Catalysts

15 pages, 792 KiB

Open AccessArticle

Palladium-Catalyzed Synthesis of 6-aryl Dopamine Derivatives

by Andrea Calcaterra, Santiago Fernández García, Federico Marrone, Roberta Bernini, Giancarlo Fabrizi, Antonella Goggiamani and Antonia Iazzetti

Catalysts 2024, 14(7), 401; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070401 (registering DOI) - 25 Jun 2024

Abstract

Dopamine is a key neurotransmitter involved in a series of biologically relevant processes and its derivatives have sparked significant interest as intriguing synthetic targets. This class of compounds is indeed not only considerable for the potential biological activities but is also promising for [...] Read more.

Dopamine is a key neurotransmitter involved in a series of biologically relevant processes and its derivatives have sparked significant interest as intriguing synthetic targets. This class of compounds is indeed not only considerable for the potential biological activities but is also promising for diverse applications in material science. In light of this, our research was focused on the synthesis of 6-aryldopamine derivatives starting from 4-(2-aminoethyl)phenol through a sequential protocol, whose main steps are hydroxylation, halogenation, and Suzuki cross-coupling. Our method demonstrated versatility, efficiency, and compatibility with various functional groups, including aldehydes, ketones, esters, ethers, and fluorine. Full article

(This article belongs to the Section Catalytic Materials)

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19 pages, 1284 KiB

Open AccessArticle

Ni-Ag Catalysts for Hydrogen Production through Dry Reforming of Methane: Characterization and Performance Evaluation

by Hayat Henni, Rafik Benrabaa, Pascal Roussel and Axel Löfberg

Catalysts 2024, 14(7), 400; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070400 (registering DOI) - 25 Jun 2024

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Abstract

To investigate the influence of Ag and the loading of Ni species, Ni-Ag type catalysts were synthesized with varying Ni/Ag ratios (1, 1.5 and 2) using the coprecipitation method. The catalysts were extensively characterized using various techniques such as TG-DSC-SM, XRD, ICP, BET, [...] Read more.

To investigate the influence of Ag and the loading of Ni species, Ni-Ag type catalysts were synthesized with varying Ni/Ag ratios (1, 1.5 and 2) using the coprecipitation method. The catalysts were extensively characterized using various techniques such as TG-DSC-SM, XRD, ICP, BET, SEM-EDX and TPR and subsequently tested in the CH₄/CO₂ reaction without any pretreatment. Regardless of the ratio employed, a phase mixture containing NiO and Ag was observed after calcination under air between 600 °C and 1200 °C. SEM analysis confirmed the presence of a close interface between Ag and NiO. The specific surface area was found to be significantly higher for the catalyst with lower Ni content (R = 1). TPR analysis demonstrated that the inclusion of Ag facilitated the reduction of Ni at lower temperatures. XRD analyses of the spent catalyst confirmed catalyst reduction during the reaction. Among the samples, a catalyst with Ni/Ag = 1 exhibited superior catalytic activity without any pretreatment under a reduction atmosphere, in which case the conversions of methane and CO₂ at 650 °C amounted to 38 and 45 mol%, respectively, with H₂/CO = 0.7 and 71 mol% of H₂. The presence of Ag species enhances the stability of the Ni catalyst and improves catalytic performance in the dry reforming of methane. Full article

(This article belongs to the Special Issue Catalytic Reforming and Hydrogen Production: From the Past to the Future)

17 pages, 5088 KiB

Open AccessFeature PaperArticle

Structural Characterization of Enzymatic Interactions with Functional Nicotinamide Cofactor Biomimetics

by Raquel A. Rocha, Liam A. Wilson, Brett D. Schwartz, Andrew C. Warden, Luke W. Guddat, Robert E. Speight, Lara Malins, Gerhard Schenk and Colin Scott

Catalysts 2024, 14(7), 399; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070399 - 24 Jun 2024

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Abstract

Synthetic nicotinamide biomimetics (NCBs) have emerged as alternatives to the use of natural cofactors. The relatively low cost and ease of manufacture of NCBs may enable the scaling of biocatalytic reactions to produce bulk chemicals (e.g., biofuels and plastics). NCBs are also recognized [...] Read more.

