Catalysts

13 pages, 3790 KiB

Open AccessFeature PaperArticle

Petal-like g-C₃N₄ Enhances the Photocatalyst Removal of Hexavalent Chromium

by Huijuan Yu, Qiang Ma, Cuiping Gao, Shaohua Liao, Yingjie Zhang, Hong Quan and Ruiqi Zhai

Catalysts 2023, 13(3), 641; https://doi.org/10.3390/catal13030641 - 22 Mar 2023

Cited by 6 | Viewed by 1981

The rapid progress of modern industry not only brings convenience to people’s lives, but also brings negative effects. Industrial development produces a large amount of waste metal, which brings harm to the environment and human health. Carbon nitride (g-C₃N₄) [...] Read more.

The rapid progress of modern industry not only brings convenience to people’s lives, but also brings negative effects. Industrial development produces a large amount of waste metal, which brings harm to the environment and human health. Carbon nitride (g-C₃N₄) was successfully prepared using the thermal-polymerization method and petal-like g-C₃N₄ (CA-g-C₃N₄) was impregnated with citric acid (CA). Compared with g-C₃N₄, CA-g-C₃N₄ showed extremely high photocatalytic activity because the petal-like g-C₃N₄ (CA-g-C₃N₄) had a larger specific surface area, which increased the active sites on the surface of the photocatalyst and improved the photocatalytic activity. After citric acid treatment, the removal of hexavalent chromium (Cr(VI)) by g-C₃N₄ increased from 48% to 93%. The photocatalytic materials were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Brunauer–Emmett–Teller (BET) and UV-vis diffuse reflectance spectra (UV-vis). In summary, this study confirmed that citric acid can improve the photocatalytic activity of g-C₃N₄ by increasing its specific surface area and the active site of the photocatalytic material so as to achieve the purpose of removing hexavalent chromium from water. Full article

(This article belongs to the Special Issue Synthesis and In-Depth Characterization of Supported and Highly Dispersed Catalysts)

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14 pages, 4527 KiB

Open AccessArticle

Ethylene Dimerization Performance of NiBTCs Synthesized Using Different Solvents

by Cong Wang, Gang Li and Hongchen Guo

Catalysts 2023, 13(3), 640; https://doi.org/10.3390/catal13030640 - 22 Mar 2023

Cited by 2 | Viewed by 2427

Abstract

MOFs have attracted widespread attention in the field of catalytic ethylene dimerization. Compared with post-synthetic modification, ion exchange and other methods to introduce external active centers, the direct use of MOF materials as catalysts is still the most convenient and prospective. Herein, the [...] Read more.

MOFs have attracted widespread attention in the field of catalytic ethylene dimerization. Compared with post-synthetic modification, ion exchange and other methods to introduce external active centers, the direct use of MOF materials as catalysts is still the most convenient and prospective. Herein, the NiBTCs are synthesized using a one-pot method in two kinds of solvent and characterized by XRD, FT–IR, ICP–OES, XPS, TGA and N₂ physical adsorption. After treatment at 150 °C, the catalytic activities of both materials in ethylene dimerization are up to 470.9, and 647.0 g_pro./(g_cat.·h) and the selectivity of 1-butene in all products could reach 83.2% and 81.7%, respectively. Stability testing of the catalysts demonstrated that they do not decompose during the reaction, but their reuse performance is degraded. In addition, a probable Cossee–Arlman–type mechanism is proposed. The NiBTCs are shown to have superior catalytic performance in ethylene dimerization compared to employing Ni(pyz)₂Cl₂ or α–Ni(im)₂ as catalysts. Full article

(This article belongs to the Special Issue MOFs Catalyst for Energy-Related Reactions)

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19 pages, 3824 KiB

Open AccessFeature PaperReview

A Review of Transition Metal Nitride-Based Catalysts for Electrochemical Nitrogen Reduction to Ammonia

by So Young Park, Youn Jeong Jang and Duck Hyun Youn

Catalysts 2023, 13(3), 639; https://doi.org/10.3390/catal13030639 - 22 Mar 2023

Cited by 9 | Viewed by 5235

Abstract

Electrochemical nitrogen reduction (NRR) has attracted much attention as a promising technique to produce ammonia at ambient conditions in an environmentally benign and less energy-consuming manner compared to the current Haber–Bosch process. However, even though much research on the NRR catalysts has been [...] Read more.

