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Academic literature on the topic 'Rhodium catalysts'

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Published: 4 June 2021
Last updated: 3 March 2023

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Journal articles on the topic "Rhodium catalysts"

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Xing, Hai Lin, Hao Zhou, Li Qun Zhang, Wei Ming Wang, and Dong Mei Yue. "Remove Rhodium Catalysts from HNBR Solution." Advanced Materials Research 311-313 (August 2011): 1152–56. http://dx.doi.org/10.4028/www.scientific.net/amr.311-313.1152.

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Rhodium complex is excellent catalyst for nitrile-butadiene rubber homogeneous hydrogenation with difficulties in its recovery. A new extraction method for recovery noble metal catalysts from hydrogenated nitrile-butadiene rubber solution was investigated. Rhodium metal catalysts can be efficiently, easily removed from hydrogenated nitrile-butadiene rubber solution using amine as ligand and hydrogen peroxide as oxidant. The condition of removing noble metal catalysts from hydrogenated nitrile-butadiene rubber solution was carefully studied, including oxidant, reaction temperature, and the concentration of amine. The removal rate of the rhodium catalyst over 96% with the optimal conditions.1H-NMR characterization showed that there was no change in the structure and nitrile group of hydrogenated nitrile-butadiene rubber after rhodium catalysts were removed.
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Hanf, Schirin, Luis Alvarado Rupflin, Roger Gläser, and Stephan Schunk. "Current State of the Art of the Solid Rh-Based Catalyzed Hydroformylation of Short-Chain Olefins." Catalysts 10, no. 5 (May 6, 2020): 510. http://dx.doi.org/10.3390/catal10050510.

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The hydroformylation of olefins is one of the most important homogeneously catalyzed processes in industry to produce bulk chemicals. Despite the high catalytic activities and selectivity’s using rhodium-based homogeneous hydroformylation catalysts, catalyst recovery and recycling from the reaction mixture remain a challenging topic on a process level. Therefore, technical solutions involving alternate approaches with heterogeneous catalysts for the conversion of olefins into aldehydes have been considered and research activities have addressed the synthesis and development of heterogeneous rhodium-based hydroformylation catalysts. Different strategies were pursued by different groups of authors, such as the deposition of molecular rhodium complexes, metallic rhodium nanoparticles and single-atom catalysts on a solid support as well as rhodium complexes present in supported liquids. An overview of the recent developments made in the area of the heterogenization of homogeneous rhodium catalysts and their application in the hydroformylation of short-chain olefins is given. A special focus is laid on the mechanistic understanding of the heterogeneously catalyzed reactions at a molecular level in order to provide a guide for the future design of rhodium-based heterogeneous hydroformylation catalysts.
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Konuspayev, Sapar, Minavar Shaimardan, Nurlan Annas, T. S. Abildin, and Y. Y. Suleimenov. "Hydrogenation of benzene and toluene over supported rhodium and rhodium-gold catalysts." MATEC Web of Conferences 340 (2021): 01026. http://dx.doi.org/10.1051/matecconf/202134001026.

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Rhodium and rhodium-gold catalysts supported on amorphous aluminosilicates (ASA), titanium dioxide (rutile, TiO2) was prepared in two different ways: absorption and colloidal method. The catalysts were characterized by an inductively coupled plasma optical emission spectrometer (ICP-OES), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The activity and selectivity of the prepared catalysts were tested by the hydrogenation of benzene and toluene. Hydrogenation was conducted at a pressure of 4 MPa and a temperature 80 °C. The bimetallic Rh-Au/ASA catalyst prepared by the absorption method showed higher activity and selectivity in benzene hydrogenation reaction, the same catalyst prepared by the colloidal method demonstrated lower selectivity.
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Konuspaev, S. R., and A. Nurlan. "Influence of the Au-Rh /ASA catalyst preparation method on the benzene hydrogenation reaction." BULLETIN of the L.N. Gumilyov Eurasian National University. Chemistry. Geography. Ecology Series 136, no. 3 (2021): 35–44. http://dx.doi.org/10.32523/2616-6771-2021-136-3-35-44.

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Comparative hydrogenation of benzene and toluene in ethanol under hydrogen pressure on rhodium and gold supported on synthetic amorphous aluminosilicate (ASA, trade name is siral-40) with a developed surface area prepared by two methods: impregnation by using the incipient wetness technique and colloidal method. Moreover, the catalysts were prepared by impregnation in two versions: co-impregnation and sequential impregnation of rhodium and gold salts. The catalysts are characterized by inductively coupled plasma-optical emission spectroscopy (ICP-OES) methods. It is shown that the catalysts prepared by impregnation according to the incipient wetness technique were the most acceptable for selective hydrogenation of benzene. The activity of the catalyst depends on the amount of rhodium on the surface of the available surface for the activation of benzene and toluene. On catalysts prepared by the colloidal method, the active metal rhodium goes inside the pores, and gold on the surface, so the activity is low, while on catalysts prepared by impregnation, the amount of rhodium on the surface is close to the theoretically possible amount. The selectivity of benzene hydrogenation in the presence of toluene on this catalyst is 84%.
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Shi, Libin, Suitao Qi, Tianyou Jiao, Jifeng Qu, Xiao Tan, Chunhai Yi, and Bolun Yang. "Catalytic Decomposition of Nitrogen Oxides by Bimetallic Catalysts Synthesized by Dielectric Barrier Discharge Plasma Technology." E3S Web of Conferences 53 (2018): 01032. http://dx.doi.org/10.1051/e3sconf/20185301032.

