Thesis advisor: Chia-kuang Tsung / Thesis advisor: Dunwei Wang / Coating porous materials is a potential pathway to improve Catalytic performance of heterogeneous catalysts. The unique properties of Metal organic frameworks (MOFs) like huge surface area, long range order and high tenability make them promising coating materials. However, two traditional MOF encapsulation methods have their own issues. Herein, we synthesized Pt/Pd metal nanoparticles @UiO-66-NH2 via a one-pot in situ method which has good control of nanoparticles size while avoids the introduction of capping agent. The catalytic performance of synthesized Pt@UiO-66-NH2 is tested via selective hydrogenation of Crotonaldehyde. And the selectivity of our desired product achieves 70.42% which is much higher than merchant Pt catalysts. A step further, we used linker exchange to replace the original NH2-BDC linker of which amine group plays an important role in the coating process. After linker exchanging, the significant decreasing in selectivity of our target product demonstrates that the interaction between Pt and amine group does have some positive impacts on their catalytic performance. We hope our research could provide some insights of the MOFs and nanoparticles interface and help rational design of catalysts with high performance. / Thesis (MS) — Boston College, 2021. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Hydrogenation and dehydrogenation on Pd- and Pt- catalysts are encountered in many industrial hydrocarbon processes. The present work considers the development of catalysts and their kinetic modeling along a general and rigorous approach. The first part deals with the kinetics of selective hydrogenation, more particularly of the C3 cut of a thermal cracking unit for olefins production. The kinetics of the gas phase selective hydrogenation of methyl-acetylene (MA) and propadiene (PD) over a Pd/γ-alumina catalyst were investigated in a fixed bed tubular reactor at temperatures 60 - 80 oC and a pressure of 20 bara. Hougen-Watson type kinetic equations were derived. The formation of higher oligomers slowly deactivated the catalyst. The effect of the deactivating agent on the rates of the main reactions as well as on the deactivating agent formation itself was expressed in terms of a deactivation function multiplying the corresponding rates at zero deactivation. Then, the kinetic model was plugged into the reactor model to simulate an industrial adiabatic reactor. In the second part the production of hydrogen from hydrocarbons was investigated. In both cyclohexane and decalin dehydrogenations, conversions higher than 98% could be obtained over Pt/γ-alumina catalyst at temperature of 320 and 340 oC, respectively, with no apparent deactivation for 30 h and with co-feed of H2 in the feed. Except for H2 and trace amounts of side cracking products, less than 0.01%, benzene was the only dehydrogenated product in cyclohexane dehydrogenation. In the case of decalin dehydrogenation, partially dehydrogenated product, tetralin, was also formed with selectivity lower than 5%, depending on operating conditions. A rigorous Hougen-Watson type kinetic model was derived, which accounted for both the dehydrogenation of cis- and trans- decalin in the feed and also the isomerization of the two isomers. Jet A is the logic fuel in the battlefields. The dehydrogenation of Jet A can produce H2 for military fuel cell application. Although the H2 production is lower than that of steam/autothermal reforming, it eliminates the needs of high temperature and product separation operation.

L’objectif de cette étude est de préparer des catalyseurs bimétalliques Ni-X/SiO2, de les caractériser, et de comparer leur activité en hydrogénation du styrène en éthylbenzène,ainsi que leur sélectivité en hydrogénation de la double liaison oléfinique du styrène, par rapport à l’hydrogénation du noyau benzénique. L’élément X est greffé de manière contrôlée sur le nickel, et est choisi selon son électronégativité, soit inférieure (Zr), soit égale (Sn), soit supérieure (Au) à celle du nickel, dans le but d’étudier les effets géométriques et/ou électroniques qu'il pourrait induire. Parmi les échantillons préparés, le catalyseur Ni-Au/SiO2s’est révélé presque aussi actif que le catalyseur non dopé et nettement plus sélectif dans l’hydrogénation du styrène en éthylbenzène. / The aim of the present study is to prepare silica-supported Ni-X bimetallic catalysts, tocharacterize them, and to compare their catalytic activity in the hydrogenation of styrene, as well as their selectivity in the hydrogenation of the styrene’s olefinic double bond instead of the hydrogenation of the aromatic ring. The element X is grafted in a controlled way on the supported nickel particles, and is chosen according to its electronegativity, which is eitherlower (Zr), or equivalent (Sn), or higher (Au) than the electronegativity of Ni, in order to study the geometrical and/or electronic effects due to the doping of Nickel. Among the prepared samples, the Ni-Au/SiO2 catalyst has exhibited high activity and high selectivity in the hydrogenation of styrene into ethylbenzene, which makes the doping of Ni by Au apromising alternative for PyGas selective hydrogenation catalysts.

