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Heterogeneous Catalysts Synthesis and Characterization

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

Deadline for manuscript submissions: closed (20 April 2022) | Viewed by 37918

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Special Issue Editors

Dr. Irina L. Simakova

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Guest Editor

Boreskov Institute of Catalysis, Novosibirsk, Russia
Interests: heterogeneous catalysis; biomass valorization
Special Issues, Collections and Topics in MDPI journals

Prof. Dr. Dmitry Yu. Murzin

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Faculty of Science and Engineering, Åbo Akademi University, 20500 Turku, Finland
Interests: heterogeneous catalysis; catalytic reaction engineering; biomass valorization
Special Issues, Collections and Topics in MDPI journals

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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

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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. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

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Keywords

Heterogeneous catalysts
Preparation
Characterization
Upscaling
Theoretical approaches in catalyst preparation

Published Papers (11 papers)

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Research

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19 pages, 5157 KiB

Open AccessArticle

CeFeO₃–CeO₂–Fe₂O₃ Systems: Synthesis by Solution Combustion Method and Catalytic Performance in CO₂ Hydrogenation

by Anna N. Matveyeva, Shamil O. Omarov, Marianna A. Gavrilova, Dmitry A. Sladkovskiy and Dmitry Yu. Murzin

Materials 2022, 15(22), 7970; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15227970 - 11 Nov 2022

Cited by 7 | Viewed by 1792

Abstract

Rare-earth orthoferrites have found wide application in thermocatalytic reduction-oxidation processes. Much less attention has been paid, however, to the production of CeFeO₃, as well as to the study of its physicochemical and catalytic properties, in particular, in the promising process of CO₂ utilization by hydrogenation to CO and hydrocarbons. This study presents the results of a study on the synthesis of CeFeO₃ by solution combustion synthesis (SCS) using various fuels, fuel-to-oxidizer ratios, and additives. The SCS products were characterized by XRD, FTIR, N₂-physisorption, SEM, DTA–TGA, and H₂-TPR. It has been established that glycine provides the best yield of CeFeO₃, while the addition of NH₄NO₃ promotes an increase in the amount of CeFeO₃ by 7–12 wt%. In addition, the synthesis of CeFeO₃ with the participation of NH₄NO₃ makes it possible to surpass the activity of the CeO₂–Fe₂O₃ system at low temperatures (300–400 °C), as well as to increase selectivity to hydrocarbons. The observed effects are due to the increased gas evolution and ejection of reactive FeO_x nanoparticles on the surface of crystallites, and an increase in the surface defects. CeFeO₃ obtained in this study allows for achieving higher CO₂ conversion compared to LaFeO₃ at 600 °C. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)

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11 pages, 2699 KiB

Open AccessArticle

One-Pot Synthesis of Al-P-O Catalysts and Their Catalytic Properties for O-Methylation of Catechol and Methanol

by Dongfei Xu, Jiaan Ren, Shengnan Yue, Xiujing Zou, Xingfu Shang and Xueguang Wang

Materials 2021, 14(20), 5942; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14205942 - 10 Oct 2021

Cited by 2 | Viewed by 1426

Abstract

A series of Al-P-O catalysts (Al-xP-O) were prepared using a P123-assisted one-pot method at different P/Al molar ratios and used for O-methylation of catechol and methanol. The influences of the P/Al molar ratio and P123 addition on catalyst structure and surface acid-base characteristics were investigated in detail. Increasing the P/Al molar ratio more favored crystalline aluminophosphate. The P123-assisted Al³⁺ and PO₄³⁻ are known to be stabilized through weak steric force so that the formation of crystalline aluminophosphate could be inhibited at higher P/Al molar ratios. The results showed that the prepared Al-P-O catalysts possessed appropriate weak acid and weak base sites, which was beneficial to the reaction of catechol and methanol. The Al-1.1P-O catalyst synthesized with the assistance of P123 exhibited superior catalytic performances, with 52.5% catechol conversion and higher guaiacol selectivity of 97.6%. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)

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18 pages, 3099 KiB

Open AccessEditor’s ChoiceArticle

Chemo-Enzymatic Baeyer–Villiger Oxidation Facilitated with Lipases Immobilized in the Supported Ionic Liquid Phase

by Anna Szelwicka, Anna Wolny, Miroslawa Grymel, Sebastian Jurczyk, Slawomir Boncel and Anna Chrobok

Materials 2021, 14(13), 3443; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14133443 - 22 Jun 2021