Electrochemical nitrogen reduction (NRR) has attracted much attention as a promising technique to produce ammonia at ambient conditions in an environmentally benign and less energy-consuming manner compared to the current Haber–Bosch process. However, even though much research on the NRR catalysts has been conducted, their low selectivity and reaction rate still hinder the practical application of the NRR process. Among various catalysts, transition metal nitride (TMN)-based catalysts are expected to be promising catalysts for NRR. This is because the NRR process can proceed via the unique Mars–Van Krevelen (MvK) mechanism with a compressed competing hydrogen evolution reaction. However, a controversial issue exists regarding the origin of ammonia produced on TMN-based catalysts. The instability of the TMN-based catalysts can lead to ammonia generation from lattice nitrogen instead of supplied N₂ gas. Thus, this review summarizes the recent progress of TMN-based catalysts for NRR, encompassing the NRR mechanism, synthetic routes, characterizations, and controversial opinions. Furthermore, future perspectives on producing ammonia electrochemically using TMN-based catalysts are provided. Full article

(This article belongs to the Special Issue Theme Issue in Honor of Prof. Dr. Jae Sung Lee)

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17 pages, 21074 KiB

Open AccessReview

Green Oxidative Catalytic Processes for the Preparation of APIs and Precursors

by Pedro D. García-Fernández, Juan M. Coto-Cid and Gonzalo de Gonzalo

Catalysts 2023, 13(3), 638; https://doi.org/10.3390/catal13030638 - 22 Mar 2023

Cited by 4 | Viewed by 2733

Abstract

Asymmetric oxidation processes have constituted a valuable tool for the synthesis of active pharmaceutical ingredients (APIs), especially for the preparation of optically active sulfoxides, compounds with interesting biological properties. Classical approaches for these oxidative procedures usually require the application of non-sustainable conditions that [...] Read more.

Asymmetric oxidation processes have constituted a valuable tool for the synthesis of active pharmaceutical ingredients (APIs), especially for the preparation of optically active sulfoxides, compounds with interesting biological properties. Classical approaches for these oxidative procedures usually require the application of non-sustainable conditions that employ hazardous reagents and solvents. In the last decades, chemists have tried to combine the preparation of valuable compounds of high yields and selectivities with the development of more sustainable protocols. To achieve this objective, greener solvents, reagents, and catalysts are employed, together with the use of novel chemical techniques such as flow catalysis or photocatalysis. The last efforts in the development of greener approaches for the preparation of APIs and their intermediates using oxidative procedure will be reviewed herein. Most of these approaches refer to biocatalytic methods, in which mild reaction conditions and reagents are employed, but other novel techniques such as photocatalysis will be described. Full article

(This article belongs to the Special Issue 10th Anniversary of Catalysts: Recent Advances in the Use of Catalysts for Pharmaceuticals)

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15 pages, 4559 KiB

Open AccessArticle

Structural Effects of Microcrystalline Cellulose-Derived Carbon Supports on Catalytic Performance of the Pd(OH)₂/C Catalysts for the Hydrogenolytic Debenzylation of Hexanitrohexaazaisowurtzitane Derivatives

by Yuling Wang, Yun Chen, Xinlei Ding, Jianwei Song, Gaixia Wei, Hengwei Dai, Hanyang Wang, Yadong Liu, Guangmei Bai and Wenge Qiu

Catalysts 2023, 13(3), 637; https://doi.org/10.3390/catal13030637 - 22 Mar 2023

Cited by 2 | Viewed by 1786

Abstract

In order to reduce the noble metal palladium dosage in the preparation of CL-20 so as to reduce its production cost, several carbon supports were prepared successfully using the hydrothermal carbonization method in the absence or presence of urea using microcrystalline cellulose (MC) [...] Read more.