Synthetic nicotinamide biomimetics (NCBs) have emerged as alternatives to the use of natural cofactors. The relatively low cost and ease of manufacture of NCBs may enable the scaling of biocatalytic reactions to produce bulk chemicals (e.g., biofuels and plastics). NCBs are also recognized by only a subset of NAD(P)/NAD(P)H-dependent enzymes, which potentially allows access to orthogonal redox cascades that can be run simultaneously within a single reactor. In the work presented here, a series of NCBs was prepared and tested for activity with alcohol dehydrogenases and ene-reductases. While the NCBs did not support enzymatic activity with the alcohol dehydrogenases, the observed rate of the ene-reductases with NCBs was greater than when incubated with the natural cofactor (consistent with previous observations). We obtained the structures of an ene-reductase and an alcohol dehydrogenase with an NCB bound in their active sites. While the NCB bound to the ene-reductases in a productive position and orientation for hydride transfer to the isoalloxazine ring of the flavin cofactor, the NCB failed to adopt a catalytically competent binding mode in the alcohol dehydrogenase. Full article

(This article belongs to the Section Biocatalysis)

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4 pages, 455 KiB

Open AccessEditorial

New Trends in Catalytic Reaction for High-Temperature and Low-Emission Combustion Technologies

by Baiqian Dai, Xiaojiang Wu and Lian Zhang

Catalysts 2024, 14(7), 398; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070398 - 24 Jun 2024

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Abstract

With the continuous rise in global energy demand and the increasing awareness of environmental protection, high-temperature low-emission combustion technology has become a research hotspot in the field of combustion science [...] Full article

(This article belongs to the Special Issue Catalytic Reaction for High-Temperature and Low-Emission Combustion Technologies)

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18 pages, 4680 KiB

Open AccessArticle

In Situ Growth of Mn-Co₃O₄ on Mesoporous ZSM-5 Zeolite for Boosting Lean Methane Catalytic Oxidation

by Yuxuan Zhang, Ruibo Wei, Lin Yang, Jinming Ge, Feiyang Hu, Tingting Zhang, Fangyin Lu, Haiwang Wang and Jian Qi

Catalysts 2024, 14(7), 397; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070397 - 23 Jun 2024

Viewed by 265

Abstract

The low-temperature oxidation of methane gas in coal mine exhaust gas is important for reducing the greenhouse effect and protecting the environment. Unfortunately, the carbon–hydrogen bonds in methane molecules are highly stable, requiring higher reaction temperatures to achieve effective catalytic oxidation. However, metal [...] Read more.

The low-temperature oxidation of methane gas in coal mine exhaust gas is important for reducing the greenhouse effect and protecting the environment. Unfortunately, the carbon–hydrogen bonds in methane molecules are highly stable, requiring higher reaction temperatures to achieve effective catalytic oxidation. However, metal oxide-based catalysts face the problem of easy sintering and the deactivation of active components at high temperatures, which is an important challenge that catalysts need to overcome in practical applications. In this work, a series of Mn-Co₃O₄ active components were grown in situ on ZSM-5 zeolite with mesoporous pore structures treated with an alkaline solution via a hydrothermal synthesis method. Due to the presence of polyethylene glycol as a structure-directing agent, manganese can be uniformly doped into the Co₃O₄ lattice. The large specific surface area of ZSM-5 zeolite allows the active component Mn-Co₃O₄ to be uniformly dispersed, effectively preventing the sintering and growth of active component particles during the catalytic reaction process. It is worth mentioning that the Mn-Co₃O₄/meso-ZSM-5-6.67 catalyst has a methane conversion rate of up to 90% at a space velocity of 36,000 mL·g⁻¹·h⁻¹ and a reaction temperature of 363 °C. This is mainly due to the mesoporous ZSM-5 carrier with a high specific surface area, which is conducive to the adsorption and mass transfer of reaction molecules. The active component has an abundance of oxygen vacancies, which is conducive to the activation of reaction molecules and enhances its catalytic activity, which is even higher than that of noble metal-based catalysts. The new ideas for the preparation of metal oxide-based low-temperature methane oxidation catalysts proposed in this work are expected to provide new solutions for low-temperature methane oxidation reactions and promote technological progress in related fields. Full article

