Catalysts

32 pages, 4789 KiB

Open AccessReview

Recent Advances in Electrocatalytic Oxidation of 5-Hydroxymethylfurfural to 2,5-Furandicarboxylic Acid by Heterogeneous Catalysts

by Zhiming Ma, Lei Wang, Guangyu Li and Tao Song

Catalysts 2024, 14(2), 157; https://doi.org/10.3390/catal14020157 - 19 Feb 2024

Cited by 4 | Viewed by 3191

Abstract

The utilization and development of biomass resources is an efficient solution to mitigate the fossil energy crisis. Based on the advantages of mild reaction conditions, rapid reaction, and high conversion, the synthesis of 2,5-furandicarboxylic acid (FDCA) by the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMFOR) [...] Read more.

The utilization and development of biomass resources is an efficient solution to mitigate the fossil energy crisis. Based on the advantages of mild reaction conditions, rapid reaction, and high conversion, the synthesis of 2,5-furandicarboxylic acid (FDCA) by the electrocatalytic oxidation of 5-hydroxymethylfurfural (HMFOR) has attracted considerable attention. This review will summarize the recent advances of HMFOR to FDCA, including the reaction pathway and mechanism, as well as the catalytic performance of various heterogeneous electrocatalysts. The challenges and prospects for HMFOR are also focused on. Finally, it is expected that this work may provide guidance for the design of high-efficiency electrocatalysts and thereby accelerate the industrialization process of biomass utilization. Full article

(This article belongs to the Section Catalysis in Organic and Polymer Chemistry)

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14 pages, 3787 KiB

Open AccessArticle

Unveiling the Exceptional Performance of ZnO/Zn₂TiO₄ Nanocomposites

by Husnain Ahmad Abbasi, Maha M. Al Moneef, Jahanzeb Khan, Muhammad Hafeez, Muhammad Usman Hameed, Muhammad Abdullah Khan, Shabnam Shahida, Habib Ahmad Abbasi and Sook-Keng Chang

Catalysts 2024, 14(2), 156; https://doi.org/10.3390/catal14020156 - 19 Feb 2024

Cited by 3 | Viewed by 1770

Abstract

In this study, we engineered a sub-70 nm nanocomposite of ZnO/Zn₂TiO₄ using a low-temperature solution-phase method with titanium isopropoxide and zinc acetate as precursors, and isopropyl alcohol and water as solvents. The investigation focused on nanocomposite growth by varying precursor [...] Read more.

In this study, we engineered a sub-70 nm nanocomposite of ZnO/Zn₂TiO₄ using a low-temperature solution-phase method with titanium isopropoxide and zinc acetate as precursors, and isopropyl alcohol and water as solvents. The investigation focused on nanocomposite growth by varying precursor and surfactant concentrations and their efficiency within different pH ranges. All three ZnO/Zn₂TiO₄ nanocomposites exhibited hexagonal wurtzite ZnO and Zn₂TiO₄ structures. The crystallite size in these nanocomposites ranged from 39.50 nm to 62.67 nm for ZnO and 21.24 nm to 26.15 nm for Zn₂TiO₄. Morphological observations using FESEM revealed the formation of dispersed cotton packet-like nanocomposites with sizes ranging from 18 to 350 nm. FTIR analysis showed peaks indicative of Ti–O and Zn–O bond formation, and EDX spectrum confirmed the presence of Ti, O, and Zn. UV spectrums and photocatalytic investigations confirmed the successful formation of ZnO/Zn₂TiO₄ nanocomposites with notable photocatalytic degradation efficiency for methylene blue dye under various conditions. These findings suggest the potential applicability of the synthesized nanocomposites for environmental pollutant degradation. Full article

(This article belongs to the Topic Advances in Inorganic Synthesis)

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20 pages, 5207 KiB

Open AccessReview

Carbon Dioxide Methanation Enabled by Biochar-Nanocatalyst Composite Materials: A Mini-Review

by Mengqi Tang, Ahmed Gamal, Arvind K. Bhakta, Khouloud Jlassi, Aboubakr M. Abdullah and Mohamed M. Chehimi

Catalysts 2024, 14(2), 155; https://doi.org/10.3390/catal14020155 - 19 Feb 2024

Cited by 6 | Viewed by 1962

Abstract

Due to ever-increasing global warming, the scientific community is concerned with finding immediate solutions to reduce or utilize carbon dioxide (CO₂) and convert it in useful compounds. In this context, the reductive process of CO₂ methanation has been well-investigated and [...] Read more.

Due to ever-increasing global warming, the scientific community is concerned with finding immediate solutions to reduce or utilize carbon dioxide (CO₂) and convert it in useful compounds. In this context, the reductive process of CO₂ methanation has been well-investigated and found to be attractive due to its simplicity. However, it requires the development of highly active catalysts. In this mini-review, the focus is on biochar-immobilized nanocatalysts for CO₂ methanation. We summarize the recent literature on the topic, reporting strategies for designing biochar with immobilized nanocatalysts and their performance in CO₂ methanation. We review the thermochemical transformation of biomass into biochar and its decoration with CO₂ methanation catalysts. We also tackle direct methods of obtaining biochar nanocatalysts, in one pot, from nanocatalyst precursor-impregnated biomass. We review the effect of the initial biomass nature, as well as the conditions that permit tuning the performances of the composite catalysts. Finally, we discuss the CO₂ methanation performance and how it could be improved, keeping in mind low operation costs and sustainability. Full article

(This article belongs to the Special Issue Nanoparticles in the Catalysis)

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12 pages, 6145 KiB

Open AccessArticle

Study on the Catalytic Oxidation Modification Effect of Heavy Oil at Low Temperature under the Action of Different Ligand Ferric-Based Systems

by Dichen Tan, Zhaofei Ma, Lian Chen, Yuanzhu Mi and Xuemin Yan

Catalysts 2024, 14(2), 154; https://doi.org/10.3390/catal14020154 - 19 Feb 2024

Viewed by 1461

Abstract

This work explores the low-temperature catalytic oxidation of heavy oil (140 °C), resulting in structural changes with reduced heavy components and increased light components. The catalytic oxidation system consists of a catalyst, an oxidant, and a proton donor. Four different complexes of iron-based [...] Read more.

