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The catalytic hydrogenation of an aromatic sulfonyl chloride was investigated in continuous and semi-batch mode processes using a Robinson-Mahoney stationary basket reactor. A complete experimental unit was designed and built. The operating and analytical procedures have been developed and the methodologies to gather the kinetic data have been described. Hydrogenation reactions were conducted at a reaction pressure of 364.7 psia, at three different reaction temperatures: 85 °C, 97 °C and 110 °C, at five different residence times: 0.6 (only at 110 °C), 1.0, 1.5, 2.0, 3.1 hr, with the hydrogen to the aromatic sulfonyl chloride molar ratio: 8.0 mol/mol and hydrogen to argon molar ratio: 3.0 mol/mol. Intrinsic reaction rates of the reacting species were obtained on the surface of a commercial 1 wt% palladium on charcoal catalyst. The conversion and molar yield profiles of the reacting species with respect to process time suggest a deactivation of the 1 wt % palladium on charcoal catalyst. Kinetic data collected in a continuous process mode show that the catalyst is deactivated during an experiment when the process time equal to two to three times the residence time of the liquid within the reactor. XRD analysis shows that the active sites are blocked and an amorphous layer was formed on the surface of the palladium catalyst. Semi-Batch mode experimental data were obtained at 110 °C after 8 hours of reaction time for several aromatic sulfonyl chlorides. A kinetic model has been developed, which includes adsorption of individual components and surface reactions as well as rate equations of the Hougen-Watson type. A hyperbolic deactivation function expressed in term of process time is implemented in the Hougen-Watson equation rates. The mathematical model consists of non-linear and simultaneous differential equations with multiple variables. The kinetic parameters were estimated from the minimization of a multi-response objective function by means of a sequential quadratic program, which includes a quasi-Newton algorithm. The statistical analysis was based on the t- and F-tests and the simulated results were compared to the experimental data.

The aim of the work was to develop an understanding of the phenomenon of rate enhancement observed when a heterogeneous catalytic reaction system is irradiated by ultrasound. The system under investigation was the catalytic hydrogenation of an a, B - unsaturated ketone, using zinc dust and aqueous nickel chloride as a source of hydrogen. When a slurry of zinc particles and aqueous nickel chloride is stirred or sonicated, nickel deposits in the form of patches on the surface of the zinc particles and simultaneously, zinc dissolves into the solution in the form of zinc ions, a process called pitting corrosion. Hydrogen atoms are formed when hydrogen ions diffuse from the bulk, adsorb onto the nickel surface and take up electrons generated by the dissolution of zinc. Once the atoms are formed on the surface, the atoms combine to form hydrogen molecules, which desorb in the form of hydrogen gas. When ketone is added to this slurry, the hydrogen atom formed on the surface of nickel is used as the source of hydrogen for the hydrogenation reaction. In these processes, nickel serves as catalyst. The ketone first has to diffuse to the bulk, adsorb onto the surface of nickel and undergo reduction by the hydrogen atoms to form the product. The product then has to desorb from the surface and diffuse into the bulk, in order to create vacant sites on the nickel surface for the adsorption of more ketone. Experiments dealing with measurements of hydrogen evolution rates pointed out that hydrogen is not a limiting reactant, since evolution was sustained for long periods of time. The evolution rates versus time data revealed that the nature of the plots for both, the stirred and sonicated systems were similar. These facts lead us to infer that the basic mechanism of nickel deposition, pitting corrosion, etc. was similar for the two cases. To study the hydrogenation reaction, experiments were first conducted keeping the nickel catalyst surface area constant. The results of these experiments showed that the hydrogenation reaction can be explained by a first order mechanism. Changing the speed of the stirrer did not effect the rate of the reaction; hence it was inferred that the reaction was not external mass transfer controlled. It was also seen that there was an no significant difference in reaction rates between the stirred and sonicated systems. Hence we conclude that sonication does not effect any process involved in the actual process of