Artículos de revistas: "CO₂ hydrogenation"

1

Godoy, Sebastian, Prashant Deshlahra, Francisco Villagra-Soza, Alejandro Karelovic y Romel Jimenez. "Effects of Site Geometry and Local Composition on Hydrogenation of Surface Carbon to Methane on Ni, Co, and NiCo Catalysts". Catalysts 12, n.º 11 (7 de noviembre de 2022): 1380. http://dx.doi.org/10.3390/catal12111380.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Zuo, Zheng y Xinzheng Yang. "Mechanistic Insights into Selective Hydrogenation of C=C Bonds Catalyzed by CCC Cobalt Pincer Complexes: A DFT Study". Catalysts 11, n.º 2 (26 de enero de 2021): 168. http://dx.doi.org/10.3390/catal11020168.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Stepanova, Liudmila N., Roman M. Mironenko, Mikhail V. Trenikhin, Aleksandra N. Serkova, Aleksei N. Salanov y Aleksandr V. Lavrenov. "CoCuMgAl-Mixed-Oxide-Based Catalysts with Fine-Tunable Composition for the Hydrogenation of Furan Compounds". Journal of Composites Science 8, n.º 2 (2 de febrero de 2024): 57. http://dx.doi.org/10.3390/jcs8020057.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Tanirbergenova Sandugash Kudaibergenovna, Тugelbayeva Dildara Abdikadyrovna, Erezhep Nurzay, Zhylybayeva Nurzhamal Kydyrkhankyzy y Dinistanova Balaussa Kanatbayevna. "OPTIMIZATION OF TECHNOLOGICAL PARAMETERS OF HYDRAGENERATION PROCESS OF ACETYLENE USING A PILOT CATALYTIC PLANT". SERIES CHEMISTRY AND TECHNOLOGY 5, n.º 443 (15 de octubre de 2020): 134–40. http://dx.doi.org/10.32014/2020.2518-1491.90.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Leroux, Killian, Jean-Claude Guillemin y Lahouari Krim. "Solid-state formation of CO and H2CO via the CHOCHO + H reaction". Monthly Notices of the Royal Astronomical Society 491, n.º 1 (13 de noviembre de 2019): 289–301. http://dx.doi.org/10.1093/mnras/stz3051.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

Li, Meng y Dong Ding. "(Invited) Tuning Selective CO₂ Electrohydrogenation Under Mid Temperature and Pressure". ECS Meeting Abstracts MA2024-01, n.º 37 (9 de agosto de 2024): 2184. http://dx.doi.org/10.1149/ma2024-01372184mtgabs.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Stuchlý, Vladimír y Karel Klusáček. "Temperature-programmed hydrogenation of surface carbonaceous deposits on a Ni/SiO2 methanation catalyst". Collection of Czechoslovak Chemical Communications 55, n.º 2 (1990): 354–63. http://dx.doi.org/10.1135/cccc19900354.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Abasov, S. I., S. B. Agaeva, M. T. Mamedova, Y. S. Isaeva, A. A. Iskenderova y 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, n.º 2 (7 de mayo de 2024): 36–43. http://dx.doi.org/10.32737/0005-2531-2024-2-36-43.

Texto completo

Resumen

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

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Su, Diefeng, Zhongzhe Wei, Shanjun Mao, Jing Wang, Yi Li, Haoran Li, Zhirong Chen y Yong Wang. "Reactivity and mechanism investigation of selective hydrogenation of 2,3,5-trimethylbenzoquinone on in situ generated metallic cobalt". Catalysis Science & Technology 6, n.º 12 (2016): 4503–10. http://dx.doi.org/10.1039/c5cy02171e.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Kongsuebchart, Wilasinee, Apipon Methachittipan, Thatpon Kongviwatanakul, Piyasan Praserthdam, Okorn Mekasuwandumrong y Joongjai Panpranot. "Solvothermal-Derived Nanocrystalline TiO₂ Supported Co Catalysts in the Hydrogenation of Carbonmonoxide". Advanced Materials Research 634-638 (enero de 2013): 595–98. http://dx.doi.org/10.4028/www.scientific.net/amr.634-638.595.

Texto completo

Resumen

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.

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Tsai, Yu-Tung, Xunhua Mo, Andrew Campos, James G. Goodwin y James J. Spivey. "Hydrotalcite supported Co catalysts for CO hydrogenation". Applied Catalysis A: General 396, n.º 1-2 (abril de 2011): 91–100. http://dx.doi.org/10.1016/j.apcata.2011.01.043.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Yang, Kaixuan, Naimeng Chen, Xiaomiao Guo, Ruoqi Zhang, Xiaoyu Sheng, Hui Ge, Zhiguo Zhu, Hengquan Yang y Hongying Lü. "Phase-Controlled Cobalt Catalyst Boosting Hydrogenation of 5-Hydroxymethylfurfural to 2,5-Dimethylfuran". Molecules 28, n.º 13 (22 de junio de 2023): 4918. http://dx.doi.org/10.3390/molecules28134918.