Thesis advisor: Matthias M. Waegele / Depositing metal-organic frameworks (MOFs) on the surfaces of metal nanoparticles (NPs) to enhance catalytic selectivity has recently attracted great attention; however, a solid understanding of how the NP-MOF interface promotes catalytic selectivity is lacking. In this thesis, we have conducted three fundamental studies and further applied the knowledge to other types of catalysts using enzymes. The first part of this thesis focuses on understanding the NP-MOF interfacial structures and their impact on catalytic performance. We have systematically probed the NP-MOF interface generated by three commonly used approaches by IR and Raman spectroscopy. We have revealed significant differences in interfacial chemical interactions between them, and have found that these differences in interfacial structure dramatically impact selectivity. For example, the interface generated by the coating approach contains trapped capping agents. This trapped capping agent reduces crotyl alcohol selectivity for the hydrogenation of crotonaldehyde. The second part of this thesis focuses on addressing the trapped capping agents at the NP-MOF interface. We developed an approach to creating a direct NP-MOF interface by utilizing weakly adsorbed capping agents during the MOF coating process. Their dynamic nature allows for their gradual dissociation from the NP surface with the assistance of the organic MOF linkers. Thus, direct chemical interactions can be built between NP and MOF, generating a clean and well-defined interface. Direct evidence on capping agent dissociation and formation of chemical interactions was obtained by Raman and IR spectroscopy. Combined with transmission electron microscopy and X-ray diffraction, we have revealed the relative orientation and facet alignment at the NP-MOF interface. The third part of this thesis investigates how various MOF components affect the selectivity of hydrogenation reactions catalyzed at the MOF-NP interface. We found that the replacement of Zr-oxo nodes with Ce-oxo nodes yields the highest selectivity for cinnamyl alcohol (~87%), whereas the functionalization of the terephthalic acid linker with -OH, CH3, -NO2 and NH2 groups only moderately modulates the selectivity relative to the Zr-UiO-66 (~58%). Reaction kinetics studies demonstrate that coating Pt NPs with Ce-UiO-66 increases the rate of C=O hydrogenation, which infrared spectroscopic observations suggest is due to the interaction of the C=O group with the Ce-oxo node. This work highlights the critical role of metal-oxo nodes in regulating the catalytic selectivity of metal NPs in specific reactions. The fourth part of this thesis extends the interface control to other catalysts involving enzymes. We compared the interfacial interactions of catalase in solid and hollow MOF microcrystals. The solid sample with confined catalase was prepared through a reported method. The hollow sample was generated by hollowing the MOFs crystal, sealing freestanding enzymes in the central cavities of the hollow MOF. By monitoring this hollowing process, we observed that the enzymes gradually changed from a confined form to a freestanding form. The freestanding enzymes in the hollow MOFs show higher activity in the decomposition of hydrogen peroxide, attributed to their lesser chemical interactions and confinement. This study highlights the importance of the freestanding state for the biological function of encapsulated enzymes. Taken together, the four sections in this thesis establish design rules for refining MOF-based catalyst design. / Thesis (PhD) — Boston College, 2022. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Tesis por compendio / Las especies de metal con diferentes tamaños (átomos individuales, nanocristales y nanopartículas) muestran un comportamiento catalítico diferente para diversas reacciones catalíticas heterogéneas. Se ha demostrado en la bibliografía que muchos factores que incluyen el tamaño de partícula, la forma, la composición química, la interacción metal-soporte, la interacción metal-reactivo / disolvente, pueden tener influencias significativas sobre las propiedades catalíticas de los catalizadores metálicos. Los desarrollos recientes de metodologías de síntesis bien controladas y herramientas de caracterización avanzada permiten correlacionar las relaciones a nivel molecular. En esta tesis, he llevado a cabo estudios sobre catalizadores metálicos desde átomos individuales hasta nanoclusters y nanopartículas. Al desarrollar nuevas metodologías de síntesis, el tamaño de las especies metálicas puede modularse y usarse como catalizadores modelo para estudiar el efecto del tamaño sobre el comportamiento catalítico de los catalizadores metálicos para la oxidación del CO, la hidrogenación selectiva, la oxidación selectiva y la fotocatálisis. Se ha encontrado que, los átomos metálicos dispersados por separado y los grupos subnanométricos de metal pueden aglomerarse en nanoclusters o nanopartículas más grandes en condiciones de reacción. Para mejorar la estabilidad de los catalizadores subnanométricos de