A síntese de zeólitas a partir de cinzas leves e pesadas de carvão mineral foi realizada por tratamento hidrotérmico alcalino, as quais foram nomeadas ZCL e ZCP, respectivamente. As zeólitas organomodificadas ZML e ZMP foram obtidas a partir da modificação superficial de ZCL e ZCP, respectivamente, utilizando o surfactante catiônico brometo de hexadeciltrimetilamônio. A partir das soluções remanescentes geradas na síntese de ZCL e ZCP foi possível sintetizar duas novas zeólitas. As características físicoquímicas dos nanomateriais zeolíticos sintetizados, bem como de suas respectivas matérias primas, tais como: capacidade de troca catiônica, massa específica, área específica, composição química, mineralógica e morfológica, entre outras, foram determinadas. Os adsorventes ZML e ZMP foram utilizados na remoção dos corantes Azul Direto 71 (DB71) e Rodamina B (RB) de soluções aquosas em sistema de batelada. Desta forma, quatro sistemas DB71/ZML, RB/ZML, DB71/ZMP e RB/ZMP foram investigados. Os modelos de pseudoprimeira ordem e pseudo-segunda ordem foram aplicados aos dados experimentais para o estudo da cinética de adsorção. O modelo de pseudosegunda ordem foi o que melhor descreveu o processo de adsorção de todos os sistemas corante/zeólita organomodificada. O equilíbrio da adsorção foi analisado a partir de quatro modelos de isoterma, sendo eles: Langmuir, Freundlich, Temkin e Dubinin-Radushkevich (D-R). Os resultados mostram que os modelos de Freundlich e Langmuir melhor descreveram os dados experimentais dos sistemas DB71/ZML e DB71/ZMP, respectivamente. Para os sistemas com RB, o modelo de D-R foi o que melhor se ajustou para ambos adsorventes ZML e ZMP. O planejamento fatorial 24 foi aplicado para a análise dos seguintes fatores que influenciam o processo de adsorção: concentração inicial do corante (Co), pH, dose de adsorvente (M) e temperatura (T). De acordo com as condições estudadas concluiu-se, com o intervalo de confiança igual a 95%, que para o sistema DB71/ZML, os fatores e suas interações que mais influenciam foram C0, M, pH, pH*M, pH*C0, M*C0, pH*M*C0, nessa ordem. No sistema DB71/ZMP, a ordem de influência foi: M, C0, pH, pH*M, pH*C0, M*C0, pH*M*C0. Para os sistemas RB/ZML e RB/ZMP, os resultados foram: M, C0, M*C0, pH, pH*M e M, C0, M*C0, respectivamente. O equilíbrio de adsorção foi atingido em cerca de 40 min para todas as amostras. As porcentagens de remoção do DB71 estavam na faixa de 50 80% e 20 50% para ZML e ZMP, respectivamente. A faixa de porcentagens de remoção do RB variou entre 60 80% e 30 50% para ZML e ZMP, respectivamente. / The synthesis of zeolites from mineral coal fly and bottom ash was performed by alkaline hydrothermal treatment, which were named ZFA and ZBA, respectively. Organo-modified zeolites, SMZF and SMZB, were obtained from surface modification of ZFA and ZBA, respectively, using the cationic surfactant hexadecyltrimethylammonium bromide. From the remaining solutions generated in ZFA and ZBA synthesis it was possible to synthesis two new zeolites. The physicochemical characteristics of the synthesized nanomaterials zeolite as well as their respective raw materials, such as cation exchange capacity, density, specific area, chemical composition, mineralogical and morphological, among others, were determined. The adsorbents SMZF and SMZB were used to remove the dyes, Direct Blue 71 (DB71) and Rhodamine B (RB) from aqueous solutions in batch system. Thus, four systems DB71/SMZF, RB/SMZF, DB71/SMZB, RB/SMZB were investigated. The models of pseudo-first order and pseudo-second order were applied to the experimental data for the study the adsorption kinetics. The model of pseudo-second order was the one that best described the adsorption of all dye/organomodified-zeolites systems. The equilibrium adsorption was analyzed from four models isotherm, namely: Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-B). The results show that the model Freundlich and Langmuir best described the experimental data systems DB71/SMZF and DB71/SMZB, respectively. For systems with RB, the model D-R was the best fit for both adsorbents (SMZF and SMZB). The factorial design 24 was applied to the analysis of