The Design and Development of Precious Metal Catalysts

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

Deadline for manuscript submissions: closed (1 February 2021) | Viewed by 9246

Special Issue Editors


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Guest Editor
School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
Interests: selective hydrogenation; precious metal catalysts; hydrogen peroxide synthesis; selective oxidation; microwave synthesis

Special Issue Information

Dear Colleagues,

In recent decades, a wide range of precious metal catalysts have emerged as key catalytic materials for the production of fine chemicals and liquid/gas fuels. Precious metal catalysts, in the form of supported mono, bimetallic or multimetallic nanoparticles are the most common materials of sustainable and green catalytic processes. A range of supported metal nanoparticles have been evaluated for a range of catalytic applications, where the control of particle size, metal composition, morphology (alloy versus core-shell structure), oxidation state, nature of support, and metal-support interaction are crucial for providing active, selective, and stable catalysts. Finally, the crucial role of reactor design and final chemical processes for controlling activity, selectivity and deactivation phenomena has been demonstrated.

We invite the scientific community to submit their contributions in the form of original research articles and review articles that seek interactions between precious metal catalysts and their catalytic applications on selected topics. We are particularly interested in articles describing:

1) Biomass transformation

2) Hydrogen peroxide synthesis

3) Alcohol oxidation

4) CO2 valorization

5) Deactivation studies using in situ and ex situ spectroscopic techniques

6) Continuous flow processes for selective transformation

7) Computational modeling and simulation of catalytic sustainable processes

Dr. Jennifer K. Edwards
Prof. Nikolaos Dimitratos
Guest Editor

Manuscript Submission Information

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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

  • metal nanoparticles
  • heterogeneous catalysis
  • green chemistry
  • biomass valorization
  • catalytic hydrogenation
  • selective oxidations
  • continuous flow processes

Published Papers (3 papers)

