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20 pages, 6304 KiB

Open AccessArticle

High-Loaded Copper-Containing Sol–Gel Catalysts for Furfural Hydroconversion

by Svetlana Selishcheva, Anastasiya Sumina, Evgeny Gerasimov, Dmitry Selishchev and Vadim Yakovlev

Int. J. Mol. Sci. 2023, 24(8), 7547; https://doi.org/10.3390/ijms24087547 - 19 Apr 2023

Cited by 2 | Viewed by 1628

Abstract

In this study, the high-loaded copper-containing catalysts modified with Fe and Al were successfully applied for the hydroconversion of furfural to furfuryl alcohol (FA) or 2-methylfuran (2-MF) in a batch reactor. The synthesized catalysts were studied using a set of characterization techniques to [...] Read more.

In this study, the high-loaded copper-containing catalysts modified with Fe and Al were successfully applied for the hydroconversion of furfural to furfuryl alcohol (FA) or 2-methylfuran (2-MF) in a batch reactor. The synthesized catalysts were studied using a set of characterization techniques to find the correlation between their activity and physicochemical properties. Fine Cu-containing particles distributed in an amorphous SiO₂ matrix, which has a high surface area, provide the conversion of furfural to FA or 2-MF under exposure to high pressure of hydrogen. The modification of the mono-copper catalyst with Fe and Al increases its activity and selectivity in the target process. The reaction temperature strongly affects the selectivity of the formed products. At a H₂ pressure of 5.0 MPa, the highest selectivity toward FA (98%) and 2-MF (76%) was achieved in the case of 35Cu13Fe1Al-SiO₂ at the temperature of 100 °C and 250 °C, respectively. Full article

(This article belongs to the Special Issue Nanoparticle for Catalysis)

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13 pages, 4732 KiB

Open AccessArticle

Spatially Formed Tenacious Nickel-Supported Bimetallic Catalysts for CO₂ Methanation under Conventional and Induction Heating

by Daniel Lach, Błażej Tomiczek, Tomasz Siudyga, Maciej Kapkowski, Rafał Sitko, Joanna Klimontko, Sylwia Golba, Grzegorz Dercz, Krzysztof Matus, Wojciech Borek and Jaroslaw Polanski

Int. J. Mol. Sci. 2023, 24(5), 4729; https://doi.org/10.3390/ijms24054729 - 1 Mar 2023

Cited by 7 | Viewed by 2237

Abstract

The paper introduces spatially stable Ni-supported bimetallic catalysts for CO₂ methanation. The catalysts are a combination of sintered nickel mesh or wool fibers and nanometal particles, such as Au, Pd, Re, or Ru. The preparation involves the nickel wool or mesh forming [...] Read more.

The paper introduces spatially stable Ni-supported bimetallic catalysts for CO₂ methanation. The catalysts are a combination of sintered nickel mesh or wool fibers and nanometal particles, such as Au, Pd, Re, or Ru. The preparation involves the nickel wool or mesh forming and sintering into a stable shape and then impregnating them with metal nanoparticles generated by a silica matrix digestion method. This procedure can be scaled up for commercial use. The catalyst candidates were analyzed using SEM, XRD, and EDXRF and tested in a fixed-bed flow reactor. The best results were obtained with the Ru/Ni-wool combination, which yields nearly 100% conversion at 248 °C, with the onset of reaction at 186 °C. When we tested this catalyst under inductive heating, the highest conversion was observed already at 194 °C. Full article

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16 pages, 4700 KiB

Open AccessArticle

Biomimetic Catalysts Based on Au@TiO₂-MoS₂-CeO₂ Composites for the Production of Hydrogen by Water Splitting

by Kenneth Fontánez, Diego García, Dayna Ortiz, Paola Sampayo, Luis Hernández, María Cotto, José Ducongé, Francisco Díaz, Carmen Morant, Florian Petrescu, Abniel Machín and Francisco Márquez

Int. J. Mol. Sci. 2023, 24(1), 363; https://doi.org/10.3390/ijms24010363 - 26 Dec 2022

Cited by 13 | Viewed by 2752

Abstract

The photocatalytic hydrogen evolution reaction (HER) by water splitting has been studied, using catalysts based on crystalline TiO₂ nanowires (TiO₂NWs), which were synthesized by a hydrothermal procedure. This nanomaterial was subsequently modified by incorporating different loadings (1%, 3% and 5%) [...] Read more.

