In most flat bimetallic strip applications, the bending is employed in the transverse direction, that is, upon the application of uniform heating to the entire strip, the initially straight strip bends transversely up from the flat plane. This study is concerned with a pre-curved bimetallic strip that upon heating up from the ambient, straightens up along the chord line tending to become flatter. The initial ambient radius of curvature of the strip is smaller, and upon heating, the radius of curvature becomes larger. By mounting the curved bimetallic strip with a rotational degree of freedom at each end, and fixing one end against displacement, a chord line displacement of the free end of the strip occurs when the strip is uniformly heated. It is this chord line case that this work investigates and characterises. This work provides a way of evaluating the net combined axial loading case whereby an external load is applied to the free end of the strip as it uniformly heated. The main application of this work is for the characterisation of a curved bimetallic blade within a thermal motor. This is a novel device for converting renewable heat energy into mechanical energy and power as part of a larger energy harvesting network. The curved bimetallic strip with minor modifications, functions as a curved bimetallic blade within the thermal motor. The application of this work has a wider impact, in that it can be used in any other temperature induced force and displacement applications. Thus as a result of this investigation, a new form of linear actuator has been created that can utilise an input heat differential, and produce an output axial force and displacement. The displacements and forces generated by the axial case can be quite large, and as a result of this work, relatively easy to calculate, when designing a thermally driven linear actuator. The thermal motor, which possesses the curved bimetallic strip at the heart of its mechanism, can also be powered by other secondary heating sources such exhaust, or waste heat, that would otherwise be lost to the surroundings.

This thesis describes the development of new procedures for the synthesis of homo- and hetero-bimetallic complexes [M-(C≡C-C≡C)-M*] linked by a butadiyndiyl (-C≡C-C≡C-) bridge (where M, M* = Mo(dppe)(η-C7H7) and Fe(dppe)Cp) and also of the diethynyl-anthracenyl bridged complex [{Mo(dppe)(-C7H7)}2(μ-C≡CC14H8C≡C)] in which an anthracenyl group is inserted into the butadiyndiyl bridge. The redox chemistry and mixed valence character of these systems are investigated by a range of synthetic, electrochemical and spectroscopic techniques. Chapter 1: (Introduction) presents a literature review related to all-carbon bridged bimetallics including their synthesis, redox chemistry and mixed valence properties. Chapter 2: describes the synthesis of the key precursor [FeI(dppe)Cp] in multi-gram quantities. A new synthetic protocol has been developed to vinylidene [Fe(C=CH2)(dppe)Cp][PF6] and acetylide [Fe(C≡CH)(dppe)Cp] complexes starting from the iodo precursor [FeI(dppe)Cp] which can be conveniently used in place of the chloro precursor [FeCl(dppe)Cp]. We also identified the carbene species [Fe{C(OMe)Me}(dppe)Cp][PF6], which is formed as a by-product from the reaction of the vinylidene with a molecule of methanol solvent. Chapter 3: describes the synthesis and characterisation of butadiyndiyl bridged [{Fe(dppe)Cp}2(-CCCC)]n+ (n = 0, 1, 2). The electronic structure of [{Fe(dppe)Cp}2(-CCCC)]n+ has been investigated in all thermally accessible oxidation states (0, 1, 2, 3) and compared directly with the closely related ruthenium analogue [{Ru(dppe)Cp}2(-CCCC)]n+. Particular focus was given to the formally 'mixed valent' radical cations [{Fe(dppe)Cp}2(-CCCC)]+ and [{Ru(dppe)Cp}2(-CCCC)]+, where the spectroscopic data highlight significant differences between the iron and ruthenium complexes. Furthermore, in this chapter the heterobimetallic complex [{Fe(dppe)Cp}(µ-C≡C-C≡C){Mo(dppe)(C7H7)}] was successfully synthesised and characterised by microanalysis, IR, mass spectrometry and cyclic voltammetry. Chapter 4: discusses the synthesis of the diethynyl-anthracene bridged complexes [{Mo(dppe)(-C7H7)}2(μ-C≡CC14H8C≡C)]n+ (n = 0, 1, 2). The focus of the investigation is to determine the effect of a diethynyl-benzene vs. diethynyl-anthracene bridge in bimetallics supported by the Mo(dppe)(C7H7) end cap. In the mixed valence (n = +1) state, the odd electron should be more localised on the ligand bridge of the anthracene derivative and this principle was investigated by EPR spectroscopy.

