Catalysts

14 pages, 2688 KiB

Open AccessArticle

CO Oxidation over Cu/Ce Binary Oxide Prepared via the Solvothermal Method: Effects of Cerium Precursors on Properties and Catalytic Behavior

by Wen Jin, Yanmin Liu, Hongyan Xue, Jun Yu and Dongsen Mao

Catalysts 2024, 14(12), 856; https://doi.org/10.3390/catal14120856 - 25 Nov 2024

Abstract

Cu/Ce binary oxides were prepared via the one-pot solvothermal method, and the effects of different cerium precursors (cerium nitrate and cerium ammonium nitrate) on the catalytic activity and resistance to water vapor or CO₂ of the prepared samples for low-temperature CO oxidation [...] Read more.

Cu/Ce binary oxides were prepared via the one-pot solvothermal method, and the effects of different cerium precursors (cerium nitrate and cerium ammonium nitrate) on the catalytic activity and resistance to water vapor or CO₂ of the prepared samples for low-temperature CO oxidation reaction were investigated. The physicochemical characteristics of the catalysts were characterized via thermal analyses (TG-DSC), X-ray diffraction (XRD), Raman spectroscopy, N₂ adsorption/desorption, inductively coupled plasma-atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTs), and temperature-programmed reduction with H₂ (H₂-TPR). The results indicated that the CuO/CeO₂ catalyst (CC-N) prepared with cerium nitrate showed higher activity for low-temperature CO oxidation, which can be ascribed to its larger specific surface area and pore volume, higher amounts of highly dispersed CuO species with strong interaction with CeO₂, Cu⁺ species, and more active surface oxygen species, compared with the counterpart prepared with cerium ammonium nitrate (CC-NH). Furthermore, the CC-N catalyst also exhibited better resistance to CO₂ poisoning than CC-NH. Full article

(This article belongs to the Special Issue Featured Papers in “Environmental Catalysis” Section)

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21 pages, 2890 KiB

Open AccessFeature PaperReview

Visible-Light-Activated TiO₂-Based Photocatalysts for the Inactivation of Pathogenic Bacteria

by Farhana Haque, Allison Blanchard, Baileigh Laipply and Xiuli Dong

Catalysts 2024, 14(12), 855; https://doi.org/10.3390/catal14120855 - 25 Nov 2024

Abstract

Pathogenic bacteria in the environment pose a significant threat to public health. Titanium dioxide (TiO₂)-based photocatalysts have emerged as a promising solution due to their potent antimicrobial effects under visible light and their generally eco-friendly properties. This review focuses on the [...] Read more.

Pathogenic bacteria in the environment pose a significant threat to public health. Titanium dioxide (TiO₂)-based photocatalysts have emerged as a promising solution due to their potent antimicrobial effects under visible light and their generally eco-friendly properties. This review focuses on the antibacterial properties of visible-light-activated, TiO₂-based photocatalysts against pathogenic bacteria and explores the factors influencing their efficacy. Various TiO₂ modification strategies are discussed, including doping with non-metals, creating structure defects, combining narrow-banded semiconductors, etc., to extend the light absorption spectrum from the UV to the visible light region. The factors affecting bacterial inactivation, and the underlying mechanisms are elucidated. Although certain modified TiO₂ nanoparticles (NPs) show antibacterial activities in the dark, they exhibit much higher antibacterial efficacies under visible light, especially with higher light intensity. Doping TiO₂ with elements such as N, S, Ce, Bi, etc., or introducing surface defects in TiO₂ NPs without doping, can effectively inactivate various pathogenic bacteria, including multidrug-resistant bacteria, under visible light. These surface modifications are advantageous in their simplicity and cost-effectiveness in synthesis. Additionally, TiO₂ can be coupled with narrow-banded semiconductors, resulting in narrower band gaps and enhanced photocatalytic efficiency and antibacterial activities under visible light. This information aids in understanding the current technologies for developing visible-light-driven, TiO₂-based photocatalysts and their application in inactivating pathogenic bacteria in the environment. Full article

(This article belongs to the Special Issue Photocatalysis towards a Sustainable Future)

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14 pages, 3587 KiB

Open AccessReview

Progress in the Synthesis and Applications of C₃N₅-Based Catalysts in the Piezoelectric Catalytic Degradation of Organics

by Shupeng Yin, Huiguo Yu, Haifeng Fu, Yinglong Wang and Fanqing Meng

Catalysts 2024, 14(12), 854; https://doi.org/10.3390/catal14120854 - 25 Nov 2024

Abstract

Piezoelectric catalysis has shown great potential for application in green chemistry due to its “clean” properties. By applying external mechanical force, this method can induce rapid charge transfer, providing an important reaction pathway for carbon neutrality and carbon peaking. Carbon nitride (C₃ [...] Read more.

