Recent study has shown that ruthenium(III) acetylacetonate acts as a homogeneous catalyst in the hydrolysis of sodium borohydride. When two equivalents of trimethylphosphite per ruthenium is added to the reaction solution containing sodium borohydride and ruthenium(III) acetylacetonate in the mixture of water and tetrahydrofuran, the rate of hydrogen generation is practically stopped (or reduced to the level of self hydrolysis). However, the catalytic hydrogen evolution of sodium borohydride restarts at an unexpectedly high rate in a certain period of time (induction time) after addition of trimethylphosphite. Consequently, trimethylphosphite known to be a poison in the hydrolysis, is involved in the formation of a new active catalyst (ruthenium species containing trimethylphosphite ligands) which has much higher catalytic activity in comparison with sole ruthenium(III) acetylacetonate. The same rate enhancement is observed by addition of two equivalents of triphenylphosphite per ruthenium into the medium. Varying the phosphorus compound affects not only the life time of catalyst but also the kinetic and activation parameters of the hydrolysis of sodium borohydride. However, varying the mole ratio of phosphorus compound to ruthenium does not affect the rate of hydrolysis or in other words, the rate of hydrogen generation is independent of phosphite concentration. Trans- and cis-[Ru(acac)2{P(OMe)3}2] complexes do not show significant catalytic activity in hydrogen generation of sodium borohydride. However, catalytic activity of cis-isomer is highly increased in the presence of two equivalents of trimethylphosphite, showing that the active catalyst formed during hydrolysis of sodium borohydride starting with Ru(acac)3 or cis-[Ru(acac)2{P(OMe)3}2], has more than two phosphine ligands. For the first time, a ruthenium(I) complex was isolated from aqueous solution after finishing the catalytic hydrolysis of sodium borohydride starting with ruthenium(III) acetylacetonate and trimethylphosphite. Hydridotetrakis(trimethylphosphite)ruthenium(I), [Ru{P(OMe)3}4H] was isolated and characterized by single crystal X-ray diffraction, Mass, UV-visible, FTIR, 1H, 13C and 31PNMR spectroscopy. Following the catalytic reaction by UV-Visible spectroscopy shows in-situ formation of a Ru(II) species which is mostly converted back to ruthenium(III) acetylacetonate after hydrolysis reaction along with formation of [Ru{P(OMe)3}4H] complex as a minor product. Although Ru(II) species could not be isolated, adding 1 equivalent of 2,2&#039 / -bipyridine yielded [Ru(acac)(bipy){P(OMe)3}H] complex which could be isolated and characterized by Mass, UV-Visible, FTIR, 1H, 13C and 31PNMR spectroscopy. In-situ generated Ru(II) species has much higher catalytic activity in comparison with its stabilized form [Ru(acac)(bipy){P(OMe)3}H] or [Ru{P(OMe)3}4H] complex. Conclusively, the fac-[Ru(acac){P(OMe)3}3H] complex is believed to be the in-situ generated Ru(II) species and the active catalyst in the hydrolysis of sodium borohydride.

Zeolites are microporous crystallines with well defined structures. Zeolites are used in variety of applications because of their properties such as high temperature stability, ion-exchange capacity, adsorption capacity and stability to harsh conditions. Some major applications of zeolites are ion-exchange, catalysis, adsorption and separation. Synthetic zeolites are normally produced as fine crystalline powder. Prior to their use, the powder is usually formed into spheres, tablets and extrudates by addition binder. Since binders present in the zeolite can block the pores and decrase the adsorption properties, preparation binderless zeolite agglomerates with high mechanical stability has great technological importance. Objective of the study is to synthesize binderless zeolite X tubular macrobodies by using the developed methods for the synthesis of zeolite A bars and tubes. Main steps of the study are synthesis of the tubular binderless zeolite X macrobodies, characterization of the macrobodies, determination the effect of hydrogel composition on zeolite phase and analyzing effect of time on the crystallinity of macrobodies. Experimental method for synthesizing the binderless tubular zeolite X macrobodies includes the following steps / preparing hydrogel by mixing sodium aluminate and sodium silicate solutions, filtration of the hydrogel, paste preparation from solid phase of the hydrogel, extrusion of green tubes from paste, calcination of green tubes and crystallization of calcined tubes in filtered liquid of the hydrogel. In this study, synthesis of binderless tubular pure zeolite X macrobodies with high crystallinity was achieved. Micropore volume and BET surface area of the zeolite X tubular macrobody I&Ccedil / S-18, which has 99.9 % crystallinity were determined as 0.178 cm3/g and 631.2 m2/g, respectively. Pure zeolite X, pure zeolite A and zeolite A, X mixtures were obtained after the crystallization of the calcined extrudates which were obtained from different hydrogel compositions. Ternary diagram which was based on the hydrogel compositions and the obtained zeolite phases was plotted.

