Transfer hydrogenation has been recognized to be an important synthetic method in both academic and industrial research to obtain valuable products including alcohols. Transition metal catalysts based on precious metals, such as Ru, Rh and Ir, are typically employed for this process. In recent years, iron-based catalysts have attracted considerable attention as a greener and more sustainable alternative since iron is earth abundant, inexpensive and non-toxic. In this work, a combination of iron disulfide with chelating bipyridine ligand was found to be effective for the transfer hydrogenation of a variety of ketones to the corresponding alcohols in the presence of a simple base. It provided a convenient and economical way to conduct transfer hydrogenation. A plausible role of sulfide next to the metal center in facilitating the catalytic reaction is demonstrated.

Zeolite-supported transition metal catalysts, which couple the unique size- and shape-selectivity arising from the well-defined microporous structure of zeolites with the inherent high activity of metal species, have demonstrated remarkable performance in numerous catalytic reactions. Conventionally, such catalysts are prepared by loading metal species in the micropores of zeolites in the form of clusters (each containing only several atoms). Despite their high catalytic activity, the ultra-small clusters are usually highly mobile, and tend to migrate from the micropores to the crystal surfaces of zeolite during the reaction, where they agglomerate and deactivate. In this dissertation, we attempted to solve this issue by encapsulating metal nanoparticles (NPs) in zeolite crystals, based on the following considerations: (i) compared to clusters, nanoparticles have similar catalytic activity but much less mobility; and (ii) as long as the active sites are inside the zeolite crystals (not necessarily in the micropores that are too small to accommodate nanoparticles), they can exhibit selectivity associated with the zeolite structure. In the first chapter, we gave a general introduction to zeolites and zeolite supported catalysts, focusing on the preparation of hierarchical zeolites that are the main catalyst support materials used in the research projects of this dissertation. In the second chapter, we encapsulated highly dispersed Pd NPs (~2.6 nm) in zeolite ZSM-5 crystals, and used the obtained catalyst (Pd@SG-ZSM-5) for the hydrogenation of cinnamaldehyde. The confinement effect gave rise to an interesting catalytic behavior: compared with the traditional supported Pd catalyst prepared by impregnation, Pd@SG-ZSM-5 showed a 2.5-fold enhancement in the selectivity of hydrocinnamaldehyde (73% vs. 30%). Liquid adsorption combined with infrared spectroscopy characterization revealed that Pd@SG-ZSM-5 catalyst adsorbs much less reactant and product molecules than traditional catalyst, thereby suppressing the formation of by-products and leading to high selectivity. In chapter three, we developed a new method to encapsulate in situ produced molybdenum carbide (MoCx) in zeolite ZSM-5 for the methane dehydroaromatization (MDA) reaction. In this method, the structure-directing agent used to synthesize hierarchical zeolite ZSM-5 was utilized to reduce molybdenum precursor through a calcination process in an inert atmosphere. The zeolite subsequently underwent a secondary growth process to achieve encapsulation. The catalytic behavior of the as prepared catalyst in MDA consolidate our previous conclusion that MoCx particles outside the microporous channels can also act as the active sites for MDA, whereas it is traditionally viewed that only MoCx clusters inside the micropores are active sites. In addition, the encapsulation strategy allowed us to design experiments to answer one open question related to MDA, namely whether the Brønsted acid (BA) sites of the zeolite play a catalytic role in the conversion of methane to aromatics or only promote the dispersion of the Mo species. We encapsulated MoCx particles, which had proven to be active sites, in pure siliceous zeolite (Silicalite-1) that does not contain BA sites. The catalyst did not exhibit MDA activity even when aromatic compounds were introduced into the system by pre-adsorption or co-feeding, indicating that the BA sites are responsible for the oligomerization/cyclization step during MDA. Finally, in chapter five, we summarized the dissertation and gave our perspectives and outlooks on the further development of encapsulated catalysts based on zeolites.

The purpose of the present investigation was to examine the various analytical methods to ascertain the suitability of the methods for our use in determining the amount of rhenium used in our catalysts, and, if necessary devise a new method. Also, several catalysts were to be prepared and used in hydrogenation or organic compounds. Evaluation of the catalytic activity of each catalyst was to be made by using them with various selected organic substrates.