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Nitrous oxide (N2O) is a common greenhouse gas and urgent need to be contained. Direct catalytic decomposition of N2O by high activity catalyst into N2 and O2 is a low-cost and harmless method. Bimetallic catalysts show good catalytic activity in many classes of reactions, and plasma technologies, applied to prepare of catalyst, are considered to be a promising method. In our contribution, DBD cold plasma is applied to synthesize Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition. The influence of cobalt and rhodium content on N2O decomposition activity shows that the optimal amount of metal is determined as 5wt. % cobalt and 0.5wt. % rhodium loaded on Al2O3. The best working voltage is determined as 18kV. The results indicated that the Rh/Al2O3 catalysts prepared by atmospheric-pressure DBD cold plasma showed smaller size and high dispersion of Rh particles, so that the metal-support interaction and the catalytic activity are enhanced. Atmospheric-pressure DBD cold plasma is proved to be an environmentally friendly and efficient method for preparing high performance Rhodium and Cobalt bimetallic catalysts for catalytic N2O decomposition.
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Sedláček, Jan, and Jiří Vohlídal. "Controlled and Living Polymerizations Induced with Rhodium Catalysts. A Review." Collection of Czechoslovak Chemical Communications 68, no. 10 (2003): 1745–90. http://dx.doi.org/10.1135/cccc20031745.

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In the last fifteen years, a large variety of specialty polymers of diverse chemical structure and functionality have been synthesized with the rhodium-based catalysts. The high tolerance to the reaction medium and functional groups of monomers, as well as ability to control various structure features of the polymer formed are typical properties of these catalysts. In addition, some rhodium catalysts can be anchored to inorganic or organic supports or dissolved in ionic liquids to form heterophase polymerization systems, which opens the way to pure, well-defined polymers free of the catalyst residues, as well as to recycling rhodium catalysts. This review provides a survey on the polymerization reactions induced with rhodium-based catalysts, in which one or more structure attributes of the polymer formed are subject to control. The structure attributes considered are (i) sequential arrangement of monomeric units along polymer chains; (ii) head-tail isomerism of polymer molecules; (iii) configurational structure of polymer molecules; (iv) conformation of polymer molecules; and (v) molecular weight and molecular-weight distribution of the polymer formed. A review with 188 references.
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Kenzhin, Roman M., Evgeny A. Alikin, Sergey P. Denisov, and Aleksey A. Vedyagin. "Study on Thermal Stability of Ceria-Supported Rhodium Catalysts." Materials Science Forum 950 (April 2019): 190–94. http://dx.doi.org/10.4028/www.scientific.net/msf.950.190.

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In the present work, the impact of the rhodium deposition on the thermal stability of ceria-based catalysts was studied. The samples were prepared by an incipient wetness impregnation of the support with aqueous solution of rhodium nitrate. The loading of Rh was 0.1 and 1 wt.%. The textural characteristics of the samples were examined by a low-temperature nitrogen adsorption. It was shown that the addition of rhodium intensifies the process of ceria agglomeration, which leads to the lower values of specific surface area along with increased average pore diameter after the aging at 1000 °C. Stability of the catalysts was investigated by means of a prompt thermal aging procedure. The high-loaded catalyst (1 wt.% Rh/CeO2) was more active than the 0.1 wt.% Rh/CeO2sample, while the stability of both the catalysts was excellent. It should be emphasized that the alumina-based reference samples with the similar rhodium loading were significantly less active and poorly stable.
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Storey, Caroline M., Audrius Kalpokas, Matthew R. Gyton, Tobias Krämer, and Adrian B. Chaplin. "A shape changing tandem Rh(CNC) catalyst: preparation of bicyclo[4.2.0]octa-1,5,7-trienes from terminal aryl alkynes." Chemical Science 11, no. 8 (2020): 2051–57. http://dx.doi.org/10.1039/c9sc06153c.

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Alikin, Evgeny A., Sergey P. Denisov, Konstantin V. Bubnov, and Aleksey A. Vedyagin. "Self-Regeneration Effect of Three-Way Catalysts during Thermal Aging Procedure." Catalysts 10, no. 11 (October 30, 2020): 1257. http://dx.doi.org/10.3390/catal10111257.

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One of the most important features of the three-way catalysts is their long-term stability. However, quite often, promising catalytic compositions with excellent activity become deactivated after a relatively short period of exploitation due to various reasons. Therefore, a study on the onboard regeneration of the deactivated three-way catalysts remains its actuality. The present work is mainly focused on the self-regeneration effect of the rhodium-containing component. Aging of the catalysts in the standard and model engine braking regimes revealed the difference in the catalytic performance. Deactivated rhodium species turned to the active state as a result of rapid cooling in air flow from 1200 to 600 °C. The regenerated catalyst shows improved activity towards NOx reduction and, therefore, widened operation window, which indicates higher accessibility of the rhodium species. X-ray diffraction analysis of the aged catalysts does not reveal any noticeable phase changes. Contrary, significant changes in the Rh oxidation state were registered by X-ray photoelectron spectroscopy. The observed effect opens new horizons for the development of the onboard purification systems with prolonged exploitation lifetime.
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Zinner, Sandra C., Mei Zhang-Preße, Wolfgang A. Herrmann, and Fritz E. Kühn. "Enantioselective Hydrosilylation with a Chiral N-Heterocyclic Carbene Complex of Rhodium(I) [1]." Zeitschrift für Naturforschung B 64, no. 11-12 (December 1, 2009): 1607–11. http://dx.doi.org/10.1515/znb-2009-11-1246.