This work explores the low-temperature catalytic oxidation of heavy oil (140 °C), resulting in structural changes with reduced heavy components and increased light components. The catalytic oxidation system consists of a catalyst, an oxidant, and a proton donor. Four different complexes of iron-based catalysts were utilized: ferric oleate, iron naphthenate, EDTA–FeNa, and EDDHA–FeNa. Catalytic oxidation processes with these catalysts produced four types of oxygenated oil, which were then analyzed using group composition analysis and a viscosity test. The results show that EDDHA–FeNa is more favorable for the catalytic oxidation of heavy oil in a low-temperature environment, achieving a viscosity reduction rate of 78.57%. Furthermore, the catalytic performance of heavy oil oxidation was investigated using EDDHA–FeNa as catalyst under three conditions: the amount of catalyst, oxidant and reaction temperature. These findings may provide researchers valuable guidance and principles for the investigation and development of advanced catalytic viscosity reduction of heavy oil. Full article

(This article belongs to the Section Industrial Catalysis)

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13 pages, 3978 KiB

Open AccessArticle

Templated Synthesis of Cu₂S Hollow Structures for Highly Active Ozone Decomposition

by Yishan Jiang, Ying Xu, Qichao Zhang, Xin Zhao, Feng Xiao, Xinbo Wang and Guojun Ma

Catalysts 2024, 14(2), 153; https://doi.org/10.3390/catal14020153 - 19 Feb 2024

Cited by 1 | Viewed by 1863

Abstract

Nowadays, it is highly desired to develop highly active and humidity-resistive ozone decomposition catalysts to eliminate the ozone contaminant, one of the primary pollutants in the air. In this work, a series of Cu₂S hollow structured materials were rapidly synthesized using [...] Read more.

Nowadays, it is highly desired to develop highly active and humidity-resistive ozone decomposition catalysts to eliminate the ozone contaminant, one of the primary pollutants in the air. In this work, a series of Cu₂S hollow structured materials were rapidly synthesized using different structured Cu₂O templates. The Cu₂S from porous Cu₂O showed the highest ozone catalytic decomposition efficiency of >95% to 400 ppm ozone with a weight hourly space velocity of 480,000 cm³·g⁻¹·h⁻¹ in dry air. Importantly, the conversion remained >85% in a high relative humidity of 90%. The mechanism was explored by diffusive reflectance infrared spectroscopy which showed the decomposition intermediate of O₂²⁻, and X-ray photoelectron spectroscopy revealed the dual active site of both Cu and S. The EPR and UPS characterization results also explained the superiority of porous Cu₂S catalysts from the material itself. All these results show the effective decomposition of ozone by Cu₂S, especially in harsh environments, promising for active ozone elimination. Full article

(This article belongs to the Section Catalytic Materials)

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16 pages, 3056 KiB

Open AccessFeature PaperArticle

Platinum-Modified Mixed Metal Oxide Electrodes for Efficient Chloralkaline-Based Energy Storage

by Jamylle Y. C. Ribeiro, Gessica O. S. Santos, Aline R. Dória, Iñaki Requena, Marcos R. V. Lanza, Katlin I. B. Eguiluz, Giancarlo R. Salazar-Banda, Justo Lobato and Manuel A. Rodrigo

Catalysts 2024, 14(2), 152; https://doi.org/10.3390/catal14020152 - 18 Feb 2024

Cited by 1 | Viewed by 1731

Abstract

In this work, a series of novel mixed metal oxide (MMO) electrodes with the composition Ti/RuO₂Sb₂O₄Pt_x (0 ≤ x ≤ 10.0) were developed, envisaging their application in a reversible electrochemical cell based on the chloralkaline process [...] Read more.

In this work, a series of novel mixed metal oxide (MMO) electrodes with the composition Ti/RuO₂Sb₂O₄Pt_x (0 ≤ x ≤ 10.0) were developed, envisaging their application in a reversible electrochemical cell based on the chloralkaline process as an energy storage system. These electrodes were synthesized via the ionic liquid method. Comprehensive physical, chemical, and electrochemical characterizations were conducted to evaluate their performance. The feasibility of employing these electrodes within reversible processes was explored, using the products generated during the electrolytic operation of the system for fuel cell operation. During the electrolyzer operation, higher current densities resulted in enhanced current efficiencies for the production of oxidized chlorine species. Notably, the presence of platinum in the catalyst exhibited a negligible impact on the coulombic efficiency at low current densities where water oxidation predominates. However, at higher current densities, the presence of platinum significantly improved coulombic efficiency, approaching values of approximately 60%. Transitioning to a fuel cell operation, despite the improved kinetic performance associated with a higher platinum content, the process efficiency was predominantly governed by ohmic losses. Curiously, the MMO electrode made without platinum (Ti/(RuO₂)₇₀-(Sb₂O₄)₃₀) displayed the lowest ohmic losses. This study establishes optimal conditions for future investigations into this promising possibility, which holds great potential for energy storage via chloralkaline-based reversible reactions. Full article

(This article belongs to the Special Issue Advanced Photo-/Electrocatalysts for Environmental and Energy Applications)

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19 pages, 5532 KiB

Open AccessArticle

Influence of Particle Size of CeO₂ Nanospheres Encapsulated in SBA-15 Mesopores on SO₂ Tolerance during NH₃-SCR Reaction

by Xinyu Han, Mengyao Bian, Kaijie Liu, Xin Yang, Daying Zheng, Xiangguang Yang and Yibo Zhang

Catalysts 2024, 14(2), 151; https://doi.org/10.3390/catal14020151 - 18 Feb 2024

Cited by 2 | Viewed by 1714

Abstract

Ce-based selective catalytic reductions with an NH₃ (NH₃-SCR) catalyst have emerged as a focal point in denitrification catalyst research. However, the correlation between the structural characteristics of Ce-based catalysts and the influence of CeO₂ nanoparticle size on SO₂ [...] Read more.

Ce-based selective catalytic reductions with an NH₃ (NH₃-SCR) catalyst have emerged as a focal point in denitrification catalyst research. However, the correlation between the structural characteristics of Ce-based catalysts and the influence of CeO₂ nanoparticle size on SO₂ resistance remains unclear. CeO₂ nanospheres with different sizes of less than 10 nm were synthesized, and a series of supported CeO₂/SBA-15 catalysts were prepared according to the 10 nm pore size of SBA-15. These catalysts were used to explore the influence of the size of the CeO₂ nanospheres on these catalysts, specifically on their SO₂ resistance in NH₃-SCR reactions. With the increase in size, their SO₂ resistance became stronger. The results of NH₃-TPD, H₂-TPR, and XPS indicated that the catalyst with the largest particle size had the lowest adsorption of SO₂, which was attributed to more acid sites and a mutual effect between Si and Ce, resulting in the best SO₂ resistance. It was also observed that there was less sulfate deposition on the catalyst by thermogravimetric analysis. In situ DRIFTs revealed that after SO₂ poisoning, the NH₃-SCR reaction on the catalyst predominantly follows the E-R mechanism. This study offers recommendations for the development of Ce-based SO₂-resistant NH₃-SCR catalysts, specifically focusing on the synthesis and interaction of nanomaterials. Full article

(This article belongs to the Special Issue Rare Earth Catalysis: From Synthesis to Sustainable Applications)

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15 pages, 3391 KiB

Open AccessArticle

Investigating the Impact of Na₂WO₄ Doping in La₂O₃-Catalyzed OCM Reaction: A Structure–Activity Study via In Situ XRD-MS

by Danyu Wang, Junyu Lang, Zhehao Qiu, Ningxujin Ding and Yong Yang

Catalysts 2024, 14(2), 150; https://doi.org/10.3390/catal14020150 - 18 Feb 2024

Viewed by 1437

Abstract

The La₂O₃ catalyst exhibits good performance in OCM reactions for its promising C₂ selectivity and yield. Previous studies have affirmed that the formation of carbonates in La₂O₃ impedes the catalyst’s activity as a result of poisoning [...] Read more.