Texto completo

Resumen

The search for non-noble metal catalysts for chemical transformations is of paramount importance. In this study, an efficient non-noble metal catalyst for hydrogenation, hexagonal close-packed cobalt (HCP-Co), was synthesized through a simple one-step reduction of β-Co(OH)2 nanosheets via a temperature-induced phase transition. The obtained HCP-Co exhibited several-times-higher catalytic efficiency than its face-centered cubic cobalt (FCC-Co) counterpart in the hydrogenation of the C=C/C=O group, especially for the 5-hydroxymethylfurfural (HMF) hydrogenation (8.5-fold enhancement). Density functional theory calculations demonstrated that HMF molecules were adsorbed more firmly on the (112_0) facet of HCP-Co than that on the (111) facet of FCC-Co, favoring the activation of the C=O group in the HMF molecule. The stronger adsorption on the (112_0) facet of HCP-Co also led to lower activation energy than that on the (111) facet of FCC-Co, thereby resulting in high activity and selectivity. Moreover, HCP-Co exhibited outstanding catalytic stability during the hydrogenation of HMF. These results highlight the possibility of fabricating hydrogenation catalysts with satisfactory catalytic properties by precisely tuning their active crystal phase.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

Endo, Yasushi, Takanobu Sato, Tadashi Kaneko, Yoshio Kawamura y Masahiko Yamamoto. "Change of Interlayer Exchange Coupling between the Adjacent Magnetic Transition Metal Layers across a Rare-Earth Metal Layer by Hydrogenation". Materials Science Forum 512 (abril de 2006): 177–82. http://dx.doi.org/10.4028/www.scientific.net/msf.512.177.

Texto completo

Resumen

We have studied the change of the interlayer exchange coupling between the adjacent magnetic transition metal (TM) layers across a rare-earth metal (REM) layer by hydrogenation in TM (10 nm)/REM (t nm)/TM (10 nm) trilayers composed of Fe and Co as the TM and Y as the REM. In the case of the Fe as TM, the magnetic properties are sensitive to hydrogenation. In particular, the interlayer exchange coupling changes remarkably by hydrogenation. On the other hand, in the case of the Co as TM, the magnetic properties do not change by hydrogenation, and the change of the coupling by hydrogenation cannot be confirmed. The difference of the change of the coupling by hydrogenation between TM=Fe and TM=Co should be attributed to the difference of the TM/Y interface state.

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Ngoc Ha, Nguyen, Nguyen Thi Thu Ha, Nguyen Binh Long y Le Minh Cam. "Conversion of Carbon Monoxide into Methanol on Alumina-Supported Cobalt Catalyst: Role of the Support and Reaction Mechanism—A Theoretical Study". Catalysts 9, n.º 1 (23 de diciembre de 2018): 6. http://dx.doi.org/10.3390/catal9010006.

Texto completo

Resumen

Density functional theory (DFT) was used to calculate the step-by-step hydrogenation of carbon monoxide (CO) to form methanol over a Co4 cluster/Al2O3 surface. A three-dimensional Co4 tetrahedral structure was selected to explore its interaction with the supporting Al2O3 (104) surface. Co4 chemically reacted with Al2O3 to form a new chemical system. The calculated results show that Al2O3 support has strengthened the Co4 catalyst during the reaction since the formation of the Co–O bond. Loading Co4 on the Al2O3 surface increases CO adsorption ability but decreases the dissociation ability of C–O to produce hydrocarbons. As such, CH3OH formation becomes more favorable both kinetically and thermodynamically on Co4/Al2O3. In CO hydrogenation, methanol was synthesized through a CO reaction with hydrogen via either an Eley–Rideal or Langmuir–Hinshelwood pathway to form the intermediates C*-O-H, H-C*-OH, H2-C*-OH, and finally the hydrogenation of H2-C*-OH to methanol with both hydrogenation steps forming C*-OH and final product as rate-limiting. These results showed that the interaction between Co, Al2O3 and H2 pressure can change the pathway of CO hydrogenation on Co/Al2O3 and it may, therefore, influence distribution of the final products.

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Priyadarshani, Nilusha, Bojana Ginovska, J. Timothy Bays, John C. Linehan y Wendy J. Shaw. "Photoswitching a molecular catalyst to regulate CO2 hydrogenation". Dalton Transactions 44, n.º 33 (2015): 14854–64. http://dx.doi.org/10.1039/c5dt01649e.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Dou, Maobin, Minhua Zhang, Yifei Chen y Yingzhe Yu. "DFT study of In2O3-catalyzed methanol synthesis from CO2 and CO hydrogenation on the defective site". New Journal of Chemistry 42, n.º 5 (2018): 3293–300. http://dx.doi.org/10.1039/c7nj04273f.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Qin, Ruixuan, Pei Wang, Pengxin Liu, Shiguang Mo, Yue Gong, Liting Ren, Chaofa Xu et al. "Carbon Monoxide Promotes the Catalytic Hydrogenation on Metal Cluster Catalysts". Research 2020 (17 de julio de 2020): 1–9. http://dx.doi.org/10.34133/2020/4172794.

Texto completo

Resumen

Size effect plays a crucial role in catalytic hydrogenation. The highly dispersed ultrasmall clusters with a limited number of metal atoms are one candidate of the next generation catalysts that bridge the single-atom metal catalysts and metal nanoparticles. However, for the unfavorable electronic property and their interaction with the substrates, they usually exhibit sluggish activity. Taking advantage of the small size, their catalytic property would be mediated by surface binding species. The combination of metal cluster coordination chemistry brings new opportunity. CO poisoning is notorious for Pt group metal catalysts as the strong adsorption of CO would block the active centers. In this work, we will demonstrate that CO could serve as a promoter for the catalytic hydrogenation when ultrasmall Pd clusters are employed. By means of DFT calculations, we show that Pdn n=2‐147 clusters display sluggish activity for hydrogenation due to the too strong binding of hydrogen atom and reaction intermediates thereon, whereas introducing CO would reduce the binding energies of vicinal sites, thus enhancing the hydrogenation reaction. Experimentally, supported Pd2CO catalysts are fabricated by depositing preestablished [Pd2(μ-CO)2Cl4]2- clusters on oxides and demonstrated as an outstanding catalyst for the hydrogenation of styrene. The promoting effect of CO is further verified experimentally by removing and reintroducing a proper amount of CO on the Pd cluster catalysts.

