Zeolite encapsulated metal complexes as heterogeneous catalysts for oxidation reactions

>Magister Scientiae - MScThis study describes the synthesis and characterisation of Cu(II) and V(IV) complexes of tri- and quadridentate ligands L1 and L2 formed by condensation of ethylenediamine with acetylacetonate in 1:1 and 1:2 molar ratio, respectively. Encapsulation of these metal complexes in the nanocage of zoilite-Y generates new heterogeneous catalysts. These catalysts were synthesized employing the flexible ligand method encapsulation technique.The structures of these encapsulated complexes were established on the basis of various physico-chemical and spectroscopic studies. The results indicated that the complexes did not hinder or modify the framework or structure of the zeolite, confirming successful immobilization of Schiff-bases through the voids of zeolite Y.These encapsulated complexes were screened as heterogeneous catalysts for various oxidation reactions such as such as phenol, benzene, styrene and cyclohexene using a green oxidant (H2O2).For comparison, the corresponding neat complexes were screened as potential homogeneous catalysts for these oxidation reactions. The results proved that the corresponding homogeneous systems described here represent an efficient and inexpensive method for oxidation of phenol, benzene, styrene and cyclohexene, having advantages over heterogeneous catalysis are its high activity and selectivity and short reaction times. Its major problem is its industrial application regarding principally the separation of the catalyst from the products.The size of the substrate has a significant effect on the conversion by encapsulated complexes such as in styrene oxidation. Therefore, it was established that steric effects of the substrates play a critical role in the poor reactive nature of the encapsulated complexes.In general, the percentage conversion decreased upon encapsulation of complexes in zeolite Y. All catalysts studied proved to be potential catalysts for the various oxidation reactions.It has been shown in this study that encapsulation can effectively improve product selectivity but requires a longer reaction time in most cases for maximum activity.Furthermore,oxovanadium complexes were more reactive than copper-based catalysts in all oxidation reactions tested in this study.A reaction mechanism study revealed that the activity of the encapsulated and neat complexes occurs through either formation of peroxovanadium (V) or hydroperoxidecopper(II) intermediate species.The studies in this thesis, therefore, conclude that the Cu(II) and V(IV) complexes encapsulated in Y-zeolite are active heterogeneous catalysts for the selective oxidation of various substrates. Encapsulation of the metal complexes in the super cages (-cages) of the zeolite matrix has the advantages of solid heterogeneous catalysts of easy separation and handling, ruggedness, thermostability, reusability (regeneration of the deactivated catalysts) as well as share many advantageous features of homogeneous catalysts

Considering the steps that could be taken by formal financial service providers to ensure increased access, by low-income individuals, to bank accounts, and to extended financial services, products and initiatives.

Financial inclusion in the world is improving, as many countries and financial institutions are focusing on including lower-income individuals and households. This research discusses a number of tools, mechanisms and the intricacies related to pertinent conceptual frameworks to support the promotion of financial inclusion at the various stakeholder levels, and many opportunities to promote financial inclusion. One such tool in South Africa; Co-operative banks (CB's), proactively focuses on inclusive innovation opportunities and the inclusion of mixed-income communities. This is done through continuous review in order to continuously align with its initial objectives of social development and lower-income community participation promotion. Capturing women and young individuals, among other marginalised groups, by; creating accounts for them at a young age, via educational literacy initiatives, and supported by various internal capability support measures, and further reinforced by government and financial institutional inclusion policy and framework promotion (including co-operative banking institutions), holds a lot of promise and opens up a world of opportunities to investigate and explore to progress the financial inclusion agenda. Other literature and themes discussed, include definitions of what financial inclusion is, why many individuals remain unbanked, pre-conditions for successful financial inclusion, alternate financial service providers being used by lower-income individuals and households successfully which we can learn from, and a few measurement tools and mechanisms which exist in order for governments and financial institutions to identify, implement, drive, and track progress. Aforementioned is discussed, and the theory, borrowed from, in order to promote sustainable financial inclusion. *The creation of bank accounts for individuals is seen as a facilitator of, as well as a measure of the level of, financial inclusion

Zeolite encapsulated metal complexes as heterogeneous catalysts for oxidation reactions

>Magister Scientiae - MScThis study describes the synthesis and characterisation of Cu(II) and V(IV) complexes of tri- and quadridentate ligands L1 and L2 formed by condensation of ethylenediamine with acetylacetonate in 1:1 and 1:2 molar ratio, respectively. Encapsulation of these metal complexes in the nanocage of zoilite-Y generates new heterogeneous catalysts. These catalysts were synthesized employing the flexible ligand method encapsulation technique.The structures of these encapsulated complexes were established on the basis of various physico-chemical and spectroscopic studies. The results indicated that the complexes did not hinder or modify the framework or structure of the zeolite, confirming successful immobilization of Schiff-bases through the voids of zeolite Y.These encapsulated complexes were screened as heterogeneous catalysts for various oxidation reactions such as such as phenol, benzene, styrene and cyclohexene using a green oxidant (H2O2). For comparison, the corresponding neat complexes were screened as potential homogeneous catalysts for these oxidation reactions. The results proved that the corresponding homogeneous systems described here represent an efficient and inexpensive method for oxidation of phenol, benzene, styrene and cyclohexene, having advantages over heterogeneous catalysis are its high activity and selectivity and short reaction times. Its major problem is its industrial application regarding principally the separation of the catalyst from the products.The size of the substrate has a significant effect on the conversion by encapsulated complexes such as in styrene oxidation. Therefore, it was established that steric effects of the substrates play a critical role in the poor reactive nature of the encapsulated complexes.In general, the percentage conversion decreased upon encapsulation of complexes in zeolite Y. All catalysts studied proved to be potential catalysts for the various oxidation reactions.It has been shown in this study that encapsulation can effectively improve product selectivity but requires a longer reaction time in most cases for maximum activity. Furthermore, oxovanadium complexes were more reactive than copper-based catalysts in all oxidation reactions tested in this study.A reaction mechanism study revealed that the activity of the encapsulated and neat complexes occurs through either formation of peroxovanadium (V) or hydroperoxidecopper(II) intermediate species.The studies in this thesis, therefore, conclude that the Cu(II) and V(IV) complexes encapsulated in Y-zeolite are active heterogeneous catalysts for the selective oxidation of various substrates. Encapsulation of the metal complexes in the super cages (-cages) of the zeolite matrix has the advantages of solid heterogeneous catalysts of easy separation and handling, ruggedness, thermostability, reusability (regeneration of the deactivated catalysts) as well as share many advantageous features of homogeneous catalysts

Lewensvaardigheidseise vir 'n multikulturele samelewing en die bevrediging daarvan deur die skool

Tesis (M. Ed.) -- Universiteit van Stellenbosch, 1992.Een kopie mikrofiche.Full text to be digitised and attached to bibliographic record

Lewensvaardigheidseise vir 'n multikulturele samelewing en die bevrediging daarvan deur die skool

Tesis (M. Ed.) -- Universiteit van Stellenbosch, 1992.Een kopie mikrofiche.Full text to be digitised and attached to bibliographic record