The La₂O₃ catalyst exhibits good performance in OCM reactions for its promising C₂ selectivity and yield. Previous studies have affirmed that the formation of carbonates in La₂O₃ impedes the catalyst’s activity as a result of poisoning from CO₂ exposure. In this study, a series of Na₂WO₄-impregnated La₂O₃ catalysts were synthesized to investigate the poisoning-resistant effect. The bulk phase and kinetics of the catalysts were analyzed in reactors employed with in situ XRD-MS and online MS, focusing on the CO₂ adsorption on La₂O₃ and the phase transition process to La₂O₂CO₃ in temperature zone correlated to OCM light-off. In situ XRD analysis revealed that, with Na₂WO₄ doped, CO₂ exposure at elevated temperatures formed La₂O₂CO₃ in tetragonal crystal phases, exhibiting distinctive differences from the hexagonal phase carbonates in undoped commercial La₂O₃. The ability to develop tetragonal or monoclinic La₂O₂CO₃ was suggested as a descriptor to assess the sensitivity of La₂O₃ catalysts to CO₂ adsorption, a tunable characteristic found in this study through varying Na₂WO₄ doping levels. Coupled XRD-MS analysis of CO₂ adsorption uptake and phase change further confirmed a positive dependence between the resistivity of La₂O₃ catalyst to CO₂ adsorption and its low-temperature C₂ selectivity. The results extended the previous CO₂ poisoning effect from multiple perspectives, offering a novel modification approach for enhancing the low-temperature performance of La₂O₃ catalysts in OCM. Full article

(This article belongs to the Special Issue Heterogeneous Catalysis for Selective Hydrogenation)

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14 pages, 3547 KiB

Open AccessFeature PaperArticle

Magnetic Metallic Nanoparticles Coated with Carbon for the Catalytic Removal of Bromate from Water

by Patrícia S. F. Ramalho, Olívia Salomé G. P. Soares, José J. M. Órfão and Manuel Fernando R. Pereira

Catalysts 2024, 14(2), 149; https://doi.org/10.3390/catal14020149 - 17 Feb 2024

Cited by 1 | Viewed by 1546

Abstract

Bromate, often detected in drinking water, is associated with a significant risk of cancer. Catalytic reduction has been recognized as an effective treatment technique to remove ions by reducing them over metal catalysts in the presence of a reducing agent, usually hydrogen. This [...] Read more.

Bromate, often detected in drinking water, is associated with a significant risk of cancer. Catalytic reduction has been recognized as an effective treatment technique to remove ions by reducing them over metal catalysts in the presence of a reducing agent, usually hydrogen. This work aims to synthesize metallic magnetic nanoparticles of iron oxide (FeO) and mixed iron oxides with manganese (MnFeO), cobalt (CoFeO), and copper (CuFeO) coated with carbon via chemical vapor deposition (C-MNP) to be applied as catalysts to the reduction of bromate in water. The use of magnetic nanoparticles coated with carbon enables catalyst recovery via magnetic separation and takes advantage of the catalytic properties of the carbon materials. The iron particles proved to be the most promising catalysts for the reduction of bromate into bromide, the highest removal being obtained with the CFeO@CVD750 sample, resulting in a 99% conversion after 120 min of reaction under the conditions tested. Due to its magnetic nature, the catalytic material was easily removed after the reaction and applied in four consecutive cycles without losing its catalytic properties. These results highlight the great potential of carbon-coated magnetic nanoparticles for reducing bromate in water. Full article

(This article belongs to the Section Environmental Catalysis)

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14 pages, 2302 KiB

Open AccessFeature PaperArticle

Immobilization of Alcohol Dehydrogenases on Silica-Based Supports and Their Application in Enantioselective Ketone Reductions

by Daria Armani, Oreste Piccolo and Antonella Petri

Catalysts 2024, 14(2), 148; https://doi.org/10.3390/catal14020148 - 17 Feb 2024

Cited by 2 | Viewed by 1832

Abstract

The use of immobilized alcohol dehydrogenases (ADHs) offers numerous advantages, especially in the reaction conditions required by industrial applications. Looking for more efficient and cost-effective methods of ADH immobilization, in this study we explored silica-based supports as an alternative to the use of [...] Read more.

The use of immobilized alcohol dehydrogenases (ADHs) offers numerous advantages, especially in the reaction conditions required by industrial applications. Looking for more efficient and cost-effective methods of ADH immobilization, in this study we explored silica-based supports as an alternative to the use of functionalized polymeric resins. Three commercially available ADHs were immobilized by adsorption and covalent bond formation. The obtained supported biocatalysts were applied for the bioreduction of acetophenone and some derivatives with good yields and excellent enantioselectivity. The important intermediate (S)-1-[3,5-bis(trifluoromethyl)phenyl]ethanol was obtained with a high enantiomeric excess (>99%) by using the highest performing immobilized ADH sample. The reusability of this biocatalyst was investigated in a flow system for five consecutive runs; the experiments showed that the biocatalyst could be recycled without a loss of activity and enantioselectivity. Finally, cross-linking with the glutaraldehyde of the supported biocatalyst was also carried out to prevent the leaching of the enzyme during the catalytic reactions. Full article

(This article belongs to the Special Issue Immobilized Biocatalysts, 3rd Edition)

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17 pages, 9298 KiB

Open AccessFeature PaperArticle

TiO₂/Zeolite Composites for SMX Degradation under UV Irradiation

by Saule Mergenbayeva, Zhanibek Abitayev, Milana Batyrbayeva, John Vakros, Dionissios Mantzavinos, Timur Sh. Atabaev and Stavros G. Poulopoulos

Catalysts 2024, 14(2), 147; https://doi.org/10.3390/catal14020147 - 16 Feb 2024

Cited by 6 | Viewed by 1810

Abstract

Sulfamethoxazole (SMX) is a common antibiotic that is considered an emerging pollutant of water bodies, as it is toxic for various aquatic species. TiO₂-based photocatalysis is a promising method for SMX degradation in water. In this work, TiO₂/zeolite (Z-45 [...] Read more.

