1. Hydrothermal synthesis of organically modified transition metal vanadates
- Author
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Law, Sui Chun and Law, Sui Chun
- Abstract
Microporous oxide solids such as the zeolites are commercially important for their selective ion exchange, absorption and catalytic properties. The incorporation of REDOX active metals in these has led to expanded applications including the selective oxidation of hydrocarbons. The aim of this research is to develop new microporous solids which are complementary to zeolitic phases and which possess frameworks that incorporate REDOX metal centers such as vanadium and manganese. The design of new porous frameworks can best be achieved using the hydrothermal method in which organic groups, such as amines, are reacted with inorganic framework components and may serve as structure directing or 'templating' agents. Frequently the organics are left as counter cations, though use of milder conditions may leave them as an integral part of the framework. The resulting new class of hybrid solids may also have interesting and unique materials properties due to the novel component combination. The background and existing literature on these subjects are reviewed in Chapter 1. The synthetic work described in this thesis begins in Chapter 2 with a study of new vanadoborate cluster solids, compounds l-7. Three goals were attempted, the first was to use transition metal ions to coordinate the cluster exteriors and serve as cross-linking agents in order to form new porous cluster frameworks. This was partially achieved using Mn2+ in the formation of [enH2]4[Mn2V12B16O58H8(H2O)4].H2O 1, which is a 2-D network of connected clusters. This demonstrated the possible success of this approach, which has since been fully realized using Cd2+ ions as the cross-linking ions. The second goal was the incorporation of metal ions into the [VB] cluster itself to form new cluster types. This was achieved using Mn2+ with the formation of [Mn 4V10B28] cluster solids 6 and 7. These clusters are notable in having [Mn2] units which resemble the active sites of hydrolase enzymes. The hydroxonium salt [H3O]1
- Published
- 2000