This research is focused on development of routes towards the rational design of nanoparticle catalysts. Primarily, it is focused on two main projects; (1) the use of imidazolium-based ionic liquids (ILs) as greener media for the design of quasi-homogeneous nanoparticle catalysts and (2) the rational design of heterogeneous-supported nanoparticle catalysts from structured nanoparticle precursors. Each project has different studies associated with the main objective of the design of nanoparticle catalysts.<p> In the first project, imidazolium-based ionic liquids have been used for the synthesis of nanoparticle catalysts. In particular, studies on recyclability, reuse, mode-of-stability, and long-term stability of these ionic-liquid supported nanoparticle catalysts have been done; all of which are important factors in determining the overall greenness of such synthetic routes. Three papers have been published/submitted for this project. In the first publication, highly stable polymer-stabilized Au, Pd and bimetallic Au-Pd nanoparticle catalysts have been synthesized in imidazolium-based 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) ionic liquid (Journal of Molecular Catalysis A: Chemical, 2008, 286, 114). The resulting nanoparticles were found to be effective and selective quasi-homogeneous catalysts towards a wide-range of hydrogenation reactions and the catalyst solution was reused for further catalytic reactions with minimal loss in activity. The synthesis of very pure and clean ILs has allowed a platform to study the effects of impurities in the imidazolium ILs on nanoparticle stability. In a later study, a new mode of stabilization was postulated where the presence of low amounts of 1-methylimidazole has substantial effects on the resulting stability of Au and Pd-Au nanoparticles in these ILs (Chemical Communications, 2009, 812). In further continuation of this study, a comparative study involving four stabilization protocols for nanoparticle stabilization in BMIMPF6 IL is described, and have shown that nanoparticle stability and catalytic activity of nanoparticles is dependent on the overall stability of the nanoparticles towards aggregation (manuscript submitted).<p> The second major project is focused on synthesizing structurally well-defined supported catalysts by incorporating the nanoparticle precursors (both alloy and core shell) into oxide frameworks (TiO2 and Al2O3), and examining their structure-property relationships and catalytic activity. a full article has been published on this project (Journal of Physical Chemistry C, 2009, 113, 12719) in which a route to rationally design supported catalysts from structured nanoparticle precursors with precise control over size, composition, and internal structure of the nanoparticles has been shown. In a continuation of this methodology for the synthesis of heterogeneous catalysts, efforts were carried out to apply the same methodology in imidazolium-based ILs as a one-pot media for the synthesis of supported-nanoparticle heterogeneous catalysts via the trapping of pre-synthesized nanoparticles into porous inorganic oxide materials. Nanoparticle catalysts in highly porous titania supports were synthesized using this methodology (manuscript to be submitted).

The research in this thesis involves the synthesis and characterization of nanoparticle catalysts for oxidation reactions. It includes two projects: 1) polymer-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts for alcohol oxidation reactions, and 2) oxidative stabilities and catalytic activities of thiolate- and dithiolate-protected Au monolayer-protected clusters (MPCs).<p>n the first project, alcohol oxidations under mild conditions using polyvinylpyrrolidone (PVP)-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts in aqueous solutions have been investigated. The catalytic activities of the nanoparticles towards the oxidation of benzyl alcohol, 1-butanol, 2-butanol, 2-buten-1-ol and 1,4-butanediol indicate that bimetallic 1:3 Au:Pd nanoparticles have higher catalytic activities than Au, Pd and other bimetallic AuPd nanoparticles, and that selectivities towards specific products can often be tuned using bimetallic particles. In addition, advantages and disadvantages for the use of such nanoparticle catalysts as mild, environmentally-friendly oxidation catalysts have been examined. This work has recently been published in the Journal of Catalysis.<p>In the second project, 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs have been synthesized and their thermal stability, oxidative stability in the presence of oxygen and cyanide anions have been studied. These systematic investigations reveal the stability of Au MPCs can be tuned by choosing different thiolate ligands and oxidation conditions. Partially-oxidized thiolate-protected Au MPCs which have substrate-accessible surfaces and are stabilized by residual thiolate ligands show indications they will be promising catalysts. The catalytic activities of 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs for catalytic 4-nitrophenol reduction with sodium borohydride were investigated, and all the Au MPCs showed high catalytic activity for this reaction.