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Tang, Qing Jie, Wen Rong Wu, Shao Fan y Bo Liu. "Effect of Ruthenium on the Performance of Iron-Based Catalyst for CO Hydrogenation". Advanced Materials Research 228-229 (abril de 2011): 496–99. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.496.

Texto completo

Resumen

A series of Iron-based complex catalyst were prepared by precipitation and immersion in order to study the effect of Ruthenium on the performance of Iron-based catalyst for CO hydrogenation in FTS. The distribution of products was studied for CO hydrogenation, and the reduction action of Iron-ruthenium complex catalyst was study by TPR. The results showed that the yield of the lower hydrocarbons in the products of CO-hydrogenation could be improved obviously with Ruthenium added, and the reduction action of Iron-based catalyst could be promoted obviously.

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Heltzel, Jacob M., Matthew Finn, Diana Ainembabazi, Kai Wang y Adelina M. Voutchkova-Kostal. "Transfer hydrogenation of carbon dioxide and bicarbonate from glycerol under aqueous conditions". Chemical Communications 54, n.º 48 (2018): 6184–87. http://dx.doi.org/10.1039/c8cc03157f.

Texto completo

Resumen

Catalytic transfer hydrogenation of CO₂ from glycerol to afford formic and lactic acid is an attractive path to valorizing two waste streams. The process is significantly more thermodynamically favorable than direct CO₂ hydrogenation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Guo, Haijun, Hairong Zhang, Weichao Tang, Can Wang, Chao Huang, Peili Chen, Xinde Chen y Xinping Ouyang. "Furfural hydrogenation over amorphous alloy catalysts prepared by different reducing agents". BioResources 12, n.º 4 (6 de octubre de 2017): 8755–74. http://dx.doi.org/10.15376/biores.12.4.8755-8774.

Texto completo

Resumen

The catalytic hydrogenation of furfural was studied over a series of Ni-B, Co-B, and Ni-Co-B amorphous alloy catalysts that were prepared by the chemical reduction method using KBH4 and NaBH4 as reducing agents. These catalysts were characterized by N2 adsorption/desorption, XRD, XPS, FE-SEM, and TEM. The results showed that NaBH4 had a much stronger reduction ability to enhance the surface concentration of the metallic active sites for furfural hydrogenation and electron transfer capability, leading to much higher hydrogenation activity. In the Ni-Co-B amorphous alloy catalyst, the equilibrium between the isolated Ni-B/Co-B active sites and the combined Ni-Co-B active sites was important in regulating furfural conversion and products distribution.

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Jang, Chol Ryong, Vasile Matei, Anca Borcea, Viorel Voicu, Raluca Proscanu y Dragos Ciuparu. "Hydrogenation of 1-octene by Co-Mo/MCM-41 catalysts". Analele Universitatii "Ovidius" Constanta - Seria Chimie 23, n.º 2 (1 de diciembre de 2012): 133–36. http://dx.doi.org/10.2478/v10310-012-0022-5.

Texto completo

Resumen

AbstractThe synthesis and characterization of MCM-41 supported Co-Mo catalysts and catalytic hydrogenation of 1-octene to n-octane were discussed. BET specific surface area of MCM-41, calculated from N2 adsorption/desorption isotherm, was 1690 m2/g. The XRD patterns of the Co-Mo/MCM-41 catalysts show that metal species are finely dispersed and the size of CoO and MoO3 particles is below the detection limit by XRD. The 1-octene hydrogenation activity of the catalysts decreased with increasing the Co content up to 9 wt.% for the Co-promoted Co-Mo/MCM-41 catalysts with a MoO3 content of 12 wt.%. All the catalysts show increased hydrogenation activity with increasing reaction temperature in the temperature range from 200 to 350°C.

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Fu, Huan, Huan Zhang, Guichun Yang, Jun Liu, Junyuan Xu, Peihuan Wang, Ning Zhao, Lihua Zhu y Bing Hui Chen. "Highly dispersed rhodium atoms supported on defect-rich Co(OH)₂ for the chemoselective hydrogenation of nitroarenes". New Journal of Chemistry 46, n.º 3 (2022): 1158–67. http://dx.doi.org/10.1039/d1nj04936d.

Texto completo

Resumen

0.54% Rh/Co(OH)2 exhibited 100% selectivity for –NO2 hydrogenation at >96% conversion for nitroarene hydrogenation. Its excellent catalytic performance is due to the interfacial effect of Rh–Co(OH)2 and Rh in the form of single atoms and nanoclusters.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Long, Jilan, Ying Zhou y Yingwei Li. "Transfer hydrogenation of unsaturated bonds in the absence of base additives catalyzed by a cobalt-based heterogeneous catalyst". Chemical Communications 51, n.º 12 (2015): 2331–34. http://dx.doi.org/10.1039/c4cc08946d.

Texto completo

Resumen

A novel non-noble Co@C–N system for catalytic transfer hydrogenation reactions is developed. The heterogeneous Co@C–N catalysts are highly active and selective in the hydrogenation of a variety of unsaturated bonds with isopropanol in the absence of base additives.

