by XRD,SEM,FT-IR and TG-DTA.At first,synthesis of aluminium phosphate,zinc phosphate and zirconium phosphate molecular sieves were investigated in triethylamine(Et₃N)-H₂O vapor-phase system at 453K for 3days.AlPO-15 crystals,new framework ZnPO-VPT1 and ZrPO-VPT1 phosphate molecular sieves were obtained.The ideal synthesis AlPO-15 for this system was Al₂O₃:P₂O₅:HF:H₂O=1.0:1.0: 0.6:3.0(molar ratio).AlPO-15 crystals show octahedral aspect and are up to 100μm×100μm×80μm.The ideal synthesis new framework ZnPO-VPT1 in this system was ZnO:P₂O₅:HF:H₂O=1.0:1.0:0.3:3.0(mol ratio).The ideal synthesis new framework ZrPO-VPT1 in this system was ZrO2:P₂O₅:HF:H₂O =1.0:1.0:0.25:3.0(mol ratio).Second,synthesis of aluminium phosphate were investigated in ethylene diamine(EDA)-H₂O vapor-phase system at 473K for 3days.AlPO-11 and new framework AlPO-VPT1 crystals were obtained.The suitable molar compositions of gels were Al₃O₂:P₂O₅:H₂O=1.0:1.0:3.0 and Al₃O₂:P₂O₅: H₂O=1.0:2.0:3.0 respectively.New framework ZrPO-VPT2 was obtained at 453K for 3days in the form of Et₃N-EDA-H₂O(10ml:10ml:10ml)as vapor source.The suitable molar compositions of gels was ZrO₂:P₂O₅:HF:H₂O=1.0: 1.0:0.25:3.0.At last,synthesis of aluminium phosphate and zirconium phosphate molecular sieves were investigated in pyridine vapor-phase system at 453K for 3days.The synthesis aluminium phosphate for this system was Al₂O₃:P₂O₅:HF: H₂O=1.0:2.0:0.15:3.0(mol ratio).The crystalline phases varied with the source of phosphorus.Utilizing phosphate acid as source of phosphorus,UT-6 single crystals was obtained.When source of phosphorus changed to tributyl phosphate,Zeolite LTA analogue was obtained.γzirconium phosphates was also studied in the same condition.The suitable molar compositions of gels was ZrO₂:P₂O₅:HF:H₂O=1.0:2.5:0.3:3.0.