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Catalysts
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Active Sites in Heterogeneous Catalysis
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Active Sites in Heterogeneous Catalysis

A special issue of Catalysts (ISSN 2073-4344).

Deadline for manuscript submissions: closed (15 February 2021) | Viewed by 13818

Special Issue Editor

Dr. Stephane Loridant

E-Mail Website
Guest Editor
Institut de Recherches sur la Catalyse et l’Environnement de Lyon, IRCELYON, CNRS-Université Claude Bernard Lyon 1, 2 Av. Einstein, CEDEX, F-69626 Villeurbanne, France
Interests: oxides catalysts; selective oxidation catalysis; acid-base catalysis; alkanes and biosourced molecules; C1 chemistry; in situ/operando Raman and IR spectroscopies

Special Issue Information

Dear Colleagues,

Knowledge of the structure and composition of active sites is crucial to understand heterogeneous catalysts and design more efficient ones. This is particularly true since the scarcity of some elements such as noble elements widely used in energy and environment fields will require doing better with less. As suggested by Taylor in 1925, active sites are considered as atoms or ensembles of atoms sparse on the surface which directly catalyze a reaction. Active sites change in a dynamic way during adsorption of reactants or reaction intermediates, and this dynamic restructuring plays an important role in bond activation. Detailed description of active sites using advanced in situ/operando techniques with high temporal and spatial resolutions as well as DFT modeling allow establishing structure–activity relationships. They are particularly interesting for single atoms and subnanometric clusters, which can be distinguished by the atomically resolved microscopes. The investigation of their catalytic properties compared to nanosized particles is crucial to determine if their presence has to be favored or avoided. Furthermore, the interface between such sites and support also deserves investigation, considering their limited size (few atoms) and since they play a key role in their structural and electronic properties, leading to important support effects. Stability and regeneration of active sites are also important topics since, for instance, they can be poisoned with relatively few molecules present in a complex feed. Finally, the design of multifunctional catalysts has led the catalysis community to investigate the role of nanoscale intimacy as well as other effects at atomic and long-range scales.

In this context, I am inviting you to submit your recent achievements to this Special Issue on “Active Sites in Heterogeneous Catalysis” in the form of original research articles or short reviews. Heterogeneous catalysis includes photo- and electrocatalysis and covers all application fields.

 

Dr. Stephane Loridant
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

  • Heterogeneous catalyst
  • Active sites
  • In situ and operando techniques
  • Structure-activity relationships
  • DFT modeling
  • Single atoms
  • Subnanometric clusters
  • Nanoparticles
  • Structural dynamics
  • Multifunctionality
  • Nanoscale intimacy
  • Support effects
  • Short- and long-range effects

Published Papers (4 papers)