metal, he desarrollado una nueva estrategia para la generación de átomos individuales y clusters en zeolitas. Esas especies subnanométricas de metales son estables en tratamientos de oxidación-reducción a 550 oC. Siguiendo esta nueva metodología de síntesis, este nuevo tipo de materiales puede servir como catalizador modelo para estudiar la evolución de especies subnanométricas de metales en condiciones de reacción. La transformación estructural de las especies subnanométricas de Pt ha sido estudiada mediante microscopía electrónica de transmisión in situ. Se ha demostrado que el tamaño de las especies de Pt está fuertemente relacionado con las condiciones de reacción, que proporcionan importantes conocimientos para comprender el comportamiento de los catalizadores de metales subnanométricos en condiciones de reacción. En la otra línea de investigación para catalizadores de metales no nobles, he desarrollado varias estrategias generales para obtener catalizadores de metales no nobles, ya sea soportados sobre óxidos metálicos o protegidos por capas delgadas de carbono. Estos materiales muestran un rendimiento excelente para varias reacciones importantes, como la hidrogenación quimioselectiva de nitroarenos, incluso cuando se comparan con los catalizadores de metales nobles convencionales. En algunos casos, los catalizadores de metales no nobles pueden incluso alcanzar selectividades para productos inviables que no ha sido posible conseguir en catalizadores de metales nobles convencionales, que es causado por la diferente ruta de reacción en catalizadores de metales no nobles. Sin embargo, la espectroscopía fotoelectrónica de rayos X a presión ambiente ha revelado que la irradiación de la luz puede modular la selectividad a los alcoholes y los hidrocarburos C2 +, lo que abre una nueva posibilidad para ajustar el comportamiento catalítico de los catalizadores metálicos. Con base en los trabajos anteriores de diferentes aspectos relacionados con catalizadores metálicos heterogéneos, las perspectivas sobre las direcciones futuras hacia una mejor comprensión del comportamiento catalítico de diferentes entidades metálicas (átomos individuales, nanoagrupamientos y nanopartículas) de una manera unificadora también se han dado en esta tesis. / Les espècies metàl·liques de diferents dimensions (àtoms individuals, nanoclusters i nanopartícules) mostren diferents comportaments catalítics per a diverses reaccions catalítiques heterogènies. S'ha demostrat a la literatura que, molts factors que inclouen la mida de la partícula, la forma, la composició química, la interacció amb el suport metàl·lic, la reacció metàl·lica i la interacció amb dissolvents poden tenir influències significatives sobre les propietats catalítiques dels catalitzadors metàl·lics. Els desenvolupaments recents de metodologies de síntesi ben controlades i eines de caracterització avançada permeten relacionar les relacions a nivell molecular. En aquesta tesi, he realitzat estudis sobre catalitzadors metàl·lics d'àtoms únics a nanoclústers i nanopartícules. Mitjançant el desenvolupament de noves metodologies de síntesi, la mida de les espècies metàl·liques es pot modular i utilitzar com a catalitzadors model per estudiar l'efecte de mida sobre el comportament catalític dels catalitzadors metàl·lics per a l'oxidació de CO, hidrogenació selectiva, oxidació selectiva i fotocatàlisi. S'ha trobat que, els àtoms metàl·lics dispersos individualment i els clústers metàl·lics subnanomètrics poden aglomerar-se en nanoclústeres o nanopartícules més grans en condicions de reacció. Per millorar l'estabilitat dels catalitzadors subnanomètrics de metall, he desenvolupat una nova estratègia per a la generació d'àtoms i racimos en zeolites. Aquestes espècies metàl·liques subnanométricas són estables en tractaments de reducció d'oxidació a 550 oC. Després d'aquesta nova metodologia de síntesi, aquest nou tipus de materials poden servir com a model de catalitzador per estudiar l'evolució de les espècies metàl·liques subnanométricas en condicions de reacció. La transformació estructural de l'espècie Pn subnanométrica ha estat estudiada per microscòpia electrònica de transmissió in situ. S'ha demostrat que la mida de les espècies de Pt està fortament relacionada amb les condicions de reacció, que proporcionen idees importants per comprendre el comportament dels catalitzadors de subnanometria en condicions de reacció. En l'altra línia de recerca dels catalitzadors de metalls no nobles, he desenvolupat diverses estratègies generals per obtenir catalizadors de metalls no nobles recolzats en òxids metàl·lics o protegits per capes de carboni primes. Aquests materials presenten un excel·lent rendiment per a diverses reaccions importants, com la hidrogenació quimioelectiva de nitroarenes, fins i tot quan es comparen amb els catalitzadors convencionals de metall noble. En alguns casos, els catalitzadors de metalls no nobles poden fins i tot aconseguir selectivitats a productes no factibles que no s'han pogut assolir en catalitzadors de metall noble convencionals, que es deuen a la via de reacció diferent en catalitzadors