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Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation...
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Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance

A special issue of Catalysts (ISSN 2073-4344). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: closed (31 October 2020) | Viewed by 26608

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editor

Dr. John Vakros

E-Mail Website
Guest Editor
Department of Chemistry, University of Patras, 26504 Patras, Greece
Interests: preparation; characterization and testing of supported catalysts; environmental friendly processes; advanced oxidation processes; biochar applications; acid-base behavior of nanoparticles; potentiometric mass titrations; metal support interactions
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In our days Cobalt and related catalysts are very attractive because they exhibit a lot of advantages like low cost and high activity in a significant variety of different applications. Cobalt - catalysts are among the most active catalysts for Fischer-Tropsch synthesis and they promote the catalytic activity of the hydrodesulfurization catalysts. Also they found other significant applications in environmental protection like oxidation of volatile organic compounds, VOC, persulfate activator, ammonia synthesis, electrocatalysis and many more. Cobalt -catalysts are active, stable and exhibit significant oxidation - reduction activity, as the Co can be found either as Co(II) or Co(III). Also many molecules can interact with cobalt supported phase by co - ordination due to partially filled d-orbital. Co- catalysts can be supported in almost all the inorganic supports like alumina, titania, zeolites etc. The cobalt oxide phase can be stabilized onto the surface of the support due to variable interactions between support and cobalt phase. These interactions are crucial for catalytic activity and can be regulated by proper selection of the preparation parameters like the type of support, the Co loading, impregnation method and thermal conditions.

This Special Issue aims to cover recent progress and advances in the field of Cobalt and related catalysts. This includes, but is not restricted to, the synthesis of catalysts with different preparation methods, their catalytic performance in different catalytic processes in which the catalyst are active and selective, the effect of preparation method in physicochemical characteristics of supported active phase and the correlation between catalytic activity and their physicochemical characteristics. Finally, new catalytic applications of Co-catalysts and comparison with other similar catalysts are strongly welcoming.

Dr. John Vakros
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Catalysts is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Co–catalysts
  • Supported catalysts
  • Catalysts preparation,
  • Physicochemical properties of supported catalysts
  • Catalytic evaluation
  • Fischer–Tropsch synthesis

Published Papers (7 papers)

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Editorial

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4 pages, 171 KiB  
Editorial
Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance
by John Vakros
Catalysts 2021, 11(4), 420; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11040420 - 25 Mar 2021
Cited by 3 | Viewed by 1517
Abstract
In our days cobalt, Co, and related catalysts are very attractive because they exhibit a lot of advantages like low cost and high activity in a significant variety of different applications [...] Full article
(This article belongs to the Special Issue Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance)

