Academic literature on the topic 'CO₂ hydrogenation'

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Journal articles on the topic "CO₂ hydrogenation"

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Godoy, Sebastian, Prashant Deshlahra, Francisco Villagra-Soza, Alejandro Karelovic, and Romel Jimenez. "Effects of Site Geometry and Local Composition on Hydrogenation of Surface Carbon to Methane on Ni, Co, and NiCo Catalysts." Catalysts 12, no. 11 (November 7, 2022): 1380. http://dx.doi.org/10.3390/catal12111380.

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Surface carbon deposits deactivate Ni and Co catalysts in reactions involving hydrocarbons and COx. Electronic properties, adsorption energies of H, C, and CHx species, and the energetics of the hydrogenation of surface C atom to methane are studied for (100) and (111) surfaces of monometallic Ni and Co, and bimetallic NiCo. The bimetallic catalyst exhibits a Co→Ni electron donation and a concomitant increase in the magnetization of Co atoms. The CHx species resulting from sequential hydrogenation are more stable on Co than on Ni atoms of the NiCo surfaces due to more favorable (C-H)–Co agostic interactions. These interactions and differences between Co and Ni sites are more significant for (111) than for (100) bimetallic surfaces. On (111) surfaces, CH is the most stable species, and the first hydrogenation of C atom exhibits the highest barrier, followed by the CH3 hydrogenation steps. In contrast, on (100) surfaces, surface C atom is the most stable species and CH2 or *CH3 hydrogenations exhibit the highest barriers. The Gibbs free energy profiles suggest that C removal on (111) surfaces is thermodynamically favorable and exhibits a lower barrier than on the (100) surfaces. Thus, the (100) surfaces, especially Ni(100), are more prone to C poisoning. The NiCo(100) surfaces exhibit weaker binding of C and CHx species than Ni(100) and Co(100), which improves C poisoning resistance and lowers hydrogenation barriers. These results show that the electronic effects of alloying Ni and Co strongly depend on the local site composition and geometry.
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Zuo, Zheng, and Xinzheng Yang. "Mechanistic Insights into Selective Hydrogenation of C=C Bonds Catalyzed by CCC Cobalt Pincer Complexes: A DFT Study." Catalysts 11, no. 2 (January 26, 2021): 168. http://dx.doi.org/10.3390/catal11020168.

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The mechanistic insights into hydrogenations of hex-5-en-2-one, isoprene, and 4-vinylcyclohex-1-ene catalyzed by pincer (MesCCC)Co (Mes = bis(mesityl-benzimidazol-2-ylidene)phenyl) complexes are computationally investigated by using the density functional theory. Different from a previously proposed mechanism with a cobalt dihydrogen complex (MesCCC)Co-H2 as the catalyst, we found that its less stable dihydride isomer, (MesCCC)Co(H)2, is the real catalyst in those catalytic cycles. The generations of final products with H2 cleavages for the formations of C−H bonds are the turnover-limiting steps in all three hydrogenation reactions. We found that the hydrogenation selectivity of different C=C bonds in the same compound is dominated by the steric effects, while the hydrogenation selectivity of C=C and C=O bonds in the same compound could be primarily influenced by the electronic effects. In addition, the observed inhabition of the hydrogenation reactions by excessive addition of PPh3 could be explained by a 15.8 kcal/mol free energy barrier for the dissociation of PPh3 from the precatalyst.
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Stepanova, Liudmila N., Roman M. Mironenko, Mikhail V. Trenikhin, Aleksandra N. Serkova, Aleksei N. Salanov, and Aleksandr V. Lavrenov. "CoCuMgAl-Mixed-Oxide-Based Catalysts with Fine-Tunable Composition for the Hydrogenation of Furan Compounds." Journal of Composites Science 8, no. 2 (February 2, 2024): 57. http://dx.doi.org/10.3390/jcs8020057.

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Catalysts based on CoCuMgAl mixed oxides were synthesized and studied in the hydrogenations of furfural and 5-hydroxymethylfurfural under different conditions. The changes in the structural properties of the catalysts at different stages of their preparation were studied using a set of physical methods (XRD, SEM, and TEM). It was shown that the fine regulation of the chemical compositions of the mixed oxides (i.e., changes in the Co/Cu ratio) made it possible to vary the structure, morphology, and catalytic properties of the samples. The phase composition of catalysts with Co/Cu = 1 did not change during the catalytic reaction, although the initial catalysts had a less-homogeneous morphology. 5-hydroxymethylfurfural conversion was higher for the samples with Co/Cu = 1. Furfural conversion increased when raising the Co/Cu ratio. The selectivity toward furfuryl alcohol for the catalyst with Co/Cu = 2 under mild conditions of furfural hydrogenation was more than 99%. The results obtained are important for the development of the scientific foundations of the preparation of hydrogenation catalysts with a fine-tunable composition in order to obtain the desired hydrogenation products.
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Tanirbergenova Sandugash Kudaibergenovna, Тugelbayeva Dildara Abdikadyrovna, Erezhep Nurzay, Zhylybayeva Nurzhamal Kydyrkhankyzy, and Dinistanova Balaussa Kanatbayevna. "OPTIMIZATION OF TECHNOLOGICAL PARAMETERS OF HYDRAGENERATION PROCESS OF ACETYLENE USING A PILOT CATALYTIC PLANT." SERIES CHEMISTRY AND TECHNOLOGY 5, no. 443 (October 15, 2020): 134–40. http://dx.doi.org/10.32014/2020.2518-1491.90.