the following factors influencing the adsorption process: initial concentration of dye (Co), pH, amount of adsorbent (M) and temperature (T). Under the conditions studied it concludes with the confidence interval of 95%, which for the DB71/SMZF system, the factors and their interactions that influence more were C0, M, pH, pH*M, pH*C0, M*C0, pH*M*C0, in that order. In DB71/SMZB system, the order of influence was: M, C0, pH, pH*M, pH*C0, M*C0, pH*M*C0. For RB/SMZF and RB/SMZB systems, the results were: M, C0, M*C0, pH, pH*M and M, C0, M*C0, respectively. The adsorption equilibrium was attained in about 40 min for all samples. The DB71 removal percentages were in the range of 50 80% and 20 50% for ZML and ZMP, respectively. The range of RB removal percentages varied between 60 80% and 30 50% for ZML and ZMP, respectively.

>Magister Scientiae - MSc / Due to the rapid depletion of fossil fuel reserves and the production of environmentally harmful by-products such as carbon dioxide, there is an urgent need for alternate sustainable clean energy. One of the leading candidates in this endeavour is hydrogen, which can be used as an energy carrier since it has a high energy density, zero emissions and is produced from non-depletable resources such as water. The major challenge hindering a hydrogen economy is the lack of safe and effective storage technologies for mobile applications. A prospective solution to this problem lies in the use of porous powdered materials, which adsorb the hydrogen gas. However, the integration of these powdered materials into a storage tank system, results in the pipelines being contaminated during filling cycles. This necessitates the shaping of the porous powdered materials. Among the many shaping techniques available, the electrospinning technique has been proposed as a promising technology since it is a versatile process that is easily scaled-up making it attractive for the applications of the study. Furthermore, the electrospinning process enables the synthesis of nano-sized fibres with attractive hydrogen sorption characteristics. In this regard, the current study employs the electrospinning technique to synthesise electrospun composite fibres for mobile hydrogen storage applications. After electrospinning three polymers, polyacrylonitrile (PAN) was selected as the most suitable polymer because it yielded bead-free electrospun fibres. However, the diameter of the PAN fibres was large/thick which prompted further optimisation of the electrospinning parameters. The optimised electrospinning conditions that yield unbeaded fibres within the desired diameter range (of 300-500 nm) were a PAN concentration of 10 wt%, a flow rate of 0.4 mL/h, a distance of 10 cm between the needle tip and collector plate, and an applied voltage of 8 kV. The study then progressed to the synthesis and characterisation of the pristine porous powdered materials which adsorb hydrogen gas. The porous powdered materials investigated were commercial zeolite 13X, its synthesised templated carbon derivative (ZTC) and Zr (UiO-66) and Cr (MIL-101) based metal-organic frameworks (MOFs). ZTC was synthesised via liquid impregnation coupled with chemical vapour deposition (CVD), and the MOFs were synthesised by the modulated solvothermal method. Analysis of the ZTCs morphology and phase crystallinity show that the carbon templated process using zeolites was successful, however, ZTC was amorphous compared to crystalline zeolite template. The BET surface area was assessed with the aid of nitrogen sorption isotherms for both zeolite 13X and ZTC, and values of 730 and 2717 m²/g, respectively were obtained. The hydrogen adsorption capacity for zeolite 13X was 1.6 wt% and increased to 2.4 wt% in the ZTC material at 77 K and 1 bar. The successful synthesis of well defined, crystalline MOFs was evident from X-ray diffraction and morphological analysis. The BET surface area and hydrogen adsorption for Zr MOF were 1186 m²/g and 1.5 wt%, respectively at 77 K and 1 bar. Cr MOF had a BET surface area of 2618 m²/g and hydrogen adsorption capacity of 1.9 wt% at 77 K and 1 bar. The main focus of the study was to synthesise electrospun composite fibres that