Quinazoline and phthalazine were hydrogenated at low pressure and temperature (60 psi, room temperature) and high pressure and temperature (2000 psi, 100°C, 150°C} in neutral and acidic solvents over 5% Pd/C, 5% Ru/C, 5% Rh/Al2O3 , 5% Rh/C, and 5% Pt/C. Chromatographic methods for determining the qualitative and quantitative composition of hydrogenation mixtures were developed. The compositions of quinazoline and phthalazine-hydrogenation mixtures were determined. Eight phthalazine-hydrogenation products were detected and isolated: (1) 1,2-dihydrophthalazine, (2) 1,2,3,4-tetrahydrophthalazine, (3) a,a'-diamino-o-xylene, (4) o-methylbenzylamine, (5) 1,3-dihydroisoindole, (6) o-xylene, (7 and 8) cis- and trans- 1,2-dimethylcyclohexane. These products were identified by isolating them from reaction mixtures and comparing their ir, nmr, and mass spectra with those of authentic samples. Pathways of hydrogenation were proposed for both quinazoline and phthalazine, and evidence for each pathway was presented.

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The hydrogenation of coal to produce petroleum and petroleum products has been an accomplished fact for several years. The investigation in the United states has been carried to the point of constructing a full-scale plant to attempt to put the process on a commercial production basis. The volatile matter and fixed carbo of a coal are the constituents which enter into the hydrogenation reaction. The volatile matter is considered to be mostly unsaturated aromatic compounds which are readily hydrogenated. Midlothian coal contains 33 per cent volatile matter, as compared with 10 to 20 per cent in higher grade coals, and for this reason this coal was selected for this investigation. The purpose of this investigation was to determine the effect of particle size, initial hydrogen pressure from 1200 to 1800 pound per square inch gage, recycled vehicles and time of reaction on the per cent liquefaction that could be obtained. A parr high pressure hydrogenation bomb with auxiliary heating and agitating apparatus was used in this investigation. The degree of liquefaction was determined by comparison of the weight of the residual coal after hydrogenation with the weight of the original coal sample. The basic assumption of the investigation was that any loss in weight of the coal was due to liquefaction of the coal, and the products lost to the atmosphere in the gases were not considered. The reactants placed in the bomb were Midlothian coal, the vehicle tetralin (or recycled tetralin or tar residue from previous tests), stannous sulfide catalyst, and hydrogen. A series of tests was made to determine the effect of pressure, particle size, recycled tetralin as the vehicle, tar residue from previous tests as the vehicle, and time on the hydrogenation reaction. The pressure range used was from 1200 to 1800 pounds per square inch gage; the temperature was used 385°C; the time of reaction was varied from one to eight hours, the catalyst used was always equal to one per cent by the weight of the coal sample; and the vehicle to coal ratio was always 3.8;1 based on the weight of the coal. A coal particle size in the range of 139-104 microns in diameter, or passed through a 100-mesh screen, but retained on a 140-mesh screen gave a maximum liquefaction of 85 per cent. An initial hydrogen pressure of 1800 pounds per square inch gage gave a maximum liquefaction of 89.5 per cent. A reaction time of three hours gave a maximum liquefaction of 88 per cent. These percentages agree closely with the maximum of 92 per cent obtained by the U.S. Bureau of Mines in hydrogenation research⁽¹¹⁶⁾. Further findings were that the use of recycled tetralin as the vehicle had no effect on the per cent liquefaction obtained, but that the use as the vehicle of the tar fractions of the products from previous tests decreased the per cent liquefaction of the coal from 85 per cent to 70 per cent based on the weight of the coal. / M.S.

An experimental investigation of the characteristics of benzene hydrogenation over nickel/kieselguhr catalyst has been made in a differential bed reactor. The study was performed at moderate temperatures (340 to 474 K), and atmospheric pressure. A Langmuir-Hinshelwood rate model assuming the Rideal-Eley mechanism for addition of molecular hydrogen to adsorbed benzene was used to describe the data. From kinetic rate data the parameters of the model were found (reproducing the experimental data to within ±10.9%). Diluting the reactant stream with nitrogen (an inert), while maintaining total pressure, temperature, and benzene mole fraction constant, linearly decreased the observed reaction rate. The diffusion-reaction characteristics of this fluid-solid system were observed by increasing the particle size, thereby forcing intraphase transport limitations to occur. Experimental effectiveness factors were compared to theoretical ones generated using the dusty gas model. Minimizing the residual sum of squares between the two yielded relationships for the effective diffusivity and the catalyst tortuosity, both of which reproduced values reported in the literature. These relationships were based on Knudsen diffusivity being the controlling diffusive mechanism, a fact shown to be true for the catalyst used in this study. / M.S.