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Both enantiomers of the chiral rhodium-NHC complex [(4X, 5X)-1,3-bis[2,6-diisopropyl-phenyl]- 4,5-ditert-butylimidazolidine-2-ylidene][1,5-cyclooctadiene]-iodo-rhodium(I) with X = R, S were applied as catalysts for the asymmetric hydrosilylation of prochiral ketones. The influence of employed solvent, substrate, silane, and catalyst enantiomer on the catalytic activity and the enantioselectivity of the desired product was investigated
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Dissertations / Theses on the topic "Rhodium catalysts"

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Jongsma, Tjeerd. "Polymer-bound rhodium hydroformylation catalysts." [S.l. : [Groningen : s.n.] ; University of Groningen] [Host], 2008. http://irs.ub.rug.nl/ppn/.

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Lamb, Gareth William. "Phosphine modified rhodium catalysts for the carbonylation of methanol /." St Andrews, 2008. http://hdl.handle.net/10023/574.

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Lamb, Gareth W. "Phosphine modified rhodium catalysts for the carbonylation of methanol." Thesis, University of St Andrews, 2008. http://hdl.handle.net/10023/574.

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The carbonylation of methanol to acetic acid is one of the most important applications in homogeneous catalysis. The first chapter comprises a review on the mechanistic studies into the catalytic cycle of the ‘Monsanto process’ and includes some of the most prominent studies into the use of phosphines in the rhodium-catalysed carbonylation of methanol. The second chapter of this thesis reports on an investigation into the application of rhodium complexes containing several C4 bridged diphosphines, namely BINAP, dppb, dppx and dcpb as catalysts for hydrogen tolerant methanol carbonylation. An investigation into the structure, reactivity and stability of pre-catalysts and catalyst resting states of these complexes has also been carried out. The origin of this hydrogen tolerance is explained based on the differing reactivities of the Rh acetyls with hydrogen gas, and by considering the structure of the complexes. In the third chapter I report on an investigation into how electronic properties and coordination mode affect the elimination of phosphonium salts from rhodium complexes. The stability of a range of monodentate, bidentate and tridentate rhodium-phosphine complexes was tested. I also report on the formation of a novel bidentate complex containing a partially quaternised TRIPHOS ligand and investigate the mechanism of formation using 13CH3I. Strong evidence is also presented supporting a dissociative mechanism as the means of phosphine loss from the rhodium centre. In the final chapters I report an investigation into the stability of rhodium-aminophosphine ligand complexes and into increasing the solubility of potential rhodium pre-catalysts through the use of amine-containing phosphine ligands.
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Schnitzer, Jill. "Liquid phase hydroformylation by zeolite supported rhodium." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45732.

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The purpose of this research was to directly compare the behavior of zeolites containing rhodium with that of homogeneous rhodium species as catalysts for liquid phase hydroformylation of 1-hexene in order to study the effects of zeolite immobilization. NaX zeolite was cation exchanged with several rhodium salts and used as hydroformylation catalysts at 50°C and 125°C in the presence of: triphenylphosphine (PPh₃), dimethylphenylphosphine (PMe₂Ph), and the poison for zeolite surface and solution rhodium: triphenylmethylmercaptan (Ph₃CSH). The results of these experiments were compared with those of several homogeneous catalysts under similar conditions. It was found that previously reported results of intrazeolitic activity with RhNaX at 50°C were probably incorrect, since, the addition of PMe₂Ph, Ph₃CSH, or both, virtually halted all reactivity of RhNax. The catalytic results at 125°C did not conclusively indicate the location of the active rhodium. Thus, intrazeolitic activity at 125°C may or may not have been observed, and needs further investigation. Reaction profiles were obtained for several of the catalyst systems, using an automatic sampling system. From these profiles, it was found that the addition of excess PMe₂Ph halted isomerization of 1-hexene to 2-hexenes for the zeolite-supported rhodium, and hindered, but did not stop isomerization for the homogeneous catalysts. Also, as expected, it was observed that the homogeneous catalysts reacted to completion faster than the heterogeneous catalyst. In addition, the effects of such treatments as preheating in air and precarbonylation of the heterogeneous catalysts were studied. Pretreatments had no effect upon the catalysis. Also, no activity was observed from the heterogeneous catalysts at 125°C unless phosphines were present. Finally, the hydrogenation of 1-hexene was studied. Heterogeneous and homogeneous rhodium catalysts showed hydrogenation activity which was accompanied by isomerization at 60°C and 125°C.
Master of Science
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Ferris, Leigh. "Rhodium carboxylates as catalysts for carbenoid transformations." Thesis, Loughborough University, 1996. https://dspace.lboro.ac.uk/2134/32620.