Cited by 9 | Viewed by 2464

Abstract

A novel method for chemo-enzymatic Baeyer–Villiger oxidation of cyclic ketones in the presence of supported ionic liquid-like phase biocatalyst was designed. In this work, multi-walled carbon nanotubes were applied as a support for ionic liquids which were anchored to nanotubes covalently by amide or imine bonds. Next, lipases B from Candida antarctica, Candida rugosa, or Aspergillus oryzae were immobilized on the prepared materials. The biocatalysts were characterized using various techniques, like thermogravimetry, IR spectroscopy, XPS, elemental analysis, and SEM-EDS microscopy. In the proposed approach, a biocatalyst consisting of a lipase as an active phase allowed the generation of peracid in situ from the corresponding precursor and a green oxidant–hydrogen peroxide. The activity and stability of the obtained biocatalysts in the model oxidation of 2-adamantanone were demonstrated. High conversion of substrate (92%) was achieved under favorable conditions (toluene: n-octanoic acid ratio 1:1 = v:v, 35% aq. H₂O₂ 2 eq., 0.080 g of biocatalyst per 1 mmol of ketone at 20 °C, reaction time 4 h) with four reaction cycles without a drop in its activity. Our ‘properties-by-design’ approach is distinguished by its short reaction time at low temperature and higher thermal stability in comparison with other biocatalysts presented in the literature reports. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)

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22 pages, 5312 KiB

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

by Yabin Wei, Shuangling Jin, Rui Zhang, Weifeng Li, Jiangcan Wang, Shuo Yang, He Wang, Minghe Yang, Yan Liu, Wenming Qiao, Licheng Ling and Minglin Jin

Materials 2020, 13(2), 475; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13020475 - 19 Jan 2020

Cited by 12 | Viewed by 2838

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 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 MnO_x–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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15 pages, 12052 KiB

Open AccessArticle

Catalytic Soot Oxidation Activity of NiO–CeO₂ Catalysts Prepared by a Coprecipitation Method: Influence of the Preparation pH on the Catalytic Performance

by Amar Bendieb Aberkane, María Pilar Yeste, Djazi Fayçal, Daniel Goma and Miguel Ángel Cauqui

Materials 2019, 12(20), 3436; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12203436 - 21 Oct 2019

Cited by 10 | Viewed by 3588

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 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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14 pages, 2898 KiB

Open AccessFeature PaperArticle

Plasma Treating Mixed Metal Oxides to Improve Oxidative Performance via Defect Generation

by Jonathan Horlyck, Alimatun Nashira, Emma Lovell, Rahman Daiyan, Nicholas Bedford, Yuexing Wei, Rose Amal and Jason Scott

Materials 2019, 12(17), 2756; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12172756 - 27 Aug 2019

Cited by 15 | Viewed by 3430

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 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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21 pages, 8984 KiB

Open AccessFeature PaperArticle

Bulk Versus Surface Modification of Alumina with Mn and Ce Based Oxides for CH₄ Catalytic Combustion

by Stefan Neatu, Mihaela M. Trandafir, Adelina Stănoiu, Ovidiu G. Florea, Cristian E. Simion, Lucia N. Leonat, Cornel Cobianu, Marin Gheorghe, Mihaela Florea and Florentina Neatu

Materials 2019, 12(11), 1771; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12111771 - 31 May 2019

Cited by 5 | Viewed by 3309

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 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–MnO_x catalyst, supported on an optimized amount of 4 wt.% La₂O₃–Al₂O_3, 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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27 pages, 6115 KiB

Open AccessArticle

Bentonites Modified with Phosphomolybdic Heteropolyacid (HPMo) for Biowaste to Biofuel Production

by Alex de Nazaré de Oliveira, Marco Aurélio Barbosa de Lima, Luíza Helena de Oliveira Pires, Moisés Rosas da Silva, Patrícia Teresa Souza da Luz, Rômulo S. Angélica, Geraldo N. da Rocha Filho, Carlos Emmerson F. da Costa, Rafael Luque and Luís Adriano Santos do Nascimento

Materials 2019, 12(9), 1431; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12091431 - 02 May 2019

Cited by 47 | Viewed by 3917

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), 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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20 pages, 38400 KiB

Open AccessArticle

Key Role of Precursor Nature in Phase Composition of Supported Molybdenum Carbides and Nitrides

by Zdeněk Tišler, Romana Velvarská, Lenka Skuhrovcová, Lenka Pelíšková and Uliana Akhmetzyanova

Materials 2019, 12(3), 415; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12030415 - 29 Jan 2019

Cited by 14 | Viewed by 4192

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 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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16 pages, 5217 KiB

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

by Robinson Dinamarca, Rodrigo Espinoza-González, Cristian H. Campos and Gina Pecchi

Materials 2019, 12(3), 413; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12030413 - 29 Jan 2019

Cited by 5 | Viewed by 4317

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 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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Review

Jump to: Research

23 pages, 2562 KiB

Open AccessEditor’s ChoiceReview

3D Printing in Heterogeneous Catalysis—The State of the Art

by Elżbieta Bogdan and Piotr Michorczyk

Materials 2020, 13(20), 4534; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13204534 - 13 Oct 2020

Cited by 37 | Viewed by 5203

Abstract

This paper describes the process of additive manufacturing and a selection of three-dimensional (3D) printing methods which have applications in chemical synthesis, specifically for the production of monolithic catalysts. A review was conducted on reference literature for 3D printing applications in the field [...] Read more.

(This article belongs to the Special Issue Heterogeneous Catalysts Synthesis and Characterization)

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