Piezoelectric catalysis has shown great potential for application in green chemistry due to its “clean” properties. By applying external mechanical force, this method can induce rapid charge transfer, providing an important reaction pathway for carbon neutrality and carbon peaking. Carbon nitride (C₃N₅)-based catalysts, as a novel material, have received widespread attention for their synthesis and application in the piezoelectric catalytic degradation of organic compounds. This review summarizes the latest research progress of C₃N₅-based catalysts, covering their applications in environmental governance and resource utilization, including the removal of organic pollutants in water. We focused on the synthesis strategy, characterization methods, and application progress of C₃N₅-based catalysts in the degradation of organic pollutants. The quantitative results show that some C₃N₅-based catalysts had removal efficiencies of over 85% in the treatment of specific pollutants. In addition, this article also discusses the piezoelectric effect and its degradation mechanism, providing direction for future research. Finally, the application prospects and potential development directions of C₃N₅-based catalysts in environmental governance are discussed. Full article

(This article belongs to the Section Catalytic Materials)

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11 pages, 962 KiB

Open AccessFeature PaperArticle

Analysis of Reaction Conditions in Palmitic Acid Deoxygenation for Fuel Production

by Karoline K. Ferreira, Lucília S. Ribeiro and Manuel Fernando R. Pereira

Catalysts 2024, 14(12), 853; https://doi.org/10.3390/catal14120853 - 24 Nov 2024

Abstract

The development of effective catalytic systems for deoxygenation reactions is critical to the conversion of renewable feedstocks into sustainable fuels. In this work, the influence of various reaction parameters on the conversion of palmitic acid into alkanes, such as temperature, stirring rate, reaction [...] Read more.

The development of effective catalytic systems for deoxygenation reactions is critical to the conversion of renewable feedstocks into sustainable fuels. In this work, the influence of various reaction parameters on the conversion of palmitic acid into alkanes, such as temperature, stirring rate, reaction time, H₂ pressure, amount of catalyst and substrate concentration was evaluated using the commercial Co-Mo/Al₂O₃ catalyst. In parallel, bimetallic Co-Mo catalysts supported on carbon nanotubes (CNTs) were prepared and characterized using various techniques, and their catalytic performance was assessed under the optimized conditions. The results showed that palmitic acid can be efficiently converted at 350 °C for 6 h at 30 bar H₂ pressure, stirring at 150 rpm and using 0.25 g of catalyst and 0.50 g of palmitic acid in 50 mL of n-decane. Under these conditions, a complete substrate conversion and yields of 89.4 and 4.8% of C₁₆ and C₁₅ were achieved. In addition, Co-Mo/CNT_ox presented a similar catalytic performance as the commercial one, with a final result of 90.9% yield in C₁₆. These findings point out the potential of using Co-Mo/CNT_ox as a competitive alternative to liquid fuel production. Full article

(This article belongs to the Special Issue Topical Advisory Panel Members' Collection Series: Biomass Catalytic Conversion)

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15 pages, 5385 KiB

Open AccessArticle

The Synergistic Effect of Pore Architect and Reducibility in Ceria-Promoted Ni Molecular Sieve for Methane Dry Reforming

by Norah Alwadai, Abdulaziz A. M. Abahussain, Vijay Kumar Shrivastava, Salma A. Al-Zahrani, Anis H. Fakeeha, Naif Alarifi, Mohammed O. Bayazed, Khaled M. Banabdwin, Rawesh Kumar and Ahmed Al-Fatesh

Catalysts 2024, 14(12), 852; https://doi.org/10.3390/catal14120852 - 24 Nov 2024

Abstract

Methane and carbon dioxide, the primary contributors to global warming, are now at critical levels, threatening the extinction of numerous organisms on our planet. In this regard, dry reforming of methane reactions have gained considerable attention because of the conversion capacity of CH [...] Read more.

Methane and carbon dioxide, the primary contributors to global warming, are now at critical levels, threatening the extinction of numerous organisms on our planet. In this regard, dry reforming of methane reactions have gained considerable attention because of the conversion capacity of CH₄ and CO₂ into synthetic/energy-important syngas (H₂ and CO). Herein, a molecular sieve (CBV3024E; SiO₂/Al₂O₃ = 30) with ZSM-8-type pore architect, is utilized as the support for the active site of Ni and Ce promoters. Catalysts are characterized by surface area and porosity, X-ray diffraction study, Raman and infrared spectroscopy, thermogravimetry analysis, and temperature-programmed reduction/desorption techniques. A total of 2 wt.% ceria is added over 5Ni/CBV3024E to induce the optimum connectivity of aluminum in the silicate framework. NiO residing in these porous cages are mostly under “prominent interaction with support” which is reduced easily into metallic Ni as the active sites for DRM reactions. The active sites over 5Ni2Ce/CBV3024E remain stable during the DRM reaction and achieve ~58% H₂ yield after 300 min TOS at 42,000 mL/(g_cat.h) GHSV and ~70% H₂ yield after 20 h at 26,000 mL/(g_cat.h) GHSV. The high activity after a longer time stream justifies using CBV3024E molecular sieves as the support and ceria as the promoter for Ni-based catalyst towards the DRM reaction. Full article