In order to reduce the noble metal palladium dosage in the preparation of CL-20 so as to reduce its production cost, several carbon supports were prepared successfully using the hydrothermal carbonization method in the absence or presence of urea using microcrystalline cellulose (MC) as the carbon source, and the corresponding Pd(OH)₂/C catalysts were fabricated using the deposition–precipitation method, which showed high activity in the debenzylation reaction of hexabenzylhexaazaisowurtzitane (HBIW) and tetraacetyldibenzylhexaazaisowurtzitane (TADB). It was found that all the catalysts showed a high efficiency in the debenzylation of HBIW, indicating that the structure of the used carbon supports had a limited impact on the catalyst performance in this reaction. On the contrary, the activities of the catalysts in the debenzylation of TADB were quite different. The results of the nitrogen sorption isotherm measurement (BET), scanning electron microscope (SEM), scanning transmission electron microscopy (STEM), powder X-ray diffraction (XRD), element analysis and temperature programmed desorption (TPD), as well as X-ray photoelectron spectra (XPS) characterizations of the supports and catalysts, showed that the relatively high activity of Pd/HTC in the debenzylation of TADB was related to the high Pd dispersion and novel mesoporous structure, while the further higher activity and stability of Pd/HTC-N_1:1 in the same reaction were related with its high Pd dispersion, high total oxidized Pd species, and high surface pyridinic N contents as well as the eggshell distribution of Pd species on the support. Full article

(This article belongs to the Special Issue Exclusive Papers in Environmentally Friendly Catalysis in China)

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15 pages, 4800 KiB

Open AccessArticle

Pluronic-123 Assisted Synthesis of Cobalt Vanadate Microparticles (µ-CoV MPs) for Durable Electrochemical Oxygen Evolution Reaction in Seawater and Connate Water

by Ibrahim Khan

Catalysts 2023, 13(3), 636; https://doi.org/10.3390/catal13030636 - 22 Mar 2023

Cited by 7 | Viewed by 2117

Abstract

Exploring different catalytic material paradigms could drive the search for the best oxygen evolution reaction (OER) catalyst to achieve industrially-feasible hydrogen fuel from water. Cobalt-based materials are considered good choices in this regard. Herein, we synthesized Pluronic-123 (P-123)-stabilized, unique, rough, globular-shaped [...] Read more.

Exploring different catalytic material paradigms could drive the search for the best oxygen evolution reaction (OER) catalyst to achieve industrially-feasible hydrogen fuel from water. Cobalt-based materials are considered good choices in this regard. Herein, we synthesized Pluronic-123 (P-123)-stabilized, unique, rough, globular-shaped cobalt vanadate microparticles (µ-CoV MPs) using an ultrasonic-assisted solvothermal method. The as-synthesized µ-CoV MPs were subjected to high-temperature annealing to improve the crystallinity and the surface polymer moieties were pyrolyzed. Conventional SEM, XRD, FTIR, and BET analyses evaluated the morphological and structural features. The temperature-controlled crystalline phase led to extensive OER performance in SW electrolytes. The OER onset potential (V_OER) was observed at 1.557 V@10 mA/cm² in seawater (SW) for µ-CoV MPs annealed at 400 °C compared to the V_OER of 1.632 V of non-annealed µ-CoV MPs. The current density showed a steep increase beyond 1.557 V, confirming the excellent electrokinetics OER behavior of the µ-CoV MPs-deposited electrode. The chronoamperometric (I–t) OER stability comparison in SW and connate water (CW) electrolytes indicated only a <20% initial current density decrease after 8 h in the case of the SW electrolyte. However, the CW electrolyte posed serious challenges to the electrode and activity was completely lost after <2 h. The electrolytic comparison indicated that SW is highly suitable for µ-CoV MPs electrodes. Full article

(This article belongs to the Special Issue Electro/Photocatalyst for Degradation of Emerging Water Pollutants and Water Splitting)

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24 pages, 3558 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Giving New Life to Waste Cigarette Butts: Transformation into Platinum Group Metal-Free Electrocatalysts for Oxygen Reduction Reaction in Acid, Neutral and Alkaline Environment

by Davide Testa, Giovanni Zuccante, Mohsin Muhyuddin, Roberto Landone, Axel Scommegna, Roberto Lorenzi, Maurizio Acciarri, Elisabetta Petri, Francesca Soavi, Lorenzo Poggini, Laura Capozzoli, Alessandro Lavacchi, Niccolò Lamanna, Andrea Franzetti, Luca Zoia and Carlo Santoro