Transition metal nanoclusters are more active and selective catalysts than their bulk counterparts as the fraction of surface atoms increases with the decreasing particle size. When stabilized in organic or aqueous solutions, they can catalyze many reactions. The catalytic activity of metal nanoclusters depends on the particle size and size distribution. Particle size can be controlled by encapsulating the nanoclusters in the cavities of highly ordered porous materials such as zeolites. In this project, osmium(0) nanoclusters were formed within the void spaces of zeolite. Thus, nanoclusters of certain size were prepared as supported catalyst. Osmium(III) cations were introduced into the cavities of zeolite by ion exchange and were reduced partially or completely to form intrazeolite osmium(0) nanoclusters. The intrazeolite osmium(0) nanocusters were characterized by HRTEM, TEM, EDX, XPS, XRD, ICP-OES spectroscopic methods and N2 adsorption-desorption technique. Intrazeolite osmium(0) nanoclusters were employed as catalyst in the aerobic oxidation of alcohols in organic solution.

Amine boranes have recently been considered as solid hydrogen storage materials with high capability of hydrogen storage. Dimethylamine borane is one of the promising amine boranes with high theoretical gravimetric capacity of 16.9 wt%. Dimethylamine borane can undergo dehydrogenation only in the presence of a suitable catalyst at moderate temperature. In this project, throughout the dehydrogenation of dimethylamine borane (DMAB), the catalytic activity of ruthenium(III) acetylacetonate was examined for the first time. During the catalytic reaction, formation of a new in-situ ruthenium(II) species, [Ru{N2Me4}3(acac)H], is observed. Mercury poisoning experiment indicates that the in-situ ruthenium(II) species is a homogeneous catalyst in the dehydrogenation of dimethylamine borane. Kinetics of catalytic dehydrogenation of dimethylamine borane starting with ruthenium(III) acetylacetonate was investigated depending on catalyst concentration, substrate concentration and temperature. As a result, the hydrogen generation rate was found to be first-order with respect to catalyst concentration and zero-order regarding the substrate concentration. Besides, evaluation of the kinetic data yielded that the activation parameters for dehydrogenation reaction: the activation energy, Ea = 85 &plusmn / 2 kJ&bull / mol-1 / the enthalpy of activation, DH# = 82 &plusmn / 2 kJ&bull / mol-1 and the entropy of activation / DS# = -85 &plusmn / 5 J&bull / mol-1&bull / K-1. Additionally, before deactivation, [Ru{N2Me4}3(acac)H] provides 1700 turnovers over 100 hours in hydrogen evolution from the dehydrogenation of dimethlyamine borane. [Ru{N2Me4}3(acac)H] complex formed during the dehydrogenation of dimethylamine borane was isolated and characterized by UV-Visible, FTIR, 1H NMR, and Mass Spectroscopy. The isolated ruthenium(II) species was also tested as homogeneous catalyst in the dehydrogenation of dimethylamine borane.