Research

Jump to: Editorial

21 pages, 4415 KiB  
Article
Pt-Co3O4 Superstructures by One-Pot Reduction/Precipitation in Bicontinuous Microemulsion for Electrocatalytic Oxygen Evolution Reaction
by Elijah T. Adesuji, Esther Guardado-Villegas, Keyla M. Fuentes, Margarita Sánchez-Domínguez and Marcelo Videa
Catalysts 2020, 10(11), 1311; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10111311 - 12 Nov 2020
Cited by 15 | Viewed by 2764
Abstract
Bicontinuous microemulsions (BCME) were used to synthesize hierarchical superstructures (HSs) of Pt-Co3O4 by reduction/precipitation. BCMEs possess water and oil nanochannels, and therefore, both hydrophilic and lipophilic precursors can be used. Thus, PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi were prepared (where Aq [...] Read more.
Bicontinuous microemulsions (BCME) were used to synthesize hierarchical superstructures (HSs) of Pt-Co3O4 by reduction/precipitation. BCMEs possess water and oil nanochannels, and therefore, both hydrophilic and lipophilic precursors can be used. Thus, PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi were prepared (where Aq and Oi stand for the precursor present in aqueous or oily phase, respectively). The characterization of the Pt-Co3O4-HS confirmed the formation of metallic Pt and Co3O4 whose composition and morphology are controlled by the initial pH and precursor combination, determining the presence of the reducing/precipitant species in the reaction media. The electrocatalytic activity of the Pt-Co3O4-HSs for oxygen evolution reaction (OER) was investigated using linear sweep voltammetry in 0.1 M KOH and compared with Pt-HS. The lowest onset overpotentials for Pt-Co3O4-Hs were achieved with PtOi-CoOi (1.46 V vs. RHE), while the lowest overpotential at a current density of 10 mA cm−2 (η10) was obtained for the PtAq-CoAq (381 mV). Tafel slopes were 102, 89, 157 and 92 mV dec−1, for PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi, respectively. The Pt-Co3O4-HSs showed a better performance than Pt-HS. Our work shows that the properties and performance of metal–metal oxide HSs obtained in BCMEs depend on the phases in which the precursors are present. Full article
(This article belongs to the Special Issue Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance)
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28 pages, 11534 KiB  
Article
Substitution of Co with Ni in Co/Al2O3 Catalysts for Fischer–Tropsch Synthesis
by Michela Martinelli, Sai Charan Karuturi, Richard Garcia, Caleb D. Watson, Wilson D. Shafer, Donald C. Cronauer, A. Jeremy Kropf, Christopher L. Marshall and Gary Jacobs
Catalysts 2020, 10(3), 334; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10030334 - 17 Mar 2020
Cited by 5 | Viewed by 3807
Abstract
The effect of cobalt substitution with nickel was investigated for the Fischer–Tropsch synthesis reaction. Catalysts having different Ni/Co ratios were prepared by aqueous incipient wetness co-impregnation, characterized, and tested using a continuously stirred tank reactor (CSTR) for more than 200 h. The addition [...] Read more.
The effect of cobalt substitution with nickel was investigated for the Fischer–Tropsch synthesis reaction. Catalysts having different Ni/Co ratios were prepared by aqueous incipient wetness co-impregnation, characterized, and tested using a continuously stirred tank reactor (CSTR) for more than 200 h. The addition of nickel did not significantly modify the morphological properties measured. XRD, STEM, and TPR-XANES results showed intimate contact between nickel and cobalt, strongly suggesting the formation of a Co-Ni solid oxide solution in each case. Moreover, TPR-XANES indicated that nickel addition improves the cobalt reducibility. This may be due to H2 dissociation and spillover, but is more likely the results of a chemical effect of intimate contact between Co and Ni resulting in Co-Ni alloying after activation. FTS testing revealed a lower initial activity when nickel was added. However, CO conversion continuously increased with time on-stream until a steady-state value (34%–37% depending on Ni/Co ratio) was achieved, which was very close to the value observed for undoped Co/Al2O3. This trend suggests nickel can stabilize cobalt nanoparticles even at a lower weight percentage of Co. Currently, the cobalt price is 2.13 times the price of nickel. Thus, comparing the activity/price, the catalyst with a Ni/Co ratio of 25/75 has better performance than the unpromoted catalyst. Finally, nickel-promoted catalysts exhibited slightly higher initial selectivity for light hydrocarbons, but this difference typically diminished with time on-stream; once leveling off in conversion was achieved, the C5+ selectivities were similar (≈ 80%) for Ni/Co ratios up to 10/90, and only slightly lower (≈ 77%) at Ni/Co of 25/75. Full article
(This article belongs to the Special Issue Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance)
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12 pages, 2173 KiB  
Article
Determining the Location of Co2+ in Zeolites by UV-Vis Diffuse Reflection Spectroscopy: A Critical View
by Andrea Bellmann, Christine Rautenberg, Ursula Bentrup and Angelika Brückner
Catalysts 2020, 10(1), 123; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10010123 - 15 Jan 2020
Cited by 18 | Viewed by 5448
Abstract
UV–Vis spectroscopy as well as in situ FTIR spectroscopy of pyridine and CO adsorption were applied to determine the nature of Co species in microporous, mesoporous, and mixed oxide materials like Co–ZSM-5, Co/Na–ZSM-5, Co/Al–SBA-15, and Co/Al2O3–SiO2. Because [...] Read more.