Catalysts 2023, 13(3), 635; https://doi.org/10.3390/catal13030635 - 22 Mar 2023

Cited by 9 | Viewed by 2482

Abstract

Following the core theme of a circular economy, a novel strategy to upcycle cigarette butt waste into platinum group metal (PGM)-free metal nitrogen carbon (M-N-C) electrocatalysts for oxygen reduction reaction (ORR) is presented. The experimental route was composed of (i) the transformation of [...] Read more.

Following the core theme of a circular economy, a novel strategy to upcycle cigarette butt waste into platinum group metal (PGM)-free metal nitrogen carbon (M-N-C) electrocatalysts for oxygen reduction reaction (ORR) is presented. The experimental route was composed of (i) the transformation of the powdered cigarette butts into carbonaceous char via pyrolysis at 450 °C, 600 °C, 750 °C and 900 °C, (ii) the porosity activation with KOH and (iii) the functionalization of the activated chars with iron (II) phthalocyanine (FePc). The electrochemical outcomes obtained by the rotating disk electrode (RRDE) technique revealed that the sample pyrolyzed at 450 °C (i.e., cig_450) outperformed the other counterparts with its highest onset (E_on) and half-wave potentials (E_1/2) and demonstrated nearly tetra-electronic ORR in acidic, neutral and alkaline electrolytes, all resulting from the optimal surface chemistry and textural properties. Full article

(This article belongs to the Special Issue Non-noble Metal Electrocatalysts for the Oxygen Reduction Reaction)

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20 pages, 14135 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

BiPO₄/Ov-BiOBr High-Low Junctions for Efficient Visible Light Photocatalytic Performance for Tetracycline Degradation and H₂O₂ Production

by Minghui Tang, Xibao Li, Fang Deng, Lu Han, Yu Xie, Juntong Huang, Zhi Chen, Zhijun Feng and Yingtang Zhou

Catalysts 2023, 13(3), 634; https://doi.org/10.3390/catal13030634 - 22 Mar 2023

Cited by 11 | Viewed by 2212

Abstract

Through a two-step solvothermal method, different molar ratios of BiPO₄ were grown in situ on the surface of oxygen-vacancy-rich BiOBr (Ov-BiOBr), successfully constructing a BiPO₄/Ov-BiOBr heterojunction composite material. By constructing a novel type I high-low junction between the semiconductor BiPO [...] Read more.

Through a two-step solvothermal method, different molar ratios of BiPO₄ were grown in situ on the surface of oxygen-vacancy-rich BiOBr (Ov-BiOBr), successfully constructing a BiPO₄/Ov-BiOBr heterojunction composite material. By constructing a novel type I high-low junction between the semiconductor BiPO₄ and Ov-BiOBr, stronger oxidative holes or reductive electrons were retained, thereby improving the redox performance of the photocatalyst. The composite catalyst with a 10% molar content of BiPO₄ demonstrated the highest degradation rate of tetracycline (TC), degrading over 95% within 90 min, with a rate constant of 0.02534 min⁻¹, which is 2.3 times that of Ov-BiOBr and 22 times that of BiPO₄. The 10% BiPO₄/Ov-BiOBr sample displayed the best photocatalytic activity, producing 139 μmol·L⁻¹ H₂O₂ in 120 min, which is 3.6 times the efficiency of Ov-BiOBr and 19 times that of BiPO₄. This was due to the appropriate bandgap matching between BiPO₄ and Ov-BiOBr, the photo-generated electron transfer channel via Bi-bridge, and efficient charge separation. It was inferred that the free radical species ·OH and ·O₂⁻ played the dominant role in the photocatalytic process. Based on experimental and theoretical results, a possible photocatalytic mechanism was proposed. Full article

(This article belongs to the Special Issue Photocatalytic Nanomaterials for Environmental Purification)

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14 pages, 2643 KiB

Open AccessArticle

Bimetal–Organic Framework-Derived CoMn@C Catalysts for Fischer–Tropsch Synthesis

by Linyan Yang, Yu Gao, Yupeng Guo, Zhengjia Li, Jie Cen, Nan Yao and Xiaonian Li

Catalysts 2023, 13(3), 633; https://doi.org/10.3390/catal13030633 - 22 Mar 2023

Viewed by 1851

Abstract

Introducing promoters to cobalt-based catalysts for Fischer–Tropsch synthesis (FTS) has been found to be efficient in adjusting their performance in converting syngas into long-chain hydrocarbons. High spatial proximity of the promoter and reactive metal is desired to maximize the effectiveness of the promoters. [...] Read more.

