Catalysts

5 pages, 976 KiB

Open AccessEditorial

Topical Advisory Panel Members’ Collection Series: Biomass Catalytic Conversion

by Sergio Nogales-Delgado

Catalysts 2025, 15(9), 804; https://doi.org/10.3390/catal15090804 - 24 Aug 2025

The transition toward a sustainable, low-carbon economy has placed biomass valorization and green fuel production at the forefront of catalytic research [...] Full article

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

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21 pages, 5451 KiB

Open AccessArticle

Reductive Amination of Cyclohexanone via Bimetallic Rh-Ni Catalysts: A Pathway to Improved Catalytic Efficiency

by Karen Morales, Camila Sandoval, Andreia Peixoto, Ricardo Chimentão, Jordi Llorca and Doris Ruiz

Catalysts 2025, 15(9), 803; https://doi.org/10.3390/catal15090803 - 23 Aug 2025

Abstract

Reductive amination of cyclohexanone with NH₃ and H₂ over Rh and Rh-Ni catalysts on SiO₂ has been studied. Research has focused on the catalytic efficiency of monometallic and bimetallic catalysts in the production of cyclohexylamine, a key intermediate in the [...] Read more.

Reductive amination of cyclohexanone with NH₃ and H₂ over Rh and Rh-Ni catalysts on SiO₂ has been studied. Research has focused on the catalytic efficiency of monometallic and bimetallic catalysts in the production of cyclohexylamine, a key intermediate in the synthesis of numerous fine chemicals. Through the wet impregnation method, Rh and Rh-Ni catalysts with varying nickel loadings (1, 2, 5, and 10 wt.%) were synthesized and characterized using techniques such as N₂ physisorption, TEM, HAADF-STEM, XRD, XPS, H₂-TPR, and NH₃-TPD. The catalytic reactions were conducted under controlled conditions using a glass-coated reactor, using ammonia as nitrogen source. Rh-Ni bimetallic catalysts exhibited the highest conversion rates on reductive amination, attributed to enhanced dispersion and advantageous surface properties. High metal dispersion and small particle sizes were confirmed by TEM, HAADF-STEM, and XRD. XPS analysis confirmed the reduced state of Rh and mainly oxidized state of Ni, while H₂-TPR and NH₃-TPD results indicated improved reducibility and acidity, respectively, which are critical for catalytic activity. Monometallic Rh/SiO₂ catalyst showed 83.4% of conversion after 300 min and selectivity of 99.1% toward the desired product cyclohexylamine. The addition of nickel, a cheap and easily available metal, increases the activity without compromising selectivity. At 300 min of the reaction, the 2 wt.% NiRh/SiO₂ catalyst exhibited the highest conversion, yield, and selectivity for the desired product cyclohexylamine, 99.8%, 96.4%, and 96.6% respectively. Additionally, this catalyst is recyclable after the fourth cycle, showing 99.5% selectivity and 74.0% yield for cyclohexylamine at 75.7% conversion. Recycling tests confirmed the stability of bimetallic catalysts, maintaining performance over multiple cycles without significant deactivation. Full article

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54 pages, 4870 KiB

Open AccessFeature PaperReview

Catalyst, Reactor, and Purification Technology in Methanol Steam Reforming for Hydrogen Production: A Review

by Ruochen Wang, Te Ma, Renkai Ding, Wei Liu and Dong Sun

Catalysts 2025, 15(9), 802; https://doi.org/10.3390/catal15090802 - 23 Aug 2025

Abstract

Methanol steam reforming (MSR) represents a highly promising pathway for sustainable hydrogen production due to its favorable hydrogen-to-carbon ratio and relatively low operating temperatures. The performance of the MSR process is strongly dependent on the selection and rational design of catalysts, which govern [...] Read more.