Sulfamethoxazole (SMX) is a common antibiotic that is considered an emerging pollutant of water bodies, as it is toxic for various aquatic species. TiO₂-based photocatalysis is a promising method for SMX degradation in water. In this work, TiO₂/zeolite (Z-45 loaded with TiO₂ labeled as TZ and ZSM-5 loaded with TiO₂ labeled as TZSM) composites were prepared by mechanical mixing and liquid impregnation methods, and the photocatalytic performance of these composites (200 mg·L⁻¹) was investigated toward the degradation of SMX (30 mg·L⁻¹) in water under UV light (365 nm). The pseudo-first-order reaction rate constant of the TZSM1450 composite was 0.501 min⁻¹, which was 2.08 times higher than that of TiO₂ (k = 0.241 min⁻¹). Complete SMX degradation was observed in 10 min using the UV/TZSM1450 system. The mineralization ability in terms of total organic carbon (TOC) removal was also assessed for all of the prepared composites. The results showed that 65% and 67% of SMX could be mineralized within 120 min of photocatalytic reaction by TZSM2600 and TZSM1450, respectively. The presence of

{Cl}^{-}

and

{CO}_{3}^{2 -}

anions inhibited the degradation of SMX, while the presence of

{NO}_{3}^{-}

had almost no effect on the degradation efficiency of the UV/TZSM1450 system. The electrical energy per order estimated for the prepared composites was in the range of 68.53–946.48 kWh m⁻³ order⁻¹. The results obtained revealed that the TZSM1450 composite shows promising potential as a photocatalyst for both the degradation and mineralization of SMX. Full article

(This article belongs to the Special Issue Nanomaterials in Catalysis: Design, Characterization and Applications)

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22 pages, 2707 KiB

Open AccessReview

Metal-Based Heterogeneous Catalysts for the Synthesis of Valuable Chemical Blends via Hydrodeoxygenation of Lignin-Derived Fractions

by Marvin Chávez-Sifontes and María Ventura

Catalysts 2024, 14(2), 146; https://doi.org/10.3390/catal14020146 - 16 Feb 2024

Cited by 1 | Viewed by 2099

Abstract

Currently, many research projects are focused on the conversion of renewable raw materials into chemicals and fuels. Lignocellulosic biomass is a raw material used for the production of bio-oils and black liquors. These biomass-derived fractions offer promising paths for the production of valuable [...] Read more.

Currently, many research projects are focused on the conversion of renewable raw materials into chemicals and fuels. Lignocellulosic biomass is a raw material used for the production of bio-oils and black liquors. These biomass-derived fractions offer promising paths for the production of valuable chemical products. Various catalytic methods have been investigated for upgrading the biomass-derived fractions. Researchers are interested in the hydrodeoxygenation process (HDO); in this process, the oxygen groups are eliminated by breaking the C-O bonds and water as a product. Incorporating heterogeneous catalysts (i.e., noble metals, transition metals, and metal sulfides) improves this process. Most HDO review articles describe catalytic results for model phenolic compounds. However, there is also a need to investigate the catalytic activity of real biomass-derived fractions. This paper explains research results regarding the upgrading of lignin-derived fractions (i.e., black liquors) by HDO. The paper has been organized according to the type of heterogeneous catalyst and shows compelling results based on different experimental conditions. The final sections present an analysis of the documented results and outline perspectives about integrating lignin into the biorefinery framework. Full article

(This article belongs to the Special Issue New Advances in Metal Oxide Catalysts)

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17 pages, 4753 KiB

Open AccessFeature PaperArticle

Nickel-Based Single-Atom Alloys for Methane Dehydrogenation and the Effect of Subsurface Carbon: First-Principles Investigations

by Naiyuan Dong, Tanglaw Roman and Catherine Stampfl

Catalysts 2024, 14(2), 145; https://doi.org/10.3390/catal14020145 - 16 Feb 2024

Cited by 2 | Viewed by 1761

Abstract

Using ab initio calculations, the reaction path for methane dehydrogenation over a series of Ni-based single-atom alloys (Cu, Fe, Pt, Pd, Zn, Al) and the effect that subsurface carbon at the Ni(111) surface has on the reaction barriers are investigated. Due to the [...] Read more.

Using ab initio calculations, the reaction path for methane dehydrogenation over a series of Ni-based single-atom alloys (Cu, Fe, Pt, Pd, Zn, Al) and the effect that subsurface carbon at the Ni(111) surface has on the reaction barriers are investigated. Due to the well-known problem of coking for Ni-based catalysts, the adsorption and associated physical properties of 0.25 ML, 1.0 ML, and 2 ML of carbon on the Ni(111) surface of various sites are first studied. It is found that the presence of subsurface carbon reduces the stability of the intermediates and increases the reaction barriers, thus reducing the performance of the Ni(111) catalyst. The presence of Al, Zn, and Pt is found to reduce the barriers for the CH₄ → CH₃ + H and CH₃ → CH₂ + H (Pt); and CH → C + H (Al, Zn) reactions, while Ni(111) yields the lowest barriers for the CH₂ → CH + H reaction. These results thus suggest that doping the Ni surface with both Al or Zn atoms and Pt atoms, functioning as distinct active sites, may bring about an improved reactivity and/or selectivity for methane decomposition. Furthermore, the results show that there can be significant adparticle–adparticle interactions in the simulation cell, which affect the reaction energy diagram and thus highlight the importance of ensuring a common reference energy for all steps. Full article

(This article belongs to the Special Issue Application of Catalysts in CO₂ Capture, Production and Utilization)

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32 pages, 9982 KiB

Open AccessArticle

Preparation and Property Characterization of Eu₂SmSbO₇/ZnBiEuO₄ Heterojunction Photocatalysts and Photocatalytic Degradation of Chlorpyrifos under Visible Light Irradiation

by Jingfei Luan, Yichun Wang, Ye Yao, Liang Hao, Jun Li and Yu Cao

Catalysts 2024, 14(2), 144; https://doi.org/10.3390/catal14020144 - 15 Feb 2024

Cited by 1 | Viewed by 1571

Abstract

Eu₂SmSbO₇ and ZnBiEuO₄ were synthesized for the first time using the hydrothermal method. Eu₂SmSbO₇/ZnBiEuO₄ heterojunction photocatalyst (EZHP) was synthesized for the first time using the solvothermal method. The crystal cell parameter of Eu₂ [...] Read more.

Eu₂SmSbO₇ and ZnBiEuO₄ were synthesized for the first time using the hydrothermal method. Eu₂SmSbO₇/ZnBiEuO₄ heterojunction photocatalyst (EZHP) was synthesized for the first time using the solvothermal method. The crystal cell parameter of Eu₂SmSbO₇ was 10.5547 Å. The band gap width of Eu₂SmSbO₇ was measured and found to be 2.881 eV. The band gap width of ZnBiEuO₄ was measured and found to be 2.571 eV. EZHP efficiently degraded the pesticide chlorpyrifos under visible light irradiation (VLID). After VLID of 160 min, the conversion rate of the chlorpyrifos concentration reached 100%, while the conversion rate of the total organic carbon (TOC) concentration was 98.02% using EZHP. After VLID of 160 min, the photocatalytic degradation conversion rates of chlorpyrifos using EZHP were 1.13 times, 1.19 times, and 2.84 times those using Eu₂SmSbO₇, ZnBiEuO₄, and nitrogen-doped titanium dioxide (N-doped TiO₂), respectively. The photocatalytic activity could be ranked as follows: EZHP > Eu₂SmSbO₇ > ZnBiEuO₄ > N-doped TiO₂. The conversion rates of chlorpyrifos were 98.16%, 97.03%, 96.03%, and 95.06% for four cycles of experiments after VLID of 160 min using EZHP. This indicated that EZHP was stable and could be reused. In addition, the experiments with the addition of capture agents demonstrated that the oxidation removal ability of three oxidation free radicals for degrading chlorpyrifos obeyed the following order: hydroxyl radical > superoxide anion > holes. This study examined the intermediates of chlorpyrifos during the photocatalytic degradation of chlorpyrifos, and a degradation path was proposed, at the same time, the degradation mechanism of chlorpyrifos was revealed. This study provides a scientific basis for the development of efficient heterojunction photocatalysts. Full article