hydrogenation, i.e., adsorption, desorption, surface reaction, etc., do not get effected. It was concluded that the observed rate enhancements of similar compounds in the same system occur only when nickel catalyst is being continuously formed. This is possible only if irradiation with ultrasound enhances the rate of formation of the surface area of the nickel deposit. To study this phenomena, experiments were conducted with continuous formation of nickel catalyst. These experiments were conducted in three ways - stirring with zinc dust, sonication with zinc dust and stirring with presonicated zinc dust. For the first two kinds of experiments, the rates were low, increased to a maximum value and then decreased, but the nature of the third kind of experiments were different. The initial rates were very high as compared to either of the other two kinds of experiments but the rate rapidly reduces and becomes comparable to the rates obtained by stirring with zinc dust. We conclude that sonication creates many active sites on the surface of the zinc particles in the form of crystal defects, which are perhaps necessary for the deposition of nickel. When presonicated zinc particles are used, there are large numbers of these sites and these get consumed rapidly when stirred with aqueous nickel chloride solution. In this work, we do not deal with this case. In the case of sonication with zinc dust, these active sites are continuously created and are consumed by nickel deposition. For the stirred system, these sites are quite small to start with and new ones are not generated since there is no irradiation by ultrasound. Hence, the rates in the latter case are low for both nickel deposition and the hydrogenation reaction. In the model, it was assumed that the rate of increase of surface area of nickel, characterized by a specific rate term k z, was proportional to the amount of nickel in the bulk and also to the amount of free zinc surface area available. Similarly, nickel which deposits on previously deposited nickel (characterized by another specific rate constant, kn) was proportional to the amount of nickel in the bulk, the nickel area already deposited and also the free zinc surface area available. The model is in excellent agreement with the experimental data obtained. The model predicted higher values of kn and kz for the sonicated system, indicating that the rate of deposition of nickel is much higher in this case than for the stirred system. Moreover, the model also predicts that the deposit in the case of a sonicated system is thinner and flatter, since it was seen that the surface area created for the same amount of nickel deposited was much higher in this case than the stirred system.

Esta Tese descreve a preparação de novos eletrodos modificados (EMs) fazendo uso de um método novo, a deposição de partículas de metais nobres, como níquel, paládio e platina sobre partículas de metais comuns, como cobre e ferro. Este método leva aos denominados EMs mistos, que podem apresentar características diferentes e mais eficientes que os EMs Ni, Pd e Pt já estudados, sendo a principal aplicação nas reações de hidrogenação eletrocatalítica (HEC) de substratos orgânicos insaturados. A preparação dos EMs mistos se inicia pelo recobrimento da superfície do eletrodo de trabalho com um filme polimérico. O polímero usado foi o poli-(éter alílico do ácido p-benzenossulfônico), um filme aniônico com boa estabilidade química e mecânica, que pode fazer troca iônica de seus íons H+ por cátions metálicos. Este filme é preparado por varreduras de voltametria cíclica de uma solução do respectivo monômero, que se oxida eletroquimicamente iniciando a reação química de polimerização. Os metais cobre e ferro são introduzidos ao polímero pelo método de troca iônica/redução eletroquímica, onde o EM é mergulhado em uma solução saturada de um sal de cobre ou de ferro para ocorrer a troca iônica. Em seguida, estes íons são reduzidos eletroquimicamente por varreduras de voltametria cíclica, usando uma faixa de potencial adequada. Para se preparar os EMs mistos, mergulhou-se estes EMs (Cu ou Fe) na solução do banho electroless de níquel, paládio e platina. Por esta metodologia partículas destes metais nobres são depositadas pelo processo de deposição metálica electroless (DME), que faz uso de um agente redutor, hipofosfito de sódio, para reduzir os íons destes metais de forma adequada nos EMs Cu ou Fe e onde se espera obter grande área superficial. Os EMs mistos preparados foram: Cu/Ni, Cu/Pd, Cu/Pt, Fe/Ni, Fe/Pd e Fe/Pt. A caracterização dos metais dos EMs mistos foi feita indiretamente por geração eletroquímica de hidrogênio (GH) de uma