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12 pages, 7762 KiB

Open AccessArticle

Electronic Effects in a Green Protocol for (Hetero)Aryl-S Coupling

by Massimo Carraro, Camillo Are, Ugo Azzena, Lidia De Luca, Silvia Gaspa, Giuseppe Satta, Wolfgang Holzer, Vittorio Pace and Luisa Pisano

Molecules 2024, 29(8), 1714; https://doi.org/10.3390/molecules29081714 - 10 Apr 2024

Viewed by 422

Abstract

Aryl and heteroaryl iodides have been efficiently converted into the corresponding thioacetates in cyclopentyl methyl ether (CPME), a green solvent, under Cu catalysis. The chemoselectivity of the reaction is mainly controlled by electronic factors, enabling the conversion of both electron-rich and electron-deficient substrates [...] Read more.

Aryl and heteroaryl iodides have been efficiently converted into the corresponding thioacetates in cyclopentyl methyl ether (CPME), a green solvent, under Cu catalysis. The chemoselectivity of the reaction is mainly controlled by electronic factors, enabling the conversion of both electron-rich and electron-deficient substrates into the corresponding thioacetates in good to excellent yields. The products can be easily deprotected to the corresponding thiolates to carry out additional synthetic transformations in situ. Surprisingly, despite CPME’s relatively low dielectric constant, the reaction rate significantly increased when conducted under microwave irradiation conditions. This synthetic methodology exhibits a remarkable tolerance to functional groups, mild reaction conditions, and a wide substrate scope, utilizing a safe and inexpensive CuI pre-catalyst in the green solvent CPME. A non-aqueous workup allowing for the complete recovery of both catalyst and solvent makes this approach an environmentally sustainable protocol for C(sp²) sulfur functionalization. Additionally, the reaction shows selective cross-coupling with iodides in competition with chlorides and bromides, allowing its use in multistep syntheses. To demonstrate the potential of this methodology, it was applied to the high-yield synthesis of a photochromic dithienylethene, where a selective synthesis had not been reported before. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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10 pages, 3085 KiB

Open AccessArticle

Silver-Loaded Chabazite in Ethanol-to-Hydrocarbon Process—Operando FT-IR and UV-Vis Spectroscopic Studies

by Karolina A. Tarach, Anna K. Walczyk, Agata Kordek, Oliwia Rogala and Kinga Góra-Marek

Molecules 2024, 29(6), 1207; https://doi.org/10.3390/molecules29061207 - 08 Mar 2024

Viewed by 596

Abstract

The ethanol dehydration process is studied regarding protonic and Ag-loaded chabazite zeolite in advanced FT-IR and UV-vis operando spectroscopic studies with simultaneous mass spectroscopy and gas chromatography analyses of products. The spectroscopic investigation provides information on the species formed on the surface of [...] Read more.

The ethanol dehydration process is studied regarding protonic and Ag-loaded chabazite zeolite in advanced FT-IR and UV-vis operando spectroscopic studies with simultaneous mass spectroscopy and gas chromatography analyses of products. The spectroscopic investigation provides information on the species formed on the surface of catalysts, while mass spectrometry and gas chromatography methods identify the desorbed products. These studies are also supported by spectroscopic, chromatographic, and thermogravimetric analyses of coke species formed over the catalyst’s surface during ethanol conversion. The Ag-chabazite catalyst shows higher selectivity for ethylene and propylene; the slower formation of coke species; and, thus, a longer lifetime. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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19 pages, 4460 KiB

Open AccessArticle

Stabilized Palladium Nanoparticles from Bis-(N-benzoylthiourea) Derived-Pd^II Complexes as Efficient Catalysts for Sustainable Cross-Coupling Reactions in Water

by Samet Poyraz, H. Ali Döndaş, Samet Belveren, Senanur Taş, Raquel Hidalgo-León, José Trujillo-Sierra, Lesly V. Rodríguez-Flórez, Mª de Gracia Retamosa, Ana Sirvent, Mohammad Gholinejad, Sara Sobhani and José M. Sansano

Molecules 2024, 29(5), 1138; https://doi.org/10.3390/molecules29051138 - 04 Mar 2024

Cited by 1 | Viewed by 704

Abstract

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki–Miyaura, Mizoroki–Heck, Hiyama, Buchwald–Hartwig, Hirao and Sonogashira–Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective [...] Read more.

