Special Issue "Heterogeneous Catalysts Synthesis and Characterization"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Catalytic Materials".

Deadline for manuscript submissions: 1 August 2020.

Special Issue Editors

Dr. Irina L. Simakova
Website
Guest Editor
Boreskov Institute of Catalysis, Novosibirsk, Russia
Interests: heterogeneous catalysis; biomass valorization
Special Issues and Collections in MDPI journals
Prof. Dr. Dmitry Yu. Murzin
Website
Guest Editor
Johan Gadolin Process Chemistry Centre, Faculty of Science and Engineering, Åbo Akademi University, Turku 20500, Finland
Interests: catalysis, chemical knetics, materials chemistry

Special Issue Information

Dear Colleagues,

Catalysts synthesis is an indispensable part of heterogeneous catalysis, which is a very multidisciplinary field comprising preparations, reactivity studies, kinetics, reaction and reactor engineering, etc. To improve activity, selectivity, and stability and to link the physico-chemical properties with catalytic behaviour, a lot of effort has been devoted to catalyst characterization, including in-situ spectroscopy and imaging.

This Special Issue aims to encompass original scientific papers, short communications, and reviews on innovative approaches for catalyst preparation without any restrictions regarding the types of catalysts (zeolites, supported metals, MOFS, clays, carbons, nanotubes, structured catalysts, immobilized homogeneous catalysts, nanoreactors, composites, membranes, thin films, etc.). Besides classical methods of preparation (hydrothermal synthesis, sol-gel methods, impregnation, precipitation, etc.), the editors also anticipate contributions addressing less conventional methods such as surfactant assisted preparations, mechanochemical or plasma activation, ALD, CVD, flame and combustion methods, application of ultrasound, etc.

Potential industrial implementation and requirements of large scale catalyst production inevitably call for research on upscaling, shaping, and structuring, including extrusion, spray drying, tabletting, high-throughput approaches, etc.

The editors especially welcome contributions in such emerging areas as numerical and theoretical approaches in catalyst preparation.

It is our pleasure to invite you to submit papers and reviews exploring the fascinating issue of heterogeneous catalyst preparation and characterization.

Prof. Irina L. Simakova
Prof. Dmitry Yu. Murzin
Guest Editors

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 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 catalysts
  • Preparation
  • Characterization
  • Upscaling
  • Theoretical approaches in catalyst preparation

Published Papers (7 papers)