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A pilot plant was launched and the modes of acetylene hydrogenation on cobalt catalysts were worked out. It has been found that the modified 7% Co/ SiAl cobalt catalyst is active in the process of hydrogenating acetylene into ethylene. Optimal conditions of acetylene hydrogenation on 7% Co/ SiAl catalyst were determined. The effects of temperature, space velocity and the ratio of initial components in the hydrogenation of acetylene to ethylene were investigated. The textural characteristics of cobalt catalysts before and after the hydrogenation of acetylene were investigated by the SEM method. The structure of cobalt catalysts after the hydrogenation of acetylene does not lose catalytic activity and selectivity. It has been found that catalyst samples have channels of different sizes, flaky particles and fibers located in the gaps between large aggregates are also present on the surface. The optimum temperature was 180 ° C in the hydrogenation of acetylene into ethylene at conversion 73.0%. Conversion of acetylene increases to 81.2% when temperature rises to 200°C, acetylene conversion decreases to 68% with further temperature exceeding to 220°C. Acetylene conversion again increases from 68 to 73.6% at 140°C in the ratio of acetylene to hydrogen 1:2. The selectivity of the catalyst 7%Co/SiAl to ethylene was studied depending on the temperature in the acetylene hydrogenation reaction. The selectivity to ethylene decreases with increasing temperature, since an increase in temperature activates side reactions.
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Leroux, Killian, Jean-Claude Guillemin, and Lahouari Krim. "Solid-state formation of CO and H2CO via the CHOCHO + H reaction." Monthly Notices of the Royal Astronomical Society 491, no. 1 (November 13, 2019): 289–301. http://dx.doi.org/10.1093/mnras/stz3051.

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ABSTRACT Glycolaldehyde (CHOCH2OH) and ethylene glycol (HOCH2CH2OH) are among many complex organic molecules detected in the interstellar medium (ISM). Astrophysical models proposed very often that the formation of these compounds would be directly linked to the hydrogenation of glyoxal (CHOCHO), a potential precursor which is not yet detected in the ISM. We have performed, in this work, surface and bulk hydrogenations of solid CHOCHO under ISM conditions in order to confirm or invalidate the astrophysical modelling of glyoxal transformation. Our results show that the hydrogenation of glyoxal does not lead to the formation of detectable amounts of heavier organic molecules such as glycolaldehyde and ethylene glycol but rather to lighter CO-bearing species such as CO, H2CO, and CO–H2CO, a reaction intermediate resulting from an H-addition–elimination process on CHOCHO and where CO is linked to H2CO. The solid phase formation of such a reaction intermediate has been confirmed through the neon matrix isolation of CO–H2CO species. Additionally, the CHOCHO + H solid-state reaction might also lead to the production of CH3OH formed under our experimental conditions as a secondary product resulting from the hydrogenation of formaldehyde.
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Li, Meng, and Dong Ding. "(Invited) Tuning Selective CO2 Electrohydrogenation Under Mid Temperature and Pressure." ECS Meeting Abstracts MA2024-01, no. 37 (August 9, 2024): 2184. http://dx.doi.org/10.1149/ma2024-01372184mtgabs.

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To address rising environmental concerns and energy challenges, it is highly desirable to develop green technologies for a sustainable future. Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds. Electrochemical CO2 hydrogenation using renewable electricity is considered one of the most promising pathways to reach the environmental economics. Among various electrochemical devices, a solid state electrolyzer working at intermediate temperatures has the advantages of high reaction rates and low overpotentials. As CO2 molecules is quite stable, it is critical to develop electrocatalysts with high activity to reduce electricity engagement. Also, CO2 hydrogenation has multiple pathways which normally results in low selectivity for a target product. A tunable electrocatalyst with high selectivity to different products is desirable for CO2 conversion reactions. Heterostructured nanomaterials attracts great attentions in electrochemical systems. With careful design, they can show very high activity and selectivity towards an electrochemical reaction pathway. In this work, we combine theoretical simulations, including density functional theory (DFT) and ab initio molecular dynamics (AIMD) calculations, with experimental methods (characterizations and electrochemical measurements) for rational design of highly efficient heterostructured nanomaterials for CO2 hydrogenations. We studied the strong metal-support interaction (SMSI) in a doped CeO2 supported noble metal nanoparticles (NPs) system using theoretical calculations. The results indicate that SMSI largely depends on chemical conditions of the support and particle size of dispersed metal NPs. By tuning the SMSI, we can successfully change the catalytic activity and selectivity towards CO2 hydrogenation reactions. Based on these findings, we designed tunable heterostructured nanomaterials for efficient hydrogenation reactions at intermediate temperatures. These predictions were further confirmed by experimental method. By using a combination of high-throughput theoretical calculations and electrochemical measurements, we successfully developed highly active catalysts for electrochemical CO2 hydrogenation reactions. This framework is also applicable to other electrochemical systems using heterostructured materials.
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Stuchlý, Vladimír, and Karel Klusáček. "Temperature-programmed hydrogenation of surface carbonaceous deposits on a Ni/SiO2 methanation catalyst." Collection of Czechoslovak Chemical Communications 55, no. 2 (1990): 354–63. http://dx.doi.org/10.1135/cccc19900354.