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki–Miyaura, Mizoroki–Heck, Hiyama, Buchwald–Hartwig, Hirao and Sonogashira–Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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12 pages, 1982 KiB

Open AccessArticle

Heterogeneous Brønsted Catalysis in the Solvent-Free and Multigram-Scale Synthesis of Polyalcohol Acrylates: The Case Study of Trimethylolpropane Triacrylate

by Massimo Melchiorre, Maria E. Cucciolito, Roberto Esposito, Simone Silvestro and Francesco Ruffo

Molecules 2024, 29(4), 918; https://doi.org/10.3390/molecules29040918 - 19 Feb 2024

Viewed by 647

Abstract

This article presents a thorough investigation into the synthesis of trimethylolpropane triacrylate (TMPTA) via the esterification reaction of trimethylolpropane (TMP) with acrylic acid using Amberlite™ 120 IR (H⁺), Amberlyst^® 15, and Dowex™ 50WX8 resins as heterogeneous catalysts. Preliminary comparative tests [...] Read more.

This article presents a thorough investigation into the synthesis of trimethylolpropane triacrylate (TMPTA) via the esterification reaction of trimethylolpropane (TMP) with acrylic acid using Amberlite™ 120 IR (H⁺), Amberlyst^® 15, and Dowex™ 50WX8 resins as heterogeneous catalysts. Preliminary comparative tests explored the impact of air flow on water removal during the reaction and different acid-to-alcohol molar ratios (3:1, 6:1, or 9:1 mol:mol). The findings revealed that introducing air significantly enhances TMPTA yield and -OH group conversion, particularly at a 6:1 acid-to-alcohol molar ratio. Based on cost considerations, Amberlite™ 120 IR (H⁺) was selected as the preferred catalyst for further optimization. This included evaluating the effect of catalyst loading (10%, 5.0%, and 2.5% w/w_tot) and assessing the impact of a pre-drying process on resin efficiency. The study concluded that optimal conditions did not necessitate drying, requiring 120 °C, a catalyst loading of 10% w/w_tot, a 4 h reaction time, an acid:alcohol ratio of 6:1 mol:mol, the presence of MEHQ (0.1% mol/mol_AA), and air bubbling at 6 ± 1 Nl/h. Catalyst recycling was effectively implemented with a slight reduction in catalytic activity over consecutive runs. Furthermore, the study explored a scaled-up system with a mechanical stirrer, demonstrating the potential for multi-hundred grams scale-up. Considerations for optimizing the air flow stripping system are also highlighted. In summary, this study provides valuable insights into designing and optimizing the esterification process for TMPTA synthesis, laying the foundation for potential industrial applications. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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10 pages, 2293 KiB

Open AccessArticle

Improved Process for the Continuous Acylation of 1,3-Benzodioxole

by Davide Pollon, Francesca Annunziata, Stefano Paganelli, Lucia Tamborini, Andrea Pinto, Sabrina Fabris, Maria Antonietta Baldo and Oreste Piccolo

Molecules 2024, 29(3), 726; https://doi.org/10.3390/molecules29030726 - 04 Feb 2024

Viewed by 859

Abstract

The acylation of 1,3-benzodioxole was studied in a continuous process using a recyclable heterogeneous substoichiometric catalyst. In a short time period (30 min), at 100 °C, the conversion rate was 73%, with a selectivity of 62% of the desired acylated product; the reaction [...] Read more.

