Oxidation Catalysis under Unconventional Methods

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

Deadline for manuscript submissions: closed (31 December 2022) | Viewed by 21101

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Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
Interests: coordination chemistry; oxidation catalysis; homogeneous catalysis; heterogeneous catalysis; microwave-assisted reactions
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Guest Editor
1. Faculdade de Engenharia, Universidade Lusófona, Campo Grande 376, 1749-024 Lisboa, Portugal
2. Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
Interests: homogeneous catalysis; heterogeneous catalysis; metal complexes; organic synthesis; oxidation; mechanism
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Selective and efficient catalysts toward oxidation reactions under sustainable conditions are an area of current research interest. It is very important to design alternative and efficient routes under mild conditions and bypass the use of toxic acid solvents for an energy-efficient catalytic process and for a clean environment. For this purpose, several techniques, such as the use of microwave irradiation, ultrasound, Advanced oxidation processes (AOPs), ionic liquid or supercritical CO2 medium and gas phase catalysis, are employed to make the catalytic process more energy-efficient and ecofriendly. Catalysts can be homogeneous, heterogenous or supported depending on their nature and activity in the catalytic reactions. This topic can also include kinetic studies, theoretical calculation, and illustrations of mechanism.

The main goal of this Special Issue is to combine a variety of new and original research results on oxidation catalysis under unconventional methods, which cover the following points:

  1. Oxidation reactions under homogeneous catalysis condition using microwave irradiation, Ultrasound, reactions in ionic liquid medium or super critical conditions, etc.;
  2. Application of AOPs for removal of organic pollutants (e.g., CECs);
  3. Oxidation reactions under heterogenous catalysis conditions or catalysts onto supported materials;
  4. Kinetic or electrochemical studies to explore the role of catalysts;
  5. Theoretical calculations to elucidate the mechanism of the catalytic reaction.

New and original research studies and review articles on this topic are welcome.

Dr. Tannistha Roy Barman
Dr. Manas Sutradhar
Guest Editors

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Keywords

  • Homogeneous catalysis
  • Heterogeneous catalysis
  • Microwave irradiation
  • Ultrasound
  • Advanced Oxidation Processes (AOPs)
  • Ionic liquid medium
  • Supercritical conditions
  • Gas phase catalysis
  • Organic synthesis
  • Oxidation
  • Mechanism

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Published Papers (7 papers)