Hydrogen is a promising renewable fuel for producing energy in transportation and domestic applications. This study investigates the production of H2 from reforming of liquefied petroleum gas (LPG). LPG is a mixture of gases, mainly propane and butane, produced from petroleum or natural gas. It is a liquid under moderate pressure and therefore a favourable feedstock for distributed hydrogen production since it is easy to store and transport with a distribution network already in place. With its wide range of propane and butane compositions world wide, in this study LPG was considered as a mixture of propane and butane. H2 production from LPG was investigated through oxidative steam reforming of propane and butane. Oxidative steam reforming (OSR) can be viewed as a combination of two reactions: partial oxidation (PO) and steam reforming (SR). By carefully controlling the steam to carbon (S/C) and oxygen to carbon (O2/C) ratios in the feed, OSR can produce higher H2 yields than PO at operational temperatures lower than SR. In the first part of this study, based on the literature and preliminarily experiments, two Ni based bimetallic catalysts, Pt-Ni/Al2O3 and Mo-Ni/Al2O3, were selected to be compared to a monometallic 15 wt% Ni/Al2O3 catalyst for OSR of a 1:1 propane to butane LPG mixture under different operational conditions. This catalysts screening study evaluated the performance of the catalysts on the basis of a statistical factorial experimental design. The factorial design was efficient in optimizing experimental runs, while testing the activity and product distribution of the catalysts at different operational limits. The importance of the factorial design was clearer when analyzing results for the Pt-Ni catalysts, as the catalyst showed different product compositions at the two selected loadings (0.2 and 1 wt%) under different conditions compared to the unpromoted catalyst. However, at both loadings, the Pt-Ni catalyst did not have a significant effect on fuel conversion or catalyst selectivity to different products. On the other had, under all stable conditions in the factorial design experiments, the Ni-Mo catalyst had higher H2 and CO yields and lower CH4 yields compared to the unpromoted catalyst. To our knowledge these product composition variations were not reported before in the literature for hydrocarbon reforming reactions over Mo promoted catalysts. The catalyst screening study also included time on stream catalysts stability tests. These experiments illustrated the high potential for solving the Ni stability problem associated with LPG reforming as the unpromoted 15Ni catalyst suffered from deactivation by coking and could not sustain its high conversion. On the other hand, promoting the Ni catalysts with 1 wt% Pt or 0.1 wt% Mo improved the catalyst resistance to coking and sustained its activity and product composition throughout the 18 hours of the stability tests. However, an increase in the Mo loading to 0.3 wt% in the Mo-Ni bimetallic catalyst, led to lower fuel conversions and loss of stability with time. Because of the interesting performance of the Mo-Ni /Al2O3 catalyst observed in the catalyst screening tests, and the lack of explanations of different aspects of this performance in the literature, especially in the presence of O2, the second part of the study was concerned with the investigation of the effect of small amounts of Mo addition on the activity, selectivity and stability of Ni catalysts when used for H2 production from LPG OSR. Individual fuels and reactions experiments showed that butane OSR gave the highest fuel conversions and H2 production rates. These experiments also revealed the importance of O2 for the catalyst activity and stability as for both hydrocarbons the catalyst suffered deactivation by coking under SR conditions. However, O2 compositions in the feed should be carefully optimized as characterization of fresh and aged catalysts showed that the loss of stability observed earlier in the catalyst screening tests for higher Mo catalysts loading, was caused by the oxidation of active Ni species to inactive Ni and Ni-Mo phases which resulted from the oxidative environment of the reaction during aging. In the last part of this study, surface and bulk properties of the monometallic Ni catalyst was compared to the Mo-Ni bimetallic catalyst using different catalyst characterization techniques ( TPR, TPO, TGA, XRD, H2 and O2 chemisorption and DRIFTS) in order to understand the structural effect of Mo addition on the catalytic properties. It was found that the improvements in the catalytic properties of the catalyst and the change in its selectivity to different products were caused by an electronic effect of Mo and its different oxide phases on Ni species. These electronic effects enhanced the O2 mobility over the catalysts surface leading to higher gasification rates of CHx species and hence, preventing coking of the catalyst. They also affected the stability of adsorbed reaction intermediates over the catalysts surface which affected the selectivity of the catalyst to different reaction products.