The photocatalytic hydrogen evolution reaction (HER) by water splitting has been studied, using catalysts based on crystalline TiO₂ nanowires (TiO₂NWs), which were synthesized by a hydrothermal procedure. This nanomaterial was subsequently modified by incorporating different loadings (1%, 3% and 5%) of gold nanoparticles (AuNPs) on the surface, previously exfoliated MoS₂ nanosheets, and CeO₂ nanoparticles (CeO₂NPs). These nanomaterials, as well as the different synthesized catalysts, were characterized by electron microscopy (HR-SEM and HR-TEM), XPS, XRD, Raman, Reflectance and BET surface area. HER studies were performed in aqueous solution, under irradiation at different wavelengths (UV-visible), which were selected through the appropriate use of optical filters. The results obtained show that there is a synergistic effect between the different nanomaterials of the catalysts. The specific area of the catalyst, and especially the increased loading of MoS₂ and CeO₂NPs in the catalyst substantially improved the H₂ production, with values of ca. 1114 μm/hg for the catalyst that had the best efficiency. Recyclability studies showed only a decrease in activity of approx. 7% after 15 cycles of use, possibly due to partial leaching of gold nanoparticles during catalyst use cycles. The results obtained in this research are certainly relevant and open many possibilities regarding the potential use and scaling of these heterostructures in the photocatalytic production of H₂ from water. Full article

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15 pages, 4844 KiB

Open AccessArticle

Zr-Based Metal−Organic Frameworks with Phosphoric Acids for the Photo-Oxidation of Sulfides

by Zhenghua Zhao, Mingjie Liu, Kai Zhou, Hantao Gong, Yajing Shen, Zongbi Bao, Qiwei Yang, Qilong Ren and Zhiguo Zhang

Int. J. Mol. Sci. 2022, 23(24), 16121; https://doi.org/10.3390/ijms232416121 - 17 Dec 2022

Cited by 4 | Viewed by 2404

Abstract

Heterogeneous Brønsted acidic catalysts such as phosphoric acids are the conventional activators for organic transformations. However, the photocatalytic performance of these catalysts is still rarely explored. Herein, a novel Zr-based metal−organic framework Zr-MOF-P with phosphoric acids as a heterogeneous photocatalyst has been fabricated, [...] Read more.

Heterogeneous Brønsted acidic catalysts such as phosphoric acids are the conventional activators for organic transformations. However, the photocatalytic performance of these catalysts is still rarely explored. Herein, a novel Zr-based metal−organic framework Zr-MOF-P with phosphoric acids as a heterogeneous photocatalyst has been fabricated, which shows high selectivity and reactivity towards the photo-oxidation of sulfides under white light illumination. A mechanism study indicates that the selective oxygenation of sulfides occurs with triplet oxygen rather than common reactive oxygen species (ROS). When Zr-MOF-P is irradiated, the hydroxyl group of phosphoric acid is converted into oxygen radical, which takes an electron from the sulfides, and then the activated substrates react with the triplet oxygen to form sulfoxides, avoiding the destruction of the catalysts and endowing the reaction with high substrate compatibility and fine recyclability. Full article

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13 pages, 3446 KiB

Open AccessArticle

Efficient Construction of Symmetrical Diaryl Sulfides via a Supported Pd Nanocatalyst-Catalyzed C-S Coupling Reaction

by Hao Jin, Penghao Liu, Qiaoqiao Teng, Yuxiang Wang, Qi Meng and Chao Qian

Int. J. Mol. Sci. 2022, 23(23), 15360; https://doi.org/10.3390/ijms232315360 - 6 Dec 2022

Cited by 1 | Viewed by 2140

Abstract

Aryl sulfides play an important role in pharmaceuticals, biologically active molecules and polymeric materials. Herein, a general and efficient protocol for Pd@COF-TB (a kind of Pd nanocatalyst supported by a covalent organic framework)/DIPEA-catalyzed one-pot synthesis of symmetrical diaryl sulfides through a C-S coupling [...] Read more.