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

7 pages, 408 KiB

Open AccessEditorial

Theme Issue in Memory to Professor Jiro Tsuji (1927–2022)

by Ewa Kowalska and Shuaizhi Zheng

Catalysts 2024, 14(7), 396; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070396 - 21 Jun 2024

Viewed by 251

Abstract

The importance of catalysis is obvious and unquestionable, especially bearing in mind that about 90% of all commercially produced chemical products involve catalysts at some step of their manufacture [...] Full article

(This article belongs to the Special Issue Theme Issue in Memory to Prof. Jiro Tsuji (1927–2022))

13 pages, 3630 KiB

Open AccessArticle

Conservatively Perturbed Equilibrium (CPE)—Phenomenon as a Tool for Intensifying the Catalytic Process: The Case of Methane Reforming Processes

by Mykhailo O. Vilboi, Vitaliy R. Trishch and Gregory S. Yablonsky

Catalysts 2024, 14(7), 395; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070395 - 21 Jun 2024

Viewed by 190

Abstract

The phenomenon of conservatively perturbed equilibrium (CPE) was applied to the processes of methane reforming (dry and steam reforming) and analyzed using kinetic computer simulations. This phenomenon was studied for two products, CO and H₂, at different temperatures. “Unperturbed” species with [...] Read more.

The phenomenon of conservatively perturbed equilibrium (CPE) was applied to the processes of methane reforming (dry and steam reforming) and analyzed using kinetic computer simulations. This phenomenon was studied for two products, CO and H₂, at different temperatures. “Unperturbed” species with inlet concentrations equal to the outlet equilibrium concentration experienced unavoidable passing through the temporary extremum (the CPE point), in this case, the maximum. Application of the CPE phenomenon to the complex catalytic methane reforming processes demonstrate two improvements: 1. Achieving the over-equilibrium product concentration. 2. This concentration is achieved at the reactor length that is much shorter than the length corresponding to the vicinity of the complete equilibrium. Full article

(This article belongs to the Section Catalytic Reaction Engineering)

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13 pages, 4379 KiB

Open AccessArticle

Expediting Corrosion Engineering for Sulfur-Doped, Self-Supporting Ni-Fe Layered Dihydroxide in Efficient Aqueous Oxygen Evolution

by Yingjun Ma, Jie Wang, Hangning Liu, Lin Wang, Changhui Sun, Liangyu Gong, Xiaogang Zhang and Jiefang Zhu

Catalysts 2024, 14(7), 394; https://0-doi-org.brum.beds.ac.uk/10.3390/catal14070394 - 21 Jun 2024

Viewed by 203

Abstract

Electrochemical water-splitting is widely acknowledged as a renewable strategy for hydrogen production, but it is primarily constrained by the sluggish reaction kinetics of the anode oxygen evolution reaction (OER). In our study, we employ a fast room-temperature corrosion engineering strategy for the construction [...] Read more.

Electrochemical water-splitting is widely acknowledged as a renewable strategy for hydrogen production, but it is primarily constrained by the sluggish reaction kinetics of the anode oxygen evolution reaction (OER). In our study, we employ a fast room-temperature corrosion engineering strategy for the construction of a sulfur-doped Ni-Fe layered dihydroxide catalyst (S-NiFe LDH). With the assistance of a sulfur source, microsphere morphology with an ultra-thin lamellar surface cross-arrangement can be rapidly grown on the surface of an iron foam substrate, ensuring a substantial electrochemical interface. The composition of Ni species in the catalysts can be regulated by simply adjusting the amount of Ni²⁺ and reaction time. Functioning as an OER catalyst, the S-NiFe LDH demonstrates high activity and reaction kinetics, featuring a minimal overpotential of 120.0 mV to deliver a current density of 10 mA cm⁻², a small Tafel slope of 39.5 mV dec⁻¹ and a notable electrical double-layer capacitance (C_dl) of 31.3 mF cm⁻². The remarkable electrocatalytic performance can be attributed to its distinctive three-dimensional (3D) structure and sulfur dopants, which effectively regulate the electrochemical interface and electronic structure of NiFe LDH. This work provides valuable insights for expeditious materials design. Full article

(This article belongs to the Special Issue Electrocatalysis for Hydrogen/Oxygen Evolution Reactions)

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Catalysts, Volume 14, Issue 7 (July 2024) – 8 articles

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