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Research

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10 pages, 20175 KiB  
Article
Hydrogen-Assisted Thermocatalysis over Titanium Nanotube for Oxidative Desulfurization
by Weiwei Tang, Yue Yao and Xiaoqiao Huang
Catalysts 2022, 12(1), 29; https://doi.org/10.3390/catal12010029 - 27 Dec 2021
Cited by 1 | Viewed by 2162
Abstract
Titanium nanotubes were hydrothermally synthesized via a two-step method for ODS (oxidative desulfurization). The catalysts’ structures were characterized by XRD (X-ray diffraction), FT-IR, UV-Vis (UV-Vis diffuse reflectance spectra), NH3-TPD, etc. The effects of O/S molar ratio and catalyst dosage, etc., were [...] Read more.
Titanium nanotubes were hydrothermally synthesized via a two-step method for ODS (oxidative desulfurization). The catalysts’ structures were characterized by XRD (X-ray diffraction), FT-IR, UV-Vis (UV-Vis diffuse reflectance spectra), NH3-TPD, etc. The effects of O/S molar ratio and catalyst dosage, etc., were systematically investigated. The catalyst exhibited remarkable performance, so that the removal of DBT (dibenzothiophene) was nearly 100% under the optimal conditions in 10 min. Also, the catalysts could be easily reused for six consecutive cycles. The hydrogen-assisted thermocatalytic mechanism over titanium nanotubes for ODS was also studied and an effective reactant concentration (ERC) number of 70.8 was calculated. Full article
(This article belongs to the Special Issue Oxidation Catalysis under Unconventional Methods)
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10 pages, 2840 KiB  
Article
Structural, Optical, and Catalytic Properties of MgCr2O4 Spinel-Type Nanostructures Synthesized by Sol–Gel Auto-Combustion Method
by Vasyl Mykhailovych, Andrii Kanak, Ştefana Cojocaru, Elena-Daniela Chitoiu-Arsene, Mircea Nicolae Palamaru, Alexandra-Raluca Iordan, Oleksandra Korovyanko, Andrei Diaconu, Viorela Gabriela Ciobanu, Gabriel Caruntu, Oleh Lushchak, Petro Fochuk, Yuriy Khalavka and Aurelian Rotaru
Catalysts 2021, 11(12), 1476; https://doi.org/10.3390/catal11121476 - 1 Dec 2021
Cited by 7 | Viewed by 3638
Abstract
Spinel chromite nanoparticles are prospective candidates for a variety of applications from catalysis to depollution. In this work, we used a sol–gel auto-combustion method to synthesize spinel-type MgCr2O4 nanoparticles by using fructose (FS), tartaric acid (TA), and hexamethylenetetramine (HMTA) as [...] Read more.
Spinel chromite nanoparticles are prospective candidates for a variety of applications from catalysis to depollution. In this work, we used a sol–gel auto-combustion method to synthesize spinel-type MgCr2O4 nanoparticles by using fructose (FS), tartaric acid (TA), and hexamethylenetetramine (HMTA) as chelating/fuel agents. The optimal temperature treatment for the formation of impurity-free MgCr2O4 nanostructures was found to range from 500 to 750 °C. Fourier transform infrared (FTIR) spectroscopy was used to determine the lattice vibrations of the corresponding chemical bonds from octahedral and tetrahedral positions, and the optical band gap was calculated from UV–VIS spectrophotometry. The stabilization of the spinel phase was proved by X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis. From field-emission scanning electron microscopy (FE-SEM), we found that the size of the constituent particles ranged from 10 to 40 nm. The catalytic activity of the as-prepared MgCr2O4 nanocrystals synthesized by using tartaric acid as a chelating/fuel agent was tested on the decomposition of hydrogen peroxide. In particular, we found that the nature of the chelating/fuel agent as well as the energy released during the auto-combustion played an important role on the structural, optical, and catalytic properties of MgCr2O4 nanoparticles obtained by this synthetic route. Full article
(This article belongs to the Special Issue Oxidation Catalysis under Unconventional Methods)
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11 pages, 5348 KiB  
Article
Selective Oxidation of Cinnamyl Alcohol to Cinnamaldehyde over Functionalized Multi-Walled Carbon Nanotubes Supported Silver-Cobalt Nanoparticles
by Zahoor Iqbal, Muhammad Sufaid Khan, Rozina Khattak, Tausif Iqbal, Ivar Zekker, Muhammad Zahoor, Helal F. Hetta, Gaber El-Saber Batiha and Eida M. Alshammari
Catalysts 2021, 11(7), 863; https://doi.org/10.3390/catal11070863 - 19 Jul 2021
Cited by 8 | Viewed by 3405
Abstract
The selective oxidation of alcohols to aldehydes has attracted a lot of attention because of its potential use in agrochemicals, fragrances, and fine chemicals. However, due to homogenous catalysis, low yield, low selectivity, and hazardous oxidants, traditional approaches have lost their efficiency. The [...] Read more.
The selective oxidation of alcohols to aldehydes has attracted a lot of attention because of its potential use in agrochemicals, fragrances, and fine chemicals. However, due to homogenous catalysis, low yield, low selectivity, and hazardous oxidants, traditional approaches have lost their efficiency. The co-precipitation method was used to synthesize the silver-cobalt bimetallic catalyst supported on functionalized multi-walled carbon nanotubes (Ag-Co/S). Brunauer Emmet Teller (BET), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD) were used to characterize the catalyst. For the oxidation of cinnamyl alcohol (CA) with O2 as an oxidant, the catalyst’s selectivity and activity were investigated. The impacts of several parameters on catalyst’s selectivity and activity, such as time, temperature, solvents, catalyst dosage, and stirring speed, were comprehensively studied. The results revealed that in the presence of Ag-Co/S as a catalyst, O2 could be employed as an effective oxidant for the catalytic oxidation of cinnamyl alcohol to cinnamaldehyde (CD) with 99% selectivity and 90% conversion. In terms of cost effectiveness, catalytic activity, selectivity, and recyclability, Ag-Co/S outperforms the competition. As a result, under the green chemistry methodology, it can be utilized as an effective catalyst for the conversion of CA to CD. Full article
(This article belongs to the Special Issue Oxidation Catalysis under Unconventional Methods)
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24 pages, 4573 KiB  
Article
Catalytic Effect of 1,4-Dioxane on the Kinetics of the Oxidation of Iodide by Dicyanobis(bipyridine)iron(III) in Water