The acylation of 1,3-benzodioxole was studied in a continuous process using a recyclable heterogeneous substoichiometric catalyst. In a short time period (30 min), at 100 °C, the conversion rate was 73%, with a selectivity of 62% of the desired acylated product; the reaction was run continuously for 6 h, showing excellent stability and selectivity. Moreover, the unreacted starting material, 1,3-benzodioxole, can be easily separated by distillation and recycled. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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20 pages, 4894 KiB

Open AccessArticle

Catalytic Ketonization over Oxide Catalysts (Part XIV): The Ketonization and Cross-Ketonization of Anhydrides, Substituted Acids and Esters

by Marek Gliński, Małgorzata Gidzińska, Łukasz Czerwiński, Kasper Drozdowski, Ewa M. Iwanek (nee Wilczkowska), Andrzej Ostrowski and Dariusz Łomot

Molecules 2024, 29(3), 584; https://doi.org/10.3390/molecules29030584 - 24 Jan 2024

Viewed by 705

Abstract

A series of 20 wt.% MO₂/S catalysts (where M = Ce, Mn or Zr and S = SiO₂ or Al₂O₃) were prepared using various precursors of the active phases. The resulting catalysts were characterized using different [...] Read more.

A series of 20 wt.% MO₂/S catalysts (where M = Ce, Mn or Zr and S = SiO₂ or Al₂O₃) were prepared using various precursors of the active phases. The resulting catalysts were characterized using different methods (XRD, TPR and S_BET). For the first time, anhydrides were used as potential starting materials for ketone synthesis. This novel reaction was performed on various aliphatic anhydrides in the presence of catalysts within a temperature range of 523–723 K. For all anhydrides, except for pivalic anhydride, the appropriate ketones were obtained with good or very good yields. The vapor-phase catalytic ketonization of esters of benzene-1,x-dicarboxylic acids (x = 2, 3 or 4) with acetic acid were studied in the range of 673–723 K in order to obtain 1,x-diacetylbenzenes. Their yields strongly increased with an increase in the x value (0, 8 and 43% for x = 2, 3 and 4, respectively). The presence of acetophenone as a side product was always noted. In the case of ω-phenylalkanoic acids, their vapor-phase ketonization with acetic acid led to the formation of appropriate ketones with 47–49% yields. Much lower yields of ketones (3–19%) were obtained for acids and ethyl esters containing heterocycle substituents (with O or S atoms) and/or vinyl groups. In the reaction between ethyl 4-nitrophenylacetate and acetic acid, only the products of ester decomposition (p-toluidine and p-nitrotoluene) were determined. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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13 pages, 1639 KiB

Open AccessArticle

Acidity Quantification and Structure Analysis of Amide-AlCl₃ Liquid Coordination Complexes for C₄ Alkylation Catalysis

by Hao Li, Qiong Wu, Ying Liu and Jinrong Bao

Molecules 2023, 28(23), 7857; https://doi.org/10.3390/molecules28237857 - 30 Nov 2023

Viewed by 798

Abstract

Liquid coordination complexes (LCCs), which are formed between metal halides and donor molecules, represent promising catalysts. Six amide-AlCl₃ LCCs were successfully synthesized, followed by their characterization through NMR, Raman, and UV-visible spectroscopy. The acidity of these LCCs was quantified by performing computational [...] Read more.

Liquid coordination complexes (LCCs), which are formed between metal halides and donor molecules, represent promising catalysts. Six amide-AlCl₃ LCCs were successfully synthesized, followed by their characterization through NMR, Raman, and UV-visible spectroscopy. The acidity of these LCCs was quantified by performing computational modelling of fluoride ion affinities (FIA) and experimental Gutmann–Beckett measurements. Spectroscopic analysis indicated bidentate coordination between amide ligands and Al, which induced asymmetric splitting of Al₂Cl₆ into diverse ions such as [AlCl₂L₂]⁺, [AlCl₄]⁻, [AlCl₃L], and [Al₂Cl₆L]. The computed FIA was found to align well with the experimental acidity trends, thereby confirming the proposed structure of the LCC. In the alkylation tests, the LCC with a high acidity demonstrated an increase in the yields of C₅-C₇ alkylates. These results provide an in-depth understanding of the tuneable structures of amide-AlCl₃ LCCs. The acidity of LCCs can be controlled by tuning the ratio of the organic ligand to AlCl₃, which allows bidentate coordination to facilitate asymmetric splitting of Al₂Cl₆. The LCCs demonstrate a high degree of potential as versatile and sustainable acid catalysts in alkylation reactions. These findings may advance the foundational knowledge of LCCs for the purpose of targeted acid catalyst design. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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21 pages, 7140 KiB