Methanol steam reforming (MSR) represents a highly promising pathway for sustainable hydrogen production due to its favorable hydrogen-to-carbon ratio and relatively low operating temperatures. The performance of the MSR process is strongly dependent on the selection and rational design of catalysts, which govern methanol conversion, hydrogen selectivity, and the suppression of undesired side reactions such as carbon monoxide formation. Moreover, advancements in reactor configuration and thermal management strategies play a vital role in minimizing heat loss and enhancing heat and mass transfer efficiency. Effective carbon monoxide removal technologies are indispensable for obtaining high-purity hydrogen, particularly for applications sensitive to CO contamination. This review systematically summarizes recent progress in catalyst development, reactor design, and gas purification technologies for MSR. In addition, the key technical challenges and potential future directions of the MSR process are critically discussed. The insights provided herein are expected to contribute to the development of more efficient, stable, and scalable MSR-based hydrogen production systems. Full article

28 pages, 2656 KiB

Open AccessReview

Challenges and Prospects of TiO₂-Based Photocatalysis for Wastewater Treatment: Keyword Analysis

by Caressa Munien, Sudesh Rathilal and Emmanuel Kweinor Tetteh

Catalysts 2025, 15(9), 801; https://doi.org/10.3390/catal15090801 - 22 Aug 2025

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Abstract

Environmental pollution driven by socioeconomic development has intensified the need for advanced and sustainable wastewater treatment technologies. Herein, TiO₂-based photocatalysis emerged as a promising solution due to its oxidative potential, chemical stability, and eco-friendliness but does have unavoidable immobilized recoverability challenges. [...] Read more.

Environmental pollution driven by socioeconomic development has intensified the need for advanced and sustainable wastewater treatment technologies. Herein, TiO₂-based photocatalysis emerged as a promising solution due to its oxidative potential, chemical stability, and eco-friendliness but does have unavoidable immobilized recoverability challenges. Therefore, this study explored the challenges and prospects of TiO₂-based photocatalysis for the degradation of emerging contaminants in wastewater. A comprehensive keyword analysis was conducted by using a decade of publications retrieved from Google Scholar, Scopus, and Web of Science (WOS) databases via Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. From a pool of 518 refined publications, 318 significant keyword occurrences related to TiO₂-based photocatalysis advanced oxidation processes (AOPs) were revealed. The review delved into various types of AOP mechanisms and catalysts and highlighted the synergistic effect of process parameters and magnetization as recoverability potential for TiO₂-based photocatalysts. Furthermore, emerging strategies including surface modifications, doping, and hybrid AOP integrations were discussed to improve photocatalysis performance and industrial scalability. The study underscores the economic opportunity and environmental sustainability of degrading persistent organic pollutants by integrating a TiO₂-based photocatalytic system with a regenerative magnetic field into the water sector. Full article

(This article belongs to the Special Issue Environmentally Friendly Catalysis for Green Future)

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39 pages, 4913 KiB

Open AccessReview

Magnetic Nanoparticle-Catalysed One-Pot Multicomponent Reactions (MCRs): A Green Chemistry Approach

by Venkatesan Kasi, Magdi EI Sayed Abdelsalam Zaki, Hussain Basha Nabisahebgari, Hussain Shaik, Sook-Keng Chang, Ling Shing Wong, Karthikeyan Parasuraman and Sobhi Mohamed Gomha

Catalysts 2025, 15(9), 800; https://doi.org/10.3390/catal15090800 - 22 Aug 2025

Viewed by 46

Abstract

The synthesis of heterocyclic compounds has gained significant attention in organic chemistry due to their diverse pharmacological properties. However, traditional synthetic approaches often involve hazardous chemicals, high energy consumption, and tedious workup procedures, leading to environmental concerns and low yields. In response, green [...] Read more.

The synthesis of heterocyclic compounds has gained significant attention in organic chemistry due to their diverse pharmacological properties. However, traditional synthetic approaches often involve hazardous chemicals, high energy consumption, and tedious workup procedures, leading to environmental concerns and low yields. In response, green chemistry strategies have emerged, emphasizing safer and more sustainable alternatives. Among these, magnetic nanoparticle (MNP)-based catalysts have shown remarkable promise in facilitating one-pot multicomponent reactions (MCRs), offering enhanced catalytic efficiency, ease of recovery, and reusability. This article provides a comprehensive overview of multicomponent reactions (MCRs) for the construction of a wide range of heterocyclic scaffolds—including chromenes, pyrazoles, phenazines, triazoles, tetrazoles, xanthenes, furans, indoles, imidazoles, pyridines, pyrimidines, oxazoles, and acridine derivatives—catalyzed by magnetic nanoparticles under sustainable and environmentally benign conditions. This review highlights recent advances (2018–2024) in the development and application of modified magnetic nanoparticles for green multicomponent synthesis. Emphasis is placed on their structural features, catalytic roles, and benefits in eco-friendly organic transformations. Full article

