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2 pages, 132 KiB

Open AccessEditorial

Engineering Materials for Catalysis

by Albin Pintar, Nataša Novak Tušar and Günther Rupprechter

Catalysts 2024, 14(5), 293; https://doi.org/10.3390/catal14050293 - 27 Apr 2024

Viewed by 1323

Abstract

The Special Issue “Engineering Materials for Catalysis” was inspired by the preceding 2020 Summer School of the European Federation of Catalysis Societies (EFCATS, https://skd2020 [...] Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

Research

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16 pages, 4803 KiB

Open AccessFeature PaperArticle

Studies of Clinoptilolite-Rich Zeolitic Tuffs from Different Regions and Their Activity in Photodegradation of Methylene Blue

by Jelena Pavlović, Andraž Šuligoj, Mojca Opresnik, Nataša Novak Tušar, Nataša Zabukovec Logar and Nevenka Rajić

Catalysts 2022, 12(2), 224; https://doi.org/10.3390/catal12020224 - 16 Feb 2022

Cited by 9 | Viewed by 2487

Abstract

The present study focuses on clinoptilolite (CLI)-rich natural zeolitic tuffs and their photocatalytic activity in the degradation of cationic organic dyes. CLI from different regions was tested in the photocatalytic degradation of methylene blue (MB) as a model cationic dye. The photocatalytic tests [...] Read more.

The present study focuses on clinoptilolite (CLI)-rich natural zeolitic tuffs and their photocatalytic activity in the degradation of cationic organic dyes. CLI from different regions was tested in the photocatalytic degradation of methylene blue (MB) as a model cationic dye. The photocatalytic tests were performed at room temperature and atmospheric pressure under visible light irradiation. For all the CLI samples, the highest activity was observed at pH = 6. Total MB degradation varied between 70 and 91% (C₀ = 10 mg dm^–3, 0.2 g dm^–3 of photocatalyst, during 300 min). It is suggested that the presence of Fe species in the studied tuffs is responsible for the photocatalytic activity. The activity increases linearly with the Fe content in the tuffs. The MB photodegradation follows the Langmuir–Hinshelwood kinetic model. The recyclability tests showed good stability and efficiency of the photocatalyst. The degradation rate decreased from 91 to 69% during three reaction cycles, indicating a promising potential of natural zeolites in the treatment of textile industry wastewater. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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15 pages, 2670 KiB

Open AccessFeature PaperArticle

Defective Grey TiO₂ with Minuscule Anatase–Rutile Heterophase Junctions for Hydroxyl Radicals Formation in a Visible Light-Triggered Photocatalysis

by Sanjay Gopal Ullattil, Janez Zavašnik, Ksenija Maver, Matjaž Finšgar, Nataša Novak Tušar and Albin Pintar

Catalysts 2021, 11(12), 1500; https://doi.org/10.3390/catal11121500 - 10 Dec 2021

Cited by 3 | Viewed by 2774

Abstract

The novelty of this work was to prepare a series of defect-rich colored TiO₂ nanostructures, using a peroxo solvothermal-assisted, high-pressure nitrogenation method. Among these solids, certain TiO₂ materials possessed a trace quantity of anatase–rutile heterojunctions, which are beneficial in obtaining high [...] Read more.

The novelty of this work was to prepare a series of defect-rich colored TiO₂ nanostructures, using a peroxo solvothermal-assisted, high-pressure nitrogenation method. Among these solids, certain TiO₂ materials possessed a trace quantity of anatase–rutile heterojunctions, which are beneficial in obtaining high reaction rates in photocatalytic reactions. In addition, high surface area (above 100 m²/g), even when utilizing a high calcination temperature (500 °C), and absorption of light at higher wavelengths, due to the grey color of the synthesized titania, were observed as an added advantage for photocatalytic hydroxyl radical formation. In this work, we adopted a photoluminescent probe method to monitor the temporal evolution of hydroxyl radicals. As a result, promising hydroxyl radical formations were observed for all the colored samples synthesized at 400 and 500 °C, irrespective of the duration of calcination. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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17 pages, 23266 KiB

Open AccessArticle

Elucidating the Influence of the d-Band Center on the Synthesis of Isobutanol

by Johannes Häusler, Joachim Pasel, Friederike Woltmann, Andreas Everwand, Maria Meledina, Helen Valencia, Marta Lipińska-Chwałek, Joachim Mayer and Ralf Peters

Catalysts 2021, 11(3), 406; https://doi.org/10.3390/catal11030406 - 23 Mar 2021

Cited by 3 | Viewed by 3832

Abstract

As the search for carbon-efficient synthesis pathways for green alternatives to fossil fuels continues, an expanding class of catalysts have been developed for the upgrading of lower alcohols. Understanding of the acid base functionalities has greatly influenced the search for new materials, but [...] Read more.