(This article belongs to the Topic New Materials and Advanced Applications in Photocatalysis)

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11 pages, 1445 KiB

Open AccessArticle

Hydrogenation of Styrene-Butadiene Rubber Catalyzed by Tris(triisopropylphosphine)hydridorhodium(I)

by Minghui Liu, Wenxin Li, Chengzhuo Zheng, Fei Yuan, Hui Wang, Chengdong Wang, Qinmin Pan and Garry L. Rempel

Catalysts 2024, 14(2), 143; https://doi.org/10.3390/catal14020143 - 13 Feb 2024

Viewed by 1837

Abstract

The hydrogenation of C=C bonds in styrene−butadiene rubber (SBR), catalyzed by RhH(P(i-Pr)₃)₃, was experimentally investigated. Tris(triisopropylphosphine)hydridorhodium(I), RhH(P(i-Pr)₃)₃ (i-Pr=CH(CH₃)₂) was prepared by using rhodium chloride (RhCl₃), tetrahydrofuran (THF), triisopropylphosphine (P(i-Pr)₃ [...] Read more.

The hydrogenation of C=C bonds in styrene−butadiene rubber (SBR), catalyzed by RhH(P(i-Pr)₃)₃, was experimentally investigated. Tris(triisopropylphosphine)hydridorhodium(I), RhH(P(i-Pr)₃)₃ (i-Pr=CH(CH₃)₂) was prepared by using rhodium chloride (RhCl₃), tetrahydrofuran (THF), triisopropylphosphine (P(i-Pr)₃) and a sodium mercury amalgam. The effect of catalyst/polymer ratio, reaction temperature, and hydrogen pressure on the reactivity of the catalytic system has been studied. The optimal experimental condition was obtained. The hydrogenated styrene-butadiene rubber (HSBR) was analyzed by FT-IR and ¹H-NMR. In the absence of any additives, the conversion of C=C bonds in SBR could easily reach 95% in a short period of time, and no obvious cross-linking was observed. The dynamic properties of SBR did not change after the hydrogenation of the unsaturated C=C bonds. A preliminary reaction mechanism was also proposed. This study provides a new route, not only for the chemical modification of SBR by using a rhodium complex but also for the hydrogenation of other unsaturated polymers, such as diene-based rubbers. Full article

(This article belongs to the Section Catalysis in Organic and Polymer Chemistry)

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14 pages, 4725 KiB

Open AccessCommunication

The Green Synthesis of Biodiesel via Esterification in Water Catalyzed by the Phosphotungstic Acid–Functionalized Hydrophobic MCM–41 Catalyst

by Dengke Li, Qinghao Shi, Fengbing Liang and Dexin Feng

Catalysts 2024, 14(2), 142; https://doi.org/10.3390/catal14020142 - 13 Feb 2024

Viewed by 1718

Abstract

Biodiesel is a non-toxic and environmentally friendly fuel that is made from renewable biological sources. It can replace petrochemical diesel and has very broad application prospects. However, the main raw materials in biodiesel are animal and plant oils, which present the problems of [...] Read more.

Biodiesel is a non-toxic and environmentally friendly fuel that is made from renewable biological sources. It can replace petrochemical diesel and has very broad application prospects. However, the main raw materials in biodiesel are animal and plant oils, which present the problems of high costs and a lack of resources. The current research primarily emphasizes the transesterification process, with comparatively less focus on the esterification of fatty acids. In this paper, a series of phosphotungstic acid (PTA)-functionalized hydrophobic MCM–41 catalysts, OTS–PTA–MCM–41(C_x), were synthesized and used to catalyze the esterification of long-chain fatty acids with methanol in water. The experimental results show that the yield of esterification reached a maximum when catalyzed by OTS–PTA–MCM–41(C_x) and synthesized with a template agent with two carbon atoms less than the number of carbon atoms of a fatty acid. The effects of different reaction variables were investigated to optimize the reaction conditions for the maximum conversion. The stability of the catalyst was also verified. Finally, a mixed catalyst was used to catalyze in situ the esterification of fatty acids in a fermentation broth, which reached a high level (close to 90%). This paper provides references for the synthesis of a hydrophobic solid acid catalyst and green synthesis by esterification reactions in an aqueous solution and a fermentation broth system. Full article

(This article belongs to the Section Catalytic Materials)

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26 pages, 5714 KiB

Open AccessReview

Influence of Impurities in the Chemical Processing Chain of Biomass on the Catalytic Valorisation of Cellulose towards γ-Valerolactone

by Preeti Kashyap, Magdalena Brzezińska, Nicolas Keller and Agnieszka M. Ruppert

Catalysts 2024, 14(2), 141; https://doi.org/10.3390/catal14020141 - 12 Feb 2024

Cited by 1 | Viewed by 2633

Abstract

The conversion of lignocellulosic biomass to valuable chemicals such as levulinic acid and γ-valerolactone is a promising approach for achieving a sustainable circular economy. However, the presence of impurities during the stepwise chemical processing chain of the biomass feedstock can significantly impact both [...] Read more.

The conversion of lignocellulosic biomass to valuable chemicals such as levulinic acid and γ-valerolactone is a promising approach for achieving a sustainable circular economy. However, the presence of impurities during the stepwise chemical processing chain of the biomass feedstock can significantly impact both the hydrolysis and hydrogenation steps implemented to convert the cellulosic feedstock to levulinic acid and further to γ-valerolactone, respectively. This review article explores the effects of those impurities by classifying them into two groups, namely endogenous and exogenous types, based on whether they originate directly from the raw lignocellulosic biomass or arise during its multi-step chemical processing. Endogenous impurities include heavy metals, alkali metals, alkaline earth metals, proteins, and side products from the downstream treatment of cellulose, while exogenous impurities are introduced during physical pre-treatments such as ball milling or during the hydrolysis step, or they might originate from the reactor setup. The specific catalyst deactivation by carbonaceous species such as humins and coke is considered. The mechanisms of impurity-induced catalyst deactivation and by-product formation are thoroughly discussed. Additionally, strategies for minimizing the detrimental effects of impurities on biomass conversion and enhancing catalytic efficiency and stability are also proposed. Full article

(This article belongs to the Section Biomass Catalysis)

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3 pages, 169 KiB

Open AccessEditorial

Gold, Silver and Copper Catalysis

by Sónia Alexandra Correia Carabineiro

Catalysts 2024, 14(2), 140; https://doi.org/10.3390/catal14020140 - 10 Feb 2024

Cited by 1 | Viewed by 1520

Abstract

In terms of catalysis, the exploration of novel materials and innovative methodologies continues to drive the field forward, offering solutions to pressing challenges in various industrial applications [...] Full article

(This article belongs to the Special Issue Gold, Silver and Copper Catalysis)

11 pages, 5920 KiB

Open AccessArticle

The Regeneration of Dolomite as a Heterogeneous Catalyst for Biodiesel Production

by Rasa Šlinkšienė, Rasa Paleckienė, Ieva Gaidė, Violeta Makarevičienė and Eglė Sendžikienė

Catalysts 2024, 14(2), 139; https://doi.org/10.3390/catal14020139 - 10 Feb 2024

Viewed by 1515

Abstract

Dolomite as a heterogeneous catalyst can be used in biodiesel synthesis. Process material costs can be reduced by regenerating and reusing the catalyst. Two methods of regeneration of dolomite were studied: (1) washing for 30 min with methanol, filtration, and washing for 30 [...] Read more.