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

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13 pages, 15513 KiB

Open AccessArticle

Fabrication of VO_x/AFCC-PG Catalyst from Waste Support for Hg⁰ Removal in Flue Gas

by Xuhui Wei, Ruoyang Du, Rushan Zhao, Wenzhi Li, Caihong Jiang and Junwei Wang

Catalysts 2025, 15(9), 799; https://doi.org/10.3390/catal15090799 - 22 Aug 2025

Viewed by 76

Abstract

The efficient removal of elemental mercury (Hg⁰) from coal-fired flue gas is a critical challenge in environmental governance. This study proposes utilizing waste fluid catalytic cracking catalyst (WFCC) as the potential support for Hg⁰ catalytic oxidation. After activation (AFCC) via [...] Read more.

The efficient removal of elemental mercury (Hg⁰) from coal-fired flue gas is a critical challenge in environmental governance. This study proposes utilizing waste fluid catalytic cracking catalyst (WFCC) as the potential support for Hg⁰ catalytic oxidation. After activation (AFCC) via calcination decarbonization, a composite support (AFCC-PG) was fabricated using palygorskite (PG) as a binder. Subsequently, VO_x was loaded onto the support to form the VO_x/AFCC-PG catalyst for Hg⁰ removal. Experimental results demonstrate that the VO_x/AFCC-PG catalyst achieves >95% Hg⁰ removal efficiency under simulated flue gas conditions (150 °C, GHSV = 6000 h⁻¹) while maintaining excellent stability over 60 h. Furthermore, Hg-TPD and XPS analyses indicate that the synergistic lattice oxygen oxidation–adsorption established between VO_x and the AFCC-PG plays a key role in efficient Hg⁰ removal. This study proposes a cost-effective strategy for both the resource utilization of waste catalysts and the control of mercury pollution in coal-fired flue gas. Full article

(This article belongs to the Section Environmental Catalysis)

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17 pages, 3442 KiB

Open AccessArticle

Flow Field Structure Optimization and Inlet Parameters in Tubular Photocatalytic Reactors: A CFD-Based Study

by Zhiyong Fang, Lizhe Ma, Jieli Duan, Kefu Zhu, Xiangshu Zhang and Zhou Yang

Catalysts 2025, 15(9), 798; https://doi.org/10.3390/catal15090798 - 22 Aug 2025

Viewed by 148

Abstract

The internal flow field and hydrodynamic properties of a photocatalytic reactor are crucial for the enhancement of degradation performance. In this study, TiO₂ films were loaded on the surface of quartz glass tubes and activated with UV-LEDs. Combining the degradation experiments with [...] Read more.

The internal flow field and hydrodynamic properties of a photocatalytic reactor are crucial for the enhancement of degradation performance. In this study, TiO₂ films were loaded on the surface of quartz glass tubes and activated with UV-LEDs. Combining the degradation experiments with computational fluid dynamics (CFD) numerical simulations, the regulation laws of film surface area, flow field configuration, ratio of film surface area to solution volume (S/V), inlet flow rate and diameter on the reaction process were systematically evaluated. The results showed that the film surface area was positively correlated with the degradation efficiency of tetracycline hydrochloride (TCH). The degradation rate of TCH ranged between 32.15% and 64.83% in 12 equal film area flow field configurations. It was further found that the S/V value was positively correlated with the degradation efficiency only for the same flow field configuration, and the degradation rate of TCH was enhanced by 32.73% when the S/V value was increased from 0.018 m⁻¹ to 0.034 m⁻¹. In addition, as the flow rate increases, the optimal inlet diameter increases accordingly (10, 25, 40, 55, and 70 mL/min corresponded to 10, 15, 20, 20, and 25 mm, respectively). The optimum structural parameters of the reactor were determined as follows: inlet flow rate of 10 mL/min, inlet diameter of 10 mm, flow field configuration type b, S/V value of 0.034 m⁻¹, and height of 450 mm. The degradation rate of TCH under these conditions was 96.34%. The relationship between the film-reactor flow field and degradation efficiency of the photocatalytic reactor established in this study provides a reference for optimizing the design of tubular catalytic reactors. Full article

(This article belongs to the Section Photocatalysis)

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Catalysts, Volume 15, Issue 9 (September 2025) – 7 articles

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