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Chapter One reviews the literature, discussing the application of metallocarbenoids in asymmetric synthesis. This introduction is mainly concerned with asymmetric carbon-carbon and carbon-heteroatom bond forming reactions and pays particular attention to the levels of stereoselectivity that have been achieved. Chapter Two discusses the use of novel homochiral rhodium(II) carboxylates to effect asymmetric induction in a range of carbenoid transformations. The preparation of these novel rhodium(II) carboxylates is discussed, together with their application in asymmetric catalysis. The work presented is particularly concerned with the insertion of rhodium carbenoids into the heteroatom-hydrogen bond of alcohols, thiols, amines and silanes to prepare enantiomerically enriched a-substituted esters. Chapter Three discusses the generation of oxygen and sulfur ylides followed by a [2,3] sigmatropic rearrangement to generate enantiomerically enriched esters containing a quaternary chiral centre. Asymmetric cyclopropanations and carbon-hydrogen insertion reactions are also discussed. Chapter Four examines the use of diazo phosphonoacetate in organic synthesis. The work has concentrated on the preparation of N-substituted aminophosphonoacetates, by the insertion reactions of anilines, amides and carbamates. These compounds have then been manipulated to prepare a series of amino esters and peptides.
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Roscioni, Otello Maria. "A computational study of supported rhodium catalysts." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/191339/.

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In this work, density functional theory (DFT) was used to obtain microscopic structures of heterogeneous catalysts based on rhodium supported on a metal oxide (-Al2O3). Two different methodologies were used. The first methodology uses a periodic model and a plane-wave basis set to solve the Schrödinger equation in the framework of Bloch’s theorem. The optimised structures of RhI(CO)2/ -Al2O3 species obtained at this level of theory have bond lengths in agreement with experimental EXAFS determinations. The weighted linear combination of Rh K-edge XANES spectra computed using the three most dominant structures reproduces well the phase and shape of the oscillations of the experimental XANES spectrum, providing support for the computed structures. The second methodology is based on hybrid quantum mechanical (QM)/molecular mechanical (MM) calculations. Within this scheme the support is described at the MM level of theory while the region of interest, the absorption site where the surface RhI(CO)2 complex lies, is described with a suitable QM approach. These hybrid calculations performed at the PBE/ECP/cc-pVDZ level of theory were used to obtainminimum-energy structures and harmonic stretching frequencies of RhI(CO)2/-Al2O3 species. The computed bond lengths and harmonic stretching frequencies were in good agreement with the experimental evidence and with the results obtained using periodic models
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Rode, Edward James. "Rhodium-zeolite hydroformylation of propylene." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/71252.

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The purpose of this research was to characterize the rhodium exchanged NaX and NaY zeolites as propylene hydroformylation catalysts. Catalytic activity was measured in a differential bed reactor. Flow in situ infrared spectroscopy was used to probe the coordination chemistry of the zeolite modified rhodium carbonyls. The catalytic activity of rhodium zeolites at atmospheric pressure and between 100-150ºC was measured. The rate of n-butyraldehyde production was approximately 5x10⁻³ moles/g- Rh hr at 150°C. Regioselectivity was dependent upon pretreatment. Precarbonylation with carbon monoxide, drying with air, and heating with N₂ prior to hydroformylation conditions produced a straight to branched isomer ratio (n/i) of 1.9-2.3. Partial reduction with 10% H₂ in N₂ at 127°C lowered n/i to 1.3. Hydrogenation to propane was 3-10 times faster than the hydroformylation rate at 150°C. Catalytic activity was sensitive to cation exchange conditions. Rhodium form, pH, temperature, and salt concentration altered catalyst behavior. Only RhCl₃•3H₂O preparations on NaY zeolite produced above 80ºC, a pH above 4, and a salt concentration of 0.1N NaCl were required in order to produce an active hydroformylation catalyst. Ammine complexes did not activate under any circumstances. It was found that the degree of hydration controlled the formation of rhodium carbonyls. On NaY, the hydrated rhodium zeolite reacted with CO at 120ºC to form Rh₆(CO)₁₆. By drying the zeolite in air at 190ºC, two rhodium dicarbonyls, Rh(CO)₂(Oz)₂-NaY and Rh(CO)₂(Oz)(H₂O)-NaY, were formed. The rhodium carbonyls were reacted with n-hexyl diphenylphosphine to determine rhodium locations. Rh(CO)₂(Oz)₂-NaY was located at the surface while the other two species were located within the zeolite cages. One dicarbonyl species, Rh(CO)₂(Oz)₂-NaX, was observed on NaX. It was determined by reactions with phosphines that this species resides in the zeolite cages. Reaction intermediates identified by FTIR under hydroformylation conditions suggested that the heterogeneous catalyst proceeds through a mechanism similar to that occurring in solution. Heterogeneous reaction orders also agreed with those reported for homogeneous hydroformylations. Addition of dimethylphenylphosphine (DMP) to the rhodium zeolites significantly increased regioselectivity. Rates were slightly less than those from the unmodified rhodium carbonyls. However, the phosphine modified rhodium zeolites deactivated within 16 hours. Continuous exposure to DMP decreased the rate of deactivation.
Ph. D.
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Solmi, Matilde Valeria. "Synthèse d'acides carboxyliques à partir de substrats oxygénés, de CO2 et de H2." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1287/document.

