Preparation And Catalytic Property Of Multi-Composite Metal Oxide Derived From Layered Purcursor

Hydrotalcite as a kind of layered uniform anionic material,whose anionis are exchangable specially,layer plates are designable and adjustable.It is a hot topic by researchers from worldwide due to its wide applications in catalysis, absorption,environment,medicine,nanometer materials,functional polymer material and so on.According to singleness to synthesize hydrotalcite,a series of new methods and conditions and reaction processes of the preparation are studied in this thesis.The copper-based multi-composite metal oxides was obtained derived from hydrotalcite prepared by separate nucleation and aging steps,and the structure,morphology,reducibility and catalytic property of this composite were furtherly studied.The researches are presented as fellows:1 a series of new methods to prepare hydrotalciteA new method to synthesize Mg-Al LDHs has been proposed with magnesium powder and aluminum hydroxide.The effect of preparing conditions on composite structure have been investigated.The reaction processes of hydrotalcite have been revealed through the characterization of product by XRD and SEM.Reduction-oxidation method was first introduced to synthesize hydrotalcite with high crystallinity,uniform layer plate.In this method,metal nucleus highly dispered in colloid mill was obtained by reduction of metal cations.After that,metal nucleus was oxidized gradually by oxygen which is dissolved in water simultaneously controling the usage of sodium carbonate in hydrothermal system and hydrotalcite including Ni-Fe LDHs,Ni-Al LDHs,Co-Fe LDHs,Ni-Mn-Fe LDHs,Ni-Zn-Fe LDHs was prepared.Influence rule of the temperatue,time,dosage of sodium carbonate on the crystallinity of hydrotalcite was studied.The reaction processes of hydrotalcite have been revealed through the characterization of product by XRD and SEM.In weak acidic environment,Cu-Ni-Al-Ac LDHs was prepared by hydrolysis of M²⁺and Al³⁺ in diethylene glycol without any protection,while Al³⁺ is ionized by Al(CH₃COO)₂(OH) with the induction of M²⁺.2 preparation of copper-based composite metal oxides for 1,4-cyclohexane dimethanolAccording to production situation of 1,4-cyclohexane dimethanol and potential development space of hydrotalcite in catalysis,ternary or quaternary composite metal oxides Cu/Zn/Al and doped Cr,Mn were derived from hydrotalcite by calcinations.Hydrotalcite is prepared by a method involving separate nucleation and aging steps,which is suitable for industrial production. According to characterization of the precursors with XRD,FT-IR,the structure of the product was proved to be hydrotalcite.Role of stability is analysised by TG-DTA.Copper-based composite oxides are proved by XRD and FT-IR.Reduction performance and existence form of copper is charactered by H₂-TPR.the hydrogen storage capacity of copper-based catalyst is charactered by H₂-TPD and the result is in good agreement with the result of hydrogenation.The influence of coversion and selectivity of 1,4-cyclohexane dimethanol is studied by manipulating temperature,pressure and hydrogen flow rate.