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Research

11 pages, 2212 KiB  
Article
Insights into Interface Charge Extraction in a Noble-Metal-Free Doped Z-Scheme NiO@BiOCl Heterojunction
by Jun Yang, Quanxi Zhu, Taiping Xie, Jiankang Wang, Yuan Peng, Yajing Wang, Chenglun Liu and Longjun Xu
Catalysts 2020, 10(9), 958; https://doi.org/10.3390/catal10090958 - 21 Aug 2020
Cited by 5 | Viewed by 2191
Abstract
It is of great significance to thoroughly explore the interface charge extraction and migration in heterojunction systems, which could guide us to synthesize higher-efficiency photocatalytic materials. A novel noble-metal-free doped Z-scheme NiO@BiOCl heterojunction was found in this work. The corresponding heterostructure, interface electron [...] Read more.
It is of great significance to thoroughly explore the interface charge extraction and migration in heterojunction systems, which could guide us to synthesize higher-efficiency photocatalytic materials. A novel noble-metal-free doped Z-scheme NiO@BiOCl heterojunction was found in this work. The corresponding heterostructure, interface electron extraction, and electron migration were investigated via first-principles calculation. 5,5′-dimethyl-1-pyrroline-N-oxide (DMPO) spin-trapping electron spin resonance (ESR) and time-resolved photoluminescence (TRPL) tests were implemented to confirm the calculation results, which showed that electrons and holes stayed in the NiO (100) facet and BiOCl (110) facet, respectively. Owing to the large chemical potential of 2.40 V (vs ENHE) for the BiOCl valence-band hole, it possessed super activity to oxidize water into hydroxyl radicals or molecular oxygen. We hope this promising multifunctional photocatalytic material, therefore, NiO@BiOCl can be applied in advanced treatment of organic wastewater and oxygen production from photolysis water. Full article
(This article belongs to the Special Issue Active Sites in Heterogeneous Catalysis)
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9 pages, 1383 KiB  
Article
Determination of Extinction Coefficients for Describing Gas Adsorption on Heterogeneous Catalysts Using In-Situ DRIFT Spectroscopy
by Maja Glorius, Tobias Reich and Cornelia Breitkopf
Catalysts 2020, 10(7), 735; https://doi.org/10.3390/catal10070735 - 2 Jul 2020
Cited by 1 | Viewed by 3080
Abstract
Diffuse reflection infrared Fourier transform (DRIFT) spectra have been quantitatively evaluated to determine unknown extinction coefficients as well as the number of active surface centers and the amount of adsorbed species. Sulfated zirconia with n-butane as probe gas was used as model [...] Read more.
Diffuse reflection infrared Fourier transform (DRIFT) spectra have been quantitatively evaluated to determine unknown extinction coefficients as well as the number of active surface centers and the amount of adsorbed species. Sulfated zirconia with n-butane as probe gas was used as model system. For quantitative evaluation of n-butane adsorption at 323 K, the sulfate band S=O at 1400 cm−1 was chosen. During adsorption, this band is red-shifted to lower wavenumbers accompanied by a structural change of the band indicating isomerization reaction. By analyzing difference spectra and determining the areas of the selected band, the extinction coefficients as well as the number of active centers and the amount of chemisorbed n-butane were calculated. The quantitative evaluation results in a mean internal decadic extinction coefficient of 60 cm−1 µmol−1, an average amount of n-butane adsorbed to the sulfated zirconia of about 4 μmol, and a number of active centers of around 21 μmol/g. These results correspond very well with values from the literature obtained by microcalorimetry. Thus, this method is suggested to be transferred also to unknown systems of interest. Full article
(This article belongs to the Special Issue Active Sites in Heterogeneous Catalysis)
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14 pages, 1709 KiB  
Article
Ag- and Cu-Promoted Mesoporous Ta-SiO2 Catalysts Prepared by Non-Hydrolytic Sol-Gel for the Conversion of Ethanol to Butadiene
by Denis D. Dochain, Aleš Stýskalík and Damien P. Debecker
Catalysts 2019, 9(11), 920; https://doi.org/10.3390/catal9110920 - 5 Nov 2019
Cited by 13 | Viewed by 4269
Abstract
The direct catalytic conversion of bioethanol to butadiene, also known as the Lebedev process, is one of the most promising solution to replace the petro-based production of this important bulk chemical. Considering the intricate reaction mechanism—where a combination of acid-catalyzed dehydration reactions and [...] Read more.
The direct catalytic conversion of bioethanol to butadiene, also known as the Lebedev process, is one of the most promising solution to replace the petro-based production of this important bulk chemical. Considering the intricate reaction mechanism—where a combination of acid-catalyzed dehydration reactions and metal-catalyzed dehydrogenation have to take place simultaneously—tailor-made bifunctional catalysts are required. We propose to use non-hydrolytic sol-gel (NHSG) chemistry to prepare mesoporous Ta-SiO2 materials which are further promoted by Ag via impregnation. An acetamide elimination route is presented, starting from silicon tetraacetate and pentakis(dimethylamido)tantalum(V), in the presence of a Pluronic surfactant. The catalysts display advantageous texture, with specific surface area in the 600–1000 m² g−1 range, large pore volume (0.6–1.0 mL g−1), an average pore diameter of 4 nm and only a small contribution from micropores. Using an array of characterization techniques, we show that NHSG allows achieving a high degree of dispersion of tantalum, mainly incorporated as single sites in the silica matrix. The presence of these monomeric TaOx active sites is responsible for the much higher dehydration ability, as compared to the corresponding catalyst prepared by impregnation of Ta onto a pristine silica support. We attempt to optimize the butadiene yield by changing the relative proportion of Ta and Ag and by tuning the space velocity. We also demonstrate that Ag or Cu can be introduced directly in one step, during the NHSG process. Copper doping is shown to be much more efficient than silver doping to guide the reaction towards the production of butadiene. Full article
(This article belongs to the Special Issue Active Sites in Heterogeneous Catalysis)
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12 pages, 3127 KiB  
Article
A DFT Study of Acetylene Hydrogenation Catalyzed by S-Doped Pd1/g-C3N4
by Lihua Kang, Mingyuan Zhu and Yu Zhao
Catalysts 2019, 9(11), 887; https://doi.org/10.3390/catal9110887 - 25 Oct 2019
Cited by 8 | Viewed by 3597
Abstract
To exploit the excellent properties of g-C3N4, more and more studies have been carried out in various fields in recent years to improve the selectivity of catalysts, especially for selective acetylene hydrogenation. To our best knowledge, Pd catalyst is [...] Read more.
To exploit the excellent properties of g-C3N4, more and more studies have been carried out in various fields in recent years to improve the selectivity of catalysts, especially for selective acetylene hydrogenation. To our best knowledge, Pd catalyst is of great importance to hydrogenate acetylene in ethylene feed. Though we have explored the hydrogenation of acetylene catalyzed by Pd1/g-C3N4 before, doping with non-metals has never been studied. In this work, the mechanisms of selective hydrogenation of acetylene to ethylene on S-doped Pd1/g-C3N4 were investigated and we also compared this result with undoped Pd1/g-C3N4. By comparing the activation energy and selectivity of undoped Pd1/g-C3N4 with those of S-doped C and N sites of Pd1/g-C3N4, we found that S-doped C sites can improve the reactivity, but with a poor selectivity, while the activity of S atom doped N sites was not improved, but the selectivity has improved. Our work provides significant insights to explore the development of high efficiency non-metallic doping single metal atoms supported on 2D layered materials. Full article
(This article belongs to the Special Issue Active Sites in Heterogeneous Catalysis)
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