The research in this thesis involves the synthesis and characterization of nanoparticle catalysts for oxidation reactions. It includes two projects: 1) polymer-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts for alcohol oxidation reactions, and 2) oxidative stabilities and catalytic activities of thiolate- and dithiolate-protected Au monolayer-protected clusters (MPCs).<p>n the first project, alcohol oxidations under mild conditions using polyvinylpyrrolidone (PVP)-stabilized Au, Pd and bimetallic AuPd nanoparticle catalysts in aqueous solutions have been investigated. The catalytic activities of the nanoparticles towards the oxidation of benzyl alcohol, 1-butanol, 2-butanol, 2-buten-1-ol and 1,4-butanediol indicate that bimetallic 1:3 Au:Pd nanoparticles have higher catalytic activities than Au, Pd and other bimetallic AuPd nanoparticles, and that selectivities towards specific products can often be tuned using bimetallic particles. In addition, advantages and disadvantages for the use of such nanoparticle catalysts as mild, environmentally-friendly oxidation catalysts have been examined. This work has recently been published in the Journal of Catalysis.<p>In the second project, 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs have been synthesized and their thermal stability, oxidative stability in the presence of oxygen and cyanide anions have been studied. These systematic investigations reveal the stability of Au MPCs can be tuned by choosing different thiolate ligands and oxidation conditions. Partially-oxidized thiolate-protected Au MPCs which have substrate-accessible surfaces and are stabilized by residual thiolate ligands show indications they will be promising catalysts. The catalytic activities of 1-dodecanethiolate-, dithiolate-, and 1:1 mixed 1-dodecanethiolate/dithiolate-protected Au MPCs for catalytic 4-nitrophenol reduction with sodium borohydride were investigated, and all the Au MPCs showed high catalytic activity for this reaction.

This research is focused on development of routes towards the rational design of nanoparticle catalysts. Primarily, it is focused on two main projects; (1) the use of imidazolium-based ionic liquids (ILs) as greener media for the design of quasi-homogeneous nanoparticle catalysts and (2) the rational design of heterogeneous-supported nanoparticle catalysts from structured nanoparticle precursors. Each project has different studies associated with the main objective of the design of nanoparticle catalysts.<p> In the first project, imidazolium-based ionic liquids have been used for the synthesis of nanoparticle catalysts. In particular, studies on recyclability, reuse, mode-of-stability, and long-term stability of these ionic-liquid supported nanoparticle catalysts have been done; all of which are important factors in determining the overall greenness of such synthetic routes. Three papers have been published/submitted for this project. In the first publication, highly stable polymer-stabilized Au, Pd and bimetallic Au-Pd nanoparticle catalysts have been synthesized in imidazolium-based 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) ionic liquid (Journal of Molecular Catalysis A: Chemical, 2008, 286, 114). The resulting nanoparticles were found to be effective and selective quasi-homogeneous catalysts towards a wide-range of hydrogenation reactions and the catalyst solution was reused for further catalytic reactions with minimal loss in activity. The synthesis of very pure and clean ILs has allowed a platform to study the effects of impurities in the imidazolium ILs on nanoparticle stability. In a later study, a new mode of stabilization was postulated where the presence of low amounts of 1-methylimidazole has substantial effects on the resulting stability of Au and Pd-Au nanoparticles in these ILs (Chemical Communications, 2009, 812). In further continuation of this study, a comparative study involving four stabilization protocols for nanoparticle stabilization in BMIMPF6 IL is described, and have shown that nanoparticle stability and catalytic activity of nanoparticles is dependent on the overall stability of the nanoparticles towards aggregation (manuscript submitted).<p> The second major project is focused on synthesizing structurally well-defined supported catalysts by incorporating the nanoparticle precursors (both alloy and core shell) into oxide frameworks (TiO2 and Al2O3), and examining their structure-property relationships and catalytic activity. a full article has been published on this project (Journal of Physical Chemistry C, 2009, 113, 12719) in which a route to rationally design supported catalysts from structured nanoparticle precursors with precise control over size, composition, and internal structure of the nanoparticles has been shown. In a continuation of this methodology for the synthesis of heterogeneous catalysts, efforts were carried out to apply the same methodology in imidazolium-based ILs as a one-pot media for the synthesis of supported-nanoparticle heterogeneous catalysts via the trapping of pre-synthesized nanoparticles into porous inorganic oxide materials. Nanoparticle catalysts in highly porous titania supports were synthesized using this methodology (manuscript to be submitted).