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Amann, Peter, Bernhard Klötzer, David Degerman, Norbert Köpfle, Thomas Götsch, Patrick Lömker, Christoph Rameshan et al. "The state of zinc in methanol synthesis over a Zn/ZnO/Cu(211) model catalyst". Science 376, n.º 6593 (6 de mayo de 2022): 603–8. http://dx.doi.org/10.1126/science.abj7747.

Texto completo

Resumen

The active chemical state of zinc (Zn) in a zinc-copper (Zn-Cu) catalyst during carbon dioxide/carbon monoxide (CO 2 /CO) hydrogenation has been debated to be Zn oxide (ZnO) nanoparticles, metallic Zn, or a Zn-Cu surface alloy. We used x-ray photoelectron spectroscopy at 180 to 500 millibar to probe the nature of Zn and reaction intermediates during CO 2 /CO hydrogenation over Zn/ZnO/Cu(211), where the temperature is sufficiently high for the reaction to rapidly turn over, thus creating an almost adsorbate-free surface. Tuning of the grazing incidence angle makes it possible to achieve either surface or bulk sensitivity. Hydrogenation of CO 2 gives preference to ZnO in the form of clusters or nanoparticles, whereas in pure CO a surface Zn-Cu alloy becomes more prominent. The results reveal a specific role of CO in the formation of the Zn-Cu surface alloy as an active phase that facilitates efficient CO 2 methanol synthesis.

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Kobzar, Elena O., Liudmila N. Stepanova, Aleksandr A. Nepomniashchii, Anastasia V. Vasilevich, Tatiana I. Gulyaeva, Mikhail V. Trenikhin y Aleksandr V. Lavrenov. "CuCoMgAlOx Mixed Oxides as Selective Catalysts for the Hydrogenation of Furan Compounds". Hydrogen 4, n.º 3 (8 de septiembre de 2023): 644–57. http://dx.doi.org/10.3390/hydrogen4030041.

Texto completo

Resumen

Single phase CuCoMgAl-layered hydroxides were obtained by making fine adjustment to their composition through changing the (Co + Cu)/Mg = 0.5; 1; 2; 3 and Co/Cu = 0.5; 1; 2 ratios. The rise of Co/Cu in systems contributed to the increase in their thermal stability. CuCoMgAl-catalysts showed high selectivity of carbonyl group hydrogenation in furfural and 5-hydroxymethylfurfural. In furfural hydrogenation, the selectivity to furfuryl alcohol was more than 99%, and in 5-hydroxymethylfurfural hydrogenation, the selectivity to 2,5-hydroxymethyl furfural was 95%. The surface of the samples with different Co/Cu after calcination and reduction was the same and had a «core-shell» structure (TEM). «Core» consisted of Cu and Co metallic particles. «Shell» consisted of CuCoMgAlOx mixed no-stoichiometric spinel oxides. There was no sintering or change in size of the metallic particles after the reaction. For the sample with Co/Cu = 1, their phase composition after reaction remained unchangeable. The increase of Co/Cu led to the formation of an X-ray amorphous phase after the reaction. This suggests the decrease in structural stability of this sample. The obtained results prove the prospects of using bimetallic CoCu-systems for hydrogenation of furan aldehydes, and opens up new directions for further research and improvement.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Vahrenkamp, Heinrich. "Hydrierungen und Dehydrierungen im System Benzonitril/Ru3 (CO)12 /Benzylamin / Hydrogenations and Dehydrogenations in the System Benzonitrile/Ru3 (CO)12 /Benzylamine". Zeitschrift für Naturforschung B 43, n.º 6 (1 de junio de 1988): 643–47. http://dx.doi.org/10.1515/znb-1988-0601.

Texto completo

Resumen

The stepwise interconversions between benzonitrile and benzylamine have been realized in both directions via Ru3 cluster intermediates. The hydrogenation/dehydrogenation system can be entered from Ph-CN, Ru3(CO)12, and H2 yielding HRu3(CO)10(NCHPh) or from PhCH2NH2 and Ru3(CO)12 yielding HRu3(CO)10(NHCH2Ph), These two clusters can be interconverted by thermal hydrogenation and dehydrogenation, with H2Ru3(CO)9(NCH2Ph) as a CO and H2 dependent intermediate. The system can be left only towards benzylamine which is formed in small yields from HRu3(CO)10(NHCH2Ph) at high temperatures and under high CO or H2 pressures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Breton, Sylvie, Anne Brisach-Wittmeyer, José Julian Rios Martín, Manuel León Camacho, Andrzej Lasia y Hugues Ménard. "Selective Electrocatalytic Hydrogenation of Linolenic Acid onPd/Al2O3andPd-Co/Al2O3Catalysts". International Journal of Electrochemistry 2011 (2011): 1–9. http://dx.doi.org/10.4061/2011/485194.

Texto completo

Resumen

Electrochemical hydrogenation of linolenic acid as a model for polyunsaturated acids was studied on Pd and Pd/Al2O3catalysts in acidic and alkaline media. The results are presented in terms of number of double bonds in the polyunsaturated fatty acid and interpreted in terms of the adsorption capacity of the catalysts in these media. The highest hydrogenation yield was obtained with Pd/Al2O3at pH 13, in good correlation with the adsorption power of linolenic acid and its first hydrogenation product, linoleic acid, measured in this solution. A preliminary electrochemical hydrogenation study was conducted on Pd/Al2O3catalyst containing Co, in the optimum electrolysis conditions, showing a cooperative effect of the noble metals regarding thecis/transselectivity with preferential formation ofcis-oriented monounsaturated compound. All the products were characterized by gas chromatography after derivatization of the samples; fifteencis-transisomers of monounsaturated fatty acid which could be identified are presented here.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

He, Jiao, Mart Simons, Gleb Fedoseev, Ko-Ju Chuang, Danna Qasim, Thanja Lamberts, Sergio Ioppolo, Brett A. McGuire, Herma Cuppen y Harold Linnartz. "Methoxymethanol formation starting from CO hydrogenation". Astronomy & Astrophysics 659 (marzo de 2022): A65. http://dx.doi.org/10.1051/0004-6361/202142414.