can adsorb hydrogen gas and thus provide significant insight in this field of research. As such it examined composite fibres that incorporates porous powdered materials such as zeolite 13X, ZTCs, UiO-66 (Zr) MOF and MIL-101 (Cr) MOF and investigated their ability to adsorb hydrogen gas, which have not been reported previously. The synthesis of composite fibres was achieved by incorporating the porous powdered materials into the PAN resulting in a polymeric blend that was then electrospun. Morphological analysis illustrated that the porous powdered materials were successfully supported by or incorporated within the PAN fibres, forming composite fibres. The BET surface area of the 40 wt% zeolite-PAN and 12.5 wt% ZTC-PAN composite fibres were 440 and 1787 m²/g respectively. Zr MOF and Cr MOF composite fibres had a BET surface area of 815 and 1134 m²/g, respectively. The BET surface area had reduced by 40, 34, 31 and 57% for zeolite 13X, ZTC, Zr MOF and Cr MOF, respectively after these porous powdered materials were incorporated into PAN. The hydrogen adoption capacity for 40 wt% zeolite-PAN, 12.5 wt% ZTC-PAN, 20 wt% Zr MOFPAN and 20 wt% Cr MOF-PAN composite fibres was 0.8, 1.8, 0.9 and 1.1 wt%, respectively. This decrease was attributed to the limited amount of porous powdered materials that could be incorporated into the fibres since only 40 wt% of zeolite 13X, 12.5 wt% of ZTC and 20 wt% of the MOFs were loaded into their respective composite fibres. This was due to the fact that incorporation of greater amounts of porous powdered materials resulted in a viscous polymeric blend that was unable to be electrospun. It is evident from the study that electrospinning is a versatile process that is able to produce composite fibres with promising properties that can potentially advance the research in this field thus providing a practical solution to the problem of integrating loose powdered materials into an on-board hydrogen storage system. / CSIR Young Researchers Establishment Fund (YREF)

The recognition of the negative impact of NOx resulted in increasingly tighter automotive emission regulations. Companies are under pressure to develop methods, which can meet the legislative demands. After treatment solutions, and especially Selective Catalytic Reduction, became the focus of research and have shown so far promising results. However, more in depth understanding of the SCR process under different conditions is needed. This thesis describes an investigation of the SCR performance using gas and urea injections under steady state and transient conditions undertaken on a light duty diesel engine using a 1D exhaust system designed for uniform flow across the catalyst. Under steady state conditions, the SCR performance was examined for low and high temperature conditions. Ammonia was supplied either as 5% ammonia gas or in form of urea injection. The engine was operating at 1500 rpm and 6 and 8 bar BMEP to provide an exhaust gas temperature of 210 °C and 265 °C respectively. Also, the effect of SCR brick length on the NOx conversion was investigated using SCR catalysts of length 30, 45 and 75 mm. To measure the influence of NO2:NOx ratio on the SCR performance, different sizes of standard DOC were used. NH3:NOx dosage levels included; α~0.5 - deficient ammonia, α~1.0 - stoichiometric ammonia, α~1.25 - excess ammonia. Gas emissions were measured before and after the SCR catalysts with a Horiba FTIR analyser during steady state and long transient tests. It was found that conditions such as temperature and NO2:NOx had the biggest impact on the SCR performance. During the steady state engine conditions, at α~1.0 ammonia dosing and NO2:NOx ratio of 0, only 17% of NO was converted in the first 30 mm of the SCR brick length. The conversion was improved at high temperature (263 °C) to 31%. A fast response CLD analyser was used during short transient testing to sample emissions with a high resolution. The short transient test with standard 0.5 and 1 DOC, and fixed ammonia dosing, showed that NOx conversion was reduced during the ramp event due to deficient ammonia and a drop in the supplied NO2:NOx ratio. During urea injection experiments, urea