Open AccessArticle

Hydrodeoxygenation of Oxygenates Derived from Biomass Pyrolysis Using Titanium Dioxide-Supported Cobalt Catalysts

by Surachet Hongkailers, Adisak Pattiya and Napida Hinchiranan

Molecules 2023, 28(22), 7468; https://doi.org/10.3390/molecules28227468 - 07 Nov 2023

Viewed by 887

Abstract

Bio-oil upgrading to produce biofuels and chemicals has become an attractive topic over the past decade. However, the design of cost- and performance-effective catalysts for commercial-scale production remains a challenge. Herein, commercial titania (TiO₂) was used as the support of cobalt [...] Read more.

Bio-oil upgrading to produce biofuels and chemicals has become an attractive topic over the past decade. However, the design of cost- and performance-effective catalysts for commercial-scale production remains a challenge. Herein, commercial titania (TiO₂) was used as the support of cobalt (Co)-based catalysts (Co/TiO₂) due to its low cost, high availability, and practicability for commercialization in the future. The Co/TiO₂ catalysts were made with two different forms of TiO₂ (anatase [TiO₂–A] and rutile [TiO₂–R]) and comparatively evaluated in the hydrodeoxygenation (HDO) of 4-propylguaicol (4PG), a lignin-derived model compound. Both Co/TiO₂ catalysts promoted the HDO of 4PG following a similar pathway, but the Co/TiO₂–R catalyst exhibited a higher activity in the early stages of the reaction due to the formation of abundant Ti³⁺ species, as detected by X-ray photoelectron spectroscopy (XPS) and hydrogen–temperature programed reduction (H₂–TPR) analyses. On the other hand, the Co/TiO₂–A catalyst possessed a higher acidity that enhanced propylcyclohexane production at prolonged reaction times. In terms of reusability, the Co/TiO₂–A catalyst showed a higher stability (less Co leaching) and reusability compared to Co/TiO₂–R, as confirmed by transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses. The HDO of the real bio-oil derived from pyrolysis of Leucaena leucocephala revealed that the Co/TiO₂–A catalyst could convert high oxygenated aromatics (methoxyphenols, dimethoxyphenols, and benzenediols) to phenols and enhanced the phenols content, hinting at its potential to produce green chemicals from bio-feedstock. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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16 pages, 2819 KiB

Open AccessArticle

Reductive Transformation of O-, N-, S-Containing Aromatic Compounds under Hydrogen Transfer Conditions: Effect of the Process on the Ni-Based Catalyst

by Nikolai S. Nesterov, Vera P. Pakharukova, Alexey A. Philippov, Igor P. Prosvirin, Anton S. Shalygin and Oleg N. Martyanov

Molecules 2023, 28(20), 7041; https://doi.org/10.3390/molecules28207041 - 12 Oct 2023

Cited by 1 | Viewed by 815

Abstract

The influence of the reaction medium on the surface structure and properties of a Ni-based catalyst used for the reductive transformations of O-, N-, and S-containing aromatic substrates under hydrogen transfer conditions has been studied. The catalysts were characterized by XRD, XPS, and [...] Read more.