As the search for carbon-efficient synthesis pathways for green alternatives to fossil fuels continues, an expanding class of catalysts have been developed for the upgrading of lower alcohols. Understanding of the acid base functionalities has greatly influenced the search for new materials, but the influence of the metal used in catalysts cannot be explained in a broader sense. We address this herein and correlate our findings with the most fundamental understanding of chemistry to date by applying it to d-band theory as part of an experimental investigation. The commercial catalysts of Pt, Rh, Ru, Cu, Pd, and Ir on carbon as a support have been characterized by means of SEM, EDX-mapping, STEM, XRD, N₂-physisorption, and H₂-chemisorption. Their catalytic activity has been established by means of c-methylation of ethanol with methanol. For all catalysts, the TOF with respect to i-butanol was examined. The Pt/C reached the highest TOF with a selectivity towards i-butanol of 89%. The trend for the TOFs could be well correlated with the d-band centers of the metal, which formed a volcano curve. Therefore, this study is another step towards the rationalization of catalyst design for the upgrading of alcohols into carbon-neutral fuels or chemical feedstock. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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23 pages, 5609 KiB

Open AccessArticle

Infrared Thermography as an Operando Tool for the Analysis of Catalytic Processes: How to Use it?

by Robin Mutschler and Emanuele Moioli

Catalysts 2021, 11(3), 311; https://doi.org/10.3390/catal11030311 - 26 Feb 2021

Viewed by 2656

Abstract

Infrared (IR) thermography is a powerful tool to measure temperature with high space and time resolution. A particularly interesting application of this technology is in the field of catalysis, where the method can provide new insights into dynamic surface reactions. This paper presents [...] Read more.

Infrared (IR) thermography is a powerful tool to measure temperature with high space and time resolution. A particularly interesting application of this technology is in the field of catalysis, where the method can provide new insights into dynamic surface reactions. This paper presents guidelines for the development of a reactor cell that can aid in the efficient exploitation of infrared thermography for the investigation of catalytic and other surface reactions. Firstly, the necessary properties of the catalytic reactor are described. Secondly, we analyze the requirements towards the catalytic system to be directly observable by IR thermography. This includes the need for a catalyst that provides a sufficiently high heat production (or absorption) rate. To achieve true operando investigation conditions, some dedicated equipment must be developed. Here, we provide the guidelines to assemble a chemical reactor with an IR transmitting window through which the reaction can be studied with the infrared camera along with other best practice tips to achieve results. Furthermore, we present selected examples of catalytic reactions that can be monitored by IR thermography, showing the potential of the technology in revealing transient and steady state chemical phenomena. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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26 pages, 9578 KiB

Open AccessFeature PaperArticle

Influence of Alumina Precursor Properties on Cu-Fe Alumina Supported Catalysts for Total Toluene Oxidation as a Model Volatile Organic Air Pollutant

by Tadej Žumbar, Alenka Ristić, Goran Dražić, Hristina Lazarova, Janez Volavšek, Albin Pintar, Nataša Zabukovec Logar and Nataša Novak Tušar

Catalysts 2021, 11(2), 252; https://doi.org/10.3390/catal11020252 - 13 Feb 2021

Cited by 12 | Viewed by 3564

Abstract

The structure–property relationship of catalytic supports for the deposition of redox-active transition metals is of great importance for improving the catalytic efficiency and reusability of the catalysts. In this work, the role of alumina support precursors of Cu-Fe/Al₂O₃ catalysts used [...] Read more.

The structure–property relationship of catalytic supports for the deposition of redox-active transition metals is of great importance for improving the catalytic efficiency and reusability of the catalysts. In this work, the role of alumina support precursors of Cu-Fe/Al₂O₃ catalysts used for the total oxidation of toluene as a model volatile organic air pollutant is elucidated. Surface characterization of the catalysts revealed that the surface area, pore volume and acid site concentration of the alumina supports are important but not the determining factors for the catalytic activity of the studied catalysts for this type of reaction. The determining factors are the structural order of the support precursor, the homogeneous distribution of the catalytic sites and reducibility, which were elucidated by XRD, NMR, TEM and temperature programed reduction (TPR). Cu–Fe/Al₂O₃ prepared from bayerite and pseudoboehmite as highly ordered precursors showed better catalytic performance compared to Cu-Fe/Al₂O₃ derived from the amorphous alumina precursor and dawsonite. Homogeneous distribution of Fe_xO_y and CuO_x with defined Cu/Fe molar ratio on the Al₂O₃ support is required for the efficient catalytic performance of the material. The study showed a beneficial effect of low iron concentration introduced into the alumina precursor during the alumina support synthesis procedure, which resulted in a homogeneous metal oxide distribution on the support. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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18 pages, 5172 KiB

Open AccessArticle

The Effect of Shape-Controlled Pt and Pd Nanoparticles on Selective Catalytic Hydrodechlorination of Trichloroethylene

by Oğuz Yunus Sarıbıyık, Christian Weilach, Selahattin Serin and Günther Rupprechter

Catalysts 2020, 10(11), 1314; https://doi.org/10.3390/catal10111314 - 13 Nov 2020

Cited by 12 | Viewed by 7465

Abstract

Tailoring the shape of nanoscale materials enables obtaining morphology-controlled surfaces exhibiting specific interactions with reactants during catalytic reactions. The specifics of nanoparticle surfaces control the catalytic performance, i.e., activity and selectivity. In this study, shape-controlled Platinum (Pt) and Palladium (Pd) nanoparticles with distinct [...] Read more.