was injected either through an oblique pipe arrangement with a mixer device placed downstream or directly into a mixing can. In this case the mixer device was replaced with a straight pipe. A 75mm SCR was fitted and to ensure that supplied NO2:NOx ratio was zero, a palladium only DOC was used post a DPF. It was found that a large proportion of urea decomposition and hydrolysis was occurring on the surface of the SCR catalyst. Comparing NOx performance between urea injection and ammonia gas dosing experiment, more NO was converted for a given NH3:NOx ratio when ammonia was supplied in the form of gas. That was true for low and high temperature tests. For most studies, a long 10 degree diffuser was used in front of the SCR to provide uniform gas distribution across the catalyst. In addition SCR performance was investigated with a 180 degree sudden expansion diffuser in order to measure the influence of temperature and velocity profiles. During this study, a 45 mm SCR catalyst was used to provide a moderate amount of NO conversion and ammonia slip. The results showed that the flow and temperature distribution upstream of the SCR catalyst will have an effect on the NOx conversion, and that gas velocity has bigger impact on NOx conversion than gas temperature.

>Magister Scientiae - MSc / In South Africa coal combustion constitutes up to 90 % of the country’s energy need. This coal combustion activity is known to contribute to the amount of about 40 % of the total CO2 atmospheric emissions worldwide that are responsible for global warming effects. In addition burning of coal generates a large quantity of fly ash which creates environmental pollution since only a small portion of it is currently used in some applications. In order, on one hand to mitigate and sequester CO2 and on the other hand to reprocess fly ash and reuse it, this study focuses on developing new technologies with cost-effective and less energy consumption in the domain of CO2 capture and sequestration. CO2 has priority attention for being the largest contributor to global warming. Various techniques have been used for CO2 capture and sequestration, such as aqueous alkylamine absorption or adsorption onto a solid adsorbent such as zeolites. In this study NaA zeolite adsorbent was hydrothermally synthesised from South African fly ash. This fly ash based NaA zeolite was then used as starting material to prepare LiA, CaA, and MgA zeolite catalysts via ion-exchange for comparative CO2 adsorption capacity. A systematic design of the ion-exchange procedure was undertaken at either 30 °C or 60 °C for a contact time of 1 hr, 4 hrs, and 8 hrs with 1, 2 and 3 consecutive exchanges in each case in order to determine the optimum conditions for loading each cation exchanged. The adsorption of CO2 on the ion- exchanged fly ash based zeolite-A catalysts was carried out at 40 °C similar to the temperature of flue gas since the catalysts obtained in this study were also prepared with a view to their applications in flue gas system. The CO2 desorption temperature ranged between 40-700 °C. All materials used in this study, starting from fly ash feedstock, werecharacterized using various techniques to monitor the mineral and structural composition, the morphology, surface area and elemental composition and the adsorption capacity. The techniques included mainly Fourier transform infra-red, X-ray diffraction, Scanning electron microscopy, Transmission electron microscopy, Energy dispersive spectroscopy, X-ray fluorescence, Temperature programmed desorption.The results obtained from both Fourier transform infra-red and the X-raydiffraction spectroscopy for samples exchanged at either 30° C or 60 °C showedlower crystallinity in CaA and MgA zeolite samples. This decrease in crystallinitymainly affected the D4R (0-20° 2) and was demonstrated in the study to beinversely proportional to the increase of the atomic radius of cations (Li+ > Mg2+ >Ca2+). In the Fourier transform infra-red, the vibration band at 677 cm-1 attributedto the extra-framework cation, also proportionally increased with the decrease ofthe atomic radius or size of the cations, and was intense in LiA zeolite samples.