Dolomite as a heterogeneous catalyst can be used in biodiesel synthesis. Process material costs can be reduced by regenerating and reusing the catalyst. Two methods of regeneration of dolomite were studied: (1) washing for 30 min with methanol, filtration, and washing for 30 min with hexane and (2) calcination at high temperature. Catalytic efficiency and catalyst changes after 1–6 cycles were evaluated. X-ray, FTIR, and SEM studies were performed. Calcination has been found to be a more effective method of catalyst regeneration than washing with solvents. The catalytic effectiveness of dolomite only slightly decreased over six application cycles. The results of the instrumental analysis showed that the structure and composition of the dolomite do not change during calcination after three cycles, while obvious changes in the structure of dolomite during catalyst washing were observed. Full article

(This article belongs to the Section Biomass Catalysis)

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14 pages, 3777 KiB

Open AccessFeature PaperArticle

Regulating the Hydrodeoxygenation Activity of Molybdenum Carbide with Different Diamines as Carbon Sources

by Linyuan Zhou, Huiru Yang, Xiangze Du and Changwei Hu

Catalysts 2024, 14(2), 138; https://doi.org/10.3390/catal14020138 - 10 Feb 2024

Viewed by 1559

Abstract

The hydrodeoxygenation (HDO) of renewable fats or fatty acids into alkanes is a powerful measure to address energy and environmental crises. Molybdenum carbide-based catalysts are promising due to their platinum-like noble metal electronic properties. In this paper, Mo₂C catalysts were prepared [...] Read more.

The hydrodeoxygenation (HDO) of renewable fats or fatty acids into alkanes is a powerful measure to address energy and environmental crises. Molybdenum carbide-based catalysts are promising due to their platinum-like noble metal electronic properties. In this paper, Mo₂C catalysts were prepared by one-step carbonization of amine molybdenum oxide (AMO) precursors using diamines with different carbon chain lengths as ligands. The physical and chemical properties and the HDO catalytic activity of the catalysts were investigated. The results indicate that as the carbon chain of diamines in the precursor increases, the carbon content of the catalysts in the surface and bulk phase increases. The Mo₂C-12 catalyst exhibited excellent catalytic performance, with a palmitic acid conversion rate of 100% and an alkane selectivity of 96.6%, which are attributed to the smallest particle size, largest pore size, and synergistic effect of carbon. This work provides a simple and safe method for regulating the surface properties of Mo₂C catalysts. Full article

(This article belongs to the Section Environmental Catalysis)

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24 pages, 2405 KiB

Open AccessFeature PaperReview

Advanced Technologies Conciliating Desulfurization and Denitrogenation to Prepare Clean Fuels

by Rui G. Faria, Dinis Silva, Fátima Mirante, Sandra Gago, Luís Cunha-Silva and Salete S. Balula

Catalysts 2024, 14(2), 137; https://doi.org/10.3390/catal14020137 - 9 Feb 2024

Cited by 4 | Viewed by 3068

Abstract

The removal of sulfur- and nitrogen-containing compounds present in fuels is and will be crucial to accomplish actual strict regulations to avoid environmental and humanity health adversities. The conventional hydrodesulfurization and hydrodenitrogenation processes conducted by refineries are limited due to severe operating conditions, [...] Read more.

The removal of sulfur- and nitrogen-containing compounds present in fuels is and will be crucial to accomplish actual strict regulations to avoid environmental and humanity health adversities. The conventional hydrodesulfurization and hydrodenitrogenation processes conducted by refineries are limited due to severe operating conditions, and even more importantly, they are inefficient for simultaneously removing nitrogen- and sulfur-containing compounds in fuels. On the other hand, non-hydrogen technologies are beneficial in terms of mild operating conditions, and during the last two decades, some successful works have shown that these can be highly effective at efficiently removing both sulfur- and nitrogen-containing compounds from liquid fuels. For more than four decades, extensive research (thousands of publications since the 1980s) has been dedicated to developing remote desulfurization technologies without taking into consideration the presence of a complex fuel matrix, or even taking into account the presence of other harmful pollutant elements, such as nitrogen. Even more recently, several effective non-hydrogen denitrogenation processes have been reported without considering the presence of sulfur compounds. This review paper is a reflection on the limited work that has been successfully performed to simultaneously remove sulfur- and nitrogen-containing compounds from fuels. An evaluation of different methodologies (adsorption, extraction, oxidative (photo)catalysis, ultrasound-assisted oxidation) is presented here. Furthermore, this review intends to define new future strategies that will allow the design of more suitable and economical technologies, effectively conciliating desulfurization and denitrogenation processes to produce more sustainable fuels. Full article

(This article belongs to the Special Issue Designing Catalytic Desulfurization Processes to Prepare Clean Fuels, 2nd Edition)

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22 pages, 10846 KiB

Open AccessArticle

Cobalt–Magnesium Oxide Catalysts for Deep Oxidation of Hydrocarbons

by Magira Zhylkybek, Bolatbek Khussain, Alexandr Sass, Ivan Torlopov, Tolkyn Baizhumanova, Svetlana Tungatarova, Alexandr Brodskiy, Galina Xanthopoulou, Kenzhegul Rakhmetova, Rabiga Sarsenova, Kaysar Kassymkan and Yermek Aubakirov

Catalysts 2024, 14(2), 136; https://doi.org/10.3390/catal14020136 - 9 Feb 2024

Cited by 1 | Viewed by 1729

Abstract

Co–Mg catalysts for methane combustion were synthesized and studied, revealing the transformation of MgCo₂O₄ spinel into a CoO–MgO solid solution with oxygen release from the spinel lattice as the calcination temperature increased. Repeated heat treatment of the calcined solid solution [...] Read more.