Tailoring the shape of nanoscale materials enables obtaining morphology-controlled surfaces exhibiting specific interactions with reactants during catalytic reactions. The specifics of nanoparticle surfaces control the catalytic performance, i.e., activity and selectivity. In this study, shape-controlled Platinum (Pt) and Palladium (Pd) nanoparticles with distinct morphology were produced, i.e., cubes and cuboctahedra for Pt and spheres and polyhedra/multiple-twins for Pd, with (100), (111 + 100), curved/stepped and (111) facets, respectively. These particles with well-tuned surfaces were subsequently deposited on a Zirconium oxide (ZrO₂) support. The morphological characteristics of the particles were determined by high resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD), while their adsorption properties were investigated by Fourier transform infrared spectroscopy (FTIR) of CO adsorbed at room temperature. The effect of the nanoparticle shape and surface structure on the catalytic performance in hydrodechlorination (HDCl) of trichloroethylene (TCE) was examined. The results show that nanoparticles with different surface orientations can be employed to affect selectivity, with polyhedral and multiply-twinned Pd exhibiting the best ethylene selectivity. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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15 pages, 3281 KiB

Open AccessArticle

Management of γ-Alumina with High-Efficient {111} External Surfaces for HDS Reactions

by Yingrui Xu, Shunqin Liang, Limin Sun, Xiaoli Hu, Yuqi Zhang, Weikun Lai, Xiaodong Yi and Weiping Fang

Catalysts 2020, 10(11), 1254; https://doi.org/10.3390/catal10111254 - 30 Oct 2020

Cited by 2 | Viewed by 2658

Abstract

A series of γ-alumina samples with different exposure ratio of {111} facet were synthesized by an efficient hydrothermal method via adjusting the pH value of the gel precursor. The nanorod alumina supported catalyst with the highest exposure of {111} facet exhibited the best [...] Read more.

A series of γ-alumina samples with different exposure ratio of {111} facet were synthesized by an efficient hydrothermal method via adjusting the pH value of the gel precursor. The nanorod alumina supported catalyst with the highest exposure of {111} facet exhibited the best hydrodesulfurization (HDS) activities of both thiophene and dibenzothiophene (DBT). Characterization of the sulfided NiMo/Al₂O₃ catalyst with preferential exposure of {111} facet showed that the MoS₂ nano slabs were inclined to distribute in the direction along the edges of alumina nanocrystal in reduced stacking layers. The selective exposure of {111} facet played a decisive role in obtaining alumina-supported HDS catalysts with improved intrinsic activity. This work helps to better understand the relationship between catalytic properties and varied support surfaces, which demonstrate a proper design of the catalyst support morphology on the facet-level. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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Review

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20 pages, 20276 KiB

Open AccessFeature PaperReview

Chemical and Laser Ablation Synthesis of Monometallic and Bimetallic Ni-Based Nanoparticles

by Niusha Lasemi and Günther Rupprechter

Catalysts 2020, 10(12), 1453; https://doi.org/10.3390/catal10121453 - 11 Dec 2020

Cited by 19 | Viewed by 5265

Abstract

The catalytic properties of nanoparticles depend on their size, shape and surface/defect structure, with the entire catalyst performance being governed by the corresponding distributions. Herein, we present two routes of mono- and bimetallic nanoparticle synthesis that enable control of the structural parameters, i.e., [...] Read more.

The catalytic properties of nanoparticles depend on their size, shape and surface/defect structure, with the entire catalyst performance being governed by the corresponding distributions. Herein, we present two routes of mono- and bimetallic nanoparticle synthesis that enable control of the structural parameters, i.e., wet-chemical synthesis and laser ablation in liquid-phase. The latter is particularly suited to create defect-rich nanoparticles. Impregnation routes were applied to prepare Ni and NiCu nanoparticles, whereas nano- and femtosecond laser ablation in liquid-phase were employed to prepare Ni and NiAu nanoparticles. The effects of the Ni:Cu ratio in impregnation and of laser fluence and liquid-medium on laser ablation are discussed. The atomic structure and (surface) composition of the nanoparticles were characterized by electron microscopic (BF-TEM, DF-TEM, HRTEM) and spectroscopic/diffraction techniques (EDX, SAED, XPS, IR), complemented by theory (DFT). The chemically synthesized bimetallic NiCu nanoparticles initially had Cu-rich surfaces, which changed to Ni-rich upon reaction. For laser ablation, depending on conditions (fluence, type of liquid), highly defective, ordered, or core/shell-like nanoparticles were produced. The case studies highlight the specific benefits of each preparation method for catalyst synthesis and discuss the potential of nanoparticles produced by pulsed laser ablation for catalytic applications. Full article

(This article belongs to the Special Issue Engineering Materials for Catalysis)

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