Zeolite catalysis plays an important role in many industrial applications due to their unique properties and has become widely used in the area of oil refining. Of particular interest is Zeolite Y, which can be hydrothermally treated into its ultrastable form, USY. USY offers a superior practicality, especially when dealuminated and metal-loaded. The importance of alkanes hydroisomerization arises from the continuingly stricter regulations imposed on the utilization of gasoline as an automotive fuel. The requirements to reduce the aromatics content in gasoline present a need to find an alternative way to maintain its research octane number (RON). An alternative to gasoline's high-octane aromatic content is to increase the RON for the paraffinic content of gasoline, which can be accomplished through hydroisomerization. Commercially, bifunctional metal-loaded zeolites are used to hydroisomerize the light naphtha stream produced at overheads of atmospheric distillation towers. However, no such process exists for the low-value heavy naphtha cut. This targeted process would, if successful, greatly improve refiner's profitability.In this work, bifunctional USY zeolite catalysts are studied in the hydroisomerization of a normal alkane (nC7, RON = 0). This nC7, found in heavy naphtha, has been used as the 'model' compound. The impact of different reaction conditions and catalyst properties on catalyst activity and stability, in addition to the catalyst selectivity to high octane isomers is one step towards determining optimum conditions and preferential catalyst formulations that favour octane maximization. Six platinum-loaded USY zeolite catalysts, four in-house and two commercial, were tested in an atmospheric glass fixed-bed reactor and a stainless steel reactor purpose-built during the course of this thesis. Reaction temperatures ranged from 170 to 250oC at pressures between 1 and 15 bar. The hydrogen to hydrocarbon molar ratio was fixed at 9, with feed space time ranging from 35.14 to 140.6 kg.s/mol. In-house catalysts were hydrothermally treated at different severities, while commercial ones were originally dealuminated through acid-leaching treatments.Results have shown commercial catalyst CBV-712 gave the best performance and highest octane values for product isomers (>30). In addition, there was no coke generation. The next best catalyst was the most severely steamed in-house catalyst (USY-D) that has shown a remarkable performance at high pressures, almost eclipsing the performance of CBV-712, yet produced higher levels of coke. Other USY catalysts tested were less robust during reactions, probably due to imbalance in their acidic to metallic functions, or diffusion limitations arising from their pore structures. The best catalysts were, nonetheless, highly sensitive to sulfur presence in the feed, which severely impacted their activity, especially their metallic functions, and thus require sulfur-free feeds in order to demonstrate their full capacities. Simple kinetic modelling of experimental data was performed using the initial rates method and estimation of kinetic parameters, whose values were in good agreement with previous literature.

Several members of the ABC-6 zeolite family, namely offretite, zeolite T, ZSM-34 and zeolite L, were synthesised with a view to studying the effect of synthetic parameters on the resulting crystal properties. A range of procedures for producing offretite and ZSM-34 were tested, and crystals with the optimal morphology, purity, crystallinity and size identified. A standard procedure for synthesising zeolite T was used, before the effect of systematically altering the cation concentration, Si/Al ratio and water content in the synthesis mixture was studied, and the optimal composition identified. Ex-situ AFM was used to study the morphology of the resulting crystals, as well as to determine information about surface features, such as the shape and height of terraces. This information could be used to infer the growth mechanism for each crystal. The AFM studies of zeolite L were compared with those of previous studies and found to agree. For offretite, zeolite T and ZSM-34, 1.2 nm high terraces elongated along the length of the {100} face of the crystals were observed. Where the crystals exhibited a micro-crystalline morphology without distinct faces HR-SEM was used to study their morphology and terracing. In-situ AFM was used to study the dissolution of the crystals in basic media. In each case the terraces were observed to dissolve primarily length-wise. The dissolution of terraces on zeolite T was considered in particular detail. The terrace height was measured during dissolution, and three distinct measurements were observed, 1.2, 0.8 and 0.2 nm. These heights were related to framework features. Lateral force AFM measurements were used to show the relationship between decreased terrace height and increased lateral deflection, indicating that dissolving areas of crystal exhibited increased tip-sample friction. The rate of dissolution of terraces on zeolite T was also considered. It was found that dissolution rate increased with increasing NaOH concentration, and with increasing tip-sample force in the AFM. These observations allowed order of reaction for the dissolution process of zeolite T to be estimated at 2.54. A magnesium substituted aluminophosphate ABC-6 family zeotype material, MgAPO-CJ60, was also synthesised and analysed. Solid-state NMR was used to determine the distribution of aluminium and phosphorous within the framework, which was found to be non-random.

Mankind makes extensive use of crude oil to fuel its insatiable demands for energy and hydrocarbon derivatives. The refining of crude oil is based on a process known as cracking, where long-chain hydrocarbons are systematically broken into smaller chain hydrocarbons known as fractions with each fraction allowing for the production of a specific material. The maximum efficiency of cracking can be achieved in the petroleum refining processes by controlling the operating parameters of the units, and over the years many studies have attempted to optimize the cracking conditions such as temperatures, pressures and the use of a variety of catalysts to reach maximum productivity. Catalysts such as the Y-type zeolite catalysts are often used because their acidity and thermal stability makes them an ideal cracking catalyst; however the developments of enhanced catalytic properties for zeolite-Y catalysts are essential to increase the production yields. Optimization of the Y-type zeolite catalyst is the focus of this research and accordingly the synthesis, characterization, modifications and catalysis have been studied in depth. A review of the literature has shown that there are three main techniques used to improve the zeolite properties following the synthesis process; (Cation exchange, Dealumination and Desilication), since the crystalline structure of a Y-type zeolite is prepared from an alkaline aluminosilicates gel. However, the literature focuses mainly on the reaction variables used in the modifications. As such this study focuses on the effects of treatment processes on the composition, behaviour and catalytic properties of the synthesized Y-zeolite framework. Laboratory experimental data has confirmed that a synthesis process using 24 h aging for crystal nuclei at 25 °C and 18 h crystallization time for crystal growth at 100 °C produced the desired zeolite NaY morphology, and NaNH4Y zeolite forms with various cation contents (3, 1.5 and 0.5 wt% Na+) were obtained by subjecting the NaY form to a multi-stage ion exchange using 0.5 M NH4NO3 at 80 °C, while the HY form was obtained by the calcination of NH4Y form under high temperature. Calcination temperatures above 450 °C were shown to indicate a removal of the framework hydroxyl groups via dehydroxylation, which led to a collapse of zeolite-Y structure, whereas raising the level of Na+ inside the zeolite lattice throughout the calcination was led to a delay in the starting point of the dehydroxylation region as confirmed via TG and DSC-analyses. This finding was also used in the preparation of the USY form by steaming the HY form, as the former is a traditional zeolite-Y form utilized in the refining units. It was found that Na-ions hindered the extraction of Al-atoms from the Y-lattice thus reducing the rate of dehydroxylation, and minimising rapid contraction of the unit cells and Y-structure collapse, which helped make a rigid structure and a more resilient lattice for steaming at high temperature. In addition, analyses data confirmed that the extraction of EFAl-species from the USY-structures using an EDTA chemical treatment led to an increase in the acidity of treated catalyst and the introduction of mesopores. Lower lattice Si/Al ratio and larger porosity were also found using the dealuminated-desilicated rather than the desilicated-dealuminated leaching method in the treatment of both Y and USY structures via dislodgement of both Si and Al-atoms in NaOH and HCl solution. Cracking was performed on deactivated catalysts (450 °C) in a PFTR using nC7 in N2 at 325 - 425 °C and W/F = 22 - 44 g.h.mol-1, and confirmed that the tuned steaming/leaching conditions succeeded in modifying the catalytic properties of the in house made catalysts, as they possess superior performance when compared to the industrial catalysts typically used.