Aryl sulfides play an important role in pharmaceuticals, biologically active molecules and polymeric materials. Herein, a general and efficient protocol for Pd@COF-TB (a kind of Pd nanocatalyst supported by a covalent organic framework)/DIPEA-catalyzed one-pot synthesis of symmetrical diaryl sulfides through a C-S coupling reaction from aryl iodides and Na₂S₂O₃ is developed. More importantly, the addition of N,N-diisopropylethylamine (DIPEA) can not only enhance the catalytic activity of a Pd@COF-TB nanocatalyst, but also effectively inhibit the formation of biphenyl byproducts, which are a product of Ullmann reaction. Besides, it has been confirmed that the aryl Bunte salts generated in situ from Na₂S₂O₃ and aryl iodides are the sulfur sources involved in this C-S coupling reaction. With the strategy proposed in this work, a variety of symmetrical diaryl sulfides could be obtained in moderate to excellent yields with a high tolerance of various functional groups. Moreover, a possible mechanism of this Pd nanoparticle-catalyzed C-S coupling reaction is proposed based on the results of controlling experiments. Full article

(This article belongs to the Special Issue Nanoparticle for Catalysis)

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13 pages, 4749 KiB

Open AccessArticle

Palladium Decorated, Amine Functionalized Ni-, Cd- and Co-Ferrite Nanospheres as Novel and Effective Catalysts for 2,4-Dinitrotoluene Hydrogenation

by Viktória Hajdu, Emőke Sikora, Ferenc Kristály, Gábor Muránszky, Béla Fiser, Béla Viskolcz, Miklós Nagy and László Vanyorek

Int. J. Mol. Sci. 2022, 23(21), 13197; https://doi.org/10.3390/ijms232113197 - 30 Oct 2022

Cited by 5 | Viewed by 1998

Abstract

2,4-diaminotoluene (TDA) is one of the most important polyurethane precursors produced in large quantities by the hydrogenation of 2,4-dinitrotoluene using catalysts. Any improvement during the catalysis reaction is therefore of significant importance. Separation of the catalysts by filtration is cumbersome and causes catalyst [...] Read more.

2,4-diaminotoluene (TDA) is one of the most important polyurethane precursors produced in large quantities by the hydrogenation of 2,4-dinitrotoluene using catalysts. Any improvement during the catalysis reaction is therefore of significant importance. Separation of the catalysts by filtration is cumbersome and causes catalyst loss. To solve this problem, we have developed magnetizable, amine functionalized ferrite supported palladium catalysts. Cobalt ferrite (CoFe₂O₄-NH₂), nickel ferrite (NiFe₂O₄-NH₂), and cadmium ferrite (CdFe₂O₄-NH₂) magnetic catalyst supports were produced by a simple coprecipitation/sonochemical method. The nanospheres formed contain only magnetic (spinel) phases and show catalytic activity even without noble metals (palladium, platinum, rhodium, etc.) during the hydrogenation of 2,4-dinitrotoluene, 63% (n/n) conversion is also possible. By decorating the supports with palladium, almost 100% TDA selectivity and yield were ensured by using Pd/CoFe₂O₄-NH₂ and Pd/NiFe₂O₄-NH₂ catalysts. These catalysts possess highly favorable properties for industrial applications, such as easy separation from the reaction medium without loss by means of a magnetic field, enhanced reusability, and good dispersibility in aqueous medium. Contrary to non-functionalized supports, no significant leaching of precious metals could be detected even after four cycles. Full article

(This article belongs to the Special Issue Nanoparticle for Catalysis)

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13 pages, 5593 KiB

Open AccessArticle

General Construction of Amine via Reduction of N=X (X = C, O, H) Bonds Mediated by Supported Nickel Boride Nanoclusters

by Da Ke and Shaodong Zhou

Int. J. Mol. Sci. 2022, 23(16), 9337; https://doi.org/10.3390/ijms23169337 - 19 Aug 2022

Cited by 3 | Viewed by 2336

Abstract

Amines play an important role in synthesizing drugs, pesticides, dyes, etc. Herein, we report on an efficient catalyst for the general construction of amine mediated by nickel boride nanoclusters supported by a TS-1 molecular sieve. Efficient production of amines was achieved via catalytic [...] Read more.