No description available.

Hydrogen is a promising renewable fuel for producing energy in transportation and domestic applications. This study investigates the production of H2 from reforming of liquefied petroleum gas (LPG). LPG is a mixture of gases, mainly propane and butane, produced from petroleum or natural gas. It is a liquid under moderate pressure and therefore a favourable feedstock for distributed hydrogen production since it is easy to store and transport with a distribution network already in place. With its wide range of propane and butane compositions world wide, in this study LPG was considered as a mixture of propane and butane. H2 production from LPG was investigated through oxidative steam reforming of propane and butane. Oxidative steam reforming (OSR) can be viewed as a combination of two reactions: partial oxidation (PO) and steam reforming (SR). By carefully controlling the steam to carbon (S/C) and oxygen to carbon (O2/C) ratios in the feed, OSR can produce higher H2 yields than PO at operational temperatures lower than SR. In the first part of this study, based on the literature and preliminarily experiments, two Ni based bimetallic catalysts, Pt-Ni/Al2O3 and Mo-Ni/Al2O3, were selected to be compared to a monometallic 15 wt% Ni/Al2O3 catalyst for OSR of a 1:1 propane to butane LPG mixture under different operational conditions. This catalysts screening study evaluated the performance of the catalysts on the basis of a statistical factorial experimental design. The factorial design was efficient in optimizing experimental runs, while testing the activity and product distribution of the catalysts at different operational limits. The importance of the factorial design was clearer when analyzing results for the Pt-Ni catalysts, as the catalyst showed different product compositions at the two selected loadings (0.2 and 1 wt%) under different conditions compared to the unpromoted catalyst. However, at both loadings, the Pt-Ni catalyst did not have a significant effect on fuel conversion or catalyst selectivity to different products. On the other had, under all stable conditions in the factorial design experiments, the Ni-Mo catalyst had higher H2 and CO yields and lower CH4 yields compared to the unpromoted catalyst. To our knowledge these product composition variations were not reported before in the literature for hydrocarbon reforming reactions over Mo promoted catalysts. The catalyst screening study also included time on stream catalysts stability tests. These experiments illustrated the high potential for solving the Ni stability problem associated with LPG reforming as the unpromoted 15Ni catalyst suffered from deactivation by coking and could not sustain its high conversion. On the other hand, promoting the Ni catalysts with 1 wt% Pt or 0.1 wt% Mo improved the catalyst resistance to coking and sustained its activity and product composition throughout the 18 hours of the stability tests. However, an increase in the Mo loading to 0.3 wt% in the Mo-Ni bimetallic catalyst, led to lower fuel conversions and loss of stability with time. Because of the interesting performance of the Mo-Ni /Al2O3 catalyst observed in the catalyst screening tests, and the lack of explanations of different aspects of this performance in the literature, especially in the presence of O2, the second part of the study was concerned with the investigation of the effect of small amounts of Mo addition on the activity, selectivity and stability of Ni catalysts when used for H2 production from LPG OSR. Individual fuels and reactions experiments showed that butane OSR gave the highest fuel conversions and H2 production rates. These experiments also revealed the importance of O2 for the catalyst activity and stability as for both hydrocarbons the catalyst suffered deactivation by coking under SR conditions. However, O2 compositions in the feed should be carefully optimized as characterization of fresh and aged catalysts showed that the loss of stability observed earlier in the catalyst screening tests for higher Mo catalysts loading, was caused by the oxidation of active Ni species to