Synthesis And Characteriztion Of Transition Metal Phosphates And Study On Their Thermal Analysis Kinetics

Chapter One:The prospect of synthesizing transition metal phosphates is of great interest with respect to their extensive use as heterogeneous catalysis and absorption.Researches on the varieties of metal phosphates and new developments on synthetic pattern were reviewed in this chapter.The study of thermal analysis kinetics was one basic approach for understanding material properties.The basic theory and research methods of thermal analysis kinetics were also introduced in this chapter.Chapter Two:A simple and novel route for the synthesis of layered sodium hydrogen zinc phosphate,NaH(ZnPO₄)₂,was studied,and the target product was obtained with Na₂HPO₄·12H₂O and Zn(NO₃)₂·6H₂O as raw materials and polyethylene glycol-400 as a surfactant via a one step solid state reaction at 60℃.Product and its thermal decomposition products were characterized by TG-DTA,IR and XRD.NaH(ZnPO₄)₂ would not decompose before heated to 430℃.This Good thermal stability of NaH(ZnPO₄)₂ is beneficial to organic catalytic application.The kinetic mechanism of thermal decomposition of NaH(ZnPO₄)₂ were studied by non-isothermally method,the mechanism function show as: G(α)=(1-α)^-1-1,E=116.98 kJ/mol and 1nA=29.87s^-1Chapter three:A simple and novel routte for the synthesis of function hydrogen zinc phosphate,ZnHPO₄·H₂O,was studied,and the target product was obtained with ZnSO₄·7H₂O and(NH₄)₂HPO₄ as raw materials and polyethylene glycol-400 as a surfactant via a one step solid state reaction at 80℃.Product and its thermal decomposition products were characterized by TG-DTA,IR and XRD.Thermal decomposition kinetics of ZnHPO₄·H₂O was studied by thermo-gravimetric-differential thermal analysis.The results showed that thermal decomposition of ZnHPO₄·H₂O at temperatures below 800℃was not a simple one step dehydration but two well-defined steps.The thermodynamic parameter show as:E is 36.58 kJ/mol,ln(A)is 13.26～14.54 s^-1and g(α)is[(1-α)^-1/3-1]² for reaction(1);E is 138.80 kJ/mol,ln(A)is 18.38～19.03 s^-1and g(α)isα² for reaction(2).Chapter four:A new 3-D cage framework structural single crystal(NH₄))4Co_0.104Zn_3.896 (PO₄)₄ has been synthesized under hydrothermal conditions using ZnSO₄·7n₂O,COCl₂·6H₂O and(NH₄)₃PO₄·3H₂O as raw materials and ethylenediamine as the structure-directing agent. The structure of this product determined by single crystal X-ray diffraction,crystal system is hexagonal and cell parameters show as:a=10.6958(3)(?),b=10.6958(3)(?),c=8.7069(5)(?),β=90°,V=862.62(6)(?)³,Z=2,Dc=2.747 Mg·m^-3.Product was characterized by TG-DTA,IR and XRD also.Ethylenediamine affected on the growth of crystal like a structure-directing agent although disappeared in crystal framework structure.