Transition Metal Complexes as Catalysts

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

Deadline for manuscript submissions: closed (31 May 2023) | Viewed by 9753

Special Issue Editors

Korean Institute for Basic Science, Center for Soft and Living Matter, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
Interests: inorganic; organic; polymer and organometallic chemistry; homogeneous catalysis (metathesis); electrochemistry (electrocatalysis and electropolymerization); single crystal X-ray crystallography (growth, measurement, and resolution of crystal structures); computational chemistry
Special Issues, Collections and Topics in MDPI journals
Departamento de Química, Facultad de Ciencias, Universidad Católica del Norte, Antofagasta, Chile
Interests: physical; inorganic; solid state; polymer; computational chemistry and crystallography (small molecules)

Special Issue Information

Dear Colleagues,

Due to their high activity and diverse characteristics, transition metal coordination compounds hold a unique place among organic chemistry catalysts, and because of their broad reactivity in facilitating numerous chemical transformations, transition metal catalysts have become widely used as valuable tools in current synthetic organic chemistry. The field has expanded in tandem with the development of supporting ligands, which have a substantial impact on the reactivity and stability of metal complexes in the primary coordination sphere. In the periodic table, several organic compounds such as phosphines, amines, ethers, and carbenes are used as supporting ligands for p-block organic elements. The catalytic properties of transition metal complexes are strongly influenced by their ligands, which serve as helpful tools for controlling the parameters of the catalytic system. The design of a coordination compound's (catalyst's) structure is critical for its catalytic applications. Despite significant advances in understanding structure–property relationships and the invention of several synthetic techniques, the catalytic parameters of many reactions are far from perfect, particularly in the realm of fine chemistry.

This Entry Collection is, therefore, devoted to the applications of transition metal complexes as well as the investigation of their structural and dynamic features in catalysis. Submissions to this Special Issue on "Transition Metal Complexes as Catalysts" are encouraged in the form of original research papers or short reviews reflecting the state of the field's research.

Dr. Guillermo Ahumada
Dr. Jonathan Cisterna
Guest Editors

Manuscript Submission Information

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Keywords

  • catalysis
  • metal complexes
  • organometallic chemistry
  • synthesis of metal complexes
  • metal catalysis
  • catalyst
  • coordination chemistry
  • supported catalysis

Published Papers (6 papers)