by Rozina Khattak, Muhammad Sufaid Khan, Zahoor Iqbal, Rizwan Ullah, Abbas Khan, Shazia Summer, Hamsa Noreen, Muhammad Zahoor, Salah M. El-Bahy and Gaber El-Saber Batiha
Catalysts 2021, 11(7), 840; https://doi.org/10.3390/catal11070840 - 11 Jul 2021
Cited by 2 | Viewed by 2819
Abstract
Dye-sensitized solar cells (DSSCs) are a technically and financially viable alternative to today’s photovoltaic systems using p-n junctions. The two functions are isolated here, which are unlike traditional systems where the semiconductor is thought to perform both light absorption and charge carrier transport. [...] Read more.
Dye-sensitized solar cells (DSSCs) are a technically and financially viable alternative to today’s photovoltaic systems using p-n junctions. The two functions are isolated here, which are unlike traditional systems where the semiconductor is thought to perform both light absorption and charge carrier transport. This article discusses the potential use of dicyanobis(bipyridine)iron(III) to oxidize iodide as a sensitizer in DSSCs. However, it is critical to understand the kinetics of this essential process in order to understand the mechanism of electron transport. The oxidation of iodide by dicyanobis(bipyridine)iron(III) in three reaction media was studied: water, 10% v/v 1,4-dioxane-water, and 20% v/v 1,4-dioxane-water. The reaction was carried out in a regular laboratory setting, with no special sensitive conditions or the use of expensive materials, making it a cost-effective and practical method. Dicyanobis(bipyridine)iron(III) oxidized iodide in selected media at 0.06 M ionic strength and constant temperature. The reaction was subjected to a spectrophotometric analysis. The data were acquired by measuring the rise in visible absorbance as a function of time after the formation of dicyanobis(bipyridine)iron(II). The reaction proceeded with an overall fractional (0.5), first order, and third order in water, 10% media, and 20% media, respectively. The presence of dicyanobis(bipyridine)iron(III) in either of the reaction media had no effect on the rate. The effect of protons (H+) on the rate constant indicated resistance in water and catalysis in dioxane-water media containing 10–20% dioxane. When the ionic strength was raised, there was no change in the rate constant in water, but there was a deceleration in both binary solvent media. In an aqueous medium, the thermodynamic parameters of activation were computed as Ea 46.23 kJ mol−1, 24.62 M s−1, ΔH# 43.76 kJ mol−1, ΔS# −226.5 J mol−1 K−1, and ΔG# 111.26 kJ mol−1 (25 °C). By increasing the rate of the reaction to its maximum, this study discovered the binary solvent media with the highest catalytic efficiency, i.e., 20% v/v 1,4-dioxane-water, which may increase the efficiency of DSSCs without using any expensive material or unusual experimental conditions. Full article
(This article belongs to the Special Issue Oxidation Catalysis under Unconventional Methods)
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12 pages, 3382 KiB  
Article
Effect of Preparation Methods on the Performance of Pt/TiO2 Catalysts for the Catalytic Oxidation of Carbon Monoxide in Simulated Sintering Flue Gas
by Jianyu Cai, Zehui Yu and Jian Li
Catalysts 2021, 11(7), 804; https://doi.org/10.3390/catal11070804 - 30 Jun 2021
Cited by 8 | Viewed by 2671
Abstract
A series of Pt/TiO2 catalysts were prepared by the impregnation (IM), dry ball mill (DB), or wet ball mill (WB) methods, and their catalytic activity for the oxidation of CO was evaluated. The structure and redox properties of the catalysts were investigated [...] Read more.
A series of Pt/TiO2 catalysts were prepared by the impregnation (IM), dry ball mill (DB), or wet ball mill (WB) methods, and their catalytic activity for the oxidation of CO was evaluated. The structure and redox properties of the catalysts were investigated by N2 desorption, XRD, SEM, TEM, XPS, H2-TPR, SO2-TPD, and CO chemisorption analysis. It was determined that the preparation method affects the physical structure of the catalyst and the particle size and dispersion of Pt on the catalyst surface. The catalyst prepared by the impregnation method had a more suitable physical structure than the other catalysts, with a smaller particle size, a higher dispersion of Pt on the surface, and the lowest strength of SO2 adsorption. Pt/TiO2(IM) catalysts presented the best catalytic activity for the oxidation of CO in simulated sintering flue gas at 140 °C, as well as better sulfur and water resistance with simulated sintering flue gas containing 50 ppm of SO2 and 15% water vapor. Full article
(This article belongs to the Special Issue Oxidation Catalysis under Unconventional Methods)
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12 pages, 2349 KiB  
Article
CO2 Self-Poisoning and Its Mitigation in CuO Catalyzed CO Oxidation: Determining and Speeding up the Rate-Determining Step
by Kai Cheng, Songjian Zhao, Jiazheng Ren, Haoran Li and Yongsheng Chen
Catalysts 2021, 11(6), 654; https://doi.org/10.3390/catal11060654 - 22 May 2021
Cited by 2 | Viewed by 2109
Abstract
Cu-based catalysts are promising for CO oxidation applications with catalyst deactivation being a major barrier. We start with a CuO/Al2O3 catalyst and find that while the CO conversion decreases, CO2 accumulates and the average Cu chemical state stays the [...] Read more.
Cu-based catalysts are promising for CO oxidation applications with catalyst deactivation being a major barrier. We start with a CuO/Al2O3 catalyst and find that while the CO conversion decreases, CO2 accumulates and the average Cu chemical state stays the same. It suggests CO2 self-poisoning, i.e., CO2 desorption is the rate-determining step. Subsequently, experiments are performed to prove this hypothesis by showing (1) CO2 adsorption inhibits O2 adsorption, (2) complete desorption of CO2 regenerate the catalyst, (3) pre-adsorbed CO2 quenches catalyst activity which recovers during the reaction and (4) the apparent activation energy is consistent with CO2 desorption. It is further evidenced by using a stronger CO2 adsorbing support CeO2 to speed up CO2 desorption from the CuO sites resulting in a superior CuO/CeO2 catalyst. It provides an example for experimentally deciding and speeding up the rate-determining step in a catalytic reaction. Full article
(This article belongs to the Special Issue Oxidation Catalysis under Unconventional Methods)
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Review