de metalls no nobles. No obstant això, s'ha observat una espectroscòpia de fotoelèctria de raigs X amb pressió d'atmosfera que la irradiació lleugera pot modular la selectivitat als alcohols i hidrocarburs C2 +, la qual cosa obre una nova possibilitat per sintonitzar el comportament catalític dels catalitzadors metàl·lics. A partir d'aquests treballs de diferents aspectes relacionats amb els catalitzadors metàl·lics heterogenis, també s'ha donat en aquesta tesi perspectives sobre les futures orientacions cap a una millor comprensió del comportament catalític de diferents entitats metàl·liques (àtoms individuals, nanoclústers i nanopartícules). / Metal species with different size (single atoms, nanoclusters and nanoparticles) show different catalytic behavior for various heterogeneous catalytic reactions. It has been shown in the literature that, many factors including the particle size, shape, chemical composition, metal-support interaction, metal-reactant/solvent interaction, can have significant influences on the catalytic properties of metal catalysts. The recent developments of well-controlled synthesis methodologies and advanced characterization tools allow to correlate the relationships at molecular level. In this thesis, I have carried out studies on metal catalysts from single atoms to nanoclusters and nanoparticles. By developing new synthesis methodologies, the size of metal species can be modulated and used as model catalysts to study the size effect on the catalytic behavior of metal catalysts for CO oxidation, selective hydrogenation, selective oxidation and photocatalysis. It has been found that, singly dispersed metal atoms and subnanometric metal clusters may agglomerate into larger nanoclusters or nanoparticles under reaction conditions. To improve the stability of subnanometric metal catalysts, I have developed a new strategy for the generation of single atoms and clusters in zeolites. Those subnanometric metal species are stable in oxidation-reduction treatments at 550 oC. Following this new synthesis methodology, this new type of materials can serve as model catalyst to study the evolution of subnanometric metal species under reaction conditions. The structural transformation of subnanometric Pt species has been studied by in situ transmission electron microscopy. It has been shown that the size of Pt species is strongly related with the reaction conditions, which provide important insights for understanding the behavior of subnanometric metal catalysts under reaction conditions. In the other research line for non-noble metal catalysts, I have developed several general strategies to obtain non-noble metal catalysts either supported on metal oxides or protected by thin carbon layers. These materials show excellent performance for several important reactions, such as chemoselective hydrogenation of nitroarenes, even when compared with conventional noble metal catalysts. In some cases, non-noble metal catalysts can even achieve selectivities to unfeasible products which has not been possible to achieve on conventional noble metal catalysts, which is caused by the different reaction pathway on non-noble metal catalysts. Nevertheless, it has been revealed by ambient-pressure X-ray photoelectron spectroscopy that light irradiation can modulate the selectivity to alcohols and C2+ hydrocarbons, which opens a new possibility for tuning the catalytic behavior of metal catalysts. Based on the above works from different aspects related with heterogeneous metal catalysts, perspectives on the future directions towards better understanding on the catalytic behavior of different metal entities (single atoms, nanoclusters and nanoparticles) in a unifying manner have also been given in this thesis. / Liu, L. (2018). Heterogeneous Metal Catalysts: From Single Atoms to Nanoclusters and Nanoparticles [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/113169 / Compendio

Die vorliegende Arbeit beschreibt die Präparation von Pt-Fe/SiO2-Katalysatorproben für die selektive Flüssigphasenhydrierung von Zimtaldehyd. Während der Herstellung wurden die Proben ausschließlich einer Reduktion bei 350 °C oder einer anschließenden Reduktion bei 750 °C unterworfen. Die präparierten Materialien wurden mit den Methoden ICP-OES, Laserbeugung, N2-Physisorption, XRD, TEM, SQUID und TPR/O charakterisiert. Daneben wurden Chemisorptions-Untersuchungen mit den Adsorptiven H2, O2 und CO durchgeführt. Infolge der angewandten Reduktionstemperatur von 750 °C konnte exemplarisch die Ausbildung von Metallpartikeln der Überstrukturphase nachgewiesen werden. Die katalytische Austestung der Materialien erfolgte in diskontinuierlich betriebenen Hydrierautoklaven. Hierbei stand die wertschöpfende Umsetzung zum Zimtalkohol im Vordergrund. Die Verwendung von Katalysatorproben, die Überstrukturphasen des Systems Fe-Pt aufweisen, führte nicht zu einer signifikanten Selektivitätsverbesserung zum Zielprodukt Zimtalkohol. Optimale Zimtalkohol-Ausbeuten ließen sich für Katalysatorproben erreichen, deren Metallpartikel nominelle Fe-Anteile von 30 bis 40 Mol.-% aufwiesen.