(This article belongs to the Special Issue Advances in Catalytic Dry Reforming of Methane)

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17 pages, 4225 KiB

Open AccessArticle

Impact of Ga, Sr, and Ce on Ni/DSZ95 Catalyst for Methane Partial Oxidation in Hydrogen Production

by Salma A. Al-Zahrani, Omer Bellahwel, Ahmed Aidid Ibrahim, Mohammed F. Alotibi, Najat Masood, Sahar Y. Rajeh, Ahmed Al Otaibi, Hessah Difallah A. Al-Enazy and Ahmed S. Al-Fatesh

Catalysts 2024, 14(12), 851; https://doi.org/10.3390/catal14120851 - 24 Nov 2024

Abstract

The greenhouse gas CH₄ is more potent than CO_2, although both these gases are solely responsible for global warming. The efficient catalytic conversion of CH₄ into hydrogen-rich syngas, which also demonstrates economic viability, can deplete the concentration of CH₄ [...] Read more.

The greenhouse gas CH₄ is more potent than CO_2, although both these gases are solely responsible for global warming. The efficient catalytic conversion of CH₄ into hydrogen-rich syngas, which also demonstrates economic viability, can deplete the concentration of CH₄. This study examines the partial oxidation of methane (POM) prepared by the wetness impregnation process using 5% Ni supported over DSZ95 (93.3% ZrO₂ + 6.7% Sc₂O₃) and promoted with 1% Ga (gallium), 1% Sr (strontium), and 1% Ce (cerium). These catalysts are characterized by surface area porosity, X-ray diffraction, FT-Infrared spectroscopy, Raman infrared spectroscopy, temperature programmed reduction, CO₂ temperature-programmed techniques, desorption techniques, thermogravimetry, and transmission electron microscopy. The characterization results demonstrate that Ni is appropriate for the POM because of its crystalline structure, improved metal support contact, and increased thermal stability with Sr, Ce, and Ga promoters. The synthesized catalyst 5Ni+1Ga-DSZ95 maintained stability for 240 min on stream during the POM at 700 °C. Adding a 1% Ga promoter and active metal Ni to the DSZ95 improved the CH₄ conversion from 70.00% to 75.90% and raised the H₂ yield from 69.21% to 74.80%, while maintaining the reactants’ stoichiometric ratio of (CH₄:O₂ = 2:1). The 5Ni+1Ga-DSZ95 catalyst is superior to the other catalysts, given its rich catalyst surface, strong metal support interaction, high surface area and low amount of carbon deposit. The high H₂/CO ratio (>2.6) and H₂ yield close to 75% indicate that 5Ni+1Ga-DSZ95 is a potent industrial catalyst for hydrogen-rich syngas production through partial oxidation of methane. Full article

(This article belongs to the Special Issue Advances in Catalytic Dry Reforming of Methane)

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18 pages, 5357 KiB

Open AccessArticle

FeCo Alloy-Decorated Proton-Conducting Perovskite Oxide as an Efficient and Low-Cost Ammonia Decomposition Catalyst

by Xueyan Zhao, Qingfeng Teng, Haoliang Tao, Wenqiang Tang, Yiwei Chen, Bofang Zhou, Junkang Sang, Senrui Huang, Wanbing Guan, Hua Li and Liangzhu Zhu

Catalysts 2024, 14(12), 850; https://doi.org/10.3390/catal14120850 - 23 Nov 2024

Abstract

Ammonia is known as an alternative hydrogen supplier because of its high hydrogen content and convenient storage and transport. Hydrogen production from ammonia decomposition also provides a source of hydrogen for fuel cells. While catalysts composed of ruthenium metal atop various support materials [...] Read more.

Ammonia is known as an alternative hydrogen supplier because of its high hydrogen content and convenient storage and transport. Hydrogen production from ammonia decomposition also provides a source of hydrogen for fuel cells. While catalysts composed of ruthenium metal atop various support materials have proven to be effective for ammonia decomposition, non-precious-metal-based catalysts are attracting more attention due to desires to reduce costs. We prepared a series of Fe, Co, Ni, Mn, and Cu monometallic catalysts and their alloys as catalysts over proton-conducting ceramics via the impregnation method as precious-metal-free ammonia decomposition catalysts. While Co and Ni showed superior performance compared to Fe, Mn, and Cu on a BaZr_0.1Ce_0.₇Y_0.1Yb_0.1O_3−б(BZCYYb) support as an ammonia decomposition catalyst, the cost of Fe is much lower than that of other metals. Alloying Fe with Co can significantly increase the conversion and stability and lower the overall cost of materials. The measured ammonia decomposition rate of FeCo/BZCYYb reached 100% at 600 °C, and the ammonia decomposition rate was almost unchanged during the long-term test of 200 h, which reveals its good catalytic activity for ammonia decomposition and thermal stability. When the metallic catalyst remained unchanged, BZCYYb also exhibited better performance compared to other commonly used oxide supports. Finally, when ammonia cracked using our alloy catalyst was fed to solid oxide fuel cells (SOFCs), the peak power densities were very close to that achieved with a simulated fully cracked gas stream, i.e., 75% H₂ + 25% N₂, thus proving the effectiveness of this new type of ammonia decomposition catalyst. Full article