Amines play an important role in synthesizing drugs, pesticides, dyes, etc. Herein, we report on an efficient catalyst for the general construction of amine mediated by nickel boride nanoclusters supported by a TS-1 molecular sieve. Efficient production of amines was achieved via catalytic hydrogenation of N=X (X = C, O, H) bonds. In addition, the catalyst maintains excellent performance upon recycling. Compared with the previous reports, the high activity, simple preparation and reusability of the Ni-B catalyst in this work make it promising for industrial application in the production of amines. Full article

(This article belongs to the Special Issue Nanoparticle for Catalysis)

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15 pages, 15932 KiB

Open AccessArticle

Copper Foam as Active Catalysts for the Borylation of α, β-Unsaturated Compounds

by Kewang Zheng, Miao Liu, Zhifei Meng, Zufeng Xiao, Fei Zhong, Wei Wang and Caiqin Qin

Int. J. Mol. Sci. 2022, 23(15), 8403; https://doi.org/10.3390/ijms23158403 - 29 Jul 2022

Cited by 1 | Viewed by 1804

Abstract

The use of simple, inexpensive, and efficient methods to construct carbon–boron and carbon–oxygen bonds has been a hot research topic in organic synthesis. We demonstrated that the desired β-boronic acid products can be obtained under mild conditions using copper foam as an [...] Read more.

The use of simple, inexpensive, and efficient methods to construct carbon–boron and carbon–oxygen bonds has been a hot research topic in organic synthesis. We demonstrated that the desired β-boronic acid products can be obtained under mild conditions using copper foam as an efficient heterogeneous catalyst. The structure of copper foam before and after the reaction was investigated by polarized light microscopy (PM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), and the results have shown that the structure of the catalyst copper foam remained unchanged before and after the reaction. The XPS test results showed that the Cu(0) content increased after the reaction, indicating that copper may be involved in the boron addition reaction. The specific optimization conditions were as follows: CH₃COCH₃ and H₂O were used as mixed solvents, 4-methoxychalcone was used as the raw material, 8 mg of catalyst was used and the reaction was carried out at room temperature and under air for 10 h. The yield of the product obtained was up to 92%, and the catalytic efficiency of the catalytic material remained largely unchanged after five cycles of use. Full article

(This article belongs to the Special Issue Nanoparticle for Catalysis)

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19 pages, 10778 KiB

Open AccessArticle

Underlying Mechanisms of Reductive Amination on Pd-Catalysts: The Unique Role of Hydroxyl Group in Generating Sterically Hindered Amine

by Zeng Hong, Xin Ge and Shaodong Zhou

Int. J. Mol. Sci. 2022, 23(14), 7621; https://doi.org/10.3390/ijms23147621 - 10 Jul 2022

Cited by 5 | Viewed by 2842

Abstract

Pd nanospecies supported on porous g-C₃N₄ nanosheets were prepared for efficient reductive amination reactions. The structures of the catalysts were characterized via FTIR, XRD, XPS, SEM, TEM, and TG analysis, and the mechanisms were investigated using in situ ATR–FTIR spectroscopic [...] Read more.

