Special Issue "Catalysis by Precious Metals, Past and Future"

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

Deadline for manuscript submissions: 31 July 2019

Special Issue Editors

Guest Editor
Dr. Marcela Martinez Tejada

Departamento de Química Inorgánica - Instituto de Ciencia de Materiales de Sevilla. Universidad de Sevilla - CSIC, Spain
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Interests: heterogeneous catalysis, catalysis by noble metals, catalysis by transition metals, structured reactors, H2 production and clean-up, steam reforming, Water Gas Shift reaction, CO oxidation, CO preferential oxidation, CO and CO2 methanation, CO2 capture, operando spectroscopies
Guest Editor
Dr. Svetlana Ivanova

Departamento de Química Inorgánica - Instituto de Ciencia de Materiales de Sevilla. Universidad de Sevilla - CSIC, Spain
Website | E-Mail
Interests: heterogeneous catalysis, gas and liquid phase gold catalysis, H2 production and clean-up, Water Gas Shift reaction, biorefinery

Special Issue Information

Dear Colleagues,

“Shiny, malleable, and resistant to corrosion”—that is the first obvious definition of precious metals, to which expensive and scarce can be added. Their use in jewellery, trade, and arts has led to a new era in which metal catalytic potential has been discovered, and, nowadays, precious metals are key players in the chemical industry. Platinum, alone or in combination with rhodium, was the first precious metal to participate catalytically in the sulfuric and nitric acid production processes. Gold, in return, has entered the group of catalytically active metals in the last few decades. The use of all those metals, in their bulk form, was successively limited due to their high cost and the highly dispersed and supported metal nanoparticles that appeared on the scene. The use of supports improves the dispersion of the precious metals, thus reducing their quantity and decreasing the cost of the final catalyst and also preventing metal sintering, loss of catalytically active sites, and deactivation. Both support and precious metals cooperate in the formation of an efficient catalytic machine. The precious metal-support interaction depends on many factors, like precious metal contents, the nature of support and metal, employed preparation methods, and also metal nanoparticles morphology. The addition of small amounts of noble metals into the formulation of other transition metals catalysts and the use of bimetallic noble metal catalysts are also quite attractive, since they can enhance the precious metal-support interaction. Thus, the diversity of supported precious metal catalysts is reflected in their versatility and enlarges their current and future horizons.

This Special Issue will reveal the importance of precious metals catalysis and will be focused on mono- and bi-metallic formulations, on any supported catalysts, and on the promoted catalytic effect of others transition metals catalysts using the precious metal effect. The application of precious metals in diverse reactions of interest, either homogeneous or heterogeneous, and complete studies of the preparation, characterization, and structuring of the supported precious metal catalysts, are welcomed, as well as operando and/or kinetics studies of mechanisms and catalytic performance.

Prof. Marcela Martinez Tejada
Prof. Svetlana Ivanova
Guest Editors

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 papers will be 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 1600 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 catalysis
  • homogeneous catalysis
  • precious metals catalysis
  • monometallic catalysts
  • bimetallic catalysts
  • gold catalysts
  • palladium catalysts
  • platinum catalysts
  • ruthenium catalysts
  • rhodium catalysts
  • silver catalysts
  • iridium catalysts
  • microchannel reactors
  • kinetic studies
  • in situ and operando studies
  • catalysts characterization

Published Papers (5 papers)