Carbon dioxide levels in atmosphere are linked with a number of adverse environmental impacts including climate change. CO2 utilization is one of the available technologies to reduce CO2 emissions released into atmosphere by its conversion into value added products. Hydrogenation of CO2 into hydrocarbons (with methanol being an intermediate) can be achieved in a single-pot using bi-functional catalysis system composed of metal/metal-oxide and zeolite. In this study, activated novel indium cobalt (InCo) and zeolite beta samples (BEA) were used for the conversion of CO2 into a hydrocarbon mixture rich of iso-paraffins via methanol in a single pot. The objective was to investigate the effect of zeolite beta acidity (represented by SiO2/Al2O3 ratio) and the configuration of the reactor on the overall performance of the above mentioned bi-functional system. Three samples of zeolite beta with different SiO2/Al2O3 ratios were synthesized in-house (Beta-20, Beta-100 and Beta-300) and used along with commercial beta as methanol to hydrocarbons catalysts. XRD patterns of the synthesized samples showed that all of the obtained samples are zeolite beta with high crystallinity. Adsorption-desorption isotherms of the studied zeolites revealed micro-mesoporosity of the samples. Analysis of SEM images suggests that the particles of the studied samples are of a similar range of size (100-200 nm). Each zeolite sample was used to fill two reactor configurations: dual bed and mixed bed. Samples were tested at a temperature of 300 oC, a pressure of 50 bar and CO2:H2 ratio of 1:4 except for Beta-100 sample which was tested at a CO2:H2 ratio of 1:3. CO2 conversion is a characteristic of the methanol synthesis catalyst (InCo) and it ranged between 15% to 20% for all cases. Dimethyl ether (DME) generation in dual bed configuration was much faster and at much higher rates than in mixed bed configuration for all tested samples, indicating that mixed bed configuration is more stable for this particular system. Heavier hydrocarbons (C6 and C7) are generated in higher amounts over low acidic zeolite beta than over beta of high acidity. More acidic zeolite beta, however, was found to be more stable than beta of less acidity.

abstract: Nanostructured zeolites, in particular nanocrystalline zeolites, are of great interest due to their efficient use in conventional catalysis, separations, and emerging applications. Despite the recent advances, fewer than 20 zeolite framework types have been synthesized in the form of nanocrystallites and their scalable synthesis has yet to be developed and understood. Geopolymers, claimed to be “amorphous cousins of zeolites”, are a class of ceramic-like aluminosilicate materials with prominent application in construction due to their unique chemical and mechanical properties. Despite the monolith form, geopolymers are fundamentally nanostructured materials and contain zeolite nanocrystallites. Herein, a new cost-effective and scalable synthesis of various types of nanocrystalline zeolites based on geopolymer chemistry is presented. The study includes the synthesis of highly crystalline discrete nanorods of a CAN zeolite framework structure that had not been achieved hitherto, the exploration of the Na−Al−Si−H2O kinetic phase diagram of hydrogels that gives SOD, CAN and FAU nanocrystalline zeolites, and the discovery of a unique formation mechanism of highly crystalline nanostructured FAU zeolite with intermediate gel products that possess an unprecedented uniform distribution of elements. This study demonstrated the possibility of using high-concentration hydrogels for the synthesis of nanocrystalline zeolites of additional framework structures. Moreover, a comprehensive study on nanostructured FAU zeolites ion-exchanged with Ag+, Zn2+, Cu2+ and Fe2+ for antibacterial applications is presented, which comprises metal ion release kinetics, antibacterial properties, and cytotoxicity. For the first time, superior metal ion release performance was confirmed for the nanostructured zeolites compared to their micron-sized counterparts. The metal ion-exchanged FAU nanostructured zeolites were established as new effective antibacterial materials featuring their unique physiochemical, antibacterial, and cytotoxic properties. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2019

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