Introducing promoters to cobalt-based catalysts for Fischer–Tropsch synthesis (FTS) has been found to be efficient in adjusting their performance in converting syngas into long-chain hydrocarbons. High spatial proximity of the promoter and reactive metal is desired to maximize the effectiveness of the promoters. In this work, CoMn@C composites were synthesized by the one-step carbonization of bimetal–organic frameworks (BMOFs: CoMn-BTC). BMOF-derived catalysts naturally exhibited that cobalt nanoparticles (NPs) are confined in the carbon matrix, with a concentrated particle size distribution around 13.0 nm and configurated with MnO highly dispersed throughout the catalyst particles. Mn species preferentially bind to the surfaces of Co NPs rather than embedded into the Co lattice. The number of Mn–Co interfaces on the catalyst surface results in the weakened adsorption of H but enhanced adsorption strength of CO and C. Hence, the incorporation of Mn significantly inhibits the production of CH₄ and C₂–C₄ paraffin boosts light olefin (C_2–4⁼) and C₅⁺ production. Furthermore, the FTS activity observed for the Mn-promoted catalysts increases with increased Mn loading and peaks at 2Co1Mn@C due to the abundance of Co–Mn interfaces. These prominent FTS catalytic properties highlight the concept of synthesizing BMOF-derived mixed metal oxides with close contact between promoters and reactive metals. Full article

(This article belongs to the Section Industrial Catalysis)

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14 pages, 4685 KiB

Open AccessArticle

Effect of MgFe-LDH with Reduction Pretreatment on the Catalytic Performance in Syngas to Light Olefins

by Jie Li, Changxiao Li, Qiong Tang, Zhijun Zuo, Lei Liu and Jinxiang Dong

Catalysts 2023, 13(3), 632; https://doi.org/10.3390/catal13030632 - 21 Mar 2023

Viewed by 2037

Abstract

MgFe-layered double hydroxides (LDH) were widely used as catalysts for Fischer–Tropsch synthesis to produce light olefins, in which the state of Fe-species may affect the resulting catalytic active sites. Herein, the typical MgFe-LDH was hydrothermally synthesized and the obtained MgFe-LDH was pretreated with [...] Read more.

MgFe-layered double hydroxides (LDH) were widely used as catalysts for Fischer–Tropsch synthesis to produce light olefins, in which the state of Fe-species may affect the resulting catalytic active sites. Herein, the typical MgFe-LDH was hydrothermally synthesized and the obtained MgFe-LDH was pretreated with H₂ at different temperatures to reveal the effects of the state of Fe-species on the catalytic performance in Fischer–Tropsch synthesis. MgFe-LDH materials were characterized by X-ray diffraction (XRD), N₂ adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), H₂ temperature-programmed reduction (H₂-TPR), and X-ray photoelectron spectroscopy (XPS). It was found that a MgO-FeO solid solution would be formed with the increase of the reduction temperature, which made the electrons transfer from Mg atoms to Fe atoms and strengthened the adsorption of CO. The pre-reduced treatment toward Mg-Fe-LDH enabled the FeC_x active sites to be easily formed in situ during the reaction process, leading to the high conversion of CO. CO₂ temperature-programmed desorption (CO₂-TPD) and H₂ temperature-programmed desorption (H₂-TPD) analysis confirmed that the surface basicity of the catalysts was increased and the hydrogenation capacity was weakened, the secondary hydrogenation of the olefins was inhibited, and therefore as were the enhancement of O/P in the product and the high selectivity of light olefins (42.7%). Full article