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Hydrogenation of surface carbonaceous deposits from CO disproportionation or methanation on a high-weight loading commercial Ni/SiO2 catalyst was investigated by temperature-programmed surface reaction (TPSR). Two types of surface carbon (Cα and Cβ)were hydrogenated following the CO disproportionation. Adsorbed carbon monoxide was probably hydrogenated after CO methanation. Hydrogenation of Cα proceeded substantially faster than hydrogenation of Cβ and faster than hydrogenation of preadsorbed CO. Significantly lower activation energy was estimated for hydrogenation of Cα than for hydrogenation of CO (50 vs 90 kJ/mol). An approach for analysis of the data from a temperature-programmed experiment is given.
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Abasov, S. I., S. B. Agaeva, M. T. Mamedova, Y. S. Isaeva, A. A. Iskenderova, and D. B. Tagiyev. "EFFECT OF AN ALKYL SUBSTITUTE ON HYDROCONVERSION OF INDIVIDUAL AROMATIC HYDROCARBONS ON Co/HZSM-5/SO42-–ZrO2 COMPOSITE CATALYST." Azerbaijan Chemical Journal, no. 2 (May 7, 2024): 36–43. http://dx.doi.org/10.32737/0005-2531-2024-2-36-43.

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A systematic study of the hydrogenation of individual aromatic hydrocarbons (benzene, toluene, xylene) and their mixtures was carried out at 1800C, H2/Ar=7, WHSV = 2h-1 and atmospheric pressure on a composite catalyst 0.4%Co/HZSM-5/SO42-(2.0%)–ZrO2. It has been established that the developed catalyst has a high hydrogenating ability with respect to aromatic hydrocarbons at low hydrogen pressures. Alkyl-substituted benzenes turned out to be more active. It was found that alkyl substituents increase the activity of hydrogenation of the benzene ring of an aromatic hydrocarbon. According to their conversion, benzene, toluene and xylene form the following sequence: benzene<toluene<xylene. It was found that the optimal temperature for the process of hydroconversion of aromatic hydrocarbons on a composite catalyst is 1800C. The influence of the concentration of the hydrogenating component of the catalyst – Co on the hydroconversion was also investigated. It was found that the optimal concentration of Co is 0.4wt %. It has been established that in a benzene:toluene:xylene mixture, the conversion of benzene in comparison with its separate hydroconversion increases by more than 10%. The hydroconversion of aromatic hydrocarbons is accompanied by the formation of high-octane naphthenic hydrocarbons - cyclohexane, methylcyclohexane and methylcyclopentane. The antibatic change in the yield of CH and MCP with the duration of the experiment shows that the hydrogenation of the aromatic ring is primary and the isomerization of C6H10 to MCP is secondary, i.e. MCP is the result of a sequential transformation. The absence of dimethylcyclohexane (DMCH) in the benzene:toluene:xylene mixture conversion products suggests that the benzene and xylene conversions additionally involve transalkylation
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Su, Diefeng, Zhongzhe Wei, Shanjun Mao, Jing Wang, Yi Li, Haoran Li, Zhirong Chen, and Yong Wang. "Reactivity and mechanism investigation of selective hydrogenation of 2,3,5-trimethylbenzoquinone on in situ generated metallic cobalt." Catalysis Science & Technology 6, no. 12 (2016): 4503–10. http://dx.doi.org/10.1039/c5cy02171e.

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We successfully developed Co-based catalysts for efficient and selective hydrogenation of TMBQ. Metallic Co was proved to be responsible for TMBQ hydrogenation. The hydrogenation process was also investigated by DFT calculation.
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Kongsuebchart, Wilasinee, Apipon Methachittipan, Thatpon Kongviwatanakul, Piyasan Praserthdam, Okorn Mekasuwandumrong, and Joongjai Panpranot. "Solvothermal-Derived Nanocrystalline TiO2 Supported Co Catalysts in the Hydrogenation of Carbonmonoxide." Advanced Materials Research 634-638 (January 2013): 595–98. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.595.

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Nanocrystalline TiO2 with the average crystallite sizes of 9 and 18 nm were synthesized by the solvothermal method and employed as supports for preparation of Co/TiO2 catalysts for CO hydrogenation reaction with various Co loadings between 5-20 wt%. For a similar Co loading, the use of larger crystallite size TiO2 resulted in higher higher CO hydrogenation activities with no influences on the product selectivities. However, an optimum amount of cobalt loading that maximized CO hydrogenation activity of Co/TiO2 was determined to be at ca. 15 wt.% for both TiO2 crystallite sizes.
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Dissertations / Theses on the topic "CO₂ hydrogenation"

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Musadi, Maya Ramadianti. "Catalytic hydrogenation of CO₂ for sustainable transport." Thesis, University of Manchester, 2009. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.505377.