(This article belongs to the Section Catalytic Materials)

13 pages, 3847 KiB

Open AccessArticle

Preparation and Electrocatalytic Properties of One-Dimensional Nanorod-Shaped N, S Co-Doped Bimetallic Catalysts of FeCuS-N-C

by Hong Shi, Lina Wu, Qi Zhang, Yizhou Zhang, Wentao Sun, Chunbo Liu and Rongxian Zhang

Catalysts 2024, 14(12), 849; https://doi.org/10.3390/catal14120849 - 23 Nov 2024

Abstract

Metal air batteries have gradually attracted public attention due to their advantages such as high power density, high energy density, high energy conversion efficiency, and clean and green products. Reasonable design of oxygen reduction reaction (ORR) catalysts with high cost-effectiveness, high activity, and [...] Read more.

Metal air batteries have gradually attracted public attention due to their advantages such as high power density, high energy density, high energy conversion efficiency, and clean and green products. Reasonable design of oxygen reduction reaction (ORR) catalysts with high cost-effectiveness, high activity, and high stability is of great significance. Metal organic frameworks (MOFs) have the advantages of large specific surface area, high porosity, and designability, which make them widely used in many fields, especially in catalysis. This paper starts with regulating and optimizing the composition and structure of MOFs. A series of N, S co-doped electrocatalysts FeCuS-N-C were prepared by two high-temperature pyrolysis processes using N-doped carbon hollow nanorods derived from ZIF-8 as the substrate. The one-dimensional nanorod material derived from this MOF exhibits excellent electrocatalytic ORR performance (Eonset = 0.998 V, E_1/2 = 0.874 V). When used as the air cathode catalyst for zinc air batteries and assembled into liquid ZABs, the battery discharge curve was calculated and found to have a maximum power density of 142.7 mW cm⁻², a specific capacity of 817.1 mAh gZn⁻¹, and a cycling stability test of over 400 h. This study provides an innovative approach for designing and optimizing non-precious metal catalysts for zinc air batteries. Full article

(This article belongs to the Special Issue Carbon-Based Catalysts and Electrocatalysts: Synthesis and Applications)

3 pages, 150 KiB

Open AccessEditorial

Editorial: Noble Metal-Based Nanomaterials for Heterogeneous Catalysis

by Menggang Li, Shuo Geng and Manyi Gao

Catalysts 2024, 14(12), 848; https://doi.org/10.3390/catal14120848 - 23 Nov 2024

Abstract

As is well known, precious metal catalysts can be widely used in fields such as environmental protection, energy conversion, food processing, petrochemicals, and fine chemicals due to their unique intrinsic properties and irreplaceable catalytic activities [...] Full article

(This article belongs to the Special Issue Noble Metal-Based Nanomaterials for Heterogeneous Catalysis)

15 pages, 1855 KiB

Open AccessFeature PaperArticle

Mechanistic and Kinetic Analysis of Complete Methane Oxidation on a Practical PtPd/Al₂O₃ Catalyst

by Min Wang, Hai-Ying Chen, Yuliana Lugo-Jose, Joseph M. Fedeyko, Todd J. Toops and Jacqueline Fidler

Catalysts 2024, 14(12), 847; https://doi.org/10.3390/catal14120847 - 23 Nov 2024

Abstract

A PtPd/Al₂O₃ catalyst developed for the complete oxidation of methane from the ventilation air of underground coal mines is compared against a model PdO/Al₂O₃ catalyst. Although the PtPd/Al₂O₃ catalyst is substantially more active and [...] Read more.

A PtPd/Al₂O₃ catalyst developed for the complete oxidation of methane from the ventilation air of underground coal mines is compared against a model PdO/Al₂O₃ catalyst. Although the PtPd/Al₂O₃ catalyst is substantially more active and stable than the model catalyst, the nature of active sites between the two catalysts is deemed to be fundamentally the same based on their response to different feed gas compositions and the evolution of surface CO adsorption complexes during time-resolved CO adsorption DRIFTS experiment. For both catalysts, coordinatively unsaturated Pd sites are considered the active centers for methane activation and the subsequent oxidation reaction. H₂O competes with CH₄ for the same active sites, resulting in severe inhibition. Additionally, the CH₄ oxidation reaction also causes self-inhibition. Taking both inhibition effects into consideration, a relatively simple kinetic model is developed. The model provides a good fit of the 72 sets of kinetic data collected on the PtPd/Al₂O₃ catalyst under practically relevant reaction conditions with CH₄ concentration in the range of 0.05–0.4%, H₂O concentration of 1.0–5.0%, and reaction temperatures of 450–700 °C. Kinetic parameters based on the model suggest that the CH₄ activation energy on the PtPd/Al₂O₃ catalyst is 96.7 kJ/mol, and the H₂O adsorption energy is −31.0 kJ/mol. Both values are consistent with the parameters reported in the literature. The model can be used to develop catalyst sizing guidelines and be incorporated into the control algorithm of the catalytic system. Full article