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Les acides carboxyliques aliphatiques sont utilisés dans de nombreux secteurs industriels et leur importance économique augmente. Ils sont actuellement produits en grande quantité, grâce à des procédés utilisant le C0 qui est principalement non- renouvelable. L'anhydride carbonique est une molécule potentiellement écologique, renouvelable et abondante. Cette thèse décrit l'étude et l'optimisation d'un système catalytique homogène de Rh, utilisé pour produire des acides carboxyliques aliphatiques à partir de substrats oxygénés, C02 et H2. Le système consiste en un précurseur de Rh, un additif à base d'iodure et un ligand PPh3, fonctionnant dans un réacteur discontinu sous une pression de C02 et de H2. Les conditions de réaction ont été optimisées pour chaque classe de substrats étudiés: alcools primaires et secondaires, cétones, aldéhydes et époxydes. 30 molécules différentes ont été converties en acides carboxyliques, conduisant à des rendements jusqu'à 80%. En plus, le système a été étudié avec une approche de « Design of Experiment », ce qui a permis d'obtenir des informations supplémentaires concernant les paramètres étudiés. Le mécanisme de réaction et les espèces catalytiques actives ont été étudiés par différentes manipulations comme des réactions compétitives, des expériences de RMN et l'utilisation de molécules marquées. La réaction est composée de transformations non catalytiques et de deux étapes catalytiques. La réaction se déroule à travers une réaction de reverse Water Gas Shift (rWGSR) transformant le C02 et l'H2 en C0 et H20, qui sont consommés dans l'hydrocarboxylation suivante de l'alcène formé in situ pour livrer l'acide carboxylique. Le système catalytique est similaire aux catalyseurs traditionnels à base du Rh pour les réactions de carbonylation et de Water Gas Shift. Le PPh3 est nécessaire pour fournir des ligands supplémentaires, permettant au catalyseur de fonctionner avec une quantité minimale de ligand toxique de C0. En plus, un système catalytique hétérogène a été étudié pour la même réaction. « Single Atom Catalysts » (SACs) reçoit beaucoup plus d'attention que les solutions catalytiques, car il présente à la fois les avantages des catalyseurs homogènes (sélectivité, haute activité) et des catalyseurs hétérogènes (séparation et recyclage faciles). Des atomes de rhodium simples dispersés sur du graphène dopé avec l'N ont été synthétisés et caractérisés, obtenant des informations concernant la structure chimique et physique du matériau. Finalement, ils ont été testés ainsi que les catalyseurs pour l'activation du C02, la production d'acides carboxyliques, les réactions d'hydrogénation et d'hydrogénolyse
Aliphatic carboxylic acids are used in many industrial sectors and their importance from an economical point of view is increasing. They are currently produced in large quantities, through processes exploiting the mostly non-renewable C0 as C1 synthon. Carbon dioxide is a potential environmentally friendly, renewable and abundant C1 building block. The aim of this work is to provide a catalytic protocol converting C02, H2 and oxygenated substrates to obtain useful chemicals, like carboxylic acids.To this end a homogeneous catalytic Rh system, used to produce aliphatic carboxylic acids starting from oxygenated substrates, C02 and H2 was investigated and optimized. The system consists of a Rh precursor, iodide additive and PPh3 ligand working in a batch reactor under C02 and H2 pressure. The reaction conditions were optimized for each class of investigated substrates: primary alcohols, secondary alcohols, ketones, aldehydes and epoxides. The reaction scope was investigated and 30 different molecules were converted into carboxylic acids, leading to yields of up to 80%. ln addition, the system was studied using a Design of Experiment approach, obtaining additional information regarding the studied parameters.The reaction mechanism and the catalytically active species were studied, by different experiments like competitive reactions, NMR and labelling experiments. This investigation resulted in a deeper knowledge of the reaction pathway, composed of some non-catalytic transformations and two catalytic steps. The reaction proceeds through a reverse Water Gas Shift Reaction (rWGSR) transforming C02 and H2 into C0 and H20, which are consumed in the following hydrocarboxylation of the in-situ formed alkene to give the final carboxylic acid product. The catalytic system is similar to traditional Rh carbonylation and Water Gas Shift catalysts. The PPh3 is needed to supply additional ligands allowing the catalyst to work in reaction conditions with a minimal amount of toxic C0 ligand. ln addition, a heterogeneous catalytic system was investigated for the same reaction. Single atom catalysts (SACs) are receiving much attention as catalytic solution, since they have both the advantages of homogeneous (selectivity, high activity) and heterogeneous (easy separation and recycling) catalysts. Single Rh atoms dispersed on N-doped graphene were synthesized and characterized, obtaining information regarding the chemical and physical structure of the material. Eventually, they were tested as catalysts for C02 activation, carboxylic acid production, hydrogenation and hydrogenolysis reactions
Aliphatische Carbonsauren werden in vielen industriellen Bereichen verwendet und ihre wirtschaftliche Bedeutung nimmt zu. Sie werden derzeit in gror.en Mengen hergestellt, indem das meistens nicht erneuerbare Kohlenmonoxid als C1-Synthon genutzt wird. Kohlendioxid ist ein potenziell umweltfreundlicher, erneuerbarer und abundanter C1-Baustein. Das Ziel dieser Arbeit ist die Entwicklung eines Protokolls zur katalytischen Umwandlung von C02, H2 und sauerstoffhaltigen Substraten, um nützliche Chemikalien, wie Carbonsauren zu erhalten. Zu diesem Zweck wird ein homogenes Rh-Katalysatorsystems zur Herstellung aliphatischer Carbonsauren aus sauerstoffhaltigen Substraten, C02 und H2 untersucht und optimiert. Das System besteht aus Rh-Prakursor, lodid-Additiv und PPh3 als Ligand, die in einem Batchreaktor unter C02 und H2 eingesetzt werden. Die Reaktionsbedingungen wurden für folgende Substratklassen optimiert: primare Alkohole, sekundare Alkohole, Ketone, Aldehyde und Epoxide. Es wurden insgesamt 30 verschiedene Substrate mit Ausbeuten bis zu 80% zu Carbonsauren umgesetzt. Darüber hinaus wurde das System mit einem ,,Statistische Versuchsplanung"-Ansatz untersucht, um zusatzliche lnformationen zu den untersuchten Parametern zu erhalten. Mechanismus und katalytisch aktive Spezies wurden durch verschiedene Experimente wie Konkurrenzreaktionen, NMR- und Markierungsexperimenten untersucht. Dies erschloss den Reaktionsweg, der aus mehreren nicht-katalytischen Transformationen und zwei katalytischen Schritten besteht. Die Reaktion verlauft durch eine ,,reverse Wassergas-Shift-Reaktion" (rWGSR), die C02 und H2 in C0 und H20 umwandelt. Diese werden wiederum bei der nachfolgenden Hydrocarboxylierung des in-situ gebildeten Alkens unter Bildung der Carbonsaure verbraucht. Das katalytische System ahnelt herkômmlichen Rh-Carbonylierungs- und WGSR-Katalysatoren. PPh3 fungiert als zusatzlicher Ligand, der es dem Katalysator ermôglicht unter den gleichen Reaktionsbedingungen mit minimaler Menge toxischen C0 als Liganden zu arbeiten. Zusatzlich wurde ein heterogenes katalytisches System für die gleiche Reaktion untersucht. ,,Single atom catalysts" (SACs) erhalten gror.e Aufmerksamkeit als neue Katalysatorklasse. Sie kombinieren die Selektivitat und hohe Aktivitat homogener und die einfache Abtrennung und Recycling heterogener Katalysatoren Verschiedene Katalysatoren aus auf N-dotiertem Graphen dispergierten Rh-Atomen, wurden synthetisiert und charakterisiert. Dadurch wurden lnformationen über die chemische und physikalische Struktur des Materials gewonnen und als Katalysatoren für C02-Aktivierung, Carbonsauresythese, Hydrierung und Hydrogenolyse getestet
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Warren, James Patrick. "Catalytic chemistry of the rhodium/ceria system : model catalysts and dispersed catalysts." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.627214.

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Buck, Richard Tony. "Rhodium carbenoids in asymmetric synthesis." Thesis, University of Exeter, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.267219.

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Books on the topic "Rhodium catalysts"

1

(Firm), Knovel, ed. Rhodium catalyzed hydroformylation. New York: Kluwer Academic Publishers, 2000.

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Trzeciak, Anna Maria. Struktura i reaktywność związków kompleksowych rodu w reakcji hydroformylacji. Wrocław: Wydawn. Uniwersytetu Wrocławskiego, 1990.

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Homogeneous catalysis with compounds of rhodium and iridium. Dordrecht: D. Reidel Pub. Co., 1985.

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Richards, David Gareth. Synthesis gas conversion to oxygenates using rhodium catalysts. Uxbridge: Brunel University, 1985.

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Andrew, Evans P., ed. Modern rhodium-catalyzed organic reactions. Weinheim: Wiley-VCH, 2005.

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Koch, Daniel. Übergangsmetallkatalysierte Synthesen in überkritischem Kohlendioxid (scCO₂). Aachen: Mainz, 1999.

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Claver, Carmen, ed. Rhodium Catalysis. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-66665-5.

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Dickson, Ronald S. Homogeneous Catalysis with Compounds of Rhodium and Iridium. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5267-6.

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Fagnou, Keith. Rhodium catalysed asymmetric ring opening of oxabicyclic alkenes and diastereoselective ring opening of expoxides with heteroatom nucleophiles. Ottawa: National Library of Canada, 2000.

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Claver, Carmen, and Piet W. N. M. van Leeuwen. Rhodium Catalyzed Hydroformylation. Springer London, Limited, 2006.

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Book chapters on the topic "Rhodium catalysts"

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Kamer, Paul C. J., Joost N. H. Reek, and Piet W. N. M. van Leeuwen. "Rhodium Phosphite Catalysts." In Rhodium Catalyzed Hydroformylation, 35–62. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/0-306-46947-2_3.

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Billig, E., and R. L. Pruett. "By Rhodium Catalysts." In Inorganic Reactions and Methods, 358–62. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch142.

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Wegman, R. W. "By Rhodium Catalysts." In Inorganic Reactions and Methods, 373–75. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch151.

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James, B. R., and M. T. Ashby. "Rhodium(l) Catalysts." In Inorganic Reactions and Methods, 80–89. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch33.

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Gras, J. L. "By Rhodium Catalysts." In Inorganic Reactions and Methods, 162–65. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch50.

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Lazzaroni, Raffaello, Roberta Settambolo, and Aldo Caiazzo. "Hydroformylation with unmodified rhodium catalysts." In Rhodium Catalyzed Hydroformylation, 15–33. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/0-306-46947-2_2.