(This article belongs to the Special Issue Catalytic Conversion of Low Carbon Alkane)

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10 pages, 1272 KiB

Open AccessFeature PaperArticle

Electrochemical Thiocyanation/Cyclization Cascade to Access Thiocyanato-Containing Benzoxazines

by Jianguo Hu, Hao Wan, Shengchun Wang, Hong Yi and Aiwen Lei

Catalysts 2023, 13(3), 631; https://doi.org/10.3390/catal13030631 - 21 Mar 2023

Cited by 4 | Viewed by 2054

Abstract

Due to the importance of SCN-containing heteroarenes, developing novel and green synthetic protocols for the synthesis of SCN-containing compounds has drawn much attention over the last decades. We reported here an electrochemical oxidative cyclization of ortho-vinyl aniline to access various SCN-containing benzoxazines. [...] Read more.

Due to the importance of SCN-containing heteroarenes, developing novel and green synthetic protocols for the synthesis of SCN-containing compounds has drawn much attention over the last decades. We reported here an electrochemical oxidative cyclization of ortho-vinyl aniline to access various SCN-containing benzoxazines. Mild conditions, an extra catalyst-free and oxidant-free system, and good tolerance for air highlight the application potential of this method. Full article

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

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20 pages, 8117 KiB

Open AccessArticle

Doped Ruthenium/Hypercrosslinked Polystyrene (HPS) Catalysts in the Modification of Fatty Acid Methyl Esters

by Romulo C. Dutra, Thatiane V. S. Martins, Delma da G. Rocha, Mario R. Meneghetti, Simoni M. P. Meneghetti, Mikhail G. Sulman, Valentina G. Matveeva and Paulo A. Z. Suarez

Catalysts 2023, 13(3), 630; https://doi.org/10.3390/catal13030630 - 21 Mar 2023

Cited by 3 | Viewed by 1694

Abstract

The modification of fatty substrates using heterogeneous catalysts have extensive industrial application and has an emphatic position in a sustainable context. Herein ruthenium, nickel, cobalt and copper-doped ruthenium, supported on hypercrosslinked polystyrene (HPS) catalysts were prepared by wet impregnation, characterized and applied on [...] Read more.

The modification of fatty substrates using heterogeneous catalysts have extensive industrial application and has an emphatic position in a sustainable context. Herein ruthenium, nickel, cobalt and copper-doped ruthenium, supported on hypercrosslinked polystyrene (HPS) catalysts were prepared by wet impregnation, characterized and applied on the modification of canola fatty acid methyl esters (FAME). The characterization showed a dispersive effect of doping metals over the ruthenium particles, the presence of acid sites and overall surface morphology, which allows targeting potential applications. The chosen modifications consisted of hydrogenation, hydroformylation, oxidative cleavage and deoxygenation, resulting in superb catalytic activities of over 99% conversions for hydrogenation and deoxygenation. The simplicity of the canola FAME composition allows the understanding of the catalytic processes and allows the upscale of more complex FAME matrixes. Finally, the obtained data stimulates further optimization studies for each application with a variation on the catalysts and the usage of residual fatty substrates, greatly enhancing the sustainability profile of the systems. Full article

(This article belongs to the Special Issue Transition-Metal-Containing Bifunctional Catalysts: Design and Catalytic Applications)

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3 pages, 181 KiB

Open AccessEditorial

Microbial Biocatalysis

by Tao Pan and Zhilong Wang

Catalysts 2023, 13(3), 629; https://doi.org/10.3390/catal13030629 - 21 Mar 2023

Cited by 2 | Viewed by 2065

Abstract

Biocatalysis, which can be performed by whole cells and isolated enzymes, has become a topic of public interest for its potential use in the chemical industry in manufacturing, monitoring, and waste management [...] Full article

(This article belongs to the Special Issue Microbial Biocatalysis)

12 pages, 2245 KiB

Open AccessFeature PaperArticle

Coal as an Effective Catalyst for Selective Oxidative Dehydrogenation of Propane to Propene

by Qiuwen Liu, Yuhua Zhang, Yawei Wu, Mingxia Song and Caijin Huang

Catalysts 2023, 13(3), 628; https://doi.org/10.3390/catal13030628 - 21 Mar 2023

Viewed by 1524

Abstract

Coal is a readily available and inexpensive material. However, its direct use as a catalyst is still rare, but attractive for practical application. In this paper, coal was directly used as a catalyst for the selective oxidative dehydrogenation of propane to propene. It [...] Read more.