The production of transition metal(0) nanoparticles with controllable size and size distribution are of great importance in catalysis since their catalytic activity decreases as nanoparticles aggregate into clumps and ultimately to the bulk metal. Reducing the particle size of heterogeneous catalyst provides a significant rise in its activity as the fraction of surface atoms increases with decreasing particle size. Therefore, transition metal(0) nanoparticles need to be stabilized to certain extend in their catalytic applications by strong stabilizers. In this regard, tert-butylammonium octanoate [(CH3)3CNH3+][CH3(CH2)6COO-] seems to be an appropriate stabilizer for rhodium(0) nanoparticles since octanoate anion and its associated tert-butylammonium cation can provide a sufficient protection for rhodium(0) nanoparticles against aggregation by the combined electrostatic and steric effects. We report herein the preparation and characterization of rhodium(0) nanoparticles stabilized by tert-butylammonium octanoate and their catalytic use in the dehydrogenation of ammonia borane, H3NBH3, which appears to be the most promising hydrogen storage material due to its high hydrogen content (19.6 wt %). Rhodium(0) nanoparticles stabilized by tert-butylammonium octanoate were reproducibly prepared by the reduction of rhodium(II) octanoate dimer with tert-butylamine borane in toluene at room temperature and characterized by EA, XRD, ICP/OES, TEM, HRTEM, STEM, FTIR, XPS, UV-VIS and NMR spectroscopy. The new rhodium(0) nanoparticles is the first example of well-defined, reproducible, and isolable true heterogeneous catalyst used in the dehydrogenation of ammonia borane. They show record catalytic activity in the dehydrogenation of ammonia borane at room temperature with an apparent initial TOF value of 342 h-1 and TTO value of 1100.

Because of the growing concerns over the depletion of fossil fuel supplies, environmental pollution and global warming caused by a steep increase in carbon dioxide and other greenhouse gases in the atmosphere, much attention has been given to the development of renewable energy sources that are the only long-term solution to the energy requirements of the world&rsquo / s population, on the way towards a sustainable energy future. Hydrogen has been considered as a clean and environmentally benign new energy carrier for heating, transportation, mechanical power and electricity generation. However, the lack of effective, safe, and low-cost hydrogen storage materials for mobile, portable, and stationary applications is one of the major hurdles to be overcome for the implementation of hydrogen economy. Among various solid state hydrogen storage materials, chemical hydrogen storage materials such as sodium borohydride (NaBH4) and ammonia borane (H3NBH3) have received much attention as promising candidates for fuel cell applications under ambient conditions due to their high gravimetric and volumetric hydrogen storage capacities. Both sodium borohydride and ammonia borane generate hydrogen upon hydrolysis in the presence of suitable metal catalysts. Transition metal nanoclusters can be used as active catalysts to catalyze the hydrolysis reactions of sodium borohydride and ammonia borane for hydrogen generation since they exhibit unique properties that differ from their bulk counterparts. Although the catalytic activity of metal nanoclusters increases with decreasing particle size, they are unstable with respect to agglomeration into the bulk metal leading to a significant decrease in activity in their catalytic applications. Therefore, the exploitation of microporous and mesoporous materials with ordered porous structures as hosts to encapsulate metal nanoclusters has attracted great interest since the pore size restriction of these host materials could limit the growth of nanoclusters leading to an increase in the percentage of the catalytically active surface atoms. In this dissertation, we report the preparation, characterization and the investigation of the catalytic activities of zeolite confined cobalt(0) nanoclusters in the hydrolysis of sodium borohydride and ammonia borane. The zeolite confined cobalt(0) nanoclusters were prepared by the reduction of cobalt(II)-exchanged zeolite-Y by sodium borohydride in aqueous solution at room temperature with no alteration in the framework lattice or loss in the crystallinity. The characterization of zeolite confined cobalt(0) nanoclusters were done by using inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-visible spectroscopy (DR-UV-Vis), infrared spectroscopy (IR), Raman spectroscopy, and N2 adsorption-desorption technique. The catalytic activity of zeolite confined cobalt(0) nanoclusters and the kinetics of hydrogen generation from the hydrolysis of sodium borohydride and ammonia borane were studied depending on catalyst concentration, substrate concentration and temperature. The rate laws and the activation parameters (Arrhenius activation energy, Ea / activation enthalpy, &Delta / H# / and activation entropy, &Delta / S#) for both catalytic hydrolysis reactions were calculated from the obtained kinetic data.