(This article belongs to the Special Issue Catalysts for Water and Air Pollution Control: Present and Future, 2nd Edition)

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14 pages, 4643 KiB

Open AccessArticle

Degradation of Tetracycline (TC) by ZrO₂-3DG/PMS System: Revealing the Role of Defects in the Conditions of Light Irradiation and Sulfate Accumulation

by Jixiang Duan, Xin Wang, Zhihong Ye and Fuming Chen

Catalysts 2024, 14(12), 846; https://doi.org/10.3390/catal14120846 - 23 Nov 2024

Abstract

The application of advance oxidation processes (AOPs) based on the activation of peroxymonosulfate (PMS) is a great concern for wastewater treatment. Herein, ZrO₂-3DG was constructed using a hydrothermal method for the degradation of tetracycline (TC) with PMS. The defective ZrO₂ [...] Read more.

The application of advance oxidation processes (AOPs) based on the activation of peroxymonosulfate (PMS) is a great concern for wastewater treatment. Herein, ZrO₂-3DG was constructed using a hydrothermal method for the degradation of tetracycline (TC) with PMS. The defective ZrO₂-3DG materials were also prepared with plasma treatment. SEM and XPS results show that the ZrO₂-3DG composite and the corresponding defective materials were successfully fabricated. The ZrO₂ particles are distributed uniformly on the substrate material. Plasma can induce defects on the composite materials and create highly active sites. TC degradation results show that the ZrO₂-3DG/PMS system can achieve a degradation efficiency of 92.9% for TC. The influences of defects on materials, light irradiation and sulfate accumulation were investigated. It has been found that defects can induce an inhibiting effect on the degradation process, which can be tuned by plasma time. The defective ZrO₂-3DG/PMS system exhibits excellent resistance to the accumulation of sulfate, even showing enhanced degradation performances in specific conditions. The light irradiation has led to a higher degradation efficiency with the accumulation of sulfate compared with a dark environment. These findings give great guidance to the application of the ZrO₂-3DG/PMS system for environmental protection. Full article

(This article belongs to the Special Issue Catalysts for Water and Air Pollution Control: Present and Future, 2nd Edition)

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28 pages, 5335 KiB

Open AccessReview

Proton-Exchange Membrane Electrolysis for Green Hydrogen Production: Fundamentals, Cost Breakdown, and Strategies to Minimize Platinum-Group Metal Content in Hydrogen Evolution Reaction Electrocatalysts

by Henrique F. Araújo, Julián A. Gómez and Diogo M. F. Santos

Catalysts 2024, 14(12), 845; https://doi.org/10.3390/catal14120845 - 22 Nov 2024

Abstract

Green hydrogen (H₂) has emerged as a promising energy carrier for decarbonizing the industrial, building, and transportation sectors. However, current green H₂ production technologies face challenges that limit cost reduction and scaling up. Platinum-group metals (PGMs), including platinum and iridium, [...] Read more.

Green hydrogen (H₂) has emerged as a promising energy carrier for decarbonizing the industrial, building, and transportation sectors. However, current green H₂ production technologies face challenges that limit cost reduction and scaling up. Platinum-group metals (PGMs), including platinum and iridium, present exceptional electrocatalytic properties for water splitting, but their high cost is a significant barrier. This directly impacts the overall cost of electrolyzers, thus increasing green H₂ production costs. The present work covers the fundamentals of water electrolysis, the currently available technologies, focusing on proton-exchange membrane electrolyzers, and the critical role of electrocatalysts, discussing potential strategies for reducing the PGM content and, consequently, decreasing green H₂ cost. Full article

(This article belongs to the Special Issue Recent Advances in Energy-Related Materials in Catalysts, 2nd Edition)

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23 pages, 4722 KiB

Open AccessArticle

Iron Promoted TiO₂-Activated Carbon Nanocomposites for Photocatalytic Degradation of Congo Red in Water

by Daniela Negoescu, Veronica Bratan, Mihaela Gherendi, Irina Atkinson, Daniela C. Culita, Andreea Neacsu, Adriana Baran, Simona Petrescu and Viorica Parvulescu

Catalysts 2024, 14(12), 844; https://doi.org/10.3390/catal14120844 - 22 Nov 2024

Abstract

Nanocomposites containingTiO₂ and activated carbon were obtained by the sol-gel method in the presence of Brij 58 surfactant. The sample with a higher surface area (185.6 m²/g) was promoted with Fe by impregnating it with aqueous solution of Fe(NO₃ [...] Read more.