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Research

Open AccessArticle
Preparation of Mesoporous Mn–Ce–Ti–O Aerogels by a One-Pot Sol–Gel Method for Selective Catalytic Reduction of NO with NH3
Materials 2020, 13(2), 475; https://doi.org/10.3390/ma13020475 - 19 Jan 2020
Abstract
Novel Mn–Ce–Ti–O composite aerogels with large mesopore size were prepared via a one-pot sol–gel method by using propylene oxide as a network gel inducer and ethyl acetoacetate as a complexing agent. The effect of calcination temperature (400, 500, 600, and 700 °C) on [...] Read more.
Novel Mn–Ce–Ti–O composite aerogels with large mesopore size were prepared via a one-pot sol–gel method by using propylene oxide as a network gel inducer and ethyl acetoacetate as a complexing agent. The effect of calcination temperature (400, 500, 600, and 700 °C) on the NH3–selective catalytic reduction (SCR) performance of the obtained Mn–Ce–Ti–O composite aerogels was investigated. The results show that the Mn–Ce–Ti–O catalyst calcined at 600 °C exhibits the highest NH3–SCR activity and lowest apparent activation energy due to its most abundant Lewis acid sites and best reducibility. The NO conversion of the MCTO-600 catalyst maintains 100% at 200 °C in the presence of 100 ppm SO2, showing the superior resistance to SO2 poisoning as compared with the MnOx–CeO2–TiO2 catalysts reported the literature. This should be mainly attributed to its large mesopore sizes with an average pore size of 32 nm and abundant Lewis acid sites. The former fact facilitates the decomposition of NH4HSO4, and the latter fact reduces vapor pressure of NH3. The NH3–SCR process on the MCTO-600 catalyst follows both the Eley–Rideal (E–R) mechanism and the Langmuir–Hinshelwood (L–H) mechanism. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
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Open AccessArticle
Catalytic Soot Oxidation Activity of NiO–CeO2 Catalysts Prepared by a Coprecipitation Method: Influence of the Preparation pH on the Catalytic Performance
Materials 2019, 12(20), 3436; https://doi.org/10.3390/ma12203436 - 21 Oct 2019
Abstract
A series of NiO–CeO2 mixed oxide catalysts have been synthesized by a modified coprecipitation method at three different pH values (pH = 8, 9, and 10). The NiO–CeO2 mixed oxide samples were characterized by TGA, XRD, inductively coupled plasma atomic emission [...] Read more.
A series of NiO–CeO2 mixed oxide catalysts have been synthesized by a modified coprecipitation method at three different pH values (pH = 8, 9, and 10). The NiO–CeO2 mixed oxide samples were characterized by TGA, XRD, inductively coupled plasma atomic emission spectroscopy (ICP-AES), FTIR, Brunauer–Emmett–Teller (BET) surface area, H2 temperature-programmed reduction (H2-TPR), and electron microscopy (high-angle annular dark-field transmission electron microscopy/energy-dispersive X-ray spectroscopy (HAADF-TEM/EDS)). The catalytic activities of the samples for soot oxidation were investigated under loose and tight contact conditions. The catalysts exhibited a high BET surface area with average crystal sizes that varied with the pH values. Electron microscopy results showed the formation of small crystallites (~5 nm) of CeO2 supported on large plate-shaped particles of NiO (~20 nm thick). XRD showed that a proportion of the Ni2+ was incorporated into the ceria network, and it appeared that the amount on Ni2+ that replaced Ce4+ was higher when the synthesis of the mixed oxides was carried out at a lower pH. Among the synthesized catalysts, Ni-Ce-8 (pH = 8) exhibited the best catalytic performance. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
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Open AccessFeature PaperArticle
Plasma Treating Mixed Metal Oxides to Improve Oxidative Performance via Defect Generation
Materials 2019, 12(17), 2756; https://doi.org/10.3390/ma12172756 - 27 Aug 2019
Abstract
The generation of structural defects in metal oxide catalysts offers a potential pathway to improve performance. Herein, we investigated the effect of thermal hydrogenation and low-temperature plasma treatments on mixed SiO2/TiO2 materials. Hydrogenation at 500 °C resulted in the reduction [...] Read more.
The generation of structural defects in metal oxide catalysts offers a potential pathway to improve performance. Herein, we investigated the effect of thermal hydrogenation and low-temperature plasma treatments on mixed SiO2/TiO2 materials. Hydrogenation at 500 °C resulted in the reduction of the material to produce Ti3+ in the bulk TiO2. In contrast, low temperature plasma treatment for 10 or 20 min generated surface Ti3+ species via the removal of oxygen on both the neat and hydrogenated material. Assessing the photocatalytic activity of the materials demonstrated a 40–130% increase in the rate of formic acid oxidation after plasma treatment. A strong relationship between the Ti3+ content and catalyst activity was established, although a change in the Si–Ti interaction after plasma treating of the neat SiO2/TiO2 material was found to limit performance, and suggests that performance is not determined solely by the presence of Ti3+. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
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Open AccessFeature PaperArticle
Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH4 Catalytic Combustion
Materials 2019, 12(11), 1771; https://doi.org/10.3390/ma12111771 - 31 May 2019
Abstract
This study presents the synthesis and characterization of lanthanum-modified alumina supported cerium–manganese mixed oxides, which were prepared by three different methods (coprecipitation, impregnation and citrate-based sol-gel method) followed by calcination at 500 °C. The physicochemical properties of the synthesized materials were investigated by [...] Read more.