The influence of the reaction medium on the surface structure and properties of a Ni-based catalyst used for the reductive transformations of O-, N-, and S-containing aromatic substrates under hydrogen transfer conditions has been studied. The catalysts were characterized by XRD, XPS, and IR spectroscopy and TEM methods before and after the reductive reaction. It has been shown that the conversion of 1-benzothiophene causes irreversible poisoning of the catalyst surface with the formation of the Ni₂S₃ phase, whereas the conversion of naphthalene, 1-benzofuran, and indole does not cause any phase change of the catalyst at 250 °C. However, after the indole conversion, the catalyst surface remains enriched with N-containing compounds, which are evenly distributed over the surface. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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12 pages, 1849 KiB

Open AccessArticle

Prediction of Cu Zeolite NH₃-SCR Activity from Variable Temperature ¹H NMR Spectroscopy

by Sambhu Radhakrishnan, Sam Smet, C. Vinod Chandran, Sreeprasanth Pulinthanathu Sree, Karel Duerinckx, Gina Vanbutsele, Johan A. Martens and Eric Breynaert

Molecules 2023, 28(18), 6456; https://doi.org/10.3390/molecules28186456 - 06 Sep 2023

Viewed by 963

Abstract

Selective catalytic reduction (SCR) of NO_x by ammonia is one of the dominant pollution abatement technologies for near-zero NO_x emission diesel engines. A crucial step in the reduction of NO_x to N₂ with Cu zeolite NH₃-SCR catalysts [...] Read more.

Selective catalytic reduction (SCR) of NO_x by ammonia is one of the dominant pollution abatement technologies for near-zero NO_x emission diesel engines. A crucial step in the reduction of NO_x to N₂ with Cu zeolite NH₃-SCR catalysts is the generation of a multi-electron donating active site, implying the permanent or transient dimerization of Cu ions. Cu atom mobility has been implicated by computational chemistry as a key factor in this process. This report demonstrates how variable temperature ¹H NMR reveals the Cu induced generation of sharp ¹H resonances associated with a low concentration of sites on the zeolite. The onset temperature of the appearance of these signals was found to strongly correlate with the NH₃-SCR activity and was observed for a range of catalysts covering multiple frameworks (CHA, AEI, AFX, ERI, ERI-CHA, ERI-OFF, *BEA), with different Si/Al ratios and different Cu contents. The results point towards universal applicability of variable temperature NMR to predict the activity of a Cu-zeolite SCR catalyst. The unique relationship of a spectroscopic feature with catalytic behavior for zeolites with different structures and chemical compositions is exceptional in heterogeneous catalysis. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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19 pages, 6496 KiB

Open AccessArticle

Methanation of CO₂ over Ruthenium Supported on Alkali-Modified Silicalite-1 Catalysts

by Michał Zieliński, Ewa Janiszewska, Adrianna Drewniak and Mariusz Pietrowski

Molecules 2023, 28(17), 6376; https://doi.org/10.3390/molecules28176376 - 31 Aug 2023

Cited by 1 | Viewed by 916

Abstract

This study focuses on the catalytic properties of ruthenium catalysts supported on modified silicalite-1 (with an MFI structure). By post-synthesis modification of silicalite-1 with solutions of alkali metal compound, a novel and cost-effective method was discovered to create basic centers on the surface [...] Read more.

This study focuses on the catalytic properties of ruthenium catalysts supported on modified silicalite-1 (with an MFI structure). By post-synthesis modification of silicalite-1 with solutions of alkali metal compound, a novel and cost-effective method was discovered to create basic centers on the surface of silicalite-1 supports. The modification not only affected the basicity of the supports but also their porosity. The influence of the type of alkali solution (KOH or NaOH) and its concentration (0.1 M or 1.0 M) on both the basicity and porosity was investigated. The modified silicalite-1 materials were employed as supports for ruthenium catalysts (1 wt.% Ru) and evaluated for their CO₂ methanation activity. The results were compared with the hydrogenation performance of ruthenium catalysts supported on unmodified silicalite-1. Characterization of the supports and catalysts was conducted using techniques such as BET, XRD, FT-IR, ICP-OES, TPR-H₂, H₂ chemisorption, TPD-CO₂, SEM, and TEM. Remarkably, the catalytic activity of ruthenium supported on silicalite-1 treated with 1.0 M NaOH (exhibiting selectivity toward methane above 90% in a reaction temperature range of 250–450 °C) outperformed both unmodified and KOH-modified silicalite-1 supported Ru catalysts. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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13 pages, 3326 KiB

