Synthesis of Carbon Nanomaterials and Carbon Nanomaterial–Metal(Oxide) Composites and Their Applications in Catalysis

A special issue of ChemEngineering (ISSN 2305-7084).

Deadline for manuscript submissions: closed (23 December 2019) | Viewed by 21619

Special Issue Editor


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Guest Editor
CNRS, Inst Chem & Proc Energy Environm & Hlth ICPEES, 25 Rue Becquerel, F-67087 Strasbourg, France
Interests: π-π conjugated nanocarbons and their metal(oxides) composites for energy related applications

Special Issue Information

Dear Colleagues,

Nanocarbons are endowed with specific and often combined properties and are interesting for a large diversity of applications. One of these applications is catalysis, which is open to graphene/carbon nanotubes and their composites with metal(oxides). This Special Issue will focus mainly on new carbon and carbon–metal composites, their preparation methods and their applications in catalysis: heterogenous catalysis, electrocatalysis, photocatalysis and photo(electro)catalysis. In this context, the investigation of active catalytic sites (including carbon defects, metal structure, and carbon–metal interactions) by spectroscopic, microscopic, (electro)chemical and other characterization techniques, as well as of related properties, are within the scope of the issue. Likewise the Special Issue will cover all approaches providing an improvement of catalytic performance and related processes, e.g. catalyst design/dispersion/separation/”non-conventional” heating. We also welcome contributions on any aspect addressing the important problems of “on-carbon” catalysis, such as the nature of true catalytic site in “metal-free” carbon, and how to avoid the excessive stacking of nanocarbons, thus protecting their efficient surface area. Contributions can be supported by experiments or presented as comments and/or perspectives that are based on solid recent advancements.

Prof. Dr. Izabela Janowska
Guest Editor

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Keywords

  • graphene
  • carbon nanotubes/fibers
  • porous carbons
  • nanocarbon-metal composites
  • (photo, electro)catalysis

Published Papers (5 papers)