Pd nanospecies supported on porous g-C₃N₄ nanosheets were prepared for efficient reductive amination reactions. The structures of the catalysts were characterized via FTIR, XRD, XPS, SEM, TEM, and TG analysis, and the mechanisms were investigated using in situ ATR–FTIR spectroscopic analysis complemented by theoretical calculation. It transpired that the valence state of the Pd is not the dominating factor; rather, the hydroxyl group of the Pd(OH)₂ cluster is crucial. Thus, by passing protons between different molecules, the hydroxyl group facilitates both the generation of the imine intermediate and the reduction of the C=N unit. As a result, the sterically hindered amines can be obtained at high selectivity (>90%) at room temperature. Full article

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8 pages, 974 KiB

Open AccessArticle

Experimental and Theoretical Study of N₂ Adsorption on Hydrogenated Y₂C₄H⁻ and Dehydrogenated Y₂C₄⁻ Cluster Anions at Room Temperature

by Min Gao, Yong-Qi Ding and Jia-Bi Ma

Int. J. Mol. Sci. 2022, 23(13), 6976; https://doi.org/10.3390/ijms23136976 - 23 Jun 2022

Cited by 4 | Viewed by 1851

Abstract

The adsorption of atmospheric dinitrogen (N₂) on transition metal sites is an important topic in chemistry, which is regarded as the prerequisite for the activation of robust N≡N bonds in biological and industrial fields. Metal hydride bonds play an important part [...] Read more.

The adsorption of atmospheric dinitrogen (N₂) on transition metal sites is an important topic in chemistry, which is regarded as the prerequisite for the activation of robust N≡N bonds in biological and industrial fields. Metal hydride bonds play an important part in the adsorption of N₂, while the role of hydrogen has not been comprehensively studied. Herein, we report the N₂ adsorption on the well-defined Y₂C₄H_0,1⁻ cluster anions under mild conditions by using mass spectrometry and density functional theory calculations. The mass spectrometry results reveal that the reactivity of N₂ adsorption on Y₂C₄H⁻ is 50 times higher than that on Y₂C₄⁻ clusters. Further analysis reveals the important role of the H atom: (1) the presence of the H atom modifies the charge distribution of the Y₂C₄H⁻ anion; (2) the approach of N₂ to Y₂C₄H⁻ is more favorable kinetically compared to that to Y₂C₄⁻; and (3) a natural charge analysis shows that two Y atoms and one Y atom are the major electron donors in the Y₂C₄⁻ and Y₂C₄H⁻ anion clusters, respectively. This work provides new clues to the rational design of TM-based catalysts by efficiently doping hydrogen atoms to modulate the reactivity towards N₂. Full article

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13 pages, 5283 KiB

Open AccessArticle

Solid-State Construction of CuO_x/Cu_1.5Mn_1.5O₄ Nanocomposite with Abundant Surface CuO_x Species and Oxygen Vacancies to Promote CO Oxidation Activity

by Baolin Liu, Hao Wu, Shihao Li, Mengjiao Xu, Yali Cao and Yizhao Li

Int. J. Mol. Sci. 2022, 23(12), 6856; https://doi.org/10.3390/ijms23126856 - 20 Jun 2022

Cited by 7 | Viewed by 2046

Abstract

Carbon monoxide (CO) oxidation performance heavily depends on the surface-active species and the oxygen vacancies of nanocomposites. Herein, the CuO_x/Cu_1.5Mn_1.5O₄ were fabricated via solid-state strategy. It is manifested that the construction of CuO_x/Cu_1.5 [...] Read more.

Carbon monoxide (CO) oxidation performance heavily depends on the surface-active species and the oxygen vacancies of nanocomposites. Herein, the CuO_x/Cu_1.5Mn_1.5O₄ were fabricated via solid-state strategy. It is manifested that the construction of CuO_x/Cu_1.5Mn_1.5O₄ nanocomposite can produce abundant surface CuO_x species and a number of oxygen vacancies, resulting in substantially enhanced CO oxidation activity. The CO is completely converted to carbon dioxide (CO₂) at 75 °C when CuO_x/Cu_1.5Mn_1.5O₄ nanocomposites were involved, which is higher than individual CuO_x, MnO_x, and Cu_1.5Mn_1.5O₄. Density function theory (DFT) calculations suggest that CO and O₂ are adsorbed on CuO_x/Cu_1.5Mn_1.5O₄ surface with relatively optimal adsorption energy, which is more beneficial for CO oxidation activity. This work presents an effective way to prepare heterogeneous metal oxides with promising application in catalysis. Full article