Die vorliegende Arbeit beschreibt die Präparation von Pt-Fe/SiO2-Katalysatorproben für die selektive Flüssigphasenhydrierung von Zimtaldehyd. Während der Herstellung wurden die Proben ausschließlich einer Reduktion bei 350 °C oder einer anschließenden Reduktion bei 750 °C unterworfen. Die präparierten Materialien wurden mit den Methoden ICP-OES, Laserbeugung, N2-Physisorption, XRD, TEM, SQUID und TPR/O charakterisiert. Daneben wurden Chemisorptions-Untersuchungen mit den Adsorptiven H2, O2 und CO durchgeführt. Infolge der angewandten Reduktionstemperatur von 750 °C konnte exemplarisch die Ausbildung von Metallpartikeln der Überstrukturphase nachgewiesen werden. Die katalytische Austestung der Materialien erfolgte in diskontinuierlich betriebenen Hydrierautoklaven. Hierbei stand die wertschöpfende Umsetzung zum Zimtalkohol im Vordergrund. Die Verwendung von Katalysatorproben, die Überstrukturphasen des Systems Fe-Pt aufweisen, führte nicht zu einer signifikanten Selektivitätsverbesserung zum Zielprodukt Zimtalkohol. Optimale Zimtalkohol-Ausbeuten ließen sich für Katalysatorproben erreichen, deren Metallpartikel nominelle Fe-Anteile von 30 bis 40 Mol.-% aufwiesen.

Surface catalysed reactions play an important role in chemical productions. Developments of catalyst requiring high activity whilst improving on product selectivity can potentially have a profound effect in the chemical industry. Traditional catalyst modifications were focused on tuning the size, shape and foreign metal doping to form well defined metal nanoparticles of unique functionalities. Here, we show new approach to engineering of metal nanocatalysts via a subsurface approach can modify the chemisorption strength of adsorbates on the surface. Carbon modified nanoparticles were synthesised using glucose to stabilise Pd nanoparticles at a molecular level. Upon heat treatment, the carbonised glucose encapsulated the Pd nanoparticles with carbon atoms take residence in the octahedral holes (15 at.%). These materials were tested in liquid phase stereoselective hydrogenations of 3-hexyn-1-ol and 4-octyne. The former has importance in the fragrance industry towards the production of leaf fragrance alcohol. It was shown for the first time that the geometrically and electronically modified Pd with interstitial carbon atoms reduced the adsorption energy of alkenes, ultimately leading to higher reaction selectivity. Boron modified Pd nanoparticles was synthesised using BH₃.THF in the liquid phase. The material possess high B interstitial saturation (20 at.%), which can be synthesised for the first time below 100°C. These materials were tested in the liquid phase selective hydrogenation of various alkynes and 2-chloronitrobenzene, of which the latter has importance in the pesticides industry. Kinetic modelling on the hydrogenation of 4-octyne suggests these subsurface occupied B does play a pivotal role on increasing the reaction selectivity, as removal of these species lead to decreased selectivity. Au nanoparticles were synthesised and characterised using H¹³COOH NMR. The new liquid NMR characterisation method is successfully applied to examine the chemisorption strength of metal nanoparticles. An attempt to synthesise PVP capped B modified Pd nanoparticles with the above NMR characterisation was investigated. It is believed the examples of subsurface atom modifications as shown here may offer future catalyst developments in this area.