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Research

Open AccessArticle Immobilization of Stabilized Gold Nanoparticles on Various Ceria-Based Oxides: Influence of the Protecting Agent on the Glucose Oxidation Reaction
Catalysts 2019, 9(2), 125; https://doi.org/10.3390/catal9020125
Received: 31 December 2018 / Revised: 16 January 2019 / Accepted: 17 January 2019 / Published: 31 January 2019
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Abstract
The influence of the protecting agent’s nature on gold particle size and dispersion was studied in this work over a series of gold-based catalysts. CO and glucose oxidation were chosen as catalytic reactions to determine the catalyst’s structure–activity relationship. The nature of the [...] Read more.
The influence of the protecting agent’s nature on gold particle size and dispersion was studied in this work over a series of gold-based catalysts. CO and glucose oxidation were chosen as catalytic reactions to determine the catalyst’s structure–activity relationship. The nature of the support appeared to be the predominant factor for the increase in activity, as the oxygen mobility was decisive for the CO oxidation in the same way that the Lewis acidity was decisive for the glucose oxidation. For the same catalyst composition, the use of montmorillonite as the stabilizing agent resulted in better catalytic performance. Full article
(This article belongs to the Special Issue Catalysis by Precious Metals, Past and Future)
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Open AccessArticle Properties of Carbon-supported Precious Metals Catalysts under Reductive Treatment and Their Influence in the Hydrodechlorination of Dichloromethane
Catalysts 2018, 8(12), 664; https://doi.org/10.3390/catal8120664
Received: 27 November 2018 / Revised: 13 December 2018 / Accepted: 14 December 2018 / Published: 18 December 2018
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Abstract
This study analyzes the effect of the reduction temperature on the properties of Rh, Pt and Pd catalysts supported on activated carbon and their performance in the hydrodechlorination (HDC) of dichloromethane (DCM). The reduction temperature plays an important role in the oxidation state, [...] Read more.
This study analyzes the effect of the reduction temperature on the properties of Rh, Pt and Pd catalysts supported on activated carbon and their performance in the hydrodechlorination (HDC) of dichloromethane (DCM). The reduction temperature plays an important role in the oxidation state, size and dispersion of the metallic phase. Pd is more prone to sintering, followed by Pt, while Rh is more resistant. The ratio of zero-valent to electro-deficient metal increases with the reduction temperature, with that effect being more remarkable for Pd and Pt. The higher resistance to sintering of Rh and the higher stability of electro-deficient species under thermal reductive treatment can be attributed to a stronger interaction with surface oxygen functionalities. Dechlorination activity and a TOF increase with reduction temperature (250–450 °C) occurred in the case of Pt/C catalyst, while a great decrease of both was observed for Pd/C, and no significant effect was found for Rh/C. Pt0 represents the main active species for HDC reaction in Pt/C. Therefore, increasing the relative amount of these species increased the TOF value, compensating for the loss of dispersion. In contrast, Pdn+ appears as the main active species in Pd/C and their relatively decreasing occurrence together with the significant decrease of metallic area reduces the HDC activity. Rh/C catalyst suffered only small changes in dispersion and metal oxidation state with the reduction temperature and thus this variable barely affected its HDC activity. Full article
(This article belongs to the Special Issue Catalysis by Precious Metals, Past and Future)
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Open AccessArticle Palladium Supported on Carbon Nanotubes as a High-Performance Catalyst for the Dehydrogenation of Dodecahydro-N-ethylcarbazole
Catalysts 2018, 8(12), 638; https://doi.org/10.3390/catal8120638
Received: 20 November 2018 / Revised: 4 December 2018 / Accepted: 6 December 2018 / Published: 8 December 2018
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Abstract
Hydrogen storage in the form of liquid organic hydrides, especially N-ethylcarbazole, has been regarded as a promising technology for substituting traditional fossil fuels owing to its unique merits such as high volumetric, gravimetric hydrogen capacity and safe transportation. However, unsatisfactory dehydrogenation has impeded [...] Read more.
Hydrogen storage in the form of liquid organic hydrides, especially N-ethylcarbazole, has been regarded as a promising technology for substituting traditional fossil fuels owing to its unique merits such as high volumetric, gravimetric hydrogen capacity and safe transportation. However, unsatisfactory dehydrogenation has impeded the widespread application of N-ethylcarbazole as ideal hydrogen storage materials in hydrogen energy. Therefore, designing catalysts with outstanding performance is of importance to address this problem. In the present work, for the first time, we have synthesized Pd nanoparticles immobilized on carbon nanotubes (Pd/CNTs) with different palladium loading through an alcohol reduction technique. A series of characterization technologies, such as X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), X-ray photoelectron spectroscopy (XPS) and transmission electron spectroscopy (TEM) were adopted to systematically explore the structure, composition, surface properties and morphology of the catalysts. The results reveal that the Pd NPs with a mean diameter of 2.6 ± 0.6 nm could be dispersed uniformly on the surface of CNTs. Furthermore, Pd/CNTs with different Pd contents were applied in the hydrogen release of dodecahydro-N-ethylcarbazole. Among all of the catalysts tested, 3.0 wt% Pd/CNTs exhibited excellent catalytic performance with the conversion of 99.6% producing 5.8 wt% hydrogen at 533 K, low activation energy of 43.8 ± 0.2 kJ/mol and a high recycling stability (>96.4% conversion at 5th reuse). Full article
(This article belongs to the Special Issue Catalysis by Precious Metals, Past and Future)
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Graphical abstract