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Research

14 pages, 8394 KiB  
Article
Investigations on Cationic Dye Degradation Using Iron-Doped Carbon Xerogel
by S. Andrada Maicaneanu, Breanna McGhee, Razvan Stefan, Lucian Barbu-Tudoran, Christopher Sedwick and Charles H. Lake
ChemEngineering 2019, 3(3), 61; https://doi.org/10.3390/chemengineering3030061 - 4 Jul 2019
Cited by 4 | Viewed by 3300
Abstract
Iron-doped carbon xerogels were prepared using sol-gel synthesis, with potassium-2,4-dihydroxybenzoate and formaldehyde as starting materials, followed by an ion exchange step. The obtained samples were characterized (XRD, FTIR, SED-EDX, TEM) and investigated as catalysts in heterogeneous Fenton and catalytic wet air oxidation (CWAO) [...] Read more.
Iron-doped carbon xerogels were prepared using sol-gel synthesis, with potassium-2,4-dihydroxybenzoate and formaldehyde as starting materials, followed by an ion exchange step. The obtained samples were characterized (XRD, FTIR, SED-EDX, TEM) and investigated as catalysts in heterogeneous Fenton and catalytic wet air oxidation (CWAO) processes. Experiments were conducted in the same conditions (0.1 g catalysts, 25 mL of 100 mg/L dye solution, 25 °C, initial solution pH, 3 h) in thermostated batch reaction tubes (shaking water bath, 50 rpm) at atmospheric pressure. A series of three cationic dyes were considered: Brilliant green (BG), crystal violet (CV), and methyl green (MG). Dyes and TOC removal efficiencies up to 99% and 92%, respectively, were obtained, in strong correlation with the iron content of the catalyst. Iron content measured in solution at the end of the reaction, indicated that its amount was less than 2 ppm for all tested catalysts. Full article
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10 pages, 8204 KiB  
Article
Few-Layer Graphene from Mechanical Exfoliation of Graphite-Based Materials: Structure-Dependent Characteristics
by Azhar A. Pirzado, François Le Normand, Thierry Romero, Sandra Paszkiewicz, Vasiliki Papaefthimiou, Dris Ihiawakrim and Izabela Janowska
ChemEngineering 2019, 3(2), 37; https://doi.org/10.3390/chemengineering3020037 - 7 Apr 2019
Cited by 21 | Viewed by 5708
Abstract
We present a high-scale method to produce few-layer graphene (FLG) based on the mechanical exfoliation of graphite and compare the obtained FLG with the one reported earlier arising from pencil lead ablation. Several elements were modified and improved in the new approach. The [...] Read more.
We present a high-scale method to produce few-layer graphene (FLG) based on the mechanical exfoliation of graphite and compare the obtained FLG with the one reported earlier arising from pencil lead ablation. Several elements were modified and improved in the new approach. The purification and the ablation set-up were simplified, and the morphology of the FLG was modified and improved in view of some applications. The morphology-dependent properties of FLGs, lead-FLG, and graphite-FLG as conductive layers and in nanocomposites were investigated. The newly obtained FLG had a higher aspect ratio (high lateral size vs thickness/higher 2D aspect), which is reflected by enhanced transparency–conductivity features of the layer (film) and elongation-at-break behavior of the polymer composites. On the contrary, the nanocomposite containing lead-FLG showed, for instance, excellent gas barrier properties due to the multi-step structure of the lead-FLG flakes. Such structure exhibited less 2D and more 3D character, which can be highly suitable for applications where the presence of active/reactive edges is beneficial, e.g., in catalysis or supercapacitors’ electrodes. Nuclear reaction analysis was employed to investigate the morphology of graphite-FLG film. Full article
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16 pages, 8140 KiB  
Article
CNT and H2 Production During CH4 Decomposition over Ni/CeZrO2. I. A Mechanistic Study
by Agata Łamacz
ChemEngineering 2019, 3(1), 26; https://doi.org/10.3390/chemengineering3010026 - 7 Mar 2019
Cited by 5 | Viewed by 3639
Abstract
This work presents a new insight into the potential of a Ni/CeZrO2 catalyst in two separate processes: (i) Chemical Vapor Deposition (CVD) using methane as a feedstock to obtain carbon nanotubes (CNTs) and H2, and (ii) catalyst regeneration with H [...] Read more.
This work presents a new insight into the potential of a Ni/CeZrO2 catalyst in two separate processes: (i) Chemical Vapor Deposition (CVD) using methane as a feedstock to obtain carbon nanotubes (CNTs) and H2, and (ii) catalyst regeneration with H2O that yields H2. The direct reaction of methane with H2O (steam methane reforming (SMR)) leads to H2 and CO (and CO2), whereas carbon deposition—regardless of its type—is an unwanted reaction. The concept presented in this work assumes dividing that process into two reactors, which allows one to obtain two valuable products, i.e., CNTs and H2. The literature data on CNT production via CVD ignores the issue of H2 formation. Moreover, there is no data concerning CNT production in fluidized bed reactors over ceria-zirconia supported metal catalysts. The results presented in this work show that CNTs can be formed on Ni/CeZrO2 during CH4 decomposition, and that the catalyst can be easily regenerated with H2O, which is accompanied by a high production of H2. The ability of Ni/CeZrO2 to be regenerated is its main advantage over the Ni-MgO catalyst that is popular for CNT production. This paper also shows that the Ni/CeZrO2 catalyst has the potential to be used for CNT and H2 production in a larger scale process, e.g., in a fluidized bed reactor. Full article
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18 pages, 12756 KiB  
Article
CNT and H2 Production during CH4 Decomposition over Ni/CeZrO2. II. Catalyst Performance and Its Regeneration in a Fluidized Bed
by Agata Łamacz and Grzegorz Łabojko
ChemEngineering 2019, 3(1), 25; https://doi.org/10.3390/chemengineering3010025 - 5 Mar 2019
Cited by 13 | Viewed by 5376
Abstract
In this work, a ceria-zirconia supported nickel catalyst (Ni/CeZrO2) was for the first time used in a fluidized bed reactor in order to obtain carbon nanotubes (CNTs) and H2 in the reaction of the decomposition of CH4. The [...] Read more.
In this work, a ceria-zirconia supported nickel catalyst (Ni/CeZrO2) was for the first time used in a fluidized bed reactor in order to obtain carbon nanotubes (CNTs) and H2 in the reaction of the decomposition of CH4. The same catalyst was afterward regenerated with H2O, which was accompanied with the production of H2. The impact of catalyst granulation, temperature, and gas hourly space velocity (GHSV) on the amount and type of carbon deposits was determined using thermogravimetric analysis (TGA) and scanning and transmission electron microscopy (SEM and TEM). The presence of randomly oriented and curved CNTs with an outer diameter of up to 64 nm was proved. The Ni/CeZrO2 particles were loosely covered with CNTs, freely dispersed over CNTs, and strongly attached to the external CNT walls. TEM proved the presence of a Ni/CeZrO2@CNT hybrid material that can be further used as catalyst, e.g., in WGS or DRM reactions. The impact of GHSV on hydrogen production during catalyst regeneration was determined. The catalyst was subjected to cyclic tests of CH4 decomposition and regeneration. According to the obtained results, Ni/CeZrO2 can be used in CH4 conversion to CNTs and H2 (instead of CH4 combustion), e.g., in the vicinity of installations that require methane utilization. Full article
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16 pages, 3698 KiB  
Article
Activated Carbon, Carbon Nanofibers and Carbon-Covered Alumina as Support for W2C in Stearic Acid Hydrodeoxygenation
by Luana Souza Macedo, Victor Teixeira da Silva and Johannes Hendrik Bitter
ChemEngineering 2019, 3(1), 24; https://doi.org/10.3390/chemengineering3010024 - 5 Mar 2019
Cited by 8 | Viewed by 2991
Abstract
Carbon materials play a crucial role in sorbents and heterogeneous catalysis and are widely used as catalyst support for several reactions. This paper reports on an investigation of tungsten carbide (W2C) catalyst on three types of carbon support, namely activated carbon [...] Read more.
Carbon materials play a crucial role in sorbents and heterogeneous catalysis and are widely used as catalyst support for several reactions. This paper reports on an investigation of tungsten carbide (W2C) catalyst on three types of carbon support, namely activated carbon (AC), carbon nanofibers (CNF) and carbon-covered alumina (CCA). We evaluated their activity and selectivity in stearic acid hydrodeoxygenation at 350 °C and 30 bar H2. Although all three W2C catalysts displayed similar intrinsic catalytic activities, the support did influence product distribution. At low conversions (<5%), W2C/AC yielded the highest amount of oxygenates relative to W2C/CNF and W2C/CCA. This suggests that the conversion of oxygenates into hydrocarbons is more difficult over W2C/AC than over W2C/CNF and W2C/CCA, which we relate to the lower acidity and smaller pore size of W2C/AC. The support also had an influence on the C18-unsaturated/C18-saturated ratio. At conversions below 30%, W2C/CNF presented the highest C18-unsaturated/C18-saturated ratio in product distribution, which we attribute to the higher mesopore volume of CNF. However, at higher conversions (>50%), W2C/CCA presented the highest C18-unsaturated/C18-saturated ratio in product distribution, which appears to be linked to W2C/CCA having the highest ratio of acid/metallic sites. Full article
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