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Research

17 pages, 6683 KiB  
Article
Evaluation of Heterogeneous Catalytic Ozonation Process for the Removal of Micropollutants from Water/Wastewater: Application of a Novel Pilot-Scale Continuous Flow System
by Efthimia Kaprara, Charalampos Belesakos, Konstantinos Kollis, Savvina Psaltou, Anastasios Zouboulis and Manassis Mitrakas
Catalysts 2023, 13(5), 899; https://doi.org/10.3390/catal13050899 - 17 May 2023
Viewed by 1195
Abstract
The present study evaluates the removal of micropollutants from water/wastewater contaminated sources through the application of a heterogeneous catalytic ozonation process, using a pilot-scale continuous operation unit, composed of a membrane module for the diffusion and effective dilution of ozone into the liquid [...] Read more.
The present study evaluates the removal of micropollutants from water/wastewater contaminated sources through the application of a heterogeneous catalytic ozonation process, using a pilot-scale continuous operation unit, composed of a membrane module for the diffusion and effective dilution of ozone into the liquid phase to be treated and a plug flow reactor/continuous stirred tank reactor (PFR/CSTR) contact reactor system in series, where the catalyst is recirculated in dispersion mode. The solid materials tested as catalysts are natural and calcined zeolite, Bayoxide and alumina, whereas the examined micropollutants, used in this case as probe compounds, are p-chlorobenzoic acid (p-CBA), atrazine, benzotriazole and carbamazepine. A high-performance liquid chromatography system was used to determine the removal of micropollutants. In the case of p-CBA, an ozone-resistant compound, the addition of catalyst was found to significantly enhance its degradation rate, leading to >99% removal under the optimum defined conditions, i.e., in terms of catalyst concentration, pH, temperature, and process time. On the other hand, in the case of atrazine, a different ozone-resistant compound, the introduction of examined catalysts in the ozonation process was found to reduce the degradation of micropollutant, when compared with the application of single ozonation, indicating the importance of specific affinity between the pollutant and the solid material used as catalyst. Benzotriazole, a moderately ozone-reactive compound was degraded by more than 95% under all experimental conditions and catalysts tested in the pilot unit, while carbamazepine, a highly ozone-reactive compound, was completely removed even during the first stage of treatment process (i.e., at the membrane contactor). When increasing the pH value (in the range 6–8) and the contact time, the performance of catalytic ozonation process also improved. Full article
(This article belongs to the Special Issue Transition Metal Complexes as Catalysts)
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12 pages, 2503 KiB  
Article
Bio-Adipic Acid Production from Muconic Acid Hydrogenation on Palladium-Transition Metal (Ni and Zn) Bimetallic Catalysts
by Elisa Zanella, Lorenzo Secundo, Silvio Bellomi, Alessandro Vomeri, Alberto Villa and Carlo Pirola
Catalysts 2023, 13(3), 486; https://doi.org/10.3390/catal13030486 - 27 Feb 2023
Viewed by 1653
Abstract
The hydrogenation of muconic acid (MA) to bio-adipic acid (AdA) is one of the green chemical processes that has attracted the most interest in recent years. Indeed, MA can be readily obtained from biomass through fermentative processes. Here, we aimed to investigate the [...] Read more.
The hydrogenation of muconic acid (MA) to bio-adipic acid (AdA) is one of the green chemical processes that has attracted the most interest in recent years. Indeed, MA can be readily obtained from biomass through fermentative processes. Here, we aimed to investigate the synergic effect of electronic promotion that the addition of a second metal, even in small quantities, can have on Pd-based catalyst, known for its low stability. Ni and Zn were taken into consideration and two different catalysts (1%Pd8Ni2/HHT and 1%Pd8Zn2/HHT) were synthetized by sol immobilization method and supported on high-temperature, heat-treated carbon nanofibers (HHT-CNFs) that are known to enhance the stability of palladium. The catalysts were tested in MA hydrogenation and thoroughly characterized by TEM, ICP, and XPS analysis to unveil the effect of the second metal. To solve the solubility issue and have a starting material as similar as feasible to the post-fermentation conditions of the biomass, sodium muconate salt was chosen as a substrate for the reaction. All of the synthetized bimetallic catalysts showed a higher activity than monometallic Pd and better stability during the recycling tests, pointing out that even a small amount of these two metals can increase the catalytic properties of monometallic Pd. Full article
(This article belongs to the Special Issue Transition Metal Complexes as Catalysts)
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16 pages, 7826 KiB  
Article
Influences of Co-Content on the Physico-Chemical and Catalytic Properties of Perovskite GdCoxFe1−xO3 in CO Hydrogenation
by Elizaveta M. Borodina, Liliya V. Yafarova, Tatiana A. Kryuchkova, Tatiana F. Sheshko, Alexander G. Cherednichenko and Irina A. Zvereva
Catalysts 2023, 13(1), 8; https://doi.org/10.3390/catal13010008 - 22 Dec 2022
Viewed by 1345
Abstract
The effect of the substitution of cobalt into the GdFeO3 perovskite structure on the selective hydrogenation of CO was investigated. A series of GdCoxFe1−xO3 (x = 0; 0.2; 0.5; 0.8; 1) samples were synthesized by sol-gel technology [...] Read more.
The effect of the substitution of cobalt into the GdFeO3 perovskite structure on the selective hydrogenation of CO was investigated. A series of GdCoxFe1−xO3 (x = 0; 0.2; 0.5; 0.8; 1) samples were synthesized by sol-gel technology and characterized by XRD, BET specific area, DSC, TG, EDX and XPS. The experimental data made it possible to reveal a correlation between the state of iron and cobalt atoms, the fractions of surface and lattice oxygen, and catalytic characteristics. It has been found that varying the composition of GdCoxFe1−xO3 complex oxides leads to a change in the oxygen-metal binding energy in Gd-O-Me, the ratio of metals in various oxidation states, and the amount of surface and lattice oxygen, which affects the adsorption and catalytic characteristics of complex oxides. Full article