This study presents the synthesis and characterization of lanthanum-modified alumina supported cerium–manganese mixed oxides, which were prepared by three different methods (coprecipitation, impregnation and citrate-based sol-gel method) followed by calcination at 500 °C. The physicochemical properties of the synthesized materials were investigated by various characterization techniques, namely: nitrogen adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and H2–temperature programmed reduction (TPR). This experimental study demonstrated that the role of the catalytic surface is much more important than the bulk one. Indeed, the incipient impregnation of CeO2–MnOx catalyst, supported on an optimized amount of 4 wt.% La2O3–Al2O3, provided the best results of the catalytic combustion of methane on our catalytic micro-convertors. This is mainly due to: (i) the highest pore size dimensions according to the Brunauer-Emmett-Teller (BET) investigations, (ii) the highest amount of Mn4+ or/and Ce4+ on the surface as revealed by XPS, (iii) the presence of a mixed phase (Ce2MnO6) as shown by X-ray diffraction; and (iv) a higher reducibility of Mn4+ or/and Ce4+ species as displayed by H2–TPR and therefore more reactive oxygen species. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
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Open AccessArticle
Bentonites Modified with Phosphomolybdic Heteropolyacid (HPMo) for Biowaste to Biofuel Production
Materials 2019, 12(9), 1431; https://doi.org/10.3390/ma12091431 - 02 May 2019
Cited by 1
Abstract
Two bentonites from Paraíba (Northeastern Brazil) were impregnated with heteropoly phosphomolybdic H3PMo12O40 (HPMo). The materials produced were characterized by various techniques such as N2 adsorption-desorption (specific surface area, SSA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), [...] Read more.
Two bentonites from Paraíba (Northeastern Brazil) were impregnated with heteropoly phosphomolybdic H3PMo12O40 (HPMo). The materials produced were characterized by various techniques such as N2 adsorption-desorption (specific surface area, SSA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA/DTG), Scanning Electron Microscopy (SEM) equipped with Dispersive Energy X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-vis), acid-base titration analysis. The catalytic activity of these materials was tested in the esterification of a waste from palm oil deodorization and the main results obtained (about 93.3% of conversion) indicated that these materials have potential to act as heterogeneous solid acid catalysts. The prepared materials exhibited satisfactory catalytic performance even after a very simple recycling process in three reuse cycles, without significant loss of their activities. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
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Open AccessArticle
Key Role of Precursor Nature in Phase Composition of Supported Molybdenum Carbides and Nitrides
Materials 2019, 12(3), 415; https://doi.org/10.3390/ma12030415 - 29 Jan 2019
Cited by 5
Abstract
In this work, we studied the effect of molybdenum precursors and the synthesis conditions on the final phase composition of bulk and supported molybdenum carbides and nitrides. Ammonium heptamolybdate, its mixture with hexamethylenetetramine, and their complex were used as the precursors at different [...] Read more.
In this work, we studied the effect of molybdenum precursors and the synthesis conditions on the final phase composition of bulk and supported molybdenum carbides and nitrides. Ammonium heptamolybdate, its mixture with hexamethylenetetramine, and their complex were used as the precursors at different temperatures. It was investigated that the synthesis of the target molybdenum nitrides strongly depended on the structure of the precursor and temperature conditions, while the synthesis of carbide samples always led to the target phase composition. Unlike the carbide samples, where the α-Mo2C phase was predominant, the mixture of β-Mo2N, MoO2 with a small amount of metal molybdenum was generally formed during the nitridation. All supported samples showed a very good dispersion of the carbide or nitride phases. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
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Open AccessFeature PaperArticle
Magnetic Fe2O3–SiO2–MeO2–Pt (Me = Ti, Sn, Ce) as Catalysts for the Selective Hydrogenation of Cinnamaldehyde. Effect of the Nature of the Metal Oxide
Materials 2019, 12(3), 413; https://doi.org/10.3390/ma12030413 - 29 Jan 2019
Cited by 2
Abstract
The type of metal oxide affects the activity and selectivity of Fe2O3–SiO2–MeO2–Pt (Me = Ti, Sn, Ce) catalysts on the hydrogenation of cinnamaldehyde. The double shell structure design is thought to protect the magnetic Fe [...] Read more.
The type of metal oxide affects the activity and selectivity of Fe2O3–SiO2–MeO2–Pt (Me = Ti, Sn, Ce) catalysts on the hydrogenation of cinnamaldehyde. The double shell structure design is thought to protect the magnetic Fe2O3 cores, and also act as a platform for depositing a second shell of TiO2, SnO2 or CeO2 metal oxide. To obtain a homogeneous metallic dispersion, the incorporation of 5 wt % of Pt was carried out over Fe2O3–SiO2–MeO2 (Me = Ti, Sn, Ce) structures modified with (3-aminopropyl)triethoxysilane by successive impregnation-reduction cycles. The full characterization by HR-TEM, STEM-EDX, XRD, N2 adsorption isotherm at −196 °C, TPR-H2 and VSM of the catalysts indicates that homogeneous core-shell structures with controlled nano-sized magnetic cores, multi-shells and metallic Pt were obtained. The nature of the metal oxide affects the Pt nanoparticle sizes where the mean Pt diameter is in the order: –TiO2–Pt > –SnO2–Pt > –CeO2–Pt. Among the catalysts studied, –CeO2–Pt had the best catalytic performance, reaching the maximum of conversion at 240 min. of reaction without producing hydrocinnamaldehyde (HCAL). It also showed a plot volcano type for the production of cinnamic alcohol (COL), with 3-phenyl-1-propanol (HCOL) as a main product. The –SnO2–Pt catalyst showed a poor catalytic performance attributable to the Pt clusters’ occlusion in the irregular surface of the –SnO2. Finally, the –TiO2–Pt catalyst showed a continuous production of COL with a 100% conversion and 65% selectivity at 600 min of reaction. Full article
(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)
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