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Abstract

A study was made of the possibility of synthesising sulphur analogues of the aluminosilicates, in which the oxygen in the framework was replaced by sulphur, From the basis of a consideration of the structures of the oxides and sulphides of the elements of Groups III b and IV b, stereochemical and radius ratio predictions suggest that such a substitution of sulphur for oxygen should be possible, ‘Two approaches were adopted in testing this hypothesis, Firstly, attempts were made to sulphide 13X zeolite (chosen as a representative and stable framework aluminosilicate) with carbon disulphide at temperatures up to 700°C. The results indicated that replacement of structural oxygen by sulphur only occurred with a destruction of the framework lattice, which was not reformed. Secondly, hydrothermal systems were set up, in which synthesis of sulphides was attempted in a manner analogous to the hydrothermal preparation of zeolites. Two experimentally distinct methods were used, employing as solvent hydrogen sulphide and water respectively. The work with hydrogen sulphide was conducted in autoclaves under both sub-critical and super-critical conditions, the maximum temperature employed being 350°C. The aqueous reactions were conducted at atmospheric pressure below 100°C. The results in both cases were similar, Solution of the Group III b and Group IV b sulphides occurred in the basic solvent media, with the formation of ternary sulphides analogous to sodium silicate. However, no tendency was found for these ternary sulphides to interact in solution with the formation of more complex phases. The materials formed were characterised by chemical analysis, x-ray diffraction, infrared analysis, adsorption and surface area measurements and tests of catalytic activity. The results obtained confirmed the view that only low surface area ternary sulphides were formed, bearing little relationship to framework aluminosilicates.

Publication Type:	Thesis (Doctoral)
Subjects:	Q Science > QD Chemistry
Departments:	School of Science & Technology > School of Science & Technology Doctoral Theses Doctoral Theses

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