solução ácida e diretamente pelas técnicas de Difração de Raios X e Microscopia de Varredura Eletrônica (MEV). O processo de deposição metálica foi investigado por medidas de potencial de circuito aberto, realizadas durante a deposição dos metais nobres que indicou a ocorrência do processo de DME em alguns casos e DG (deposição galvânica) em outros. Devido a alguns resultados do processo de deposição metálica, foi estudado o mecanismo de catalise na deposição direta das partículas de níquel, paládio e platina pela redução química por hipofosfito dos íons correspondentes. Preparou-se EMs Ni, Pd e Pt por dois métodos: troca iônica/redução eletroquímica e troca iônica/redução química catalisada pelo filme. Estes foram caracterizados por GH e utilizando o ácido p-toluenossulfônico como modelo, estudos de espectroscopia na região UV/Vis. foram realizados. Estas medidas comprovaram a catálise, pois os EMs preparados por redução química apresentaram melhores resultados para a GH e as análises de UV/Vis. mostraram a forte ligação existente entre os grupos sulfonatos do polímero e os íons metálicos bivalentes, ligação essencial para ocorrer a catálise do filme. Verificou-se que as partículas dos metais nobres podiam estar sendo depositadas por DME ou por DG seguido de DME, mas que em todos os casos ocorria a deposição causada pela catálise do filme. A reatividade dos EMs mistos foi avaliada por um estudo cinético, onde HECs de alguns substratos orgânicos foram realizadas e acompanhadas por medidas de UV/Vis. durante as reações. Obteve-se a constante de velocidade (k) destas reações, as quais foram comparadas entre si e encontrou-se como o EM misto mais eficiente o Cu/Pt. As ks das reações deste EM foram comparadas com ks de outros EMs de Pt, já estudados em nossos laboratórios. / This thesis describes the preparation of new modified electrodes (MEs) using the method of noble metal particles deposition like nickel, palladium and platinum in the surface of commum metals particles as cooper and iron. This new electrodes were denominated mixed MEs, and can show different caractheristics and present higher efficiency than others already studied, being their principal application in electrocatalytic hydrogenation (ECH) of unsaturated organic substrates. The surface electrode were coated with the polymer poly-(ether allyl p-benzenesulfonic), an anionic film with good chemical and mechanic stability that can undergoes ion exchange of ions H+ by metallic cations. This film is prepared by anodic oxidation of the monomer using voltammetric cycles, producing a cation radical initiador of a chain reaction polymerization. Cooper and iron metals are incorporated in the polymer by ion exchange/ electrochemical reduction; the ME were dipped in saturated solution of cooper or iron salt to produce the ion exchange. The ions are then electrochemically reduced. The preparation of mixed MEs is carried out by electrolessly deposidated Ni, Pd or Pt. This methodology use NaH2PO2, to reduce the metal ions. This procedure deposits Ni, Pd and Pt in the surface of Cu or Fe MEs with an expected higher superficial area. The mixed Cu/Ni, Cu/Pd, Cu/Pt, Fe/Ni, Fe/Pd e Fe/Pt MEs were prepared. The characterization of the MEs metals was made indirectly by electrochemically hydrogen generation from an acid solution (HG) and directly by SEM-EDX and Ray X Diffraction analysis. The metallic deposition process was investigated by open circuit during the deposition of nobles metals that indicate the occurrence of electroless deposition (EMD) process in some cases or spontaneous displacement reaction (galvanic deposition - GD) in others. Despite the two mechanisms related above, a catalytic process would occur. To rut in evidence this third process Ni, Pd and Pt MEs were prepared by two methods: ion exchange/electrochemical reduction and ion exchange/chemical reduction catalyzed by the film. The resulting MEs were characterized by HG and spectroscopy in the UV/Vis. For this last analysis, p-toluenossulfonic acid was used as model and the results proved the catalytic mechanism. UV spectroscopy analysis showed strong bonds between the p-toluenossulfonic and the noble metal salts. So particles of noble metals can be deposited not only by EMD or GD but in all cases occur the deposition by film catalysis too. The reactivity of mixed MEs was done by kinetic study, where ECH of some organic substrates were carried out and monitored by UV/Vis spectroscopy. The constant rate (k) of the reactions was calculated and compared with the others mixed MEs. The ks of this ME were compared with the ks of other Pt MEs, already studied. The more reactive of them was the Cu/Pt ME.