Nanocomposites containingTiO₂ and activated carbon were obtained by the sol-gel method in the presence of Brij 58 surfactant. The sample with a higher surface area (185.6 m²/g) was promoted with Fe by impregnating it with aqueous solution of Fe(NO₃)₃. The obtained iron loadings, measured using X-ray fluorescence, were 0.83%, 3.30% and 7.17%. TiO₂ anatase was identified in all the samples by X-ray diffraction and Raman spectroscopy, but the presence of iron oxides could not be detected. However, infrared spectroscopy indicated the existence of Fe-O and Fe-O-Ti bonds. X-ray photoelectron spectroscopy revealed the presence of Fe²⁺ for samples with a lower Fe content and a mixture of Fe²⁺ and Fe³⁺ in the sample with 7.17% Fe. UV-Vis and photoluminescence spectroscopy showed the presence of carbon and Fe alongside TiO₂. This combination led to new properties due to the generation of intermediate energy levels and defects, contributing to an enhancement in the photocatalytic performance. The highest photodegradation efficiency of Congo red in solution (84.46%) was obtained for the sample with 7.17% Fe under visible light irradiation and acidic conditions. The synergistic contribution of dye adsorption and photodegradation was demonstrated, taking into account ZPC values of nanocomposites. Kinetic studies were completed with reaction mechanisms based on the results obtained in the presence of scavengers. Full article

(This article belongs to the Special Issue Photocatalysts for Efficient Removal of Dyes from Industrial Effluents: Prospects and Challenges)

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14 pages, 4037 KiB

Open AccessFeature PaperArticle

Hydrogen and Oxygen Evolution on Flexible Catalysts Based on Nickel–Iron Coatings

by Dmytro Shyshkin, Loreta Tamašauskaitė-Tamašiūnaitė, Dijana Šimkūnaitė, Aldona Balčiūnaitė, Zita Sukackienė, Jūratė Vaičiūnienė, Birutė Šimkūnaitė-Stanynienė, Antanas Nacys and Eugenijus Norkus

Catalysts 2024, 14(12), 843; https://doi.org/10.3390/catal14120843 - 22 Nov 2024

Abstract

The electrolysis of water is one of low-cost green hydrogen production technologies. The main challenge regarding this technology is designing and developing low-cost and high-activity catalysts. Herein, we present a strategy to fabricate flexible electrocatalysts based on nickel–iron (NiFe) alloy coatings. NiFe coatings [...] Read more.

The electrolysis of water is one of low-cost green hydrogen production technologies. The main challenge regarding this technology is designing and developing low-cost and high-activity catalysts. Herein, we present a strategy to fabricate flexible electrocatalysts based on nickel–iron (NiFe) alloy coatings. NiFe coatings were plated on the flexible copper-coated polyimide surface (Cu/PI) using the low-cost and straightforward electroless metal-plating method, with morpholine borane as a reducing agent. It was found that Ni₉₀Fe₁₀, Ni₈₀Fe₂₀, Ni₆₀Fe₄₀, and Ni₃₀Fe₇₀ coatings were deposited on the Cu/PI surface; then, the concentration of Fe²⁺ in the plating solution was 0.5, 1, 5, and 10 mM, respectively. The morphology, structure, and composition of Ni_xFe_y/Cu/PI catalysts have been examined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and inductively coupled plasma–optical emission spectroscopy (ICP-OES), whereas their activity has been investigated for hydrogen evolution (HER) and oxygen evolution (OER) reactions in 1 M KOH using linear sweep voltammetry (LSVs). It was found that the Ni₈₀Fe₂₀/Cu/PI catalyst exhibited the lowest overpotential value of −202.7 mV for the HER, obtaining a current density of 10 mA cm⁻² compared to Ni₉₀Fe₁₀/Cu/PI (−211.9 mV), Ni₆₀Fe₄₀/Cu/PI (−276.3 mV), Ni₃₀Fe₇₀/Cu/PI (−278.4 mV), and Ni (−303.4 mV). On the other hand, the lowest OER overpotential (344.7 mV) was observed for the Ni₆₀Fe₄₀/Cu/PI catalyst, obtaining a current density of 10 mA cm⁻² compared to the Ni₃₅Fe₆₅ (369.9 mV), Ni₈₀Fe₂₀ (450.2 mV), and Ni₉₀Fe₁₀ (454.2 mV) coatings, and Ni (532.1 mV). The developed Ni₆₀Fe₄₀/Cu/PI catalyst exhibit a cell potential of 1.85 V at 10 mA cm⁻². The obtained catalysts seem to be suitable flexible catalysts for HER and OER in alkaline media. Full article

(This article belongs to the Section Catalytic Materials)

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19 pages, 2959 KiB

Open AccessArticle

A Green Chemistry Approach to Catalytic Synthesis of Ethyl Levulinate

by Martina Sušjenka, Fran Prašnikar, Martina Jakovljević Kovač, Maja Molnar, Luz Fernandes, Ana Vital Marques Nunes, Ana Rita Cruz Duarte and Małgorzata Ewa Zakrzewska

Catalysts 2024, 14(12), 842; https://doi.org/10.3390/catal14120842 - 21 Nov 2024

Abstract

Esterification of levulinic acid with ethanol was investigated using deep eutectic systems based on choline chloride and oxalic or p-toluenesulfonic acid as catalysts under conventional heating and alternative energy inputs, namely microwave, ultrasound, and mechanochemical treatment. The experiments were performed under varying operating [...] Read more.