Les liquides ioniques (LIs) à base d’imidazolium présentent une très grande organisation en réseaux 3D et sont constitués de microdomaines polaires et apolaires, dû à la présence des canaux ioniques et au regroupement des chaînes alkyles lipophiles. L’objectif de ce travail est d’utiliser leurs propriétés de solvatation, liées à cette organisation, pour générer et stabiliser in situ des nanoparticules métalliques (NPs) d’une taille contrôlée et prévisible. Cette approche a trouvé de nombreuses applications dans des domaines tels que la catalyse et la microélectronique. Le phénomène de croissance cristalline des NPs (ruthénium, nickel et tantale) générées in situ lors de la décomposition sous H2 des complexes organométalliques, est contrôlé i) par la taille des poches apolaires, dans lesquelles le complexe se dissout, ii) par les conditions expérimentales (température, agitation) et iii) par la nature du métal et du complexe précurseur. Le mécanisme de stabilisation des NPs, jusqu'alors mal compris, dépend du mécanisme de formation des NPs, qui pourrait entraîner la présence de ligands hydrures ou carbènes N-hétérocycliques (NHC) à leur surface. Cette présence a été démontrée par marquage isotopique et analysée en RMN ainsi qu’en spectrométrie de masse. Les LIs sont également des milieux intéressants en catalyse. Des études sur l’influence du LI sur l’activité des catalyseurs homogènes ont souligné l’importance cruciale des paramètres physico-chimiques des LIs, et particulièrement de la viscosité, qui intervient ainsi dans la loi cinétique. Enfin, une étude approfondie de l’effet de la taille des NPs sur l’activité catalytique et la sélectivité pour l’hydrogénation, réalisée en milieu LI, a confirmé l’importance du contrôle de la taille des NPs pour les applications catalytiques / Imidazolium based ionic liquids (ILs) consist of a continuous 3-D network of ionic channels, coexisting with non polar domains created by the grouping of lipophilic alkyl chains, forming dispersed or continuous microphases. The aim of this work is to use the specific solvation properties of ILs, related to this 3-D organisation, to generate and stabilise in situ metal nanoparticles (NPs) of a controlled and predictable size. This approach has found application in fields such as catalysis and microelectronics. The phenomenon of crystal growth of NPs (ruthenium, nickel, tantalum) generated in situ in ILs from the decomposition of organometallic complexes under molecular hydrogen, is found not only to be controlled by i) the size of non-polar domains, in which the complexes dissolve, but also by ii) the experimental conditions (temperature, stirring) and iii) the nature of the metal and its precursor complex. The previously unexplained stabilisation mechanism of NPs in ILs is found to depend on the mechanism of formation of NPs, which may lead to the presence of either hydrides or N-heterocyclic carbenes (NHC) at their surface. These have both been evidenced through isotopic labelling experiments analysed by NMR and mass spectrometry. Another advantage of ILs is that they provide an interesting medium for catalytic reactions. Studies on the influence of the IL on the catalytic performance in homogeneous catalysis have highlighted the crucial importance of the physical-chemical parameters of ILs, in particular the viscosity, for which a term must be included in the kinetic rate law. Using these findings, a thorough investigation of the effect of the NP size on catalytic activity and selectivity in hydrogenation in ILs was undertaken, confirming the importance of controlling NP size for catalytic applications.

Chemical catalysts are divided into two traditional categories: homogeneous and heterogeneous catalysts. Although homogeneous (molecular) catalysts tend to have high activity and selectivity, their wide application is hampered by the difficulties in catalyst separation. In contrast, the vast majority of industrial scale catalysts are heterogeneous catalysts based on solid materials. Immobilized catalysts, combining the advantages of homogeneous and heterogeneous catalysts, have developed into an important field in catalysis research. This dissertation presents synthesis, characterization and evaluation of several novel immobilized catalysts. In the first part, MNP supported aluminum isoproxide was developed for ROP of Є-caprolactone to achieve facile magnetic separation of catalysts from polymerization system and reduce toxic metal residues in the poly(caprolactone) product. Chapter 3 presents a silica coated MNP supported DMAP catalyst that was synthesized and displayed good activity and regio-selectivity in epoxide ring opening reactions. In Chapter 4, hybrid sulfonic acid catalysts based on polymer brush materials have been developed. The unique polymer brush architecture permits high catalyst loadings as well as easy accessibility of the active sites to be achieved in this catalytic system. In Chapter 5, aminopolymer-silica composite supported Pd catalysts with good activity and selectivity were developed for the selective hydrogenation of alkynes. In this case, the aminopolymer composite works as a stabilizer for palladium nanoparticles, as well as a modifier to tune the catalyst selectivity. All in all, the general theme of the thesis is developing new immobilized catalysts with improved activity/selectivity as well as easy separation via rational catalyst design.