Texto completo

Resumen

Context. Methoxymethanol (CH3OCH2OH) has been identified through gas-phase signatures in both high- and low-mass star-forming regions. Like several other C-, O-, and H-containing complex organic molecules (COMs), this molecule is expected to form upon hydrogen addition and abstraction reactions in CO-rich ice through radical recombination of CO hydrogenation products. Aims. The goal of this work is to experimentally and theoretically investigate the most likely solid-state methoxymethanol reaction channel – the recombination of CH2OH and CH3O radicals – for dark interstellar cloud conditions and to compare the formation efficiency with that of other species that were shown to form along the CO-hydrogenation line. We also investigate an alternative hydrogenation channel starting from methyl formate. Methods. Hydrogen atoms and CO or H2CO molecules were co-deposited on top of predeposited H2O ice to mimic the conditions associated with the beginning of “rapid” CO freeze-out. The formation of simple species was monitored in situ using infrared spectroscopy. Quadrupole mass spectrometry was used to analyze the gas-phase COM composition following a temperature-programmed desorption. Monte Carlo simulations were used for an astrochemical model comparing the methoxymethanol formation efficiency with that of other COMs. Results. The laboratory identification of methoxymethanol is found to be challenging, in part because of diagnostic limitations, but possibly also because of low formation efficiencies. Nevertheless, unambiguous detection of newly formed methoxymethanol has been possible in both CO+H and H2CO+H experiments. The resulting abundance of methoxymethanol with respect to CH3OH is about 0.05, which is about six times lower than the value observed toward NGC 6334I and about three times lower than the value reported for IRAS 16293B. Astrochemical simulations predict a similar value for the methoxymethanol abundance with respect to CH3OH, with values ranging between 0.03 and 0.06. Conclusions. We find that methoxymethanol is formed by co-deposition of CO and H2CO with H atoms through the recombination of CH2OH and CH3O radicals. In both the experimental and modeling studies, it is found that the efficiency of this channel alone is not sufficient to explain the observed abundance of methoxymethanol with respect to methanol. The rate of a proposed alternative channel, the direct hydrogenation of methyl formate, is found to be even less efficient. These results suggest that our knowledge of the reaction network is incomplete or involving alternative solid-state or gas-phase formation mechanisms.

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Xu, You Min, Ya Dong Bi y Xiao Hong Yin. "Liquid Phase Hydrogenation of Maleic Anhydride over Ni Catalysts: Effect of Support on the Catalytic Performance". Advanced Materials Research 1033-1034 (octubre de 2014): 57–60. http://dx.doi.org/10.4028/www.scientific.net/amr.1033-1034.57.

Texto completo

Resumen

Ni catalysts supported on CeO2 and HZSM-5 supports were prepared and tested as catalysts in the liquid hydrogenation of maleic anhydride. Particularly Ni/HZSM-5 was active and selective in the hydrogenation of maleic anhydride to ڃ-butyrolactone. The characterization results of X-ray diffraction (XRD), N2 adsorption and CO temperature programmed reduction (CO-TPR) evidenced that the higher C=O hydrogenation ability of Ni/HZSM-5 catalyst was related to strong interaction between Ni particles and HZSM-5, and the high dispersion of fine Ni particles on the surface of support. Further, the acidic HZSM-5 support benefits the dehydration performance during the C=O bond hydrogenation process, which favored the production of ڃ-butyrolactone. The dual-functional Ni/HZSM-5 catalyst possesses both hydrogenation and dehydration activity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Novodárszki, Gyula, Ferenc Lónyi, Magdolna R. Mihályi, Anna Vikár, Róbert Barthos, Blanka Szabó, József Valyon y Hanna E. Solt. "Reaction Pathways of Gamma-Valerolactone Hydroconversion over Co/SiO2 Catalyst". Catalysts 13, n.º 7 (23 de julio de 2023): 1144. http://dx.doi.org/10.3390/catal13071144.

Texto completo

Resumen

The hydroconversion of γ-valerolactone (GVL) over Co/SiO2 catalyst proceeds in a complex reaction network, resulting in 2-methyltetrahydrofuran (2-MTHF) as the main product, and C4–C5 alcohol and alkane side-products. The catalyst was shown to contain Co0 sites and Lewis acid (Co2+ ion)/Lewis base (O2− ion) pair sites, active for hydrogenation/dehydrogenation and dehydration reactions, respectively. The initial reaction step was confirmed to be the hydrogenation of GVL to key intermediate 1,4-pentanediol (1,4-PD). Cyclodehydration of 1,4-PD led to the main product 2-MTHF, whereas its dehydration/hydrogenation gave 1-pentanol and 2-pentanol side-products, with about the same yield. In contrast, 2-pentanol was the favored alcohol product of 2-MTHF hydrogenolysis. 2-Butanol was formed by decarbonylation of 4-hydroxypentanal intermediate. The latter was the product of 1,4-PD dehydrogenation. Alkanes were formed from the alcohol side-products via dehydration/hydrogenation reactions.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Sapag, K., S. Rojas, M. López Granados, J. L. G. Fierro y S. Mendioroz. "CO hydrogenation with Co catalyst supported on porous media". Journal of Molecular Catalysis A: Chemical 167, n.º 1-2 (febrero de 2001): 81–89. http://dx.doi.org/10.1016/s1381-1169(00)00494-5.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Panpranot, J. "CO Hydrogenation on Ru-Promoted Co/MCM-41 Catalysts". Journal of Catalysis 211, n.º 2 (25 de octubre de 2002): 530–39. http://dx.doi.org/10.1016/s0021-9517(02)93761-9.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