Open AccessFeature PaperArticle

Role of Peripheral Coordination Boron in Electrocatalytic Nitrogen Reduction over N-Doped Graphene-Supported Single-Atom Catalysts

by Ruijie Ma, Xintong Weng, Linghui Lin, Jia Zhao, Fenfei Wei and Sen Lin

Molecules 2023, 28(12), 4597; https://doi.org/10.3390/molecules28124597 - 07 Jun 2023

Cited by 3 | Viewed by 1381

Abstract

In this work, we investigate the effect of peripheral B doping on the electrocatalytic nitrogen reduction reaction (NRR) performance of N-doped graphene-supported single-metal atoms using density functional theory (DFT) calculations. Our results showed that the peripheral coordination of B atoms could improve the [...] Read more.

In this work, we investigate the effect of peripheral B doping on the electrocatalytic nitrogen reduction reaction (NRR) performance of N-doped graphene-supported single-metal atoms using density functional theory (DFT) calculations. Our results showed that the peripheral coordination of B atoms could improve the stability of the single-atom catalysts (SACs) and weaken the binding of nitrogen to the central atom. Interestingly, it was found that there was a linear correlation between the change in the magnetic moment (μ) of single-metal atoms and the change in the limiting potential (U_L) of the optimum NRR pathway before and after B doping. It was also found that the introduction of the B atom suppressed the hydrogen evolution reaction, thereby enhancing the NRR selectivity of the SACs. This work provides useful insights into the design of efficient SACs for electrocatalytic NRR. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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15 pages, 4443 KiB

Open AccessArticle

Peroxymonosulfate Activation by Facile Fabrication of α-MnO₂ for Rhodamine B Degradation: Reaction Kinetics and Mechanism

by Juexiu Li, Qixu Shi, Maiqi Sun, Jinming Liu, Rui Zhao, Jianjing Chen, Xiangfei Wang, Yue Liu, Weijin Gong, Panpan Liu and Kongyao Chen

Molecules 2023, 28(11), 4388; https://doi.org/10.3390/molecules28114388 - 27 May 2023

Cited by 5 | Viewed by 1237

Abstract

The persulfate-based advanced oxidation process has been an effective method for refractory organic pollutants’ degradation in aqueous phase. Herein, α-MnO₂ with nanowire morphology was facially fabricated via a one-step hydrothermal method and successfully activated peroxymonosulfate (PMS) for Rhodamine B (RhB) degradation. Influencing [...] Read more.

The persulfate-based advanced oxidation process has been an effective method for refractory organic pollutants’ degradation in aqueous phase. Herein, α-MnO₂ with nanowire morphology was facially fabricated via a one-step hydrothermal method and successfully activated peroxymonosulfate (PMS) for Rhodamine B (RhB) degradation. Influencing factors, including the hydrothermal parameter, PMS concentration, α-MnO₂ dosage, RhB concentration, initial pH, and anions, were systematically investigated. The corresponding reaction kinetics were further fitted by the pseudo-first-order kinetic. The RhB degradation mechanism via α-MnO₂ activating PMS was proposed according to a series of quenching experiments and the UV-vis scanning spectrum. Results showed that α-MnO₂ could effectively activate PMS to degrade RhB and has good repeatability. The catalytic RhB degradation reaction was accelerated by increasing the catalyst dosage and the PMS concentration. The effective RhB degradation performance can be attributed to the high content of surface hydroxyl groups and the greater reducibility of α-MnO₂, and the contribution of different ROS (reactive oxygen species) was ¹O₂ >

O_{2}^{\cdot -}

>

{SO}_{4}^{\cdot -}

> ·OH. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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18 pages, 2579 KiB

Open AccessArticle

Liquid-Phase Dehydration of Glycerol to Acrolein with ZSM-5-Based Catalysts in the Presence of a Dispersing Agent

by Lin Huang, Bo Wang, Licheng Liu and Armando Borgna

Molecules 2023, 28(8), 3316; https://doi.org/10.3390/molecules28083316 - 08 Apr 2023

Cited by 1 | Viewed by 1366

Abstract

Liquid-phase dehydration of glycerol to acrolein was investigated with solid acid catalysts, including H-ZSM-5, H₃PO₄-modified H-ZSM-5, H₃PW₁₂O₄₀·14H₂O and Cs_2.5H_0.5PW₁₂O₄₀, in the presence of [...] Read more.