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van Leeuwen, Piet W. N. M., and Paul C. J. Kamer. "New Rhodium Hydroformylation Catalysts." In Organic Synthesis via Organometallics OSM 5, 229–51. Berlin, Heidelberg: Springer Berlin Heidelberg, 1997. http://dx.doi.org/10.1007/978-3-642-49348-5_17.

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Billig, E., and R. L. Pruett. "By Rhodium and Iridium Catalysts." In Inorganic Reactions and Methods, 367–69. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch147.

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Ojima, I. "By Rhodium and Nickel Catalysts." In Inorganic Reactions and Methods, 225–29. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch72.

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Ojima, I. "By Rhodium, Cobalt, and Chromium Catalysts." In Inorganic Reactions and Methods, 239–40. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2007. http://dx.doi.org/10.1002/9780470145319.ch77.

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Conference papers on the topic "Rhodium catalysts"

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Brisiey, R. J., N. R. Collins, A. C. French, D. Morris, R. D. O'Sullivan, and M. V. Twigg. "Advanced Platinum-Rhodium Exhaust Catalysts - An Economic Alternative To Palladium-Rhodium." In SAE 2000 India Mobility Conference. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2000. http://dx.doi.org/10.4271/2000-01-1418.

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Wan, C. Z., and J. C. Dettling. "Effective Rhodium Utilization in Automotive Exhaust Catalysts." In SAE International Congress and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1986. http://dx.doi.org/10.4271/860566.

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Brisley, R. J., R. D. O'Sullivan, and A. J. J. Wilkins. "The Effect of High Temperature Ageing on Platinum-Rhodium and Palladium-Rhodium Three Way Catalysts." In International Congress & Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1991. http://dx.doi.org/10.4271/910175.

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Vohidov, Farrukh, Brian V. Popp, and Zachary T. Ball. "Designing Enzyme-Like Catalysts: A Rhodium(II) Metallopeptide Case Study." In The 24th American Peptide Symposium. Prompt Scientific Publishing, 2015. http://dx.doi.org/10.17952/24aps.2015.024.

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Raoufi, Arman, Sagar Kapadia, and James C. Newman. "Sensitivity Analysis and Computational Optimization of Fuel Reformer." In ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology collocated with the ASME 2016 Power Conference and the ASME 2016 10th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fuelcell2016-59110.

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In this study, the catalytic combustion of methane is numerically investigated using an unstructured, implicit, fully coupled finite volume approach. Nonlinear system of equations is solved by Newton’s method. The catalytic partial oxidation of methane over both platinum and rhodium catalysts are studied three-dimensionally. Eight gas-phase species (CH4, CO2, H2O, N2, O2, CO, OH and H2) are considered for the simulation. Surface chemistry is modeled by detailed reaction mechanisms including 24 heterogeneous reactions with 11 surface-adsorbed species for Pt catalyst and 38 heterogeneous reactions with 20 surface-adsorbed species for Rh catalyst. The numerical results are compared with the experimental data and good agreement is observed. The performance of the fuel reformer is analyzed for two different catalysts. The sensitivity analysis for the reactor is performed using three different approaches: finite difference, direct differentiation and adjoint method. The design cycle is performed using two gradient-based optimization algorithms to improve the value of the implemented cost function and optimize the reactor performance.
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Goryunova, V. D., and L. O. Nindakova. "Asymmetric transfer hydrogenation over rhodium catalysts in the presence of chiral diamine." In INTERNATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF COMBUSTION AND PROCESSES IN EXTREME ENVIRONMENTS (COMPHYSCHEM’20-21) and VI INTERNATIONAL SUMMER SCHOOL “MODERN QUANTUM CHEMISTRY METHODS IN APPLICATIONS”. AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0033044.

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Ghosh, Bankim B., Prokash Chandra Roy, Mita Ghosh, Paritosh Bhattacharya, Rajsekhar Panua, and Prasanta K. Santra. "Control of S.I. Engine Exhaust Emissions Using Non-Precious Catalyst (ZSM-5) Supported Bimetals and Noble Metals as Catalyst." In ASME 2005 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ices2005-1025.

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Three Way Catalysts (TWC) are extensively used for simultaneous control of three principal automotive pollutants, namely carbon monoxide (CO), Oxides of nitrogen (NOx), and hydrocarbon (HC). Most of works on three way catalytic converter have been carried out with noble metals such as Platinum, Rhodium, and Iridium have been tried individually and in different combinations and proportions. Noble metal catalysts give very good performance of reduction of (NOx), CO and HC in the narrow range of stoichiometric Air Fuel ratio. Noble metals are costly and not abundantly available. These draw backs of the noble metal catalysts have inspired to search for the alternative catalysts, which will perform well over the wide range of A/F ratio and are economical and abundantly available. This paper discusses the processing of ZSM-5 to Cu-Ion- Exchanged ZSM-5, ZSM-5 supported Cu-Pt bimetallic catalyst and Cu-Rh bimetallic catalyst and placing them in a three staged converter to study the reduction efficiencies of exhaust emissions CO, NOx, and HC in a 800 cc Maruti S. I. Engine. The experiments are carried out at 1500 rpm, 17.6 A/F ratio, different catalyst bed temperatures and different engine loads 0%, 17.5%, 35%, 52.5%, and 70% of full load. The results achieved are the maximum reduction of CO 90% at 375 °C NOx 90% at 375 °C and HC 61% at 380 °C. The same engine was also run for Noble metal converter (NMC) (EURO-II) purchased from an authorized Maruti distributor and the maximum reduction achieved were CO 89% at 375° C, NOx 91% at 375° C, and HC 70% at 390° C comparable to Zeolite Catalytic Converter (ZCC).
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Wierzbicki, Teresa A., Ivan C. Lee, and Ashwani K. Gupta. "Catalytic and Non-Catalytic Combustion of Propane in a Meso-Scale Heat Recirculating Combustor." In ASME 2014 Power Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/power2014-32215.