Esterification of levulinic acid with ethanol was investigated using deep eutectic systems based on choline chloride and oxalic or p-toluenesulfonic acid as catalysts under conventional heating and alternative energy inputs, namely microwave, ultrasound, and mechanochemical treatment. The experiments were performed under varying operating conditions such as catalyst type and loading, alcohol to carboxylic acid molar ratio, temperature, or time. The obtained results demonstrate the overall better catalytic performance of the p-toluenesulfonic acid-based deep eutectic mixture in comparison with the oxalic acid-based analogue. The best results: levulinic acid conversion of 76% and 58%, for p-toluenesulfonic and oxalic acid containing deep eutectic systems, respectively, with 100% selectivity for both cases, were achieved for microwave-assisted synthesis with 5 wt.% of catalyst and excess alcohol to acid (molar ratio 5), at 413.15 K and for 10 min. The main advantage of all of the alternative activation methods studied (microwaves, ultrasounds, and ball mill processing) was the significant reduction in the reaction time. Full article

(This article belongs to the Special Issue Ionic Liquids and Eutectic Mixtures for Green Catalytic Processes)

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22 pages, 2578 KiB

Open AccessReview

Recent Advancements in Catalysts for Petroleum Refining

by Muhammad Saeed Akhtar, Sajid Ali and Wajid Zaman

Catalysts 2024, 14(12), 841; https://doi.org/10.3390/catal14120841 - 21 Nov 2024

Abstract

In petroleum refining, catalysts are used to efficiently convert crude oil into valuable products such as fuels and petrochemicals. These catalysts are employed in a range of processes, including catalytic cracking, hydrotreating, and reforming to meet stringent fuel quality standards. This review explores [...] Read more.

In petroleum refining, catalysts are used to efficiently convert crude oil into valuable products such as fuels and petrochemicals. These catalysts are employed in a range of processes, including catalytic cracking, hydrotreating, and reforming to meet stringent fuel quality standards. This review explores recent advancements in refining catalysts, focusing on novel materials, enhanced synthesis methods, and their industrial applications. The development of nano-, hierarchically structured, and supported metal catalysts has led to significant improvements in catalyst selectivity, yield, and longevity. These innovations are particularly important for processes such as hydrocracking, fluid catalytic cracking, and catalytic reforming, where catalysts improve conversion rates, product quality, and environmental sustainability. Advances in synthesis techniques such as sol-gel processes, microwave-assisted synthesis, and atomic layer deposition have further optimized catalyst performance. Environmental considerations have also driven the development of catalysts that reduce harmful emissions, particularly sulfur oxides and nitrogen oxides while promoting green catalysis through the use of bio-based materials and recyclable catalysts. Despite these advancements, challenges remain, particularly in scaling novel materials for industrial use and integrating them with existing technologies. Future research should focus on the exploration of new catalytic materials, such as metal-organic frameworks and multi-functional catalysts, which promise to further revolutionize the refining industry. This review thus demonstrates the transformative potential of advanced catalysts in enhancing the efficiency and environmental sustainability of petroleum refining. Full article

(This article belongs to the Special Issue Feature Papers in "Industrial Catalysis" Section)

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14 pages, 2487 KiB

Open AccessArticle

Eco-Friendly Synthesis of Thiazole Derivatives Using Recyclable Cross-Linked Chitosan Hydrogel Biocatalyst Under Ultrasonic Irradiation as Anti-Hepatocarcinogenic Agents

by Sobhi M. Gomha, Nahed A. Abd El-Ghany, Manal S. Ebaid, Tariq Z. Abolibda, Magdi E. A. Zaki, Mohammad Alhilal, Suzan Alhilal and Nadia A. Mohamed

Catalysts 2024, 14(12), 840; https://doi.org/10.3390/catal14120840 - 21 Nov 2024

Abstract

In the current study, pyromellitimide benzoyl thiourea cross-linked chitosan (PIBTU-CS) hydrogel, was evaluated as a green biocatalyst for the efficient synthesis of novel thiazole derivatives. The PIBTU-CS hydrogel showcased key advantages, such as an expanded surface area and superior thermal stability, establishing it [...] Read more.