Liquid-phase dehydration of glycerol to acrolein was investigated with solid acid catalysts, including H-ZSM-5, H₃PO₄-modified H-ZSM-5, H₃PW₁₂O₄₀·14H₂O and Cs_2.5H_0.5PW₁₂O₄₀, in the presence of sulfolane ((CH₂)₄SO₂) as a dispersing agent under atmospheric pressure N₂ in a batch reactor. High weak-acidity H-ZSM-5, high temperatures and high-boiling-point sulfolane improved the activity and selectivity for the production of acrolein through suppressing the formation of polymers and coke and promoting the diffusion of glycerol and products. Brønsted acid sites were soundly demonstrated to be responsible for dehydration of glycerol to acrolein by infrared spectroscopy of pyridine adsorption. Brønsted weak acid sites favored the selectivity to acrolein. Combined catalytic and temperature-programmed desorption of ammonia studies revealed that the selectivity to acrolein increased as the weak-acidity increased over the ZSM-5-based catalysts. The ZSM-5-based catalysts produced a higher selectivity to acrolein, while the heteropolyacids resulted in a higher selectivity to polymers and coke. Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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13 pages, 2828 KiB

Open AccessArticle

BaTiO₃ Functional Perovskite as Photocathode in Microbial Fuel Cells for Energy Production and Wastewater Treatment

by Noureddine Touach, Abdellah Benzaouak, Jamil Toyir, Youssra El Hamdouni, Mohammed El Mahi, El Mostapha Lotfi, Najoua Labjar, Mohamed Kacimi and Leonarda Francesca Liotta

Molecules 2023, 28(4), 1894; https://doi.org/10.3390/molecules28041894 - 16 Feb 2023

Cited by 6 | Viewed by 1854

Abstract

Microbial fuel cells (MFCs) provide new opportunities for the sustainable production of energy, converting organic matter into electricity through microorganisms. Moreover, MFCs play an important role in remediation of environmental pollutants from wastewater with power generation. This work focuses on the evaluation of [...] Read more.

Microbial fuel cells (MFCs) provide new opportunities for the sustainable production of energy, converting organic matter into electricity through microorganisms. Moreover, MFCs play an important role in remediation of environmental pollutants from wastewater with power generation. This work focuses on the evaluation of ferroelectric perovskite materials as a new class of non-precious photocatalysts for MFC cathode construction. Nanoparticles of BaTiO₃ (BT) were prepared and tested in a microbial fuel cell (MFC) as photocathode catalytic components. The catalyst phases were synthesized, identified and characterized by XRD, SEM, UV–Vis absorption spectroscopy, P-E hysteresis and dielectric measurements. The maximum absorption of BT nanoparticles was recorded at 285 nm and the energy gap (Eg) was estimated to be 3.77 eV. Photocatalytic performance of cathodes coated with BaTiO₃ was measured in a dark environment and then in the presence of a UV–visible (UV–Vis) light source, using a mixture of dairy industry and domestic wastewater as a feedstock for the MFCs. The performance of the BT cathodic component is strongly dependent on the presence of UV–Vis irradiation. The BT-based cathode functioning under UV–visible light improves the maximum power densities and the open circuit voltage (OCV) of the MFC system. The values increased from 64 mW m⁻² to 498 mW m⁻² and from 280 mV to 387 mV, respectively, showing that the presence of light effectively improved the photocatalytic activity of this ceramic. Furthermore, the MFCs operating under optimal conditions were able to reduce the chemical oxygen demand load in wastewater by 90% (initial COD = 2500 mg L⁻¹). Full article

(This article belongs to the Special Issue Research on Heterogeneous Catalysis)

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