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This thesis concerns the hydrothermal stability of two zeolite molecular sieves with the MFI structure, ZSM-5 and its 'aluminium free' form silicalite. Silicalite was synthesised from low pH alkali metal free aqueous gels at 95°C and characterised by XRD, SEM, DTA and TG. ZSM-5 was crystallised from similar reaction mixtures but with the addition of aluminium salts. It was found that the incorporation of aluminium into the ZSM-5 framework was favoured by higher reaction temperatures (l50°C) and the use of aluminium nitrate. Solubilities were measured for silicalite, ZSM-5, ZSM-11, ZSM-39, ZSM-48 and EU-4 at temperatures up to 95°C. The solubilities were influenced by framework structure, the presence of template within the zeolite channels and the aluminium content of the lattice. Solubility measurements over a range of liquid/solid ratios showed that calcined silicalite was contaminated with about 1% amorphous silica. Treatment with liquid water over the temperature range 95 to 230°C was used to remove amorphous silica and alnminosilicate species from silicalite and ZSM-5. This hydrothermal treatment had many other effects on the properties of these materials. The water uptake, orthorhombic to monoclinic symmetry transition, framework Si/Al ratio and thermal properties were all affected. SEM showed that the inside of the silicalite crystals was more soluble than the outer surface. The use of hydrothermally treated H-ZSM-5 as a catalyst for but-1-ene isomerisation showed that the treatment could have a marked effect on catalytic behaviour, and particularly on product selectivity.

The objective of this research was to develop new molecular sieve materials and to examine their applications in adsorptive gas separation processes. Several techniques to modify zeolite molecular sieve materials were developed, including a new pore size control mechanism and novel surface modification procedures. The new materials derived from these modification techniques were found to be potentially useful in many adsorptive gas separation processes. A novel mechanism was developed to systematically control the pore size of titanium silicate molecular sieves through halogen substitution of terminal hydroxyl groups. These halogen containing zorites represent a new class of size-selective adsorbents with readily tailored and highly specific pore sizes. Anion-controlled titanium silicates were demonstrated to have promise in multiple areas of size-based separation, particularly light hydrocarbon purification and permanent gas separation. By controlling the type and quantity of the extra-framework cations, titanium silicate molecular sieve adsorbents were modified to separate ethylene and ethane by either the kinetic phenomenon or an equilibrium process. All of these modification techniques were synergistically integrated to illustrate that multi-functional adsorbents can be designed and prepared for many target separations. This approach was demonstrated through the separations of CO2/C2H6 and CO2/CH4. Anion-controlled adsorbents were modified to selectively exclude ethane and methane by the steric effect, while the equilibrium and kinetic properties of the adsorbents were concomitantly adjusted by surface modification. The concept of gas adsorption and separation through nanometals interaction was introduced. Surface-supported nanometals, such as nanosilver, formed on titanium silicate ETS-10 were applied as unique adsorbents to separate gas mixtures, such as Ar/O2 and N2/O2. Continual research and development in new molecular sieve materials will be crucial to the future of the chemical processing industry, and should be viewed as an avenue for the discovery of next-generation adsorptive gas separation technologies. / Chemical Engineering

Thesis (M.S.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (leaves 81-82).

Thesis (M.S.)--Ohio University, August, 2004. / Title from PDF t.p. Includes bibliographical references (leaves 62-63).

Thesis (Ph. D.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Aug. 31, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Engineering, Department of Chemical and Materials Engineering, University of Alberta." Includes bibliographical references.

Thesis (Ph.D.) - University of St Andrews, October 2008. / Restricted until 29th October 2009.