(This article belongs to the Special Issue Nanoparticle for Catalysis)

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12 pages, 2540 KiB

Open AccessArticle

Development of High-Efficiency, Magnetically Separable Palladium-Decorated Manganese-Ferrite Catalyst for Nitrobenzene Hydrogenation

by Viktória Hajdu, Gábor Muránszky, Miklós Nagy, Erika Kopcsik, Ferenc Kristály, Béla Fiser, Béla Viskolcz and László Vanyorek

Int. J. Mol. Sci. 2022, 23(12), 6535; https://doi.org/10.3390/ijms23126535 - 10 Jun 2022

Cited by 9 | Viewed by 2194

Abstract

Aniline (AN) is one of the most important compounds in the chemical industry and is prepared by the catalytic hydrogenation of nitrobenzene (NB). The development of novel, multifunctional catalysts which are easily recoverable from the reaction mixture is, therefore, of paramount importance. Compared [...] Read more.

Aniline (AN) is one of the most important compounds in the chemical industry and is prepared by the catalytic hydrogenation of nitrobenzene (NB). The development of novel, multifunctional catalysts which are easily recoverable from the reaction mixture is, therefore, of paramount importance. Compared to conventional filtration, magnetic separation is favored because it is cheaper and more facile. For satisfying these requirements, we developed manganese ferrite (MnFe₂O₄)–supported, magnetically separable palladium catalysts with high catalytic activity in the hydrogenation of nitrobenzene to aniline. In addition to high NB conversion and AN yield, remarkable aniline selectivity (above 96 n/n%) was achieved. Surprisingly, the magnetic support alone also shows moderate catalytic activity even without noble metals, and thus, up to 94 n/n% nitrobenzene conversion, along with 47 n/n% aniline yield, are attainable. After adding palladium nanoparticles to the support, the combined catalytic activity of the two nanomaterials yielded a fast, efficient, and highly selective catalyst. During the test of the Pd/MnFe₂O₄ catalyst in NB hydrogenation, no by-products were detected, and consequently, above 96 n/n% aniline yield and 96 n/n% selectivity were achieved. The activity of the Pd/MnFe₂O₄ catalyst was not particularly sensitive to the hydrogenation temperature, and reuse tests indicate its applicability in at least four cycles without regeneration. The remarkable catalytic activity and other favorable properties can make our catalyst potentially applicable to both NB hydrogenation and other similar or slightly different reactions. Full article

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Review

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13 pages, 1952 KiB

Open AccessReview

Recent Studies on the Application of Microwave-Assisted Method for the Preparation of Heterogeneous Catalysts and Catalytic Hydrogenation Processes

by Anna A. Strekalova, Anastasiya A. Shesterkina, Alexander L. Kustov and Leonid M. Kustov

Int. J. Mol. Sci. 2023, 24(9), 8272; https://doi.org/10.3390/ijms24098272 - 5 May 2023

Cited by 11 | Viewed by 2727

Abstract

Currently, microwave radiation is widely used in various chemical processes in order to intensify them and carry out processes within the framework of “green” chemistry approaches. In the last 10 years, there has been a significant increase in the number of scientific publications [...] Read more.

Currently, microwave radiation is widely used in various chemical processes in order to intensify them and carry out processes within the framework of “green” chemistry approaches. In the last 10 years, there has been a significant increase in the number of scientific publications on the application of microwaves in catalytic reactions and synthesis of nanomaterials. It is known that heterogeneous catalysts obtained under microwave activation conditions have many advantages, such as improved catalytic characteristics and stability, and the synthesis of nanomaterials is accelerated several times compared to traditional methods used to produce catalysts. The present review article is to summarize the results of modern research on the use of microwave radiation for the synthesis of heterogeneous catalytic nanomaterials and discusses the prospects for research in the field of microwave-induced liquid-phase heterogeneous catalysis in hydrogenation. Full article

(This article belongs to the Special Issue Nanoparticle for Catalysis)

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