Coal is a readily available and inexpensive material. However, its direct use as a catalyst is still rare, but attractive for practical application. In this paper, coal was directly used as a catalyst for the selective oxidative dehydrogenation of propane to propene. It exhibited a high selectivity over 90% with a yield of 8.4% at a high space velocity (12,000 mL·(h·g-cat)⁻¹). The productivity up to 2.84 gC₃H₆ g_cat⁻¹ h⁻¹ was obtained with propene selectivity above 80% (20,000 mL·(h·g-cat)⁻¹). The kinetic showed first-order dependence with respect to propane or oxygen partial pressures. Meanwhile, electron paramagnetic resonance (EPR) and X-ray photoelectron spectrum (XPS) demonstrated that the carbonyl groups act as active sites for oxidative dehydrogenation of propane to propene. This work expands the use of earth-abundant and low-price coal in catalysis with expectable scale application. Full article

(This article belongs to the Special Issue Engineering Novel Heterojunctions for Photocatalytic Energy and Environmental Applications)

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5 pages, 219 KiB

Open AccessEditorial

Nanomaterials in Catalysis Applications

by Ioannis V. Yentekakis, Dimitrios P. Gournis and Michael A. Karakassides

Catalysts 2023, 13(3), 627; https://doi.org/10.3390/catal13030627 - 21 Mar 2023

Cited by 3 | Viewed by 3835

Abstract

The interconnected rapid development of nanomaterials science and advanced analysis and imaging techniques at the nano-level scale (some “operando”) fostered the parallel growth of heterogeneous catalysis and its evolution into “nano-catalysis” [...] Full article

(This article belongs to the Special Issue Nanomaterials in Catalysis Applications)

14 pages, 3507 KiB

Open AccessArticle

Promotion Effects of Ce-Doping on Catalytic Oxidation of Ethane over Pt/Ce_xTi_1−xO₂

by Dengmao Wu, Xianyan Lv, Xiurong Ren, Changming Hou, Qianwei Ma, Junxuan Yao and Jiangliang Hu

Catalysts 2023, 13(3), 626; https://doi.org/10.3390/catal13030626 - 21 Mar 2023

Cited by 2 | Viewed by 1375

Abstract

The catalytic oxidation of VOCs is widely acknowledged as the most available technology to reduce air pollution. Among the catalysts for VOCs, 1 wt%-Pt/TiO₂ catalysts using metal as a doping element have shown amazing potential in many fields. However, achieving high catalytic [...] Read more.

The catalytic oxidation of VOCs is widely acknowledged as the most available technology to reduce air pollution. Among the catalysts for VOCs, 1 wt%-Pt/TiO₂ catalysts using metal as a doping element have shown amazing potential in many fields. However, achieving high catalytic performance at relatively low temperatures based on the activation of molecules is still a formidable challenge owing to the catalytic activity being highly dependent on temperature. Here, the role of the rare earth metal Ce in the catalytic oxidation of ethane was studied by preparing Pt/Ce_xTi_1−xO₂ (x = 0, 0.002, 0.005, 0.01, 0.02, and 0.05) catalysts. When the Ce/(Ce+Ti) molar ratio was 0.01, Pt/Ce_0.01Ti_0.99O₂ achieved 90% ethane conversion at 436 °C. This reaction temperature is 15% lower than that for Pt/TiO₂. The characterization results show that the doping of Ce caused lattice expansion of TiO₂ and its distortion brought about by oxygen vacancies. Additionally, the appropriate amount of Ce-doping can alter the interaction between the active component Pt and the carrier TiO₂, thereby improving the activity and concentration of the active surface lattice oxygen species of the catalyst. These results provide a foundation for the design of the catalytic oxidation of VOCs under mild operating conditions. Full article

(This article belongs to the Section Environmental Catalysis)