Co–Mg catalysts for methane combustion were synthesized and studied, revealing the transformation of MgCo₂O₄ spinel into a CoO–MgO solid solution with oxygen release from the spinel lattice as the calcination temperature increased. Repeated heat treatment of the calcined solid solution at lower temperatures led to spinel regeneration with segregation of the solid solution phase. A TPR of the samples showed the presence of two characteristic peaks, the first of which relates to the transition of Co³⁺_Oh spinel to the Co²⁺_Oh structure of CoO, and the second to the reduction of CoO to Co°. The second peak was observed at 540–620 °C for samples calcined at temperatures below spinel decomposition, and for high-temperature samples at 900–1100 °C. Taking into account the identity of the structure of phases obtained in both cases, the formation of not a true CoO–MgO solid solution, but rather a mixture of ordered oxides (“pseudo-solid solution”) in the low-temperature region, was postulated. A study of the activity of the samples showed the high activity of the spinel systems and a linear relationship between the activation energy of methane oxidation and the heat treatment temperature. Full article

(This article belongs to the Special Issue Synthesis and Application of Catalytic Materials in Energy and Environment, 2nd Edition)

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14 pages, 2639 KiB

Open AccessArticle

Modification of SmMn₂O₅ Catalyst with Silver for Soot Oxidation: Ag Loading and Metal–Support Interactions

by Baofang Jin, Yuxin Liu, Yue Ma, Zhenguo Li, Kaixiang Li, Shuang Liu, Rui Ran and Xiaodong Wu

Catalysts 2024, 14(2), 135; https://doi.org/10.3390/catal14020135 - 9 Feb 2024

Cited by 2 | Viewed by 1542

Abstract

A series of Ag-modified manganese-mullite (SmMn₂O₅) catalysts with different Ag contents (1, 3, and 6 wt.%) were prepared via a citric acid sol–gel method for catalytic soot oxidation. The catalysts were characterized by powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), [...] Read more.

A series of Ag-modified manganese-mullite (SmMn₂O₅) catalysts with different Ag contents (1, 3, and 6 wt.%) were prepared via a citric acid sol–gel method for catalytic soot oxidation. The catalysts were characterized by powder X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Raman spectroscopy, transmission electron microscopy (TEM), high-resolution transmission electron microscopy analysis (HRTEM), X-ray photoelectron spectroscopy (XPS), and H₂ temperature-programmed reduction (H₂-TPR). The soot oxidation activity of the mullite was significantly promoted by the addition of silver and affected by the loading amount of the metal. Herein, the influences of silver loading on the metal size distribution and its interactions with the mullite were studied. Based on these characterizations, a possible soot oxidation reaction mechanism was proposed for silver-modified SmMn₂O₅. Full article

(This article belongs to the Section Industrial Catalysis)

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13 pages, 3500 KiB

Open AccessArticle

Catalytic Partial Oxidation of Methane to Methanol over Fe₂O₃/MWCNTs

by Zhengqing Zhou, Yinghua Zhang, Zhian Huang, Jia Liu, Jinguo Sang, Zuochun Luan, Wei Tian, Yukun Gao, Xingyu Zhang, Yucheng Ji and Tao Tang

Catalysts 2024, 14(2), 134; https://doi.org/10.3390/catal14020134 - 8 Feb 2024

Cited by 1 | Viewed by 1800

Abstract

The catalytic partial oxidation of methane (CPOM) to methanol has been regarded as a promising approach for methane utilization, despite that the conversion remains a formidable challenge in the perspective of catalysts. A novel catalyst system of multi-wall carbon nanotubes (MWCNTs) that supported [...] Read more.

The catalytic partial oxidation of methane (CPOM) to methanol has been regarded as a promising approach for methane utilization, despite that the conversion remains a formidable challenge in the perspective of catalysts. A novel catalyst system of multi-wall carbon nanotubes (MWCNTs) that supported Fe₂O₃ with existing I₂, consisting of non-noble metal and working in weak acid at an ambient temperature, was investigated for CPOM. MWCNTs supported the Fe₂O₃ catalyst, which was prepared by the impregnation method and characterized via HRTEM, XRD, XPS, FT-IR, and BET techniques. The characterization results reveal that, as a non-noble metal catalyst, the Fe₂O₃/MWCNTs catalyst had a good catalytic performance and stability in the CPOM. With the variation of reaction pressure and the dosage of Fe₂O₃/MWCNTs, the catalyst system obtained the highest methane conversion rate of 7.41% and methanol selectivity of 86.3%, which is analogous to that of the equivalently strong acid catalyst system. The I₂-Fe₂O₃/MWCNTs catalyst system has great potential in the application of CPOM under mild, environmentally benign conditions, such as non-noble metal requirement, ambient temperature, and weak acid. The reaction mechanism was discussed. Full article

(This article belongs to the Section Environmental Catalysis)

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13 pages, 3365 KiB

Open AccessArticle

Study on the Degradation Effect of Tetracycline Using a Co-Catalyst Loaded on Red Mud

by Yang Yue, Qu Wu, Chaofan Zheng, Yongjun Sun and Kinjal J. Shah

Catalysts 2024, 14(2), 133; https://doi.org/10.3390/catal14020133 - 8 Feb 2024

Cited by 2 | Viewed by 1446

Abstract

Red mud was modified by impregnation with Co element loading. The Co-RM catalyst was characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray fluorescence (XRF), and UV full-band scanning. The results showed that the modified Co-RM catalyst successfully loaded the Co [...] Read more.

Red mud was modified by impregnation with Co element loading. The Co-RM catalyst was characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), X-ray fluorescence (XRF), and UV full-band scanning. The results showed that the modified Co-RM catalyst successfully loaded the Co element and formed an irregular pore structure on the surface, thereby increasing the number of active sites of the red mud catalyst and effectively improving the degradation efficiency of tetracycline. Under the optimal conditions of a catalyst dosage of 0.3 g/L, a persulfate dosage of 3 g/L, a reaction temperature of 50 °C, and a pH value of 7, a removal rate of 50 mg/L of tetracycline can be achieved: 89.5% after 90 min. The effects of common anions and humic acids in water, as well as radical quenchers (anhydrous ethanol and tert-butanol), on the degradation of tetracycline were investigated. The results showed that Cl⁻, CO₃²⁻, HCO₃⁻, H₂PO₄⁻, NO₃²⁻, HPO₄²⁻, and humic acids showed inhibitory effects on the degradation of tetracycline, while SO₄²⁻ showed a promoting effect on the degradation of tetracycline. The free radical quenching experiment showed that the most important free radicals that can degrade tetracycline in the system are sulfate radicals. Full article

(This article belongs to the Special Issue Heterogeneous Catalysts for Organic Wastewater Treatment)

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12 pages, 2760 KiB

Open AccessArticle

Forming a Cu-Based Catalyst for Efficient Hydrogenation Conversion of Starch into Glucose

by Shenghua Zhu, Jue Li, Fuchang Cheng and Jinghua Liang

Catalysts 2024, 14(2), 132; https://doi.org/10.3390/catal14020132 - 8 Feb 2024

Cited by 1 | Viewed by 1800

Abstract

A pellet-forming as-catalyst, CuO/Al₂O₃, was prepared by the precipitation–tablet molding method and characterized by the Brunner–Emmet–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) techniques and TEM. The characterization results showed that the formed [...] Read more.

