Synergistic Effect of Alkali Na and K Promoter on Fe-Co-Cu-Al Catalysts for CO2 Hydrogenation to Light Hydrocarbons

Alkali metal K- and/or Na-promoted FeCoCuAl catalysts were synthesized by precipitation and impregnation, and their physicochemical and catalytic performance for CO2 hydrogenation to light hydrocarbons was also investigated in the present work. The results indicate that Na and/or K introduction leads to the formation of active phase metallic Fe and Fe-Co crystals in the order Na < K < K-Na. The simultaneous introduction of Na and K causes a synergistic effect on increasing the basicity and electron-rich property, promoting the formation of active sites Fe@Cu and Fe-Co@Cu with Cu0 as a crystal core. These effects are advantageous to H2 dissociative adsorption and CO2 activation, giving a high CO2 conversion with hydrogenation. Moreover, electron-rich Fe@Cu (110) and Fe-Co@Cu (200) provide active centers for further H2 dissociative adsorption and O-C-Fe intermediate formation after adsorption of CO produced by RWGS. It is beneficial for carbon chain growth in C2+ hydrocarbons, including olefins and alkanes. FeCoCuAl simultaneously modified by K-Na exhibits the highest CO2 conversion and C2+ selectivity of 52.87 mol% and 89.70 mol%, respectively.

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Highly Selective Au/ZnO via Colloidal Deposition for CO2 Hydrogenation to Methanol: Evidence of AuZn Role

BULLETIN OF CHEMICAL REACTION ENGINEERING AND CATALYSIS ◽

10.9767/bcrec.16.1.9375.44-51 ◽

2021 ◽

Vol 16 (1) ◽

pp. 44-51

Author(s):

Hasliza Bahruji ◽

Mshaal Almalki ◽

Norli Abdullah

Keyword(s):

Active Sites ◽

Au Nanoparticles ◽

High Selectivity ◽

Average Diameter ◽

Co2 Hydrogenation ◽

Impregnation Method ◽

Co2 Conversion ◽

Methanol Production ◽

Surface Oxygen Vacancy ◽

Colloidal Method

Gold, Au nanoparticles were deposited on ZnO, Al2O3, and Ga2O3 via colloidal method in order to investigate the role of support for CO2 hydrogenation to methanol. Au/ZnO was also produced using impregnation method to investigate the effect of colloidal method to improve methanol selectivity. Au/ZnO produced via sol immobilization showed high selectivity towards methanol meanwhile impregnation method produced Au/ZnO catalyst with high selectivity towards CO. The CO2 conversion was also influenced by the amount of Au weight loading. Au nanoparticles with average diameter of 3.5 nm exhibited 4% of CO2 conversion with 72% of methanol selectivity at 250 °C and 20 bar. The formation of AuZn alloy was identified as active sites for selective CO2 hydrogenation to methanol. Segregation of Zn from ZnO to form AuZn alloy increased the number of surface oxygen vacancy for CO2 adsorption to form formate intermediates. The formate was stabilized on AuZn alloy for further hydrogenation to form methanol. The use of Al2O3 and Ga2O3 inhibited the formation of Au alloy, and therefore reduced methanol production. Au/Al2O3 showed 77% selectivity to methane, meanwhile Au/Ga2O3 produced 100% selectivity towards CO. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

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CO2 Hydrogenation over Nanoceria-Supported Transition Metal Catalysts: Role of Ceria Morphology (Nanorods versus Nanocubes) and Active Phase Nature (Co versus Cu)

Nanomaterials ◽

10.3390/nano9121739 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1739 ◽

Cited By ~ 9

Author(s):

Michalis Konsolakis ◽

Maria Lykaki ◽

Sofia Stefa ◽

Sόnia A. C. Carabineiro ◽

Georgios Varvoutis ◽

...

Keyword(s):

Specific Activity ◽

Active Phase ◽

Physicochemical Characteristics ◽

Co2 Hydrogenation ◽

Transition Metal Catalysts ◽

Co2 Conversion ◽

Reverse Water Gas Shift ◽

Wide Range ◽

Combined Impact

In this work we report on the combined impact of active phase nature (M: Co or Cu) and ceria nanoparticles support morphology (nanorods (NR) or nanocubes (NC)) on the physicochemical characteristics and CO2 hydrogenation performance of M/CeO2 composites at atmospheric pressure. It was found that CO2 conversion followed the order: Co/CeO2 > Cu/CeO2 > CeO2, independently of the support morphology. Co/CeO2 catalysts demonstrated the highest CO2 conversion (92% at 450 °C), accompanied by 93% CH4 selectivity. On the other hand, Cu/CeO2 samples were very selective for CO production, exhibiting 52% CO2 conversion and 95% CO selectivity at 380 °C. The results obtained in a wide range of H2:CO2 ratios (1–9) and temperatures (200–500 °C) are reaching in both cases the corresponding thermodynamic equilibrium conversions, revealing the superiority of Co- and Cu-based samples in methanation and reverse water-gas shift (rWGS) reactions, respectively. Moreover, samples supported on ceria nanocubes exhibited higher specific activity (µmol CO2·m−2·s−1) compared to samples of rod-like shape, disclosing the significant role of support morphology, besides that of metal nature (Co or Cu). Results are interpreted on the basis of different textural and redox properties of as-prepared samples in conjunction to the different impact of metal entity (Co or Cu) on CO2 hydrogenation process.