The direct catalytic hydrogenation of nitrile butadiene rubber (NBR) in latex form was studied as a model system for the development of a new latex hydrogenation process for the modification of unsaturated diene-based polymers. NBR is a synthetic rubber of copolymerized acrylonitrile and butadiene produced in latex form by emulsion polymerization. The catalytic hydrogenation of NBR is an important post-polymerization process resulting in a more stable and tougher derivative, hydrogenated NBR (HNBR), which has been widely used in the automotive and oil drilling industry. The present commercial process involves a number of cumbersome steps to obtain solid NBR from the latex and subsequent dissolution of the solid NBR in a large amount of organic solvent followed by solvent recovery after coagulation of the hydrogenated NBR. Since NBR is produced in latex form, it is very desirable to directly hydrogenate NBR in the latex form which will significantly simplify the hydrogenation process and facilitate subsequent applications. As an economical and environmentally benign alternative to the commercial processes based on the hydrogenation of NBR in organic solution, this direct latex hydrogenation process is of special interest to industry. The objective of this project is to develop an efficient catalytic system in order to realize the direct catalytic hydrogenation of NBR in latex form. OsHCl(CO)(O2)(PCy3)2 was initially used as the catalyst to investigate the possibility of hydrogenation of NBR in latex form and to understand the major factors which affect the hydrogenation operation. It was found that an organic solvent which is capable of dissolving or swelling the NBR was needed in a very small amount for the latex hydrogenation using the Os catalyst, and gel occurred in such a catalytic system during hydrogenation. Wilkinson’s catalyst, RhCl(PPh3)3, was then used for the latex hydrogenation in the presence of a small amount of solvent successfully without gel formation. Further investigation found that Wilkinson’s catalyst has a high activity for NBR latex hydrogenation without the use of any organic solvent. The influences of various operation conditions on hydrogenation rate, such as catalyst and polymer concentrations, latex system composition, agitation, reaction temperature and hydrogen pressure, have been investigated. It was found that the addition of triphenylphosphine (TPP) has a critical effect for the hydrogenation of NBR latex, and the hydrogenation rate was mainly controlled by the amount of catalyst which diffused into the polymer particles. In the presence of TPP, NBR latex can be hydrogenated to more than 95% degree of hydrogenation after about 30 hours at 160oC using Wilkinson’s catalyst with a catalyst to NBR rubber ratio of 1 wt%, without the addition of any organic solvent. The apparent activation energy for such NBR latex hydrogenation over the temperature range of 152oC to 170oC was found to be 57.0 kJ/mol. In the present study, it was also found that there are some impurities within the NBR latex which are detrimental to the hydrogenation reaction and are suspected to be water-soluble surfactant molecules. Deliberately designed solution hydrogenation experiments were conducted to study the impurity issue, and proper latex treatment methods have been found to purify the latex before hydrogenation. To improve the hydrogenation rate and to optimize the latex hydrogenation system, water soluble RhCl(TPPMS)3 catalyst (TPPMS: monosulphonated-triphenylphosphine) was used for the latex hydrogenation of NBR. The latex hydrogenation using the water soluble catalyst with TPP can achieve more than 90% degree of hydrogenation within 20 hours at 160oC. Further experiments using RhCl3 with TPP proved that the water soluble RhCl3 can be directly used as a catalyst precursor to generate the catalytic species in situ for the latex hydrogenation, and a stable NBR latex with 96% degree of hydrogenation can be produced without any gel problem within 19 hours of reaction at 160oC. The catalyst mass transport processes for these Rh based catalysts in the latex system were investigated in order to further optimize the solvent-free latex hydrogenation process. While maintaining the emulsified state of the original latex, the direct catalytic hydrogenation of NBR latex can be carried out efficiently without any cross-linking problem to more than 92% degree of hydrogenation within 8 hours at 160oC. As a result of this research project, new latex hydrogenation technologies were successfully developed to fulfill all major requirements for a solvent-free polymer latex hydrogenation route, which is a significant milestone for the improvement of this polymer modification technology. The finding of TPP’s role as the “catalyst mass transfer promoter” is a breakthrough for the research field related to the hydrogenation of unsaturated diene-based polymers in latex form.

