| Nano-scale magnetic solid base catalysts with coated structure have been designed and prepared for more easy and high efficiency reclaim of the catalysts. The emphasis of this paper is that nano-scale MgFe2O4 spinel served as magnetic core provides magnetism for the catalyst and MgAl(O) and/or MgAl-OH-LDH coating on the surface layer offered basic sites required in base catalyzed reactions. These kinds of bifunctional catalysts (magnetism and basicity) not only possess excellent catalytic property, but also achieve the reclaim more easily and effectively through an exterior magnetic field. In this thesis, the structural and magnetic property of MgFe2O4 spinel; the optimum preparing methods and conditions of magnetic catalyst precursor MgAl-CO3-LDH/MgFe2O4; the structural and textural properties, basic and magnetic properties, particle size distributions of magnetic solid base catalysts MgAl(O)/MgFe2O4 and MgAl-OH-LDH/MgFe2O4 have been thoroughly characterized by various techniques, including XRD, XPS, M?ssbauar, TEM, SEM, TPD, N2 adsorption, and vibration sample magnetometer (VSM). Also, ester exchange reaction and self-condensation of acetone have been employed to examine catalytic properties of the catalysts.(1) Nano-scale MgFe2O4 spinel having narrow particle size distribution and good magnetic property has been prepared by a method involving separate nucleation and aging steps developed in our groop. (2) Magnetic precursor MgAl-CO3-LDH/MgFe2O4, using MgFe2O4 as magnetic core, is prepared by different methods including a method involving separate nucleation and aging steps, conventional coprecipitation method, and coprecipitation method employing urea. XRD, TEM characterization, and dispersion-separation test manifest that the method involving separate nucleation and aging steps, with that the magnetic core MgFe2O4 simultaneously added to nucleus system, is the best method.(3) Magnetic solid base catalyst MgAl(O)/MgFe2O4 have been obtained from magnetic precursor MgAl-CO3-LDH/MgFe2O4 calcined at proper temperature in open air. XRD and XPS analyses show that a double shell structure formed, with MgFe2O4 served as magnetic core and MgAl(O) coating on its surface. The granularity measurement, BET, VSM, and CO2-TPD analyses manifest that the particle size of MgAl(O)/MgFe2O4 is in nanometer range, MgAl(O)/MgFe2O4 has very large specific surface areas and large amount of basic sites with lower basic intensity than MgAl(O). The magnetism of MgAl(O)/MgFe2O4 is related to the relative content of MgAl(O) to MgAl(O)/MgFe2O4. The less content of MgAl(O) is, the higher magnetism of MgAl(O)/MgFe2O4 is. The function of MgFe2O4 is not only offering magnetism but also promoting the surface properties of MgAl(O)/MgFe2O4. When used as basic catalyst for ester exchange reaction, MgAl(O)/MgFe2O4 shows comparatively high catalytic reactivity.(4) Magnetic solid base catalyst MgAl-OH-LDH/MgFe2O4 has been obtained from calcinations/rehydration processes, i.e., magnetic precursor MgAl-CO3-LDH /MgFe2O4 calcined at proper temperature in open air, and then rehydrated in decarbonated water under N2 nitrogen. XRD and XPS analyses show that MgAl-OH-LDH/MgFe2O4 possesses a structure of MgFe2O4 spinel phase being located in interior of particles, and MgAl-OH-LDH on the surface of MgFe2O4. There are chemical linkages of Mg-O-Fe and Al-O-Fe formed between the two phases. The granularity measurement, BET and VSM analyses manifest that the particle size of MgAl-OH-LDH/MgFe2O4 falls in nanometer range. It is just because of the optimum synthesis conditions and the introduction of the magnetic core MgFe2O4 that the catalyst MgAl-OH-LDH/MgFe2O4 have large amount of active OH- basic sites derivated from MgAl-OH-LDH coating on the surface and a mesoporous structure with pore size ranging from 2 to 20 nm from dispersion function of the magnetic core MgFe2O4. Dispersion-Separation test shows that the rehydration of MgAl(O)/MgFe2O4 in decarbonated water into MgAl-OH-LDH/MgFe2O4 results in the more tightly combination of magnetic an...
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