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Fischer-Tropsch Synthesis over Co/SiO2 Catalysts Modified with Ethylenediamine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.512-515.2143 ◽

2012 ◽

Vol 512-515 ◽

pp. 2143-2146

Author(s):

Yue Lun Wang ◽

Bo Hou ◽

De Bao Li ◽

Jian Gang Chen ◽

Yu Han Sun

Keyword(s):

Active Sites ◽

Cobalt Nanoparticles ◽

Tropsch Synthesis ◽

Molar Ratio ◽

Chain Growth ◽

Light Hydrocarbons ◽

Fischer Tropsch ◽

Fischer Tropsch Synthesis ◽

Dispersed Catalysts ◽

Highly Dispersed

The influence of ethylenediamine (en)/Co molar ratio on the preparation of Co/SiO2catalysts was studied. The decomposition of these Co-en species resulted in the formation of small cobalt nanoparticles. The highly dispersed catalysts led to lower FT activity due to an increase of cobalt-silica interaction except Co(en)2/SiO2catalyst. Meanwhile, higher selectivity for light hydrocarbons was observed, which was ascribed that smaller cobalt particles containing active sites depressed the chain growth.

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Identification of active sites for CO2 hydrogenation in Fe catalysts by first-principles microkinetic modelling

Journal of Materials Chemistry A ◽

10.1039/d0ta01634a ◽

2020 ◽

Vol 8 (26) ◽

pp. 13014-13023 ◽

Cited By ~ 2

Author(s):

Seung Ju Han ◽

Sun-Mi Hwang ◽

Hae-Gu Park ◽

Chundong Zhang ◽

Ki-Won Jun ◽

...

Keyword(s):

First Principles ◽

Active Sites ◽

Active Phase ◽

Co2 Hydrogenation ◽

Fe Catalysts

The active phase of Fe catalysts for RWGS is identified and an efficient promoter is proposed using DFT-microkinetics.

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What catalysis needs from the electron microscopist

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100105539 ◽

1988 ◽

Vol 46 ◽

pp. 694-695

Author(s):

Alexis T. Bell

Keyword(s):

Active Sites ◽

Heterogeneous Catalysts ◽

Catalyst Deactivation ◽

Surface Composition ◽

Internal Surface ◽

Active Phase ◽

Atomic Scale ◽

Metal Catalyst ◽

Internal Surface Area ◽

Porous Support

Heterogeneous catalysts, used in industry for the production of fuels and chemicals, are microporous solids characterized by a high internal surface area. The catalyticly active sites may occur at the surface of the bulk solid or of small crystallites deposited on a porous support. An example of the former case would be a zeolite, and of the latter, a supported metal catalyst. Since the activity and selectivity of a catalyst are known to be a function of surface composition and structure, it is highly desirable to characterize catalyst surfaces with atomic scale resolution. Where the active phase is dispersed on a support, it is also important to know the dispersion of the deposited phase, as well as its structural and compositional uniformity, the latter characteristics being particularly important in the case of multicomponent catalysts. Knowledge of the pore size and shape is also important, since these can influence the transport of reactants and products through a catalyst and the dynamics of catalyst deactivation.

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Investigation of Gas Diffusion Electrode Systems for the Electrochemical CO2 Conversion

Catalysts ◽

10.3390/catal11040482 ◽

2021 ◽

Vol 11 (4) ◽

pp. 482

Author(s):

Hilmar Guzmán ◽

Federica Zammillo ◽

Daniela Roldán ◽

Camilla Galletti ◽

Nunzio Russo ◽

...

Keyword(s):

Carbon Capture ◽

Active Sites ◽

Co2 Reduction ◽

Gas Diffusion ◽

Gas Diffusion Electrode ◽

Catalyst Loading ◽

Co2 Conversion ◽

Atmospheric Conditions ◽

Electrochemical Co2 Reduction ◽

Liquid Products

Electrochemical CO2 reduction is a promising carbon capture and utilisation technology. Herein, a continuous flow gas diffusion electrode (GDE)-cell configuration has been studied to convert CO2 via electrochemical reduction under atmospheric conditions. To this purpose, Cu-based electrocatalysts immobilised on a porous and conductive GDE have been tested. Many system variables have been evaluated to find the most promising conditions able to lead to increased production of CO2 reduction liquid products, specifically: applied potentials, catalyst loading, Nafion content, KHCO3 electrolyte concentration, and the presence of metal oxides, like ZnO or/and Al2O3. In particular, the CO productivity increased at the lowest Nafion content of 15%, leading to syngas with an H2/CO ratio of ~1. Meanwhile, at the highest Nafion content (45%), C2+ products formation has been increased, and the CO selectivity has been decreased by 80%. The reported results revealed that the liquid crossover through the GDE highly impacts CO2 diffusion to the catalyst active sites, thus reducing the CO2 conversion efficiency. Through mathematical modelling, it has been confirmed that the increase of the local pH, coupled to the electrode-wetting, promotes the formation of bicarbonate species that deactivate the catalysts surface, hindering the mechanisms for the C2+ liquid products generation. These results want to shine the spotlight on kinetics and transport limitations, shifting the focus from catalytic activity of materials to other involved factors.