Mendes, F. M. T., C. A. C. Perez, F. B. Noronha y M. Schmal. "TPSR of CO hydrogenation on Co/Nb2O5/Al2O3 catalysts". Catalysis Today 101, n.º 1 (marzo de 2005): 45–50. http://dx.doi.org/10.1016/j.cattod.2004.12.009.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Athariboroujeny, Motahare, Andrew Raub, Viacheslav Iablokov, Sergey Chenakin, Libor Kovarik y Norbert Kruse. "Competing Mechanisms in CO Hydrogenation over Co-MnOx Catalysts". ACS Catalysis 9, n.º 6 (8 de mayo de 2019): 5603–12. http://dx.doi.org/10.1021/acscatal.9b00967.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Panpranot, Joongjai, James G. Goodwin Jr. y Abdelhamid Sayari. "CO Hydrogenation on Ru-Promoted Co/MCM-41 Catalysts". Journal of Catalysis 211, n.º 2 (25 de octubre de 2002): 530–39. http://dx.doi.org/10.1006/jcat.2002.3761.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Haddad, George J., Bin Chen y James G. Goodwin, Jr. "Effect of La3+Promotion of Co/SiO2on CO Hydrogenation". Journal of Catalysis 161, n.º 1 (junio de 1996): 274–81. http://dx.doi.org/10.1006/jcat.1996.0185.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Christensen, Jakob M., Andrew J. Medford, Felix Studt y Anker D. Jensen. "High Pressure CO Hydrogenation Over Bimetallic Pt–Co Catalysts". Catalysis Letters 144, n.º 5 (2 de marzo de 2014): 777–82. http://dx.doi.org/10.1007/s10562-014-1220-x.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Scharnagl, Florian Korbinian, Maximilian Franz Hertrich, Francesco Ferretti, Carsten Kreyenschulte, Henrik Lund, Ralf Jackstell y Matthias Beller. "Hydrogenation of terminal and internal olefins using a biowaste-derived heterogeneous cobalt catalyst". Science Advances 4, n.º 9 (septiembre de 2018): eaau1248. http://dx.doi.org/10.1126/sciadv.aau1248.

Texto completo

Resumen

Hydrogenation of olefins is achieved using biowaste-derived cobalt chitosan catalysts. Characterization of the optimal Co@Chitosan-700 by STEM (scanning transmission electron microscopy), EELS (electron energy loss spectroscopy), PXRD (powder x-ray diffraction), and elemental analysis revealed the formation of a distinctive magnetic composite material with high metallic Co content. The general performance of this catalyst is demonstrated in the hydrogenation of 50 olefins including terminal, internal, and functionalized derivatives, as well as renewables. Using this nonnoble metal composite, hydrogenation of terminal C==C double bonds occurs under very mild and benign conditions (water or methanol, 40° to 60°C). The utility of Co@Chitosan-700 is showcased for efficient hydrogenation of the industrially relevant examples diisobutene, fatty acids, and their triglycerides. Because of the magnetic behavior of this material and water as solvent, product separation and recycling of the catalyst are straightforward.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Chung, S. R., K. W. Wang y T. P. Perng. "Electrochemical Hydrogenation of Crystalline Co Powder". Journal of The Electrochemical Society 153, n.º 6 (2006): A1128. http://dx.doi.org/10.1149/1.2189978.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Agnelli, M., H. M. Swaan, C. Marquez-Alvarez, G. A. Martin y C. Mirodatos. "CO Hydrogenation on a Nickel Catalyst". Journal of Catalysis 175, n.º 1 (abril de 1998): 117–28. http://dx.doi.org/10.1006/jcat.1998.1978.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Agnelli, M., M. Kolb y C. Mirodatos. "Co Hydrogenation on a Nickel Catalyst ." Journal of Catalysis 148, n.º 1 (julio de 1994): 9–21. http://dx.doi.org/10.1006/jcat.1994.1180.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Bowker, Michael. "Methanol Synthesis from CO 2 Hydrogenation". ChemCatChem 11, n.º 17 (10 de julio de 2019): 4238–46. http://dx.doi.org/10.1002/cctc.201900401.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Lee, Younghyun, Sung Woo Lee, Hyung Ju Kim, Yong Tae Kim, Kun-Yi Andrew Lin y Jechan Lee. "Hydrogenation of Adiponitrile to Hexamethylenediamine over Raney Ni and Co Catalysts". Applied Sciences 10, n.º 21 (26 de octubre de 2020): 7506. http://dx.doi.org/10.3390/app10217506.