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Research

13 pages, 5504 KiB  
Article
Rh Particles Supported on Sulfated g-C3N4: A Highly Efficient and Recyclable Heterogeneous Catalyst for Alkene Hydroformylation
by Yukun Shi, Yang Lu, Tongxin Ren, Jie Li, Qiqige Hu, Xiaojing Hu, Baolin Zhu and Weiping Huang
Catalysts 2020, 10(11), 1359; https://doi.org/10.3390/catal10111359 - 23 Nov 2020
Cited by 11 | Viewed by 2589
Abstract
The hydroformylation of alkenes with CO and H2 to manufacture aldehydes is one of the most large-scale chemical reactions. However, an efficient and recyclable heterogeneous catalyst for alkene hydroformylation is extremely in demand in academia and industry. In this study, a sulfated [...] Read more.
The hydroformylation of alkenes with CO and H2 to manufacture aldehydes is one of the most large-scale chemical reactions. However, an efficient and recyclable heterogeneous catalyst for alkene hydroformylation is extremely in demand in academia and industry. In this study, a sulfated carbon nitride supported rhodium particle catalyst (Rh/S-g-C3N4) was successfully synthesized via an impregnation-borohydride reduction method and applied in the hydroformylation of alkenes. The catalysts were characterized by XRD, FTIR, SEM, TEM, XPS, and nitrogen adsorption. The influence of the sulfate content, pressure of syngas, temperature, and reaction time, as well as the stability of Rh/S-g-C3N4, on the hydroformylation was examined in detail. The delocalized conjugated structure in g-C3N4 can lead to the formation of electron-deficient aromatic intermediates with alkenes. The sulphate g-C3N4 has a defected surface owing to the formation of oxygen vacancies, which increased the adsorption and dispersion of RhNPs on the surface of g-C3N4. Therefore, Rh/S-g-C3N4 exhibited an outstanding catalytic performance for styrene hydroformylation (TOF = 9000 h−1), the conversion of styrene could reach 99.9%, and the regioselectivity for the branched aldehyde was 52% under the optimized reaction conditions. The catalytic properties of Rh/S-g-C3N4 were also studied in the hydroformylation of various alkenes and displayed an excellent catalytic performance. Furthermore, the reuse of Rh/S-g-C3N4 was tested for five recycling processes, without an obvious decrease in the activity and selectivity under the optimum reaction conditions. These findings demonstrated that Rh/S-g-C3N4 is a potential catalyst for heterogeneous hydroformylation. Full article
(This article belongs to the Special Issue The Design and Development of Precious Metal Catalysts)
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22 pages, 15307 KiB  
Article
Bimetallic Substituted Ceria: An Alternative Approach to Ligand-Free Heck-Mizoroki Cross-Coupling Reactions
by Zanele P. Vundla and Holger B. Friedrich
Catalysts 2020, 10(7), 794; https://doi.org/10.3390/catal10070794 - 16 Jul 2020
Cited by 1 | Viewed by 2329
Abstract
This work describes Ce0.89Zr0.03Pd0.08O2-δ as a heterogeneous catalyst for Heck-Mizoroki reactions. The material was synthesised by urea-assisted solution combustion to give a zirconium-stabilised cerium fluorite structure, with a fraction of palladium incorporated into the host structure. [...] Read more.
This work describes Ce0.89Zr0.03Pd0.08O2-δ as a heterogeneous catalyst for Heck-Mizoroki reactions. The material was synthesised by urea-assisted solution combustion to give a zirconium-stabilised cerium fluorite structure, with a fraction of palladium incorporated into the host structure. Characterisation techniques included ICP-OES, P-XRD and electron microscopy. The catalyst illustrated a high TOF of 1860 h−1 for the cross-coupling of iodobenzene with methyl acrylate, when trimethylamine (TEA) was used as a base and dimethylformamide (DMF) as the solvent at 130 °C. To establish the activity of coupling pairs, screening was limited to aryliodobenzenes, with various electronic properties, to determine the influence of aryliodobenzene electronic density on the trans product yield. Electron-donating substituents showed good yields, while electron-withdrawing groups had lower yields. Furthermore, various classes of electron-deficient olefins were screened to determine any effect on the trans product yield. Electron-deficient olefins showed higher yields with regard to the trans product than neutral styrene. Full article
(This article belongs to the Special Issue The Design and Development of Precious Metal Catalysts)
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25 pages, 9275 KiB  
Article
The Effect of Noble Metal (M: Ir, Pt, Pd) on M/Ce2O3-γ-Al2O3 Catalysts for Hydrogen Production via the Steam Reforming of Glycerol
by Nikolaos D. Charisiou, Georgios I. Siakavelas, Kyriakos N. Papageridis, Davide Motta, Nikolaos Dimitratos, Victor Sebastian, Kyriaki Polychronopoulou and Maria A. Goula
Catalysts 2020, 10(7), 790; https://doi.org/10.3390/catal10070790 - 15 Jul 2020
Cited by 18 | Viewed by 3510
Abstract
A promising route for the energetic valorisation of the main by-product of the biodiesel industry is the steam reforming of glycerol, as it can theoretically produce seven moles of H2 for every mole of C3H8O3. In [...] Read more.
A promising route for the energetic valorisation of the main by-product of the biodiesel industry is the steam reforming of glycerol, as it can theoretically produce seven moles of H2 for every mole of C3H8O3. In the work presented herein, CeO2–Al2O3 was used as supporting material for Ir, Pd and Pt catalysts, which were prepared using the incipient wetness impregnation technique and characterized by employing N2 adsorption–desorption, X-Ray Diffraction (XRD), Temperature Programmed Reduction (TPR), Temperature Programmed Desorption (TPD), X-ray Photoelectron Spectroscopy (XPS) and Transmission Electron Microscopy (TEM). The catalytic experiments aimed at identifying the effect of temperature on the total conversion of glycerol, on the conversion of glycerol to gaseous products, the selectivity towards the gaseous products (H2, CO2, CO, CH4) and the determination of the H2/CO and CO/CO2 molar ratios. The main liquid effluents produced during the reaction were quantified. The results revealed that the Pt/CeAl catalyst was more selective towards H2, which can be related to its increased number of Brønsted acid sites, which improved the hydrogenolysis and dehydrogenation–dehydration of condensable intermediates. The time-on-stream experiments, undertaken at low Water Glycerol Feed Ratios (WGFR), showed gradual deactivation for all catalysts. This is likely due to the dehydration reaction, which leads to the formation of unsaturated hydrocarbon species and eventually to carbon deposition. The weak metal–support interaction shown for the Ir/CeAl catalyst also led to pronounced sintering of the metallic particles. Full article
(This article belongs to the Special Issue The Design and Development of Precious Metal Catalysts)
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