inactive Ni and Ni-Mo phases which resulted from the oxidative environment of the reaction during aging. In the last part of this study, surface and bulk properties of the monometallic Ni catalyst was compared to the Mo-Ni bimetallic catalyst using different catalyst characterization techniques ( TPR, TPO, TGA, XRD, H2 and O2 chemisorption and DRIFTS) in order to understand the structural effect of Mo addition on the catalytic properties. It was found that the improvements in the catalytic properties of the catalyst and the change in its selectivity to different products were caused by an electronic effect of Mo and its different oxide phases on Ni species. These electronic effects enhanced the O2 mobility over the catalysts surface leading to higher gasification rates of CHx species and hence, preventing coking of the catalyst. They also affected the stability of adsorbed reaction intermediates over the catalysts surface which affected the selectivity of the catalyst to different reaction products.

This dissertation research resulted in the development of a Fe based catalyst with Co as a co catalyst, and Ru and ZnO as promoters. The role of Cu and K as promoters and the effect of SiO2 as an alternate support to gamma- Al2O3 were also investigated. A series of Fe-based catalysts for Fischer-Tropsch (F-T) synthesis were prepared. The different promoters were incorporated into the catalyst by impregnation The catalysts were characterized by several methods. The catalytic performance of these materials for F-T synthesis were investigated in a newly designed fixed bed reactor system in the gas phase. It should be noted that the three phase slurry bubble reactors systems are commercially preferred. The reaction conditions were varied for benchmarking the Fe-Zn-K/ gamma- Al2O3 catalyst and for the bimetallic Fe-Co-Zn/ gamma- Al2O3 catalyst and to identify optimal process parameters for further catalyst designs. The H2:CO ratio used in this study was 2. The newly designed catalysts showed significantly high activity towards CO conversion (>70 %), along with low selectivity towards CO2 (5 -15 %) and methane (ND - 3 %). The data show that varying the process conditions, it is possible to achieve narrow distribution of the liquid products. The results employing Fe-Zn-K catalysts showed that an increase in pressure increased the mean carbon chain length. In contrast, an increase in temperature resulted in a decline in the average carbon chain length. Increasing the feed flow rate, or in other words decreasing the residence time of the reactants and the intermediates, resulted in a decrease in the average carbon number in the product hydrocarbons. The evaluation of the effect of process conditions on the performance of Fe-Co-Zn catalysts revealed that the effect of pressure on the carbon chain length was reversed. Increasing the pressure from 250 to 350 psig decreased the carbon chain length. The increase in temperature, however, resulted in a decrease in the carbon chain length as observed in the Fe-Zn-K catalysts. Fe catalysts groups containing different proportions of Co were prepared. It was determined that an Fe:Co ratio of 4:1 is sufficient to obtain high CO conversions with a high selectivity towards liquid hydrocarbons. The hydrocarbon distribution on the other hand remained almost unchanged due to a change in the Co content. The use of silica, as opposed to alumina as the catalyst support, enhanced the CO conversion and the selectivity of the process towards liquid hydrocarbons. The methane and CO2 selectivities on both the supports remained unchanged. However, a significant difference in the liquid hydrocarbon distribution was observed. Addition of K to the catalyst resulted in a change in the liquid hydrocarbon distribution in that a slight increase in the heavier hydrocarbons was observed. A series of Fe4Co1Zn0.04 based catalysts for Fischer-Tropsch (F-T) synthesis, in which the different amounts of Ru are incorporated by the impregnation were also studied. The results showed the incorporation of Ru suppressed the CH4 formation at the cost of increasing the CO2 selectivity.