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The results from the observed combustion behavior of propane over platinum and rhodium catalysts in a meso-scale heat recirculating combustor are presented. The extinction limits, conversion, product selectivity/yield, and activation energy using the two catalysts were compared in an effort to determine their performance using a liquid fuel. The extinction limits were also compared to those of non-catalytic combustion in the same reactor. The results showed that the addition of a catalyst greatly expanded the range of stable operating conditions, in respect to both extinction limits and flow rates supported. The Rh catalyst was found to exhibit a higher propane conversion rate, reaching a maximum of 90.4% at stoichiometric conditions (as opposed to the 61.4% offered by the Pt catalyst at lean conditions); however, the Pt catalyst had superior CO2 selectivity for most studied conditions, indicating higher combustion efficiency. The Pt catalyst also had a significantly smaller activation energy (13.8 kJ/mol) than the Rh catalyst (74.7 kJ/mol), except at equivalence ratios richer than Φ = 1.75 (corresponding to catalyst temperatures below 500 °C), where it abruptly changed to 211.4 kJ/mol, signifying a transition from diffusion-limited reactions to kinetically limited reactions at this point. The results reveal that Rh would be a more suitable catalyst for use in a liquid-fueled meso-scale combustor, as fuel conversion has been shown to be a limiting factor for combustion stability in these systems.
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Kim, Young-Deuk, Woo-Seung Kim, and Soo-Jin Jeong. "Analysis of Transient Thermal and Conversion Characteristics of Dual-Monolith Catalytic Converter with Palladium and Palladium/Rhodium Catalysts." In Asia Pacific Automotive Engineering Conference. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2007. http://dx.doi.org/10.4271/2007-01-3453.

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Evans, John, Andrew J. Dent, Sofia Diaz-Moreno, Steven G. Fiddy, Bhrat Jyoti, Mark A. Newton, and Moniek Tromp. "In Situ Structure-Function Studies of Oxide Supported Rhodium Catalysts by Combined Energy Dispersive XAFS and DRIFTS Spectroscopies." In X-RAY ABSORPTION FINE STRUCTURE - XAFS13: 13th International Conference. AIP, 2007. http://dx.doi.org/10.1063/1.2644606.

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Reports on the topic "Rhodium catalysts"

1

Grass, Michael Edward. Monodisperse Platinum and Rhodium Nanoparticles as Model Heterogeneous Catalysts. Office of Scientific and Technical Information (OSTI), September 2008. http://dx.doi.org/10.2172/940776.

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Bhore, N. A. Modifiers in rhodium catalysts for carbon monoxide hydrogenation: Structure-activity relationships. Office of Scientific and Technical Information (OSTI), May 1989. http://dx.doi.org/10.2172/6119986.

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Keehan, D., and J. Richardson. Carbon monoxide rich methanation kinetics on supported rhodium and nickel catalysts. Office of Scientific and Technical Information (OSTI), August 1989. http://dx.doi.org/10.2172/5622217.

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Kanan, Matthew W. Local Electric Field Effects on Rhodium-Porphyrin and NHC-Gold Catalysts. Fort Belvoir, VA: Defense Technical Information Center, January 2015. http://dx.doi.org/10.21236/ad1013216.

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Gerber, Mark A., James F. White, Michel J. Gray, and Don J. Stevens. Evaluation of Promoters for Rhodium-Based Catalysts for Mixed Alcohol Synthesis. Office of Scientific and Technical Information (OSTI), December 2008. http://dx.doi.org/10.2172/944506.

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Gerber, Mark A., Michel J. Gray, Karl O. Albrecht, and Becky L. Thompson. Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis ? 2012 Progress Report. Office of Scientific and Technical Information (OSTI), November 2012. http://dx.doi.org/10.2172/1110484.

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Gerber, Mark A., Michel J. Gray, Karl O. Albrecht, and Becky L. Rummel. Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis -- 2011 Progress Report. Office of Scientific and Technical Information (OSTI), October 2011. http://dx.doi.org/10.2172/1089617.

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Gerber, Mark A., Michel J. Gray, Karl O. Albrecht, J. F. White, Becky L. Rummel, and Don J. Stevens. Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis -- 2010 Progress Report. Office of Scientific and Technical Information (OSTI), October 2010. http://dx.doi.org/10.2172/1089618.

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Gerber, Mark A., Michel J. Gray, Don J. Stevens, J. F. White, and Becky L. Rummel. Optimization of Rhodium-Based Catalysts for Mixed Alcohol Synthesis -- 2009 Progress Report. Office of Scientific and Technical Information (OSTI), December 2010. http://dx.doi.org/10.2172/1013309.

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Gerber, Mark A., Michel J. Gray, and Becky L. Thompson. Long-Term Testing of Rhodium-Based Catalysts for Mixed Alcohol Synthesis ? 2013 Progress Report. Office of Scientific and Technical Information (OSTI), September 2013. http://dx.doi.org/10.2172/1095445.

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