Open AccessArticle Toward the Sustainable Synthesis of Propanols from Renewable Glycerol over MoO3-Al2O3 Supported Palladium Catalysts
Catalysts 2018, 8(9), 385; https://doi.org/10.3390/catal8090385
Received: 17 August 2018 / Revised: 6 September 2018 / Accepted: 6 September 2018 / Published: 9 September 2018
Cited by 1 | PDF Full-text (7093 KB) | HTML Full-text | XML Full-text
Abstract
The catalytic conversion of glycerol to value-added propanols is a promising synthetic route that holds the potential to overcome the glycerol oversupply from the biodiesel industry. In this study, selective hydrogenolysis of 10 wt% aqueous bio-glycerol to 1-propanol and 2-propanol was performed in [...] Read more.
The catalytic conversion of glycerol to value-added propanols is a promising synthetic route that holds the potential to overcome the glycerol oversupply from the biodiesel industry. In this study, selective hydrogenolysis of 10 wt% aqueous bio-glycerol to 1-propanol and 2-propanol was performed in the vapor phase, fixed-bed reactor by using environmentally friendly bifunctional Pd/MoO3-Al2O3 catalysts prepared by wetness impregnation method. The physicochemical properties of these catalysts were derived from various techniques such as X-ray diffraction, NH3-temperature programmed desorption, scanning electron microscopy, 27Al NMR spectroscopy, surface area analysis, and thermogravimetric analysis. The catalytic activity results depicted that a high catalytic activity (>80%) with very high selectivity (>90%) to 1-propanol and 2-propanol was obtained over all the catalysts evaluated in a continuously fed, fixed-bed reactor. However, among all others, 2 wt% Pd/MoO3-Al2O3 catalyst was the most active and selective to propanols. The synergic interaction between the palladium and MoO3 on Al2O3 support and high strength weak to moderate acid sites of the catalyst were solely responsible for the high catalytic activity. The maximum glycerol conversion of 88.4% with 91.3% selectivity to propanols was achieved at an optimum reaction condition of 210 C and 1 bar pressure after 3 h of glycerol hydrogenolysis reaction. Full article
(This article belongs to the Special Issue Catalysis by Precious Metals, Past and Future)
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Open AccessArticle Effect of Microwave Drying, Calcination and Aging of Pt/Al2O3 on Platinum Dispersion
Catalysts 2018, 8(9), 348; https://doi.org/10.3390/catal8090348
Received: 11 August 2018 / Revised: 22 August 2018 / Accepted: 24 August 2018 / Published: 26 August 2018
PDF Full-text (1215 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
The effect of heating method employed for drying and calcination during the synthesis of 1 wt% Pt/Al2O3 catalyst was investigated. Conventional heating (CH) in resistive oven and microwave heating (MW) in single mode were applied, and the Pt dispersion and [...] Read more.
The effect of heating method employed for drying and calcination during the synthesis of 1 wt% Pt/Al2O3 catalyst was investigated. Conventional heating (CH) in resistive oven and microwave heating (MW) in single mode were applied, and the Pt dispersion and Brunauer-Emmett-Teller (BET) surface area were measured to characterize the samples. It was evidenced that the fast and homogeneous heating offered by the microwave heating led to higher Pt dispersion. However, this benefit was only achieved when the subsequent calcination was performed in a conventional oven. The aging in microwave oven of conventionally prepared—as well as MW-prepared—catalysts demonstrated the great ability of microwave irradiation to accelerate platinum sintering. After 1 h at 800 °C under microwave, catalysts showed a dispersion of 5%. Therefore, microwave treatment should be considered for accelerated catalyst aging but should be avoided as a calcination technique for the synthesis of highly dispersed Pt/Al2O3. Full article
(This article belongs to the Special Issue Catalysis by Precious Metals, Past and Future)
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Graphical abstract

Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: Old Catalysts Can Do New Tricks:  Cross-coupling Reactions with Palladium Amino Acid Complexes
Authors: David B. Hobart 1 and Joseph S. Merola1,*
Affiliation: 1   Department of Chemistry, Virginia Tech; VA, USA
Abstract: Palladium complexes with an enormous variety of ligands have been studied for an enormous variety of catalytic reactions.  This paper will detail the synthesis and structure of a wide series of bis-beta-amino acid complexes of palladium.  The single crystal x-ray structures show interesting variations of hydrogen-bonding motifs with and without inclusion of water in the crystal lattices. All complexes were examined for the cross-coupling reaction of phenylboronic acid with methyl tiglate with a detailed study of the bis-proline palladium complex.  This catalyst showed some asymmetric induction in the product andbut, more importantly, showed multiple phenyl additions to the tiglic acid backbone.
Keywords: palladium; beta-amino acids; phenylboronic acid; tiglic acid; cross-coupling; catalysis; x-ray structures; hydrogen-bonding

Type: Article
Title: Old Catalysts Can Do New Tricks: Cross-coupling Reactions with Palladium Amino Acid Complexes
Authors: David B. Hobart 1 and Joseph S. Merola1,*
Affiliation: 1 Department of Chemistry, Virginia Tech; VA, USA.
Abstract: Palladium complexes with an enormous variety of ligands have been studied for an enormous variety of catalytic reactions. This paper will detail the synthesis and structure of a wide series of bis-beta-amino acid complexes of palladium. The single crystal x-ray structures show interesting variations of hydrogen-bonding motifs with and without inclusion of water in the crystal lattices. All complexes were examined for the cross-coupling reaction of phenylboronic acid with methyl tiglate with a detailed study of the bis-proline palladium complex. This catalyst showed some asymmetric induction in the product andbut, more importantly, showed multiple phenyl additions to the tiglic acid backbone.
Keywords: palladium; beta-amino acids; phenylboronic acid; tiglic acid; cross-coupling; catalysis; x-ray structures; hydrogen-bonding

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