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24 pages, 4172 KiB  
Review
Recent Developments in Advanced Oxidation Processes for Organics-Polluted Soil Reclamation
by Crina Calenciuc, Antía Fdez-Sanromán, Gabriela Lama, Sivasankar Annamalai, Angeles Sanromán and Marta Pazos
Catalysts 2022, 12(1), 64; https://doi.org/10.3390/catal12010064 - 7 Jan 2022
Cited by 23 | Viewed by 2966
Abstract
Soil pollution has become a substantial environmental problem which is amplified by overpopulation in different regions. In this review, the state of the art regarding the use of Advanced Oxidation Processes (AOPs) for soil remediation is presented. This review aims to provide an [...] Read more.
Soil pollution has become a substantial environmental problem which is amplified by overpopulation in different regions. In this review, the state of the art regarding the use of Advanced Oxidation Processes (AOPs) for soil remediation is presented. This review aims to provide an outline of recent technologies developed for the decontamination of polluted soils by using AOPs. Depending on the decontamination process, these techniques have been presented in three categories: the Fenton process, sulfate radicals process, and coupled processes. The review presents the achievements of, and includes some reflections on, the status of these emerging technologies, the mechanisms, and influential factors. At the present, more investigation and development actions are still desirable to bring them to real full-scale implementation. Full article
(This article belongs to the Special Issue Oxidation Catalysis under Unconventional Methods)
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