A pellet-forming as-catalyst, CuO/Al₂O₃, was prepared by the precipitation–tablet molding method and characterized by the Brunner–Emmet–Teller (BET), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) techniques and TEM. The characterization results showed that the formed CuO/Al₂O₃ was in situ reduced to Cu/Al₂O₃ and Cu₂O/ Al₂O₃ catalysts in the reaction system. The catalytic performance of catalyzing hydrogenation starch into glucose was investigated in an autoclave over CuO/Al₂O₃. The yield of glucose reached 83.16% at a temperature of 160 °C, a pressure of 1.8 MPa, a 100 g starch solution of 15 wt%, a catalyst dosage of 2.25%, a reaction time of 4 h, and a rotational speed of 630 r/min. The reusability of the catalyst was evaluated, and the glucose yield did not decrease obviously even after being reused for five consecutive cycles. Starch was converted into glucose through the synergistic action of Cu⁺ and Cu⁰ catalysis. This work is expected to provide valuable insights into the design of catalysts and the hydrogenation process for efficient starch hydrogenation. Full article

(This article belongs to the Section Catalytic Materials)

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16 pages, 7713 KiB

Open AccessFeature PaperArticle

Improvement of NH₃-SCR Performance by Exposing Different Active Components in a VCeMn/Ti Catalytic System

by Shifei Gu, Chengheng Huang, Xiaorong Han, Qiuju Qin, Donghai Mo, Chen Li, Yuhua You, Lihui Dong and Bin Li

Catalysts 2024, 14(2), 131; https://doi.org/10.3390/catal14020131 - 7 Feb 2024

Viewed by 1423

Abstract

The physicochemical properties of active components play a key role in enhancing catalytic performance. In multi-component catalysts, different components offer a wide range of structural possibilities and catalytic potential. However, determining the role of specific components in enhancing efficiency may be blurry. This [...] Read more.

The physicochemical properties of active components play a key role in enhancing catalytic performance. In multi-component catalysts, different components offer a wide range of structural possibilities and catalytic potential. However, determining the role of specific components in enhancing efficiency may be blurry. This study synthetized a range of catalysts with various metal compositions on their external surfaces to investigate their catalytic activity on NH₃-SCR. The V/CeMn/Ti catalysts exhibited exceptional catalytic efficiency and strong tolerance to SO₂ during the SCR process. In the system, Mn and Ce facilitated electron transfer during the catalytic removal of NO_x. As an assisting agent, increased the number of active species and acidic sites, playing a crucial role in oxidizing NO to NO₂ and facilitating the denitrogenation reaction process at low temperatures. Further studies showed that the three ingredients exhibited unique adsorbent behaviors on the reacting gases, which provided different catalytic possibilities. This work modeled the particular catalysis of V and Ce (Mn) species, respectively, and offers experimental instruction for improving the activity and excellent tolerance to SO₂ by controlling active ingredients. Full article

(This article belongs to the Special Issue Rare Earth Catalysis: From Synthesis to Sustainable Applications)

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12 pages, 6434 KiB

Open AccessArticle

Regulating Lattice Oxygen on the Surfaces of Porous Single-Crystalline NiO for Stabilized and Enhanced CO Oxidation

by Xin Wen and Kui Xie

Catalysts 2024, 14(2), 130; https://doi.org/10.3390/catal14020130 - 7 Feb 2024

Viewed by 1497

Abstract

The long-range ordered lattice structure and interconnected porous microstructure of porous single crystals (PSCs) provide structural regularity and connectivity in remote electron movement to stabilize oxygen vacancies and activate lattice oxygen linked to surface active sites. In this work, we prepare NiO powder, [...] Read more.

The long-range ordered lattice structure and interconnected porous microstructure of porous single crystals (PSCs) provide structural regularity and connectivity in remote electron movement to stabilize oxygen vacancies and activate lattice oxygen linked to surface active sites. In this work, we prepare NiO powder, single-crystal (SC) NiO, and PSC NiO. NiO contains a significant amount of oxygen vacancies. We find that the structure of porous NiO can create more oxygen vacancies. We load Pt onto these NiO crystals by atomic layer deposition (ALD) to activate lattice oxygen on definite NiO surfaces. The results show that Pt-loaded NiO effectively exhibits CO oxidation performance, in which Pt-loaded PSC NiO completely oxidizes CO at 65 °C. With 1% CO fully adsorbed, the density of activate lattice oxygen becomes an essential factor affecting performance. PSC NiO with deposited Pt clusters exhibited stable CO oxidation catalysis when run in air at ~65 °C for 300 h. Full article

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23 pages, 7253 KiB

Open AccessArticle

Insight into the Catalytic Performance of a Zinc-Pillared Curcumin/Bentonite Composite for Enhanced Oxidation of Ibuprofen Residuals into Environmental Products: The Pathway and Toxicity

by Sarah I. Othman, Marwa H. Shemy, Haifa E. Alfassam, Haifa A. Alqhtani, Ahmed A. Allam, Mostafa R. Abukhadra and Stefano Bellucci

Catalysts 2024, 14(2), 129; https://doi.org/10.3390/catal14020129 - 7 Feb 2024

Cited by 1 | Viewed by 1590

Abstract

Environmental organo bentonite synthesis using curcumin-derived chemicals is used as catalyst support for zinc with a Zn-pillaring structure (Zn@CU/BEN). The obtained composite was assessed as an affordable, highly effective, and multifunctional photocatalyst for enhanced oxidation of ibuprofen (IBU) residuals in water supplies. The [...] Read more.

Environmental organo bentonite synthesis using curcumin-derived chemicals is used as catalyst support for zinc with a Zn-pillaring structure (Zn@CU/BEN). The obtained composite was assessed as an affordable, highly effective, and multifunctional photocatalyst for enhanced oxidation of ibuprofen (IBU) residuals in water supplies. The Zn@CU/BEN composite (0.4 g/L) displayed significant catalytic activities, resulting in the complete oxidation of IBU (25 mg/L) after 80 min. Then, the complete mineralization based on the full elimination of TOC content was recognized after 160 min, with significant indications about the formed intermediates. The identified intermediates, together with the identification of hydroxyl radicals as the essential oxidizing agent, declared an oxidation pathway of IBU over Zn@CU/BEN that involved three steps: hydroxylation, decarboxylation/demethylation, and ring-opening processes. The toxic properties of raw pollutants as well as the oxidizing product at different durations were assessed based on the cell viability results of kidney (HEK293T) and liver (HepG2) cell lines. The partially oxidized sample in the initial duration displayed a higher toxicity impact than the raw IBU. However, the treated sample after 160 min reflected high biosafety and non-toxic properties (cell viability > 97%). The synergetic impact of bentonite and bentonite organo-modified by curcumin extract reflects enhancements in the adsorption as well as the oxidation performance of pillared zinc as a catalyst. Full article

(This article belongs to the Topic Advanced Oxidation Processes for Wastewater Purification)

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