Texto completo

Resumen

Hexamethylenediamine (HMDA), a chemical for producing nylon, was produced on Raney Ni and Raney Co catalysts via the hydrogenation of adiponitrile (ADN). HMDA was hydrogenated from ADN via 6-aminohexanenitrile (AHN). For the two catalysts, the effects of five different reaction parameters (reaction temperature, H2 pressure, catalyst loading, and ADN/HMDA ratio in the reactant) on the hydrogenation of ADN were investigated. Similar general trends demonstrating the dependence of ADN hydrogenation on the reaction conditions for both catalysts were observed: higher temperature (60–80 °C) and H2 pressure, as well as lower ADN/catalyst and ADN/HMDA ratios, led to higher HMDA yields. A further increase in temperature from 80 to 100 °C increased the HMDA yield from 90.5 to 100% for the Raney Ni catalyst, but did not affect the HMDA yield (85~87%) for the Raney Co catalyst. A 100% HMDA yield (the highest yield reported to date) was also achieved via ADN hydrogenation over the Raney Ni catalyst, with a high HMDA content in the reactant (e.g., ADN/HMDA volumetric ratio of 0.06). No sign of metal leaching into the product solution was found, meaning that the Raney Ni and Raney Co catalysts were stable during ADN hydrogenation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Vasiliades, Michalis A., Konstantina K. Kyprianou, Nilenindran S. Govender, Ashriti Govender, Renier Crous, Denzil Moodley y Angelos M. Efstathiou. "The Effect of CO Partial Pressure on Important Kinetic Parameters of Methanation Reaction on Co-Based FTS Catalyst Studied by SSITKA-MS and Operando DRIFTS-MS Techniques". Catalysts 10, n.º 5 (22 de mayo de 2020): 583. http://dx.doi.org/10.3390/catal10050583.

Texto completo

Resumen

A 20 wt% Co-0.05 wt% Pt/γ-Al2O3 catalyst was investigated to obtain a fundamental understanding of the effect of CO partial pressure (constant H2 partial pressure) on important kinetic parameters of the methanation reaction (x vol% CO/25 vol% H2, x = 3, 5 and 7) by performing advanced transient isotopic and operando diffuse reflectance infrared Fourier transform spectroscopy–mass spectrometry (DRIFTS-MS) experiments. Steady State Isotopic Transient Kinetic Analysis (SSITKA) experiments conducted at 1.2 bar, 230 °C after 5 h in CO/H2 revealed that the surface coverages, θCO and θCHx and the mean residence times, τCO, and τCHx (s) of the reversibly adsorbed CO-s and active CHx-s (Cα) intermediates leading to CH4, respectively, increased with increasing CO partial pressure. On the contrary, the apparent activity (keff, s−1) of CHx-s intermediates, turnover frequency (TOF, s−1) of methanation reaction, and the CH4-selectivity (SCH4, %) were found to decrease. Transient isothermal hydrogenation (TIH) following the SSITKA step-gas switch provided important information regarding the reactivity and concentration of active (Cα) and inactive -CxHy (Cβ) carbonaceous species formed after 5 h in the CO/H2 reaction. The latter Cβ species were readily hydrogenated at 230 °C in 50%H2/Ar. The surface coverage of Cβ was found to vary only slightly with increasing CO partial pressure. Temperature-programmed hydrogenation (TPH) following SSITKA and TIH revealed that other types of inactive carbonaceous species (Cγ) were formed during Fischer-Tropsch Synthesis (FTS) and hydrogenated at elevated temperatures (250–550 °C). The amount of Cγ was found to significantly increase with increasing CO partial pressure. All carbonaceous species hydrogenated during TIH and TPH revealed large differences in their kinetics of hydrogenation with respect to the CO partial pressure in the CO/H2 reaction mixture. Operando DRIFTS-MS transient isothermal hydrogenation of adsorbed CO-s formed after 2 h in 5 vol% CO/25 vol% H2/Ar at 200 °C coupled with kinetic modeling (H-assisted CO hydrogenation) provided information regarding the relative reactivity (keff) for CH4 formation of the two kinds of linear-type adsorbed CO-s on the cobalt surface.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

He, Zhenhong, Qingli Qian, Zhaofu Zhang, Qinglei Meng, Huacong Zhou, Zhiwei Jiang y Buxing Han. "Synthesis of higher alcohols from CO 2 hydrogenation over a PtRu/Fe 2 O 3 catalyst under supercritical condition". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, n.º 2057 (28 de diciembre de 2015): 20150006. http://dx.doi.org/10.1098/rsta.2015.0006.

Texto completo

Resumen

Hydrogenation of CO 2 to alcohols is of great importance, especially when producing higher alcohols. In this work, we synthesized heterogeneous PtRu/Fe 2 O 3 , in which the Pt and Ru bimetallic catalysts were supported on Fe 2 O 3 . The catalyst was used to catalyse CO 2 hydrogenation to alcohols. It was demonstrated that the activity and selectivity could be tuned by the bimetallic composition, and the catalyst with a Pt to Ru molar ratio of 1:2 (Pt 1 Ru 2 /Fe 2 O 3 ) had high activity and selectivity at 200°C, which is very low for heterogeneous hydrogenation of CO 2 to produce higher alcohols. The conversion and the selectivity increased with increasing pressures of CO 2 and/or H 2 . The catalyst could be reused at least five times without any obvious change in activity or selectivity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Liu, He, Shiguang Fan, Xu Gong, Jian Wang, Aijun Guo, Kun Chen y Zongxian Wang. "Partial Hydrogenation of Anthracene with In Situ Hydrogen Produced from Water-Gas Shift Reaction over Fe-Based Catalysts". Catalysts 10, n.º 12 (25 de noviembre de 2020): 1379. http://dx.doi.org/10.3390/catal10121379.