In the current study, pyromellitimide benzoyl thiourea cross-linked chitosan (PIBTU-CS) hydrogel, was evaluated as a green biocatalyst for the efficient synthesis of novel thiazole derivatives. The PIBTU-CS hydrogel showcased key advantages, such as an expanded surface area and superior thermal stability, establishing it as a potent eco-friendly catalyst. By employing PIBTU-CS alongside ultrasonic irradiation, we successfully synthesized a series of novel thiazoles through the reaction of 2-(4-((2-carbamothioylhydrazineylidene)methyl)phenoxy)-N-(4-chlorophenyl)acetamide with a variety of hydrazonoyl halides (6a–f) and α-haloketones (8a–c or 10a,b). A comparative analysis with TEA revealed that PIBTU-CS hydrogel consistently delivered significantly higher yields. This synthetic strategy provided several benefits, including mild reaction conditions, reduced reaction times, and consistently high yields. The robustness of PIBTU-CS was further underscored by its ability to be reused multiple times without a substantial reduction in catalytic efficiency. The structures of the synthesized thiazole derivatives were meticulously characterized using a range of analytical techniques, including IR, ¹H-NMR, ¹³C-NMR, and mass spectrometry (MS), confirming their successful formation. These results underscore the potential of PIBTU-CS hydrogel as a sustainable and recyclable catalyst for the synthesis of heterocyclic compounds. Additionally, all synthesized products were tested for their anticancer activity against HepG2-1 cells, with several new compounds exhibiting good anticancer effects. Full article

(This article belongs to the Special Issue Catalytic Energy Conversion and Catalytic Environmental Purification)

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16 pages, 4661 KiB

Open AccessArticle

Synthesis and Experimental Screening of Catalysts for H₂S to H₂ Decomposition Under Close-to-Industry Conditions

by Timur Palankoev, Anton Manakhov, Andrey Kovalskii, Ekaterina Sukhanova, Zakhar Popov, Dmitry Chareev, Konstantin Dement’ev, Anton Maximov and Abdulaziz Al-Qasim

Catalysts 2024, 14(11), 839; https://doi.org/10.3390/catal14110839 - 20 Nov 2024

Abstract

The chemical engineering community has shown significant interest in investigating methods to decompose hydrogen sulfide into hydrogen and sulfur. However, there is still a lack of detailed experimental data enabling us to choose the optimal catalyst, reaction, and regeneration conditions, as well as [...] Read more.

The chemical engineering community has shown significant interest in investigating methods to decompose hydrogen sulfide into hydrogen and sulfur. However, there is still a lack of detailed experimental data enabling us to choose the optimal catalyst, reaction, and regeneration conditions, as well as the overall process design. The purpose of this work is to synthesize a series of catalysts and compare their catalytic activity under the same conditions, chosen on the basis of a possible large-scale H₂S conversion process. To achieve this, the obtained catalysts were characterized by BET, XRD, SEM, TEM, and XPS before and after the reaction. Decomposition was conducted in a laboratory fixed-bed reactor at a temperature of 500 °C, 10 vol% of H₂S in the feed, and a GHSV of 540–1000 h⁻¹. DFT calculations evaluated the H₂S bond cleavage on various catalyst surfaces. It was shown that the most promising catalyst was Ni₃S₂, offering an acceptable H₂S conversion of 40%. We also observed that Ni₃S₂ catalyst regeneration could be conducted at much milder conditions compared to those previously reported in the literature. These results highlight the viability of upscaling the process with the selected catalyst. Full article

(This article belongs to the Section Industrial Catalysis)

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14 pages, 2519 KiB

Open AccessArticle

Electrochemical Ammonia Synthesis from Dilute Gaseous Nitric Oxide Reduction at Ambient Conditions

by Haroon Ur Rasheed, Jae Hyung Kim, Taek-Seung Kim, Kyungho Lee, Joonmok Shim, Sung Hyung Kim and Hyung Chul Yoon

Catalysts 2024, 14(11), 838; https://doi.org/10.3390/catal14110838 - 20 Nov 2024

Abstract

Converting gaseous nitric oxide (NO) to ammonia (NH₃) is important because of its environmental and industrial implications. The electrochemical transformation of nitrogen (N₂) to NH₃ faces several challenges, including a slow reaction rate and low Faradaic efficiency (FE). [...] Read more.

Converting gaseous nitric oxide (NO) to ammonia (NH₃) is important because of its environmental and industrial implications. The electrochemical transformation of nitrogen (N₂) to NH₃ faces several challenges, including a slow reaction rate and low Faradaic efficiency (FE). This study presents an innovative approach by integrating NO elimination and NH₃ production by electrochemical gaseous NO reduction reaction (NORR) under ambient conditions. Co and Mo-based catalysts were investigated for the continuous reduction of diluted NO gas (1%) to NH₃ within a proton exchange membrane (PEM) cell under ambient conditions. In electrochemical NORR tests conducted without a catholyte, CoMo-NC demonstrated notable NORR performance, achieving an NH₃ yield rate of 23.2 × 10⁻¹⁰ mol s⁻¹ cm⁻² at −2.2 V_cell and FE_NH3 of 94.6% at −1.6 V_cell, along with enhanced durability. Notably, this performance represents one of the highest FE_NH3 achievements for electrochemical gas-phase NO reduction at room temperature. Full article

(This article belongs to the Section Electrocatalysis)

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