UV–Vis spectroscopy as well as in situ FTIR spectroscopy of pyridine and CO adsorption were applied to determine the nature of Co species in microporous, mesoporous, and mixed oxide materials like Co–ZSM-5, Co/Na–ZSM-5, Co/Al–SBA-15, and Co/Al2O3–SiO2. Because all sample types show comparable UV–Vis spectra with a characteristic band triplet, the former described UV–Vis band deconvolution method for determination and quantification of individual cationic sites in the zeolite appears doubtful. This is also confirmed by results of pyridine and CO adsorption revealing that all Co–zeolite samples contain two types of Co2+ species located at exchange positions as well as in oxide-like clusters independent of the Co content, while in Co/Al–SBA-15 and Co/Al2O3–SiO2 only Co2+ species in oxide-like clusters occur. Consequently, the measured UV–Vis spectra represent not exclusively isolated Co2+ species, and the characteristic triplet band is not only related to γ-, β-, and α-type Co2+ sites in the zeolite but also to those dispersed on the surface of different oxide supports. The study demonstrates that for proper characterization of the formed Co species, the use of complementary methods is required. Full article
(This article belongs to the Special Issue Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance)
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15 pages, 2995 KiB  
Article
The Influence of Preparation Method on the Physicochemical Characteristics and Catalytic Activity of Co/TiO2 Catalysts
by John Vakros
Catalysts 2020, 10(1), 88; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10010088 - 07 Jan 2020
Cited by 9 | Viewed by 2441
Abstract
Two Co/TiO2 catalysts with 7% CoO/g loading were prepared using equilibrium deposition filtration and the dry impregnation method. The two catalysts were characterized with various physicochemical techniques and tested for the degradation of sulfamethaxazole (SMX) using sodium persulfate (SPS) as the oxidant. [...] Read more.
Two Co/TiO2 catalysts with 7% CoO/g loading were prepared using equilibrium deposition filtration and the dry impregnation method. The two catalysts were characterized with various physicochemical techniques and tested for the degradation of sulfamethaxazole (SMX) using sodium persulfate (SPS) as the oxidant. It was found that the two catalysts exhibit different physicochemical characteristics. The equilibrium deposition filtration (EDF) catalyst had a higher dispersion of cobalt phase, more easily reduced Co(III) species, and a higher ratio of Co(III)/Co(II) species. The interactions between Co-deposited species and the titania surface were monitored with diffuse reflectance spectroscopy in all the preparation steps, and it was found that they increased during drying and calcination, while EDF favored the formation of surface species with strong interactions with the support. Finally, the EDF catalyst was more active for the degradation of sulfamethaxazole due to its better physicochemical characteristics. Full article
(This article belongs to the Special Issue Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance)
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15 pages, 3695 KiB  
Article
Manganese and Cobalt Doped Hierarchical Mesoporous Halloysite-Based Catalysts for Selective Oxidation of p-Xylene to Terephthalic Acid
by Eduard Karakhanov, Anton Maximov, Anna Zolotukhina, Vladimir Vinokurov, Evgenii Ivanov and Aleksandr Glotov
Catalysts 2020, 10(1), 7; https://0-doi-org.brum.beds.ac.uk/10.3390/catal10010007 - 18 Dec 2019
Cited by 21 | Viewed by 6158
Abstract
Bimetallic MnCo catalyst, supported on the mesoporous hierarchical MCM-41/halloysite nanotube composite, was synthesized for the first time and proved its efficacy in the selective oxidation of p-xylene to terephthalic acid under conditions of the AMOCO process. Quantitative yields of terephthalic acid were [...] Read more.
Bimetallic MnCo catalyst, supported on the mesoporous hierarchical MCM-41/halloysite nanotube composite, was synthesized for the first time and proved its efficacy in the selective oxidation of p-xylene to terephthalic acid under conditions of the AMOCO process. Quantitative yields of terephthalic acid were achieved within 3 h at 200–250 °C, 20 atm. of O2 and at a substrate to the Mn + Co ratio of 4–4.5 times higher than for traditional homogeneous system. The influence of temperature, oxygen, pressure and KBr addition on the catalyst activity was investigated, and the mechanism for the oxidation of p-toluic acid to terephthalic acid, excluding undesirable 4-carboxybenzaldehyde, was proposed. Full article
(This article belongs to the Special Issue Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance)
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10 pages, 3736 KiB  
Article
Nitrogen and Cobalt Co-Coped Carbon Materials Derived from Biomass Chitin as High-Performance Electrocatalyst for Aluminum-Air Batteries
by Mi Wang, Jian Ma, Haoqi Yang, Guolong Lu, Shuchen Yang and Zhiyong Chang
Catalysts 2019, 9(11), 954; https://0-doi-org.brum.beds.ac.uk/10.3390/catal9110954 - 14 Nov 2019
Cited by 17 | Viewed by 3212
Abstract
Development of convenient, economic electrocatalysts for oxygen reduction reaction (ORR) in alkaline medium is of great significance to practical applications of aluminum-air batteries. Herein, a biomass chitin-derived carbon material with high ORR activities has been prepared and applied as electrocatalysts in Al-air batteries. [...] Read more.
Development of convenient, economic electrocatalysts for oxygen reduction reaction (ORR) in alkaline medium is of great significance to practical applications of aluminum-air batteries. Herein, a biomass chitin-derived carbon material with high ORR activities has been prepared and applied as electrocatalysts in Al-air batteries. The obtained cobalt, nitrogen co-doped carbon material (CoNC) exhibits the positive onset potential 0.86 V vs. RHE (reversible hydrogen electrode) and high-limiting current density 5.94 mA cm−2. Additionally, the durability of the CoNC material in alkaline electrolyte shows better stability when compared to the commercial Pt/C catalyst. Furthermore, the Al-air battery using CoNC as an air cathode catalyst provides the power density of 32.24 mW cm−2 and remains the constant discharge voltage of 1.17 V at 20 mA cm−2. This work not only provides a facile method to synthesize low-cost and efficient ORR electrocatalysts for Al-air batteries, but also paves a new way to explore and utilize high-valued biomass materials. Full article
(This article belongs to the Special Issue Recent Advances in Cobalt and Related Catalysts: From Catalyst Preparation to Catalytic Performance)
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