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C02 emissions are one of the main causes of the greenhouse effect. Reactions between C02 and H2, such as methanol synthesis and methanation, could play an important role in reducing these emissions. The low methanol yield, both selectivity and conversion, is the main problem in the methanol synthesis. Methanation could be considered as another alternative process, because recent research showed that the yield in methanation'process is high, the conversion of C02 to C~ was nearly 100%. By using a combination of the Zero Emission Petrol Vehicle (ZEPV) concept, catalytic hydrogenation of CO2 and methanol to gasoline (MTG) process gasoline can be re-synthesised from recycle C02. The objectives of this thesis are to examine the methanol sY!lthesis behaviour in the lab scale tubular catalytic reactor, to investigate the effect of molecular Sieve 4A (MS 4A) on this synthesis and to analyse the feasibility study for a re-syn fuel refinery. First, methanol synthesis experiments were performed on a CuO/ZnO/AhOJ catalyst at 190- 2200 C, 1 bar, 3600 - 7200 h-I and H2/C02 = 3 - 4. The results indicated that methanol was produced from reaction between H2 and CO2 at those conditions. A maximum C02 conversion was reached at 1900 C, 1 bar, 3600 h-I and H2/C02 = 4. The numerical model results predicted that the initial rate of methanol synthesis increase sharply at pressures into 50 atm and is then relativ~ly constant at pressures above 50 atm. At 50 atm, the initial rate ratio is predicted to increase 35 - 45 times than the initial rate at 1 atm. The presence of water is one of the problems affecting the synthesis. Then to investigate the effect of adding a desiccant, methanol synthesis using a CuO/ZnO/AhOJ catalyst and a MS 4A were carried out at the conditions with the maximum CO2 conversion. The results showed that MS 4A adsorbed water hence the conversion of C02 increased from 1.13% to 2.12%. According to the numerical model, these conversions are predicted 35 - 45 times at pressure around 50 atm. Finally, material and energy balances were calculated for four possible chemical pathways for this re-synthesis (the direct CO2 hydrogenation, the Camere process, the methane to methanol process and the electrolysis process) to determine energy requirements in the re-syn fuel refineries. By using the ZEPV concept, some 70 MT/year of C02 from the combustion of about 22 MT/year of gasoline in around 30 million vehicles in UK can be liquefied at 70 bar and stored on board. This liquid C02 is available to be converted back to gasoline via methanol. The 30% conversion, which was obtained from combination of experiment and numerical model results, was applied for direct hydrogenation of CO2. For the other chemical pathways, the conversion used was based on previous studies. Carrying out this recycling in a set of geographically distributed 're-syn fuel' refineries using offshore wind energy has no further requirement for exploration of crude oil, no limitation of raw material and furthermore no cost penalty for the emitted carbon value. The economic analysis shows that the present (2008) forecourt price for the typical oil refinery (98 p/l) is lower than this forecourt price for the 're-syn fuel' refinery using the offshore wind energy (l09 p/l). By predicting that the wind energy cost will be reduced to as Iowa 2.5 plkWh in the future (2020), it is estimated that the forecourt price of gasoli~e from this futuristic sustainable resynthesis refinery would be decreased to 89 p/l. This forecourt price is cheaper than the current gasoline forecourt price from a typical conventional oil refinery. Based on this preliminary economic assessment, gasoline re-synthesis from recycled CO2 using offshore wind energy is both perfectly sustainable and almost competitive for today and will be cheaper than gasoline from crude oil in the future.
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Rennison, A. J. "CO hydrogenation on reduced solid solution catalysts." Thesis, University of Bath, 1987. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378000.

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Balakrishnan, Nianthrini. "Theoretical Studies of Co Based Catalysts on CO Hydrogenation and Oxidation." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4434.

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CO hydrogenation and CO oxidation are two important processes addressing the energy and environmental issues of great interest. Both processes are carried out using metallic catalysts. The objective of this dissertation is to study the catalytic processes that govern these two reactions from a molecular perspective using quantum mechanical calculations. Density Functional Theory (DFT) has proven to be a valuable tool to study adsorption, dissociation, chain growth, reaction pathways etc., on well-defined surfaces. DFT was used to study the CO reduction reactions on promoted cobalt catalyst surfaces and CO oxidation mechanisms on cobalt surfaces. CO hydrogenation via Fischer-Tropsch Synthesis (FTS) is a process used to produce liquid fuels from synthesis gas. The economics of the Fischer-Tropsch process strongly depends on the performance of the catalyst used. The desired properties of a catalyst include selectivity towards middle distillate products such as diesel and jet fuel, higher activity and longer catalyst life. Catalysts are often modified by adding promoters to obtain these desirable properties. Promoters can influence the reaction pathways, reducibility, dispersion, activity and selectivity. In FTS, understanding the effect of promoters in the molecular scale would help in tailoring catalysts with higher activity and desired selectivity. Preventing deactivation of catalyst is important in FTS to increase the catalyst life. Deactivation of Co catalyst can occur by reoxidation, C deposition, sintering, formation of cobalt-support compounds etc. Designing catalyst with resistance to deactivation by the use of promoters is explored in this dissertation. The influence of promoters on the initiation pathways of CO hydrogenation is also explored as a first step towards determining the selectivity of promoted catalyst. The influence of Pt promoter on O removal from the surface of Co catalyst showed that Pt promoter reduced the activation barrier for the removal of O on both flat and stepped Co surfaces. An approximate kinetic model was developed and a volcano plot was established. The turn-over frequency (TOF) calculated based on the activation barriers showed that Pt promoted Co surface had a higher rate than unpromoted Co surface. The effect of Pt and Ru promoters on various pathways of C deposition on Co catalyst was studied to gain a mechanistic understanding. The promoters did not affect the subsurface C formation but they increased the barriers for C-C and C-C-C formation and also decreased the barriers for C-H formation. The promoters also influence the stabilities of C compounds on the Co surface suggesting that Pt and Ru promoters would decrease C deposition on Co catalysts. The effect of Pt promoter on unassisted and H-assisted CO activation pathways on Co catalyst was studied. Pt promoted Co surface followed H-assisted CO activation. Pt promoter decreased the activation barriers for CO activation pathways on Co catalyst thereby increasing the activity of Co catalyst. CO oxidation is a process used to prevent poisoning of fuel cell catalysts and reduce pollution of the atmosphere through exhaust gases containing CO. Expensive catalysts like Pt are widely used for CO oxidation which significantly increases the cost of the process and hence it is necessary to search for alternative lower cost catalysts. Understanding the mechanism of a reaction is the first step towards designing better and efficient catalyst. DFT is helpful in determining the basic mechanism and intermediates of reactions. The mechanism of CO oxidation on CoO catalyst was explored. Four possible mechanisms for CO oxidation on CoO catalyst were studied to determine the most likely mechanism. The mechanism was found to be a two-step process with activation barrier for formation of CO2 larger than the barrier for formation of the intermediate species.
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Nozonke, Dumani. "Iron modification of rhodium nano-crystallites for CO hydrogenation." Master's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/16858.