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20 pages, 4219 KiB

Open AccessArticle

Rational Design of a Biocatalyst Based on Immobilized CALB onto Nanostructured SiO₂

by Carlos R. Llerena Suster, María V. Toledo, Silvana R. Matkovic, Susana R. Morcelle and Laura E. Briand

Catalysts 2023, 13(3), 625; https://doi.org/10.3390/catal13030625 - 20 Mar 2023

Cited by 3 | Viewed by 1631

Abstract

The adsorption of the lipase B from Candida antarctica (CALB) over nanostructured SiO₂ (Ns SiO₂ from now on) with and without the addition of polyols (sorbitol and glycerol) was investigated. The isotherms of adsorption made it possible to establish that the [...] Read more.

The adsorption of the lipase B from Candida antarctica (CALB) over nanostructured SiO₂ (Ns SiO₂ from now on) with and without the addition of polyols (sorbitol and glycerol) was investigated. The isotherms of adsorption made it possible to establish that the maximum dispersion limit was 0.029 µmol of protein per surface area unit of Ns SiO₂ (29.4 mg per 100 mg of support), which was reached in 30 min of exposure. The studies through SDS-PAGE of the immobilization solutions and infrared spectroscopy of the prepared solids determined that CALB (from a commercial extract) is selectively adsorbed, and its secondary structure distribution is thus modified. Its biocatalytic activity was corroborated through the kinetic resolution of rac-ibuprofen. Conversions of up to 70% and 52% enantiomeric excess toward S-ibuprofen in 24 h of reaction at 45 °C were achieved. The biocatalytic performance increased with the increase in protein loading until it leveled off at 0.021 µmol.m⁻², reaching 0.6 µmol.min⁻¹. The biocatalyst containing the lipase at the maximum dispersion limit and co-adsorbed polyols presented the best catalytic performance in the kinetic resolution of rac-ibuprofen, an improved thermal resistance (up to 70 °C), and stability under long-term storage (more than 2 years). Full article

(This article belongs to the Special Issue Applications of Hydrolases in Medicinal Chemistry)

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36 pages, 1914 KiB

Open AccessReview

Role of Ion-Exchange Resins in Hydrogenation Reactions

by Jordi H. Badia, Rodrigo Soto, Eliana Ramírez, Roger Bringué, Carles Fité, Montserrat Iborra and Javier Tejero

Catalysts 2023, 13(3), 624; https://doi.org/10.3390/catal13030624 - 20 Mar 2023

Cited by 3 | Viewed by 4523

Abstract

The role of ion-exchange resins (IERs) as catalysts or catalysts supports, in hydrogenation reactions is revised and their potential application is presented. Both gel-type and macroreticular, basic or acid, IERs have been used for manifold metal-catalyzed hydrogenation processes in gas and liquid phase, [...] Read more.

The role of ion-exchange resins (IERs) as catalysts or catalysts supports, in hydrogenation reactions is revised and their potential application is presented. Both gel-type and macroreticular, basic or acid, IERs have been used for manifold metal-catalyzed hydrogenation processes in gas and liquid phase, including hydrogenation of alkenes, alkynes, carbonyls, arenes, nitroaromatics, and more. When available, qualitative relationships between the morphology and structure of resins and their performance as solid supports for metal catalysts are observed. Noble metals, such as Pt, Au, and Pd, and non-noble metals, such as Fe and Cu, have been introduced into IERs polymeric backbones by simple ion-exchange of a metal salt precursor with the resin, or by a combination of ion-exchange and other protocols, to obtain mono- and bimetallic catalysts supported on IERs. High yields towards target product, as well as the recyclability of metal-doped IERs, have been reported in the literature, with low metal leaching, which makes them highly interesting solid catalysts for a wide array of industrial applications. Multistep reaction processes, involving hydrogenation and hydration/cyclization/aldol condensation/etc., constitute promising applications due to the one-pot synthesis approach and relatively low temperatures required, which adds environmental interest in terms of process integration and optimization. Full article

(This article belongs to the Special Issue Advances in the Catalytic Behavior of Ion-Exchange Resins)

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14 pages, 1700 KiB

Open AccessEditor’s ChoiceArticle

Four-Component Synthesis of 9H-Pyrimