In this study, an attempt was made to synthesis SAPO-34 using piperidine as structure directing agent/ template. The synthesis parameters such as crystallization temperature, crystallization time, phosphorus content and silicon content, as well as Na, Fe, Co and Ni impregnation were varied. The resulting materials were characterized by a combination of physicochemical techniques such as XRD, SEM spectroscopy, NH3-TPD and SS NMR spectroscopy. The peaks at 2θ = 9.9⁰, 13.0⁰, 15.0⁰, 18.0⁰, 21⁰, 26⁰, 32⁰ on XRD patterns confirmed the presence of SAPO-34 phase, extra peaks at 2θ = 7.9 ⁰, 20 ⁰, 23 ⁰and 26 of XRD patterns indicated the existence of SAPO-5. Most of the samples of the molecular sieves comprised SAPO- 5 and SAPO-34. The SAPO-5 materials were the main domain and SAPO-34 materials were less. The two peaks that appeared in the temperature regions between the ranges 190-250 ⁰C and 340-380 ⁰C that were assigned for weak and medium BrØnsted acid site on NH3-TPD profiles. The SS NMR spectroscopy and XRD patterns confirmed a SAPO-34 phase with amorphous phase in a sample prepared with SiO2/Al2O3 = 2.4 molar ratio at 200 ⁰C for 5 days. The NH3-TPD profile and SS NMR spectroscopy for this molecular sieve confirmed the presence of weak and strong acid sites assigned to P-OH-Al and Si-OH-Al hydroxyl groups. All the molecular sieves were used in MTO reaction. The selectivity to ethylene and propylene on the molecular sieves prepared at 190 ⁰C for 5 days is better than the selectivity to ethylene and propylene on the molecular sieve synthesized at 170 ⁰C, 200 ⁰C and 210 ⁰C for 5 days. Molecular sieve prepared at 200 ⁰C for 4 days was better in ethylene and propylene selectivity than the molecular sieve prepared at 200 ⁰C for 2-3 days, 5-6 days. Methane and DME were the main products on most of the molecular sieves. Methane, ethylene and propylene and some impurities were the products on molecular sieve prepared with SiO2/Al2O3 = 2.4 molar ratio in MTO reaction. The conversions of DME towards light olefins were extremely low. Na- SAPO reduced methane, and improved ethylene and propylene selectivity. Nonmodified and Co-SAPO molecular sieves improved the selectivity towards light olefins. Piperidine can be used as a template to synthesis SAPO-34 molecular sieve within a short period of five days. SAPO-5 was synthesized instead of SAPO, and DME was the main product instead of light olefins on the molecular sieves during MTO reactions.

The aim of this thesis was to synthesise CoAPO-34 and FeAPO-34 using ionothermal synthesis in the presence of organic amines. Using this method provides an alternative route to prepare such materials under low pressure instead of the higher pressure associated with hydrothermal or solvothermal synthesis. Both materials have chabazite (CHA) topology and they are known to act as catalysts. CoAPO-34 was ionothermally prepared using 1-ethyl-3-methylimidazolium bromide (EMIMBr) in presence of 1, 6-hexadiamine (HDA). This study has found that when the synthesis was carried out without HDA, AlPO-11 was preferentially obtained instead of CoAPO-34. Broad line signals which appear between 2000 to 5000 ppm in both spin-echo ³¹P NMR spectra of as-synthesised and calcined CoAPO-34 confirm that the Co²⁺ ions have been successfully incorporated within the framework of the material. FeAPO-34 was synthesised under ionothermal conditions using 1-ethyl-3-methylimidazolium chloride in the presence of ethylenediamine (EDA). In the absence of EDA, the synthesis has produced AlPO-34 instead of FeAPO-34. Broad line signals that appear between 1000 to 14000 ppm in spin-echo ³¹P NMR spectra of both as-synthesised and calcined FeAPO-34 are direct evidence of isomorphous substitution of framework aluminum by Fe(II) or Fe(III). Another aim of this study was to explore the ionothermal synthesis of copper containing aluminophoshate of DNL-1 (Cu/DNL-1). This material was attractive to explore because it contains 20 ring extra-large pores and Cu(I) species in the channels of the framework, potentially giving material the ability to simultaneous store NO and to generate NO from NO₂⁻ anions. Cu/DNL-1 was successfully prepared under ionothermal conditions using EMIMBr and HDA. Without HDA in the synthesis, AlPO-11 was obtained. In this material, copper ions were not incorporated in the Cu/DNL-1 skeleton framework. This was confirmed by absence of broadline signal at >500 ppm in spin-echo ³¹P NMR spectrum of the sample. The copper ions are expected to be present as extra-framework cations. Extra-framework Cu(I) species that were formed by high temperature calcination of Cu/DNL-1 are active to produce NO from NO₂⁻. Therefore, the calcined Cu/DNL-1 can be used to simultaneously store and produce NO from nitrite. This has the potential to significantly extend the lifetime of gas delivery in the material to prevent thrombus formation.

Structure direction in the formation of zeolitic materials has been investigated through the parallel approaches of structural and synthesis studies. The structures of gallosilicates TNU-6 and TNU-7 have been solved from powder X-ray diffraction. TNU-6 (P6₃, a = b = 10.5078(1)Å, c = 8.5277(1)Å) is found to possess a stuffed tridymite-like structure isostructural with BaFeGaO₄. Evidence from electron diffraction, single crystal and high-resolution powder X-ray diffraction suggests the presence of a √3a superstructure, analogous to the related KAlGeO₄ phase, arising from a subtle variation in tilt of tetrahedral units. The structure of TNU-7 consists of an ordered 1:1 intergrowth of alternating sheets of mazzite and mordenite (Pmmn, a = 7.5721(1)Å, b = 17.0739(2)Å, c = 25.8438(5)Å). The crystallisation field of TNU-7 is found to lie between those of mazzite and mordenite, suggesting that this is an example of a ‘boundary phase’ - phase selectivity being governed strongly by the presence and quantity of Ga in the synthesis gel. The distribution of extra-framework Na⁺ cations in the as-made material, and Cs⁺ and Sr²⁺ in ion-exchanged samples, suggests a higher extra-framework charge per T-site associated with the mazzite region of the structure, indicating the possible existence of compositional zoning, consistent with the preference to form mazzite at high Ga gel-content. The structures and synthesis conditions for both TNU-6 and TNU-7 suggests a cooperative effect between Ga and extra-framework species in directing the formation of these phases. The structure of the novel aluminosilicate TNU-9 has been confirmed by energy minimisation and powder neutron diffraction studies (C2/m, a = 28.177(2)Å, b = 20.030(1)Å, c = 19.464(1)Å, β = 92.311(4)º ). Monte Carlo-Simulated Annealing studies have been employed to investigate the favoured location of the 1,4-bis(N- methylpyrrolidinium)butane template molecule within the complex pore system. Remarkably, three (possibly four) different positions are assumed by the structure-directing agent, forming head-to-middle and head-to-head motifs between constituent framework aluminosilicate sheets. TNU-9 crystallises in a very narrow gel composition window suggesting a strong cooperative effect between organic and inorganic gel components. Structure direction of phosphate-based materials (aluminophosphates, magnesium aluminophosphates and silicoaluminophosphates) has been investigated through co-templating synthesis studies. In particular, the structure-directing activity of Cu²⁺ (and to a lesser extent Ni²⁺) complexes of the azamacrocyles cyclam and cyclen, and related derivatives, is investigated in the presence of additional amines (dipropylamine, diisopropylamine, tetraethylammonium hydroxide, diisopropylethylamine). Complexes of a selection of linear polyamines, and also cobalticinium are studied for comparison. Although added primarily as pH moderators, the additional amines are also found to influence the crystallisation and hence provide effective routes to the synthesis of transition metal-containing materials with potential catalytic application. The ‘strength’ of the structure-directing ability of the additional amines is found to vary depending on the identity of the primary structure-directing agent, with behaviour ranging from passive pH moderator to dominating structure-directing agent. The outcome of syntheses is also highly dependent on inorganic gel composition. Through appropriate combination of structure-directing agent and additional amine, mixed Cu²⁺/Ni²⁺-containing MgAPO and SAPO STA-6 (SAS) and STA-7 (SAV) materials have been synthesised for the first time, as well as a low Si form of SAPO STA-7 (with and without Cu²⁺). Also, the combination of cyclam, tetraethylammonium hydroxide and HF has been found to produce a SAPO analogue of STA-7 possessing silicate islands. In addition, transition metal-containing materials possessing the AEL, AFI, CHA, UT-6 and LEV topologies have also been synthesised via this approach. Elemental analysis, UV-Vis, ESR and NMR spectroscopy are employed to confirm the presence of the desired complex in selected samples, while X-ray diffraction and ESR spectroscopy are employed to investigate the environment of extra-framework transition metal species, post calcination, in MgAPO STA-6, SAPO STA-6 and STA-7, MgAPO-18, and MgAPO-5.

Structure direction in the synthesis of phosphate-based materials (aluminophosphates, AlPOs; magnesiumaluminophosphates, MgAPOs; silicoaluminophosphates, SAPOs; magnesiumsilicoaluminophosphates, MgAPSOs), has been investigated through co-templating synthesis studies supported by molecular modelling. These solids have been characterised by diffraction and solid-state NMR, and their properties in gas adsorption and catalysis have been measured. The parameters in the hydrothermal synthesis of SAPO STA-7, St Andrews porous solid number 7, (SAV), in which the macrocycle 1,4,7,11- tetraazacyclotetradecane (cyclam) and tetraethylammonium (TEA) cations are used as co-templates, were investigated in detail. A new route involving a reversal of the mixing order of reagents leads to the formation of single crystals up to 50 μm with perfect tetragonal prismatic morphology that was not achieved via previous synthetic routes. For the first time in SAPO STA-7, X-ray diffraction locates the tetraethylammonium cation (TEA) in tg.tg. conformation. The synthesis and full characterisation of a novel aluminophosphate structure designated STA-14 (KFI) represents the first example of a designed synthesis of a zeotype. The synthesis route is based on a co-templating approach supported by molecular modelling to design the specific template for one of the two types of cages within the structure. The first, a larger type of cage, also present in AlPO-42 (LTA), is templated by the azaoxacryptand 4,7,13,16,21,41-diaza-1,10-bicyclo[8,8,8]- hexocosane (‘Kryptofix 222’, hereafter K222). The modelled co-template configuration, in this case TEA in the tt.tt configuration, was experimentally observed by X-ray diffraction. Modifying the gel chemistry leads to SAPO and MgAPSO STA-14, which display high pore volumes for N₂ adsorption, similar to those of STA-7 and SAPO-34 (CHA). Furthermore, during these synthetic studies, a novel fully tetrahedrally- coordinated magnesiumaluminophosphate layer phase has been prepared, with a structure of relevance to hypothetical VPI-5 (VFI) type extended structures. Molecular modelling was also applied in another aluminophosphate-based material, that of STA-2 (SAT), to predict a template that could be prepared from inexpensive reagents. Existing routes required the use of expensive quinuclidine as a precursor to the template 1,4-bisquinuclidinium butane. The template suggested by modelling, 1,4-diazabicyclo (2,2,2)octane butane (NC₆H₁₂N⁺-C₄H₈-⁺NC₆H₁₂N), labelled DABCO_C4, templated AlPO STA-2 successfully. Structure characterisation of the as- prepared form of AlPO STA-2 using X-ray synchrotron data suggest the formation of Al- OH-Al units to accommodate the positively-charged template within the neutral framework and a combination of ¹³C, ¹⁴N and ¹⁵N NMR studies have been used to give further details of the template environment in the cages. The gas adsorption behaviour of the stable materials STA-7, STA-14 and STA-2 was evaluated for CO₂. High pressure adsorption (0 to 40 bars) on STA-7 and STA-14 shows similar behaviour due to their structural and chemical similarities. The total uptake of CO₂ for SAPO STA-7 is less than for the zeolite NaX (FAU) (3.4 and 5.2 mmolg -1 respectively at 373 K and 12 bars) but the usable capacity for pressure swing adsorption technology (PSA) between 1 to 20 bar for STA-7 is twice the value for NaX. The affinity of adsorption towards CO₂ and its low uptake at 1 bar made SAPO STA-7 a desirable sorbent for PSA. The zeotype affinity of adsorption for different probe gases is different, CO₂ >> CH₄ > CO, to that for zeolite NaX CO₂ >> CO > CH₄. Low pressure CO₂ adsorption (0 to 1 bar) in STA-7, STA-14 and STA-2 at temperatures between 273 and 303 K demonstrates that the topology and therefore the total free pore volume accessible to the gas molecules is the most important factor in determining the uptake in these solids, but that the composition and distribution of the silicon cations within the framework also has an important effect. For example at 273 K and 1 bar, the uptake of the STA-2 framework in the SAPO form is ca. 2wt% higher than in the AlPO form, but compared with SAPO STA-7, the uptake due to pore volume limitations is 10wt% lower under same conditions. In addition, the high quality of the SAPO STA-7 crystals obtained by the new route made them suitable in collaborations for the direct observation of diffusion of methanol by interference microscopy (IFM) and the study of their crystal growth by combined atomic force microscopy (AFM) and high resolution scanning electron microscopy (HRSEM). The catalytic applications of the STA-7 and STA-14 for the methanol-to-olefins reaction (MTO) and the argon adsorption at 87 K were also performed collaboratively. The results are reported and discussed here in the light of their structure and composition.