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CO Oxidation Efficiency and Hysteresis Behavior over Mesoporous Pd/SiO2 Catalyst

Catalysts ◽

10.3390/catal11010131 ◽

2021 ◽

Vol 11 (1) ◽

pp. 131 ◽

Cited By ~ 1

Author(s):

Rola Mohammad Al Soubaihi ◽

Khaled Mohammad Saoud ◽

Myo Tay Zar Myint ◽

Mats A. Göthelid ◽

Joydeep Dutta

Keyword(s):

Carbon Monoxide ◽

Catalytic Activity ◽

Co Oxidation ◽

Active Sites ◽

Bond Activation ◽

Dissociative Adsorption ◽

High Catalytic Activity ◽

Good Catalytic Activity ◽

Pretreatment Conditions ◽

Oxidation Efficiency

Carbon monoxide (CO) oxidation is considered an important reaction in heterogeneous industrial catalysis and has been extensively studied. Pd supported on SiO2 aerogel catalysts exhibit good catalytic activity toward this reaction owing to their CO bond activation capability and thermal stability. Pd/SiO2 catalysts were investigated using carbon monoxide (CO) oxidation as a model reaction. The catalyst becomes active, and the conversion increases after the temperature reaches the ignition temperature (Tig). A normal hysteresis in carbon monoxide (CO) oxidation has been observed, where the catalysts continue to exhibit high catalytic activity (CO conversion remains at 100%) during the extinction even at temperatures lower than Tig. The catalyst was characterized using BET, TEM, XPS, TGA-DSC, and FTIR. In this work, the influence of pretreatment conditions and stability of the active sites on the catalytic activity and hysteresis is presented. The CO oxidation on the Pd/SiO2 catalyst has been attributed to the dissociative adsorption of molecular oxygen and the activation of the C-O bond, followed by diffusion of adsorbates at Tig to form CO2. Whereas, the hysteresis has been explained by the enhanced stability of the active site caused by thermal effects, pretreatment conditions, Pd-SiO2 support interaction, and PdO formation and decomposition.

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Identification of C2–C5 products from CO2 hydrogenation over PdZn/TiO2–ZSM-5 hybrid catalysts

Faraday Discussions ◽

10.1039/d0fd00135j ◽

2021 ◽

Author(s):

Jonathan Ruiz Esquius ◽

Hasliza Bahruji ◽

Michael Bowker ◽

Graham J. Hutchings

Keyword(s):

High Temperature ◽

Co2 Hydrogenation ◽

Chain Growth ◽

Hybrid Catalysts

PdZn/TiO2 combined with ZSM-5 zeolites allowed for consecutive CO2 hydrogenation to CH3OH, CH3OH dehydration to DME, and MTH/DMTH in a one-pass single bed reactor. PdZn alloys, although stable at high temperature, hydrogenate olefins, limiting MTH/DMTH chain growth.

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Tailoring of Hydrotalcite-Derived Cu-Based Catalysts for CO2 Hydrogenation to Methanol

Catalysts ◽

10.3390/catal9121058 ◽

2019 ◽

Vol 9 (12) ◽

pp. 1058 ◽

Cited By ~ 4

Author(s):

Leone Frusteri ◽

Catia Cannilla ◽

Serena Todaro ◽

Francesco Frusteri ◽

Giuseppe Bonura

Keyword(s):

Metallic Copper ◽

Chemical Properties ◽

Active Phase ◽

Co2 Hydrogenation ◽

High Dispersion ◽

Experimental Conditions ◽

Typical Structure ◽

Methanol Production ◽

Physico Chemical ◽

Space Time Yield

Ternary CuxZnyAlz catalysts were prepared using the hydrotalcite (HT) method. The influence of the atomic x:y:z ratio on the physico-chemical and catalytic properties under CO2 hydrogenation conditions was probed. The characterization data of the investigated catalysts were obtained by XRF, XRD, BET, TPR, CO2-TPD, N2O chemisorption, SEM, and TEM techniques. In the “dried” catalyst, the typical structure of a hydrotalcite phase was observed. Although the calcination and subsequent reduction treatments determined a clear loss of the hydrotalcite structure, the pristine phase addressed the achievement of peculiar physico-chemical properties, also affecting the catalytic activity. Textural and surface effects induced by the zinc concentration conferred a very interesting catalyst performance, with a methanol space time yield (STY) higher than that of commercial systems operated under the same experimental conditions. The peculiar behavior of the hydrotalcite-like samples was related to a high dispersion of the active phase, with metallic copper sites homogeneously distributed among the oxide species, thereby ensuring a suitable activation of H2 and CO2 reactants for a superior methanol production.

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