The direct catalytic hydrogenation of nitrile butadiene rubber (NBR) in latex form was studied as a model system for the development of a new latex hydrogenation process for the modification of unsaturated diene-based polymers. NBR is a synthetic rubber of copolymerized acrylonitrile and butadiene produced in latex form by emulsion polymerization. The catalytic hydrogenation of NBR is an important post-polymerization process resulting in a more stable and tougher derivative, hydrogenated NBR (HNBR), which has been widely used in the automotive and oil drilling industry. The present commercial process involves a number of cumbersome steps to obtain solid NBR from the latex and subsequent dissolution of the solid NBR in a large amount of organic solvent followed by solvent recovery after coagulation of the hydrogenated NBR. Since NBR is produced in latex form, it is very desirable to directly hydrogenate NBR in the latex form which will significantly simplify the hydrogenation process and facilitate subsequent applications. As an economical and environmentally benign alternative to the commercial processes based on the hydrogenation of NBR in organic solution, this direct latex hydrogenation process is of special interest to industry. The objective of this project is to develop an efficient catalytic system in order to realize the direct catalytic hydrogenation of NBR in latex form. OsHCl(CO)(O2)(PCy3)2 was initially used as the catalyst to investigate the possibility of hydrogenation of NBR in latex form and to understand the major factors which affect the hydrogenation operation. It was found that an organic solvent which is capable of dissolving or swelling the NBR was needed in a very small amount for the latex hydrogenation using the Os catalyst, and gel occurred in such a catalytic system during hydrogenation. Wilkinson’s catalyst, RhCl(PPh3)3, was then used for the latex hydrogenation in the presence of a small amount of solvent successfully without gel formation. Further investigation found that Wilkinson’s catalyst has a high activity for NBR latex hydrogenation without the use of any organic solvent. The influences of various operation conditions on hydrogenation rate, such as catalyst and polymer concentrations, latex system composition, agitation, reaction temperature and hydrogen pressure, have been investigated. It was found that the addition of triphenylphosphine (TPP) has a critical effect for the hydrogenation of NBR latex, and the hydrogenation rate was mainly controlled by the amount of catalyst which diffused into the polymer particles. In the presence of TPP, NBR latex can be hydrogenated to more than 95% degree of hydrogenation after about 30 hours at 160oC using Wilkinson’s catalyst with a catalyst to NBR rubber ratio of 1 wt%, without the addition of any organic solvent. The apparent activation energy for such NBR latex hydrogenation over the temperature range of 152oC to 170oC was found to be 57.0 kJ/mol. In the present study, it was also found that there are some impurities within the NBR latex which are detrimental to the hydrogenation reaction and are suspected to be water-soluble surfactant molecules. Deliberately designed solution hydrogenation experiments were conducted to study the impurity issue, and proper latex treatment methods have been found to purify the latex before hydrogenation. To improve the hydrogenation rate and to optimize the latex hydrogenation system, water soluble RhCl(TPPMS)3 catalyst (TPPMS: monosulphonated-triphenylphosphine) was used for the latex hydrogenation of NBR. The latex hydrogenation using the water soluble catalyst with TPP can achieve more than 90% degree of hydrogenation within 20 hours at 160oC. Further experiments using RhCl3 with TPP proved that the water soluble RhCl3 can be directly used as a catalyst precursor to generate the catalytic species in situ for the latex hydrogenation, and a stable NBR latex with 96% degree of hydrogenation can be produced without any gel problem within 19 hours of reaction at 160oC. The catalyst mass transport processes for these Rh based catalysts in the latex system were investigated in order to further optimize the solvent-free latex hydrogenation process. While maintaining the emulsified state of the original latex, the direct catalytic hydrogenation of NBR latex can be carried out efficiently without any cross-linking problem to more than 92% degree of hydrogenation within 8 hours at 160oC. As a result of this research project, new latex hydrogenation technologies were successfully developed to fulfill all major requirements for a solvent-free polymer latex hydrogenation route, which is a significant milestone for the improvement of this polymer modification technology. The finding of TPP’s role as the “catalyst mass transfer promoter” is a breakthrough for the research field related to the hydrogenation of unsaturated diene-based polymers in latex form.