(This article belongs to the Special Issue Transition Metal Complexes as Catalysts)
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15 pages, 7431 KiB  
Article
Ni5P4-NiP2-Ni2P Nanocomposites Tangled with N-Doped Carbon for Enhanced Electrochemical Hydrogen Evolution in Acidic and Alkaline Solutions
by Miaomiao Pei, Xiaowei Song, Haihong Zhong, Luis Alberto Estudillo-Wong, Yingchun Gao, Tongmengyao Jin, Ju Huang, Yali Wang, Jun Yang and Yongjun Feng
Catalysts 2022, 12(12), 1650; https://doi.org/10.3390/catal12121650 - 15 Dec 2022
Cited by 2 | Viewed by 1680
Abstract
Heterostructured non-precious metal phosphides have attracted increasing attention in the development of high-performance catalysts for hydrogen evolution reaction (HER), particularly in acidic media. Herein, a catalyst composed of ternary Ni5P4-NiP2-Ni2P nanocomposites and N-doped carbon nanotubes/carbon [...] Read more.
Heterostructured non-precious metal phosphides have attracted increasing attention in the development of high-performance catalysts for hydrogen evolution reaction (HER), particularly in acidic media. Herein, a catalyst composed of ternary Ni5P4-NiP2-Ni2P nanocomposites and N-doped carbon nanotubes/carbon particulates (Ni5P4-NiP2-Ni2P/NC) was prepared from a Ni-containing hybrid precursor through approaches of a successive carbonization and phosphating reaction. Benefiting from the synergistic effect from three-component nickel phosphides and the support role of porous carbon network, the Ni5P4-NiP2-Ni2P/N-doped carbon catalyst presents the promising HER performance with overpotentials of 168 and 202 mV at the current density of 10 mA cm−2 and Tafel slopes of 69.0 and 74 mV dec−1 in both acidic and alkaline solutions, respectively, which surpasses the Ni2P/N-doped carbon counterpart. This work provides an effective strategy for the preparation and development of highly efficient HER non-precious metal electrocatalysts by creating heterostructure in acidic and alkaline media. Full article
(This article belongs to the Special Issue Transition Metal Complexes as Catalysts)
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10 pages, 2178 KiB  
Article
Green Dynamic Kinetic Resolution—Stereoselective Acylation of Secondary Alcohols by Enzyme-Assisted Ruthenium Complexes
by Monika Heba, Anna Wolny, Anna Kastelik-Hryniewiecka, Dominika Stradomska, Sebastian Jurczyk, Anna Chrobok and Nikodem Kuźnik
Catalysts 2022, 12(11), 1395; https://doi.org/10.3390/catal12111395 - 09 Nov 2022
Cited by 2 | Viewed by 1538
Abstract
Dynamic kinetic resolution allows for the synthesis of enantiomerically pure asymmetric alcohols. Cyclopentadienyl-derived ruthenium catalysts were immobilized with an ionic liquid, [BMIM][NTf2], on multiwall carbon nanotubes and used for the racemization of chiral secondary alcohols. This successful approach was combined with [...] Read more.
Dynamic kinetic resolution allows for the synthesis of enantiomerically pure asymmetric alcohols. Cyclopentadienyl-derived ruthenium catalysts were immobilized with an ionic liquid, [BMIM][NTf2], on multiwall carbon nanotubes and used for the racemization of chiral secondary alcohols. This successful approach was combined with the enantioselective enzymatic acylation of secondary alcohols (1-phenylethanol and 1-(1-naphthyl)ethanol) using Novozyme® 435. The resulting catalytic system of the ruthenium racemization catalysts and enzymatic acylation led to chiral esters being obtained by dynamic kinetic resolution. The immobilized catalytic system in the ionic liquid gave the same activity of >96% yield within 6 h and a selectivity of 99% enantiomeric excess as the homogeneous system, while allowing for the convenient separation of the desired products from the catalyst. Additionally, the process can be regarded as green, since the efficient reuse of the catalytic system was demonstrated. Full article
(This article belongs to the Special Issue Transition Metal Complexes as Catalysts)
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12 pages, 2262 KiB  
Article
Pt2 Dimer Anchored Vertically in Defective BN Monolayer as an Efficient Catalyst for N2 Reduction: A DFT Study
by Linke Yu and Fengyu Li
Catalysts 2022, 12(11), 1387; https://doi.org/10.3390/catal12111387 - 08 Nov 2022
Cited by 6 | Viewed by 1490
Abstract
The electrochemical nitrogen reduction reaction (NRR) using clean energy is considered a promising alternative to the conventional Haber–Bosch process; however, developing a highly active electrocatalyst is still a great challenge. In this study, ten metal dimers anchored in a defective boron nitride (BN) [...] Read more.
The electrochemical nitrogen reduction reaction (NRR) using clean energy is considered a promising alternative to the conventional Haber–Bosch process; however, developing a highly active electrocatalyst is still a great challenge. In this study, ten metal dimers anchored in a defective boron nitride (BN) monolayer as double-atom catalysts (DACs) with reverse sandwich structures were screened for their stability and catalytic activity towards NRR by density functional theory (DFT) calculations. Among them, three DACs (Rh2⊥vb-BN, Pt2⊥vb-BN and Rh2⊥vn-BN) were confirmed to be stable and have high promise as NRR electrocatalysts, and Pt2⊥vb-BN particularly distinguishes itself due to its very low limiting potential (−0.06 V). In addition, the electrocatalytic performance of all three DACs prevailed over that of their single-atom catalyst counterparts. We believe that the unique conformation of the reverse sandwich structure has impressive potential for the development of DACs, and we hope that our study provides a new design strategy for DACs for NRR and beyond. Full article
(This article belongs to the Special Issue Transition Metal Complexes as Catalysts)
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