The property transition metal nanoclusters are more active catalysts than their bulk counterparts because of increasing proportion of surface atoms with decreasing paricle size. The development of efficient and economical catalysts to further improve the kinetic properties under moderate conditions is therefore important for the practical application of nanoclusters as catalyst in the hydrogen generation from hydrolysis of ammonia borane this. In this regard, the development of active iron catalysts is a desired goal because it is the most ubiquitous of the transition metals, the fourth most plentiful element in the Earth&rsquo / s crust. In this dissertation, we report the preparation, characterization and investigation of the catalytic activity of the water soluble polymer stabilized iron(0) nanoclusters. They were prepared from the reduction of iron(III) chloride by a mixture of sodium borohydride (NaBH4, SB) and ammonia borane (H3NBH3, AB) mixture in the presence of polyethylene glycol (PEG) as stabilizer and ethylene glycol as solvent at 80 &deg / C under nitrogen atmosphere. PEG stabilized iron(0) nanoclusters were isolated from the reaction solution by centrifugation and characterized by SEM, EDX, TEM, HRTEM, XRD, UV-Vis, ICP-OES and FT-IR techniques. PEG stabilized iron(0) nanoclusters have almost uniform size distribution with an average particle size of 6.3 &plusmn / 1.5 nm. They were redispersible in water and yet highly active catalyst in hydrogen generation from the hydrolysis of AB. They provide a turnover frequency of TOF = 6.5 min-1 for the hydrolysis of AB at 25.0 &plusmn / 0.5 &deg / C. The TOF value is the best ever reported among the Fe catalyst and comparable to other non-noble metal catalyst systems for the catalytic hydrolysis of AB. Kinetics of hydrogen generation from the hydrolysis of AB in the presence of PEG stabilized iron(0) nanoclusters were also studied by varying the catalyst concentration, substrate concentration, and temperature. This is the first kinetic study on the hydrolysis of AB in the presence of an iron catalyst. Moreover, PEG stabilized iron(0) nanoclusters can be separated magnetically from the catalytic reaction solution by using a magnet and show catalytic activity even after tenth run.

Metal coordinated polymer nanocomposites have gained great attention due to their superior characteristics. Polymethylmethacyrlate (PMMA) is the most commonly used polymer since it is easily processed. In this study, modified TiO2 nanoparticles prepared by insitu and exsitu methods were embedded into PMMA in order to improve its thermal stability and the effects of TiO2 nanoparticles on thermal characteristics of PMMA were investigated by direct pyrolysis mass spectrometry. The insitu method which is a sol gel method, TiO2/SiO2 nanoparticles were synthesized by mixing titanium(IV) tetraisopropoxide, TTIP, with silane coupling agent, 3-(3-methoxysilyl)methylmetacrylate, MSMA in absolute ethanol. In exsitu method, TiO2 powder was directly mixed with silane coupling reagent. TiO2/SiO2 nanoparticles were embedded into the PMMA by direct mixing resulting in exsitu and insitu TiO2/SiO2/PMMA nanocomposites. The synthesized TiO2/SiO2/PMMA nanocomposites were characterized by TEM, ATR-FT-IR and analyzed for the investigation of their reaction mechanism and thermal characteristics by pyrolysis mass spectroscopy. iv TEM images confirmed the formation of TiO2/SiO2 nanoparticles and TiO2/SiO2/PMMA nanocomposites and indicated that the average particle size of TiO2/SiO2 nanoparticles was around 6 nm whereas average particle size of SiO2/TiO2/PMMA nanocomposites were around 25 nm. The increase in the size of nanoparticles is associated with incorporation of TiO2/SiO2 nanoparticles into PMMA matrix. ATR-FTIR spectrum of 5% TiO2/SiO2/PMMA nanocomposites showed the formation of TiO2/SiO2 nanopartciles clearly. Pyrolysis mass spectrometry analysis revealed that incorporation of TiO2/SiO2 nano- particles into PMMA resulted in higher thermal stability only for low weight percentage insitu TiO2/SiO2/PMMA. At high weight percentages a decrease in thermal stability was detected. On the other hand, in case of exsitu TiO2/SiO2/PMMA, contrary to our expectations a decrease in thermal stability was detected. The decrease in thermal stability was attributed to evolution of methacrylic acid during thermal degradation of silane groups.

There are several studies in order to control drug delivery, decrease the toxicity of drugs and also for novel biomedical applications. It is necessary to be able to control the release of the drug within the body by using drug delivery systems. Mesoporous silica compounds have only been discovered twenty years ago and they have already attracted many researchers to study these materials for several applications. SBA-15 particles have a highly ordered regular structure and are a good matrix for guest-host applications. The aim of this study is to be able to address whether the surface functionalization of SBA-15 samples would improve the loading of a drug into these particles. The synthesized SBA-15 particles were surface functionalized by post - grafting synthesis method in order to be used as carrier materials for drug delivery. Amoxicillin was used as a model drug. These mesoporous materials have been characterized using X-ray diffraction (XRD), small-angle X-ray spectroscopy (SAXS), fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), N2 adsorption/ desorption, solid-state silicon nuclear magnetic resonance (Si-NMR), high-performance liquid chromatography (HPLC), ultra-violet (UV) spectroscopy, elemental and thermo gravimetric analysis (TGA). The effect of concentration difference and the type of alkoxysilanes used for the functionalization have been discussed in terms of loading amoxicillin and controlling the delivery. Drug delivery systems have many further applications that still need to be investigated in areas such as neurosciences, cancer and biomedical engineering.

This dissertation presents the preparation and characterization of rhodium(0) nanoparticles supported on hydroxyapatite, and investigation of their catalytic activity in hydrogen generation from the hydrolysis of hydrazine-borane and ammonia-borane. Rh+3 ions were impregnated on hydroxyapatite by ion-exchange / then rhodium(0) nanoparticles supported on hydroxyapatite were formed in-situ during the hydrolysis of hydrazine-borane at room temperature. The rhodium(0) nanoparticles supported on hydroxyapatite were isolated as black powders by centrifugation and characterized by ICP-OES, SEM, TEM, EDX, XRD, XPS, and N2 adsorption-desorption spectroscopy. Rhodium(0) nanoparticles supported on hydroxyapatite have a mean particle size of 2.7&plusmn / 0.7 nm. The catalytic activity of rhodium(0) nanoparticles supported on hydroxyapatite was tested separately in the hydrolysis of hydrazine-borane and ammonia-borane. The hydrolysis of hydrazine-borane was started by adding the precatalysts, Rh+3-exchanged hydroxyapatite into the aqueous solution of hydrazine-borane / whereas, the hydrolysis of ammonia-borane was initiated by adding the catalyst rhodium(0) nanoparticles supported on hydroxyapatite which have been isolated from the first run of hydrolysis of hydrazine-borane. Rhodium(0) nanoparticles supported on hydroxyapatite provide a turnover frequency value of 6700 h-1 in the hydrolysis of hydrazine-borane at room temperature. The reuse experiments reveal that these supported nanoparticles are isolable, bottlable, and redispersible in solution. Furthermore, they retain 62 % of their initial activity at the fifth run in the hydrolysis of hydrazine-borane with release of 3 equivalents hydrogen. Activity of rhodium(0) nanoparticles supported on hydroxyapatite is maintained after the redispersion of the sample and 3 equivalents hydrogen generation from the hydrolysis of ammonia-borane confirms the activity of preformed catalyst. Rhodium(0) nanoparticles supported on hydroxyapatite provide a turnover frequency value of 3990 h-1 in the hydrolysis of ammonia-borane at room temperature.