Heterogeneous catalysis is a key industrial process involved in the synthesis of nearly all chemicals currently produced. The environmental impact of these processes is huge so improvements must be made to current catalysts. Should a new material provide better yields at lower energy cost the benefits to both the industry and the planet are significant. There are many ways to change the behaviour of a catalyst, the addition of dopants, the selective blocking of active sites, and changing the strength of the support interaction to name a few. One technique that has become increasingly investigated is interstitial modification, the insertion of a light element into a metal lattice to change the metal's catalytic properties. The work presented in this thesis devises greener synthetic routes to the known Pd-^interstitialB/C catalyst and investigates potential routes to a novel interstitial material, Pd-^interstitialLi/C. Initially, successful verification of interstitial modification comes from the characteristic increase in palladium lattice parameter from 3.89 to 4.00 Å and the blocking of the β-hydride formation. Initial catalytic screening determines the synthetic route which yields the most active catalyst which subsequently undergoes thorough characterisation. The wealth of evidence generated confirms the interstitial location of lithium within the palladium lattice, as well as adding to the current understanding of the Pd-^interstitialB/C material. EELS analysis on Pd-^interstitialB is the closest to direct observation of boron within the palladium lattice to date. PDF on Pd-^interstitialLi shows 13.7 % of the palladium octahedral interstitial sites are occupied by lithium. This is the first report of interstitial lithium within palladium to date. The effect of the interstitial modification on catalytic hydrogenation by two elements that have opposite effects on the surface electronics of the host palladium gives intriguing results. The effect on catalysis varies depending on the conditions investigated. This bank of hydrogenation data allows an informed choice as to which interstitial material would be best suited to the gas or liquid phase catalytic hydrogenation under investigation.

The application of heterogeneous catalysts to industrial processes is a key factor in the synthesis of nearly all chemicals currently produced, however billions of pounds are lost every year due to unplanned reactor shutdowns and catalyst replacement as a result of catalytic deactivation processes. Poisoning of heterogeneous catalysts by sulfur compounds is a particularly prominent class of deactivation processes, affecting a wide range of catalytic materials and catalytic reactions, including the industrially-prominent Haber-Bosch process for the synthesis of ammonia and steam reforming of methane for the synthesis of hydrogen. However, while the effects of sulfur adsorption on catalytic behaviour are often unmistakably apparent, the fundamental interactions leading to these effects are not yet well understood. The work presented in this thesis uses a combination of models systems, novel and traditional characterization techniques, and methods of modifying catalyst geometric and electronic structure to approach the topic of sulfur poisoning from a fundamental perspective. Particular focus is placed on using selective decoration of active sites to develop a system of model hydrogenation reactions to relate changes in catalytic behaviour to changes in geometric and electronic structure. Application of these model reactions to investigate the sensitivities of palladium- and ruthenium-based catalytic systems to modification by sulfur shows contrasting effects for the two metals. While both systems exhibit similar geometric effects of modification, the palladium-based catalysts are far more sensitive than the ruthenium-based catalysts to modification of electronic structure. Additionally, controlled variation in particle size for the palladium-based catalysts demonstrates that catalytic behaviour is dominated by electronic structure for small nanoparticles and geometric structure for large nanoparticles. This leads small nanoparticles to show increased sensitivity to electronic modification effects resulting from sulfur adsorption. Ultimately, the research presented within this thesis provides a basis for the intelligent design of heterogeneous catalysts for improving tolerance for sulfur poisoning, and for utilizing the effects of sulfur modification to optimize catalytic activity and selectivity for the synthesis of fine chemicals.