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The aim of this study was to investigate the effect of iron on alumina-supported well defined nano-sized rhodium crystallites on the activity and selectivity for CO hydrogenation. The objective was to prepare model catalysts with similar average crystallite size and narrow size distribution.
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Schweicher, Julien. "Kinetic and mechanistic studies of CO hydrogenation over cobalt-based catalysts." Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210036.

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During this PhD thesis, cobalt (Co) catalysts have been prepared, characterized and studied in the carbon monoxide hydrogenation (CO+H2) reaction (also known as “Fischer-Tropsch” (FT) reaction). In industry, the FT synthesis aims at producing long chain hydrocarbons such as gasoline or diesel fuels. The interest is that the reactants (CO and H2) are obtained from other carbonaceous sources than crude oil: natural gas, coal, biomass or even petroleum residues. As it is well known that the worldwide crude oil reserves will be depleted in a few decades, the FT reaction represents an attractive alternative for the production of various fuels. Moreover, this reaction can also be used to produce high value specialty chemicals (long chain alcohols, light olefins…).

Two different types of catalysts have been investigated during this thesis: cobalt with magnesia used as support or dispersant (Co/MgO) and cobalt with silica used as support (Co/SiO2). Each catalyst from the first class is prepared by precipitation of a mixed Co/Mg oxalate in acetone. This coprecipitation is followed by a thermal decomposition under reductive atmosphere leading to a mixed Co/MgO catalyst. On the other hand, Co/SiO2 catalysts are prepared by impregnation of a commercial silica support with a chloroform solution containing Co nanoparticles. This impregnation is then followed by a thermal activation under reductive atmosphere.

The mixed Co/Mg oxalates and the resulting Co/MgO catalysts have been extensively characterized in order to gain a better understanding of the composition, the structure and the morphology of these materials: thermal treatments under reductive and inert atmospheres (followed by MS, DRIFTS, TGA and DTA), BET surface area measurements, XRD and electron microscopy studies have been performed. Moreover, an original in situ technique for measuring the H2 chemisorption surface area of catalysts has been developed and used over our catalysts.

The performances of the Co/MgO and Co/SiO2 catalysts have then been evaluated in the CO+H2 reaction at atmospheric pressure. Chemical Transient Kinetics (CTK) experiments have been carried out in order to obtain information about the reaction kinetics and mechanism and the nature of the catalyst active surface under reaction conditions. The influence of several experimental parameters (temperature, H2 and CO partial pressures, total volumetric flow rate) and the effect of passivation are also discussed with regard to the catalyst behavior.

Our results indicate that the FT active surface of Co/MgO 10/1 (molar ratio) is entirely covered by carbon, oxygen and hydrogen atoms, most probably associated as surface complexes (possibly formate species). Thus, this active surface does not present the properties of a metallic Co surface (this has been proved by performing original experiments consisting in switching from the CO+H2 reaction to the propane hydrogenolysis reaction (C3H8+H2) which is sensitive to the metallic nature of the catalyst). CTK experiments have also shown that gaseous CO is the monomer responsible for chain lengthening in the FT reaction (and not any CHx surface intermediates as commonly believed). Moreover, CO chemisorption has been found to be irreversible under reaction conditions.

The CTK results obtained over Co/SiO2 are quite different and do not permit to draw sharp conclusions concerning the FT reaction mechanism. More detailed studies would have to be carried out over these samples.

Finally, Co/MgO catalysts have also been studied on a combined DRIFTS/MS experimental set-up in Belfast. CTK and Steady-State Isotopic Transient Kinetic Analysis (SSITKA) experiments have been carried out. While formate and methylene (CH2) groups have been detected by DRIFTS during the FT reaction, the results indicate that these species play no role as active intermediates. These formates are most probably located on MgO or at the Co/MgO interface, while methylene groups stand for skeleton CH2 in either hydrocarbon or carboxylate. Unfortunately, formate/methylene species have not been detected by DRIFTS over pure Co catalyst without MgO, because of the full signal absorption.


Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished

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DAUBREGE, FRANCK. "Etude de la mise en regime des catalyseurs a base de cuivre et de cobalt destines a la synthese d'alcools superieurs a partir de co/h#2." Paris 6, 1990. http://www.theses.fr/1990PA066465.