Texto completo

Resumen

Partial hydrogenation of anthracene under CO-H2O, N2-H2O, and H2-H2O over Fe-based catalysts was studied at 400 °C and 10 MPa. Results show that the Fe-based catalysts display obvious catalytic activity for anthracene hydrogenation under CO-H2O instead of hydrogenation under N2-H2O and H2-H2O. The activity follows in the order of Fe(NO3)3·9H2O > Fe naphthenate > FeSO4·7H2O. Even though the amount of molecular hydrogen remains higher than that of in situ hydrogen, the anthracene conversion with in situ hydrogen is remarkably higher. It demonstrates that the in situ hydrogen is more active than molecular hydrogen for PAH hydrogenation. To further reveal the exact fate of these Fe-based catalysts, the decomposed products under CO-H2O, N2-H2O and H2-H2O were characterized by TG, XRD, and TEM. Results indicate that the Fe3O4 species play a key role in hydrogenation of anthracene under CO and H2O. Higher catalytic activity for Fe(NO3)3·9H2O is due to its complete decomposition at 350 °C to acquire higher concentration of active Fe3O4 species. The possible form of in situ hydrogen during this process is also discussed. Given that heavy oil contains abundant polyaromatics, these results are meaningful for enhancing hydrogen shuttling to heavy oil by producing natural hydrogen donors and, thus, benefiting the high-efficient upgrading.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Popandopulo, M. V., M. I. Ivantsov, M. V. Kulikova y F. G. Zhagfarov. "Hydrogenation of Carbon Monoxide on Composite Catalytic Systems Based on Nickel and Polyvinyl Alcohol". Chemistry and Technology of Fuels and Oils 629, n.º 1 (2022): 29–33. http://dx.doi.org/10.32935/0023-1169-2022-629-1-29-33.

Texto completo

Resumen

The article considers the catalytic and physico-chemical properties of composite materials obtained by heat treatment of nickel nitrate immobilized on polyvinyl alcohol. The influence of the composite formation temperature on the phase composition of metal-containing and the particle size is studied. It is shown that the resulting composite material is an active catalyst for the hydrogenation of carbon monoxide without a pre-activation stage. The following synthesis parameters were achieved: the degree of carbon monoxide conversion under the conditions of CO catalytic hydrogenation process: CO conversion — 29%, CH4 yield — 28 g/m3 . Assumptions about the particle size effect on the activity of the synthesized composite and the effect of volume velocity on the parameters of the CO hydrogenation process are made.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Du, Chang Hai, Yong Zhao y De Sun. "A Co-Promoted Ni-B Amorphous Nanoalloy Catalyst for Liquid Phase Hydrogenation of Furfural to Furfural Alcohol". Advanced Materials Research 183-185 (enero de 2011): 2322–26. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.2322.

Texto completo

Resumen

The Co-promoted Ni-B amorphous nanoalloy catalysts were prepared by the chemical reduction of the aqueous solution containing nickel acetate and cobalt acetate with NaBH4 at room temperature and characterized by BET, XRD and DSC. They were used as catalysts for the liquid phase hydrogenation of furfural to furfural alcohol in alcohol at 353 K under 2.0 MPa of hydrogen. Ni-Co-B catalyst was characterized by XRD as amorphous structure. It was active in the hydrogenation of furfural, and it was significantly more active than Ni-B and Co-B. The optimal Co/ ( Co+Ni ) mole ratio in Ni-Co-B was 0.5.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Wu, Song-Bai, Tonghuan Zhang, Lung Wa Chung y Yun-Dong Wu. "A Missing Piece of the Mechanism in Metal-Catalyzed Hydrogenation: Co(−I)/Co(0)/Co(+I) Catalytic Cycle for Co(−I)-Catalyzed Hydrogenation". Organic Letters 21, n.º 2 (2 de enero de 2019): 360–64. http://dx.doi.org/10.1021/acs.orglett.8b03463.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Tanirbergenova, S. K., N. K. Zhylybayeva, S. Zh Tairabekova, D. A. Tugelbayeva, G. M. Naurzbayeva, G. M. Moldazhanova y B. A. Mansurov. "Nanosized Catalysts in the Process of Hydrogenating Acetylene". Eurasian Chemico-Technological Journal 20, n.º 3 (28 de septiembre de 2018): 249. http://dx.doi.org/10.18321/ectj730.

Texto completo

Resumen

Hydrogenating process of the acetylene to ethylene using automated flow catalytic installation at nanoscaled catalysts Ni, Co and carriers at a pressure of 5 atm was studied. The actions of carriers and nanosized catalysts during hydrogenation reaction of acetylene to ethylene at low temperatures in the range from 50–120 °С were analyzed. With ratio of С2Н2:Н2 being equal to (1:2), at 80 °С the aluminum oxide carrier exhibits an activity, conversion of acetylene makes up 70%, when using zeolite 3A it is 63%. When the temperature rises to 120 °С, the aluminum activity is decreasing and conversion is 53%. However, zeolite exhibits its activity at high temperatures, at a temperature of 120 °С conversion of acetylene reaches to 73.5%. It is shown that with increasing of hydrogen ratio, the ethylene yield increases from 5 to 10.7% using catalyst 5% Ni/3A. In addition, in reaction of acetylene hydrogenation there are not formed waste products. For this process, the optimum reaction temperature is 80 °С, feedstock ratio (1:3) is positive, where the ethylene yield increased up to 16.7% and at catalyst to 5% Co/3A.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "CO₂ hydrogenation"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros