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Study On Synthesis, Characterization And Catalytic Properties Of Mo(Ⅵ) Catalysts Used In The Epoxidation Of Cyclohexene

Posted on:2004-07-10Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y D ZhangFull Text:PDF
GTID:1101360095950015Subject:Chemical processes
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This dissertation was financially supported by Henan Province Elitist Innovation Fund.The epoxidation of alkene is a kind of complicated reactions because the oxidation can take palce either at the C=C double bond or at the a - H atom which result in low selectivity of the epoxidation. At present, most of the well-known catalysts with high activity for the epoxidation are homogeneous, such as high valence transition metal complexes of Ti(IV), V(V), Cr(VI), Mo(VI) and W(VI), which possess the merits of moderate reaction condition, high activity, selectivity and so on, but are difficult to be separated from the reaction system and to be reused. Thus, the methods and techniques to surpport high valence transition metal complexes on organic or inorganic materials is one of the key steps to make the homogeneous catalysts heterogeneous.Divinylbenzene cross-linked macropore polystyrene resin( simply named with PS) is a kind of organic macromolecule materials which do not dissolve in water, acid, alkali or organic solvent, and own the merits of strong anti-oxidizability, good stability, easiness of being functionalized and due to the presence of macropores, their reactive properties are same to those of liquids. In this work, we designed and prepared several series of of macromolecule ligands and macromolecule metal complexes catalysts based on the structural characters of PS resin. Moreover, inexpensive and available inorganic macromolecule materials SiC>2, are also used as carriers to be anchored with Mo active species, which have the promising properties of anti-oxidizability, thermal stability, mechanical intensity, porousness, high specific surface area and which can also form strong chemical bond or absorption with the active sites through the H groups in the surface. All the above supported catalysts are used in the catalytic epoxidation of cyclohexene.In the dissertation, we mainly carried out the following several aspects of research works and have made significant achievements:(1) We have synthesized three kinds of micromolecule homogeneous catalysts, i.e. VO(acac)2, MoO2(acac)2 and MoO2(oxine)2, which are characterized by elemental analysis, IR etc. The results of epoxidation of cyclohexene with f-BuOOH catalyzed by such catalysts as VO(acac)2, MoO2(acac)2, Mo02(oxine)2, MoO3, WO3, Na2MoO4 and Na2W04, are compared to those of the previous researches with the transition metal complexes catalysts and finally we selected Mo(VI) O2(acac)2 as the active species. Effects of different factors, such as the mole ratio between different matariels, reaction time, tempreture,WLPage]=006reactive circumstance and amount of solvent on the yield of cyclohexene oxide, were discussed in this epoxidation and the optimal synthesis conditions were obtained by orthogonal technique, which are detailed as follow: ( based on 0.1 mol of f-BuOOH), 10 mL of solvent, temperature 353 K, raction time 60 min and 0.1 g of MoO2(acac)2. Under the above conditions, the yield of cyclohexene oxide were all over 99.5% and which are also used as the main reaction conditions to test the catalytic properties of different macromolecule Mo(VI) complexes prepared. In this research, we also found the easily operable GC analysis method of cyclohexene oxide.(2) In this section, we designed and prepared three series of macromolecule ligands, i.e. ethylenediamine Hands in which the coordinate atom is N, acetylacetone( 3 -dione) and glycol( a -diol) ligands in which the coordinate atom is O and other macromolecule ligands with the coordinate atoms of both N and O, such as ethanolamine and the condensate of ethylenediamine and salicylaldehyde Schiff Base. And for the first time, we have synthesized PS-grafted different Mo(VI) complexes with the above ligands which are characterized by using IR, AAS, XPS etc to confirm that Mo active species have been grafted on the PS resin. We also determined the amount and the valence of the grafted Mo(VI) active species and built the chemical analysis method of amount of Mo in the PS-grafted Mo co...
Keywords/Search Tags:cyclohexene, epoxidation, cyclohexene oxide, macromolecule Mo(VI) complex, macropore polystyrene resin( PS), SiO2, heterogeneous catalysis
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