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Les catalyseurs a base de cuivre et de cobalt (cu-co-al-zn) acalinises ou non, destines a la synthese d'alcools superieurs a partir du co/co#2/h#2, se caracterisent lors de leur phase initiale de fonctionnement par une methanation transitoire importante. A l'issue de cette mise en regime, le comportement du systeme catalytique evolue soit vers celui d'un catalyseur de synthese du methanol, soit vers celui d'un catalyseur de synthese d'hydrocarbures ou d'alcools c#1-c#6 en melange. L'objet de ce travail concerne l'etude des parametres reactionnels et structuraux qui regissent les transformations du systeme catalytique conduisant a de tels comportements. Pour cette etude, la preparation et la caracterisation par dx, stem, tpr et esca de systeme modeles a ete entreprise. Le comportement de ces systemes modeles, en synthese co/h#2 sous pression et vis-a-vis de reactions tests a ete examine. L'importance du rapport zn/co de surface sur l'orientation des selectivites en synthese co/h#2 a ete degage. Apres mise en regime, le comportement de ces systemes apparait lie au depot d'entites carbonnees et a la plus ou moins grande stabilite des listes bimetalliques cuivre-cobalt selon la formulation
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Yao, Libo. "Sustainable, energy-efficient hydrogenation processes for selective chemical syntheses." University of Akron / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=akron1626172267871778.

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Aoyama, Yoshimasa. "Hybridization of 4d Metal Nanoparticles with Metal-Organic Framework and the Investigation of the Catalytic Property." Kyoto University, 2020. http://hdl.handle.net/2433/254504.

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Ji, Qinqin. "The synthesis of higher alcohols from CO2 hydrogenation with Co, Cu, Fe-based catalysts." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF023/document.

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Le CO2 est une source de carbone propre pour les réactions chimiques, nombreux chercheurs ont étudié l'utilisation du CO2. Les alcools supérieurs sont des additifs de carburant propres. La synthèse des alcools supérieurs à partir de l'hydrogénation du CO a également été étudiée par de nombreux chercheurs, mais il existe peu de littératures sur la synthèse des alcools supérieurs à partir de l'hydrogénation du CO2, qui est une réaction complexe et difficile. Les catalyseurs utilisés pour la synthèse des alcools supérieurs nécessitent au moins deux phases actives et une bonne synergie. Dans notre étude, nous avons étudié les catalyseurs spinelle basés sur Co. Cu. Fe et l'effet des supports (CNTs et TUD-1) et celui des promoteurs (K, Na, Cs) à la réaction de HAS. Nous avons trouvé que le catalyseur CuFe-précurseur-800 est favorable pour la synthèse d'hydrocarbures en C2+ et d'alcools supérieurs. Dans l'hydrogénation du CO2, Co agit comme catalyseur de méthanisation plutôt que comme catalyseur FT, en raison du mécanisme de réaction différent entre l'hydrogénation du CO et celle du CO2. Afin d'inhiber la formation d'hydrocarbures de quantités importante, il est préférable de choisir des catalyseurs sans Co dans la réaction d'hydrogénation du CO2. En comparant les fonctions des CNT et du TUD-1, nous avons constaté que le CNT est un support parfait pour la synthèse de produits à longue chaîne (alcools supérieurs et hydrocarbures C2+). Le support TUD-1 est plus adapté à la synthèse de produits à un seul carbone (méthane et méthanol) .L'addition d'alcalis en tant que promoteurs conduit non seulement à augmenter la conversion de CO2 et H2, mais augmente également la sélectivité des produits visés fortement, des alcools supérieurs. Le catalyseur 0.5K30CuFeCNTs possède une productivités les plus élevées (370.7 g ∙ kg-1 ∙ h-1) d'alcools supérieurs à 350 ° C et 50 bar
CO2 is a clean carbon source for the chemical reactions, many researchers have studied the utilization of CO2. Higher alcohols are clean fuel additives. The synthesis of higher alcohols from CO hydrogenation has also been studied by many researchers, but there are few literatures about the synthesis of higher alcohols from CO2 hydrogenation, which is a complex and difficult reaction. The catalysts that used for higher alcohols synthesis need at least two active phases and goodcooperation. In our study, we tested the Co. Cu. Fe spinel-based catalysts and the effect of supports (CNTs and TUD-1) and promoters (K, Na, Cs) to the HAS reaction. We found that catalyst CuFe-precursor-800 is beneficial for the synthesis of C2+ hydrocarbons and higher alcohols. In the CO2 hydrogenation, Co acts as a methanation catalyst rather than acting as a FT catalyst, because of the different reaction mechanism between CO hydrogenation and CO2 hydrogenation. In order to inhibit the formation of huge amount of hydrocarbons, it is better to choose catalysts without Co in the CO2 hydrogenation reaction. Compared the functions of CNTs and TUD-1, we found that CNTs is a perfect support for the synthesis of long-chain products (higher alcohols and C2+ hydrocarbons). The TUD-1 support are more suitable for synthesis of single-carbon products (methane and methanol).The addition of alkalis as promoters does not only lead to increase the conversion of CO2 and H2, but also sharply increased the selectivity to the desired products, higher alcohols. The catalyst 0.5K30CuFeCNTs owns the highest productivities (370.7 g∙kg-1∙h-1) of higher alcohols at 350 °C and 50 bar
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FERREIRA, ELINER A. "Estudo das propriedades magnéticas e da microestrutura em imãs permanentes à base de Pr-Fe-B-Co-Nd obtidos pelos processos HD e HDDR." reponame:Repositório Institucional do IPEN, 2008. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11694.

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP
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Books on the topic "CO₂ hydrogenation"

1

Gascoin, F. Co hydrogenation over Ru-Co/SiO2 catalysts. Manchester: UMIST, 1994.

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Moman, A. A. CO hydrogenation over Ru-Cs/SiO2 catalysts. Manchester: UMIST, 1994.

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Tungkamani, S. CO hydrogenation over Ru-Rb/SiO2 catalysts. Manchester: UMIST, 1996.

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Fatolas, K. CO Hydrogenation over Ru - Mn/SiO2 catalysts. Manchester: UMIST, 1996.

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Verbrugge, Alwin S. CO hydrogenation over Ru-Cu/SiO2 catalysts. Manchester: UMIST, 1996.

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Braca, Giuseppe, ed. Oxygenates by Homologation or CO Hydrogenation with Metal Complexes. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0874-4.

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1937-, Braca Giuseppe, ed. Oxygenates by homologation or CO hydrogenation with metal complexes. Dordrecht [The Netherlands]: Kluwer Academic Publishers, 1994.

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Scott, M. W. CO hydrogenation over Ru-Mn supported BI-metallic catalyst. Manchester: UMIST, 1995.

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Kollenburg, O. Van. CO hydrogenation over Ni/SiO2 catalysts calcined at different temperatures. Manchester: UMIST, 1996.

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Reynier, Stephan Francois A. Synthesis and hydrogenation activity of heterogeneous dichlorodicarbonylbis (triphenylphosphine) ruthenium(II), (Ph3P)2RuCl2(CO)2, catalysts. Ottawa: National Library of Canada, 1996.

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Book chapters on the topic "CO₂ hydrogenation"

1

Zhang, Y., Y. Tsushio, Hirotoshi Enoki, and Etsuo Akiba. "Hydrogenation Properties of Mg-Co and Its Related Alloys." In Materials Science Forum, 2453–56. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-960-1.2453.

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Holladay, Johnathan E., Todd A. Werpy, and Danielle S. Muzatko. "Catalytic Hydrogenation of Glutamic Acid." In Proceedings of the Twenty-Fifth Symposium on Biotechnology for Fuels and Chemicals Held May 4–7, 2003, in Breckenridge, CO, 857–69. Totowa, NJ: Humana Press, 2004. http://dx.doi.org/10.1007/978-1-59259-837-3_70.

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Braca, Giuseppe. "Mono Alcohols, Glycols, and their Ethers and Esters by CO Hydrogenation." In Oxygenates by Homologation or CO Hydrogenation with Metal Complexes, 1–88. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0874-4_1.

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Braca, Giuseppe. "Alcohols and Derivatives by Homologation with Syngas." In Oxygenates by Homologation or CO Hydrogenation with Metal Complexes, 89–190. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0874-4_2.

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Braca, Giuseppe. "Hydrocarbonylation of Aldehydes and their Derivatives." In Oxygenates by Homologation or CO Hydrogenation with Metal Complexes, 191–219. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0874-4_3.

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Wesner, D. A., F. P. Coenen, and H. P. Bonzel. "Structural Changes on Ni Surfaces Induced by Catalytic CO Hydrogenation." In Springer Series in Surface Sciences, 612–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-642-73343-7_100.

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Anderson, James A., and Mahmoud M. Khader. "An in Situ Infrared Study of Hydrogenation of CO over Rh/ZrO2." In Progress in Fourier Transform Spectroscopy, 363–65. Vienna: Springer Vienna, 1997. http://dx.doi.org/10.1007/978-3-7091-6840-0_83.

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Yang, Qingxin, and Evgenii V. Kondratenko. "Status of Catalyst Development for CO2 Hydrogenation to Platform Chemicals CH3OH and CO." In Green Chemistry and Sustainable Technology, 81–104. Singapore: Springer Nature Singapore, 2024. http://dx.doi.org/10.1007/978-981-99-8822-8_4.

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Panagiotopoulou, Paraskevi, and Xenophon E. Verykios. "Metal–support interactions of Ru-based catalysts under conditions of CO and CO2 hydrogenation." In Catalysis, 1–23. Cambridge: Royal Society of Chemistry, 2020. http://dx.doi.org/10.1039/9781788019477-00001.

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Oskam, A., R. R. Andréa, D. J. Stufkens, and M. A. Vuurman. "Identification of H2-, D2-, N2- Bonded Intermediates in the Cr(CO)6 Photocatalyzed Hydrogenation Reactions." In Photochemistry and Photophysics of Coordination Compounds, 243–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-72666-8_44.

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Conference papers on the topic "CO₂ hydrogenation"

1

Cui, Z., Y. Zheng, and Y. Hao. "Water-Promoted Ethanol Production via CO2 Hydrogenation through Plasma Catalysis over Cu-based Catalyst." In 2024 IEEE International Conference on Plasma Science (ICOPS), 1. IEEE, 2024. http://dx.doi.org/10.1109/icops58192.2024.10626062.

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Dou, L., Y. Gao, Y. Xu, C. Zhang, and T. Shao. "A sustainable route for CH3OH synthesis via plasma-enabled CO2 hydrogenation: the effects of H2O additive and packing materials." In 2024 IEEE International Conference on Plasma Science (ICOPS), 1. IEEE, 2024. http://dx.doi.org/10.1109/icops58192.2024.10627361.

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Wang, Yi, Lei Sun, Yan Li, Yi-fan Zhang, De-dong Han, Li-feng Liu, Jin-feng Kang, Xing Zhang, and Ru-qi Han. "Hydrogenation Induced Room-Temperature Ferromagnetism in Co-doped ZnO Nanocrystals." In 2007 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2007. http://dx.doi.org/10.7567/ssdm.2007.p-12-1.

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Tang Qingjie, Liu Bo, and Fan Shao. "Effect of manganese on Iron-Ruthenium complex catalyst for CO hydrogenation." In Environment (ICMREE). IEEE, 2011. http://dx.doi.org/10.1109/icmree.2011.5930645.

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HUANG, PENGMIAN, ZILI LIU, and MIAO ZHENG. "SELECTIVE HYDROGENATION OF CINNAMALDEHYDE TO CINNAMYL ALCOHOL OVER CO-FE/Γ-AL2O3 CATALYSTS." In Proceedings of the 4th International Conference. WORLD SCIENTIFIC, 2004. http://dx.doi.org/10.1142/9789812702623_0174.

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Shopska, Maya, Alfonso Caballero, Silviya Todorova, Katerina Aleksieva, Krassimir Tenchev, Hristo Kolev, Martin Fabian, and Georgi Kadinov. "Comparative Investigation of (10%Co+0.5%Pd)/TiO2(Al2O3) Catalysts in CO Hydrogenation at Low and High Pressure." In The 2nd International Electronic Conference on Catalysis Sciences—A Celebration of Catalysts 10th Anniversary. Basel Switzerland: MDPI, 2021. http://dx.doi.org/10.3390/eccs2021-11105.

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Watanabe, Naoki, Hiroshi Hidaka, and Akira Kouchi. "Relative Reaction Rates of Hydrogenation and Deuteration of Solid CO at Very Low Temperatures." In ASTROCHEMISTRY: From Laboratory Studies to Astronomical Observations. AIP, 2006. http://dx.doi.org/10.1063/1.2359547.

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Joshi, Niharika, Indu Kaul, Nirmalya Ballav, and Prasenjit Ghosh. "Spin enhancement and band gap opening of ferrimagnetic graphene on fcc-Co(111) surface upon hydrogenation." In SOLID STATE PHYSICS: PROCEEDINGS OF THE 57TH DAE SOLID STATE PHYSICS SYMPOSIUM 2012. AIP, 2013. http://dx.doi.org/10.1063/1.4791227.

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Koh, Mei Kee, Munirah Md Zain, and Abdul Rahman Mohamed. "Exploring transition metal (Cr, Mn, Fe, Co, Ni) promoted copper-catalyst for carbon dioxide hydrogenation to methanol." In 6TH INTERNATIONAL CONFERENCE ON ENVIRONMENT (ICENV2018): Empowering Environment and Sustainable Engineering Nexus Through Green Technology. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5117066.

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Pinkard, Brian R., Elizabeth G. Rasmussen, John C. Kramlich, Per G. Reinhall, and Igor V. Novosselov. "Supercritical Water Gasification of Ethanol for Fuel Gas Production." In ASME 2019 13th International Conference on Energy Sustainability collocated with the ASME 2019 Heat Transfer Summer Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/es2019-3950.

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Abstract Supercritical water gasification of dilute ethanol at the industrial scale promises a sustainable route to bio-syngas production for use in combined cycle power plants. Cost-effective bio-syngas production would reduce reliance on fossil fuels for electricity generation and reduce greenhouse gas emissions by utilizing waste biomass resources. Continuous supercritical water gasification offers high reactant conversion at short residence times without an added catalyst. The decomposition of ethanol in supercritical water is studied in a continuous reactor at 560 °C, 25 MPa, residence times between 3 and 8 s, and a constant initial ethanol concentration of 8.1 wt%. High-resolution, in-situ Raman spectroscopy facilitates identification of reaction products. Significant yields of H2, CO, and CH4 indicate the dominance of a dehydrogenation reaction pathway at studied conditions, while minor yields of ethane indicate a secondary dehydration reaction pathway. Ethylene yields are virtually nonexistent, indicating rapid hydrogenation of ethylene to ethane at these conditions. Ethanol dehydrogenation to H2, CO, and CH4 results in an overall fuel value upgrade of 84.5 kJ/mol-EtOH. Dehydration of ethanol to ethane results in an overall fuel degradation of −3.8 kJ/mol-EtOH.
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Reports on the topic "CO₂ hydrogenation"

1

Bartholomew, C. H. Effects of dispersion and support on adsorption, catalytic and electronic properties of cobalt/alumina Co hydrogenation catalysts. Office of Scientific and Technical Information (OSTI), September 1990. http://dx.doi.org/10.2172/5575665.

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Author, Not Given. Hydrogenation of Clean Carbon Monoxide (CO) and Carbon Dioxide (CO2) Gas Streams to Higher Molecular Weight Alcohols. Office of Scientific and Technical Information (OSTI), February 2012. http://dx.doi.org/10.2172/1035373.

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Bartholomew, C. H. Effects of dispersion and support on adsorption, catalytic and electronic properties of cobalt/alumina Co hydrogenation catalysts. Final progress report, August 1, 1987--July 31, 1990. Office of Scientific and Technical Information (OSTI), September 1990. http://dx.doi.org/10.2172/10135056.

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Kung, Kyle Yi. Sum frequency generation vibrational spectroscopy studies of adsorbates on Pt(111): Studies of CO at high pressures and temperatures, coadsorbed with olefins and its role as a poison in ethylene hydrogenation. Office of Scientific and Technical Information (OSTI), December 2000. http://dx.doi.org/10.2172/790020.

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Rucker, T. G. The effect of additives on the reactivity of palladium surfaces for the chemisorption and hydrogenation of carbon monoxide: A surface science and catalytic study. [LaMO/sub 3/(M = Cr, Mn, Fe, Co, Rh)]. Office of Scientific and Technical Information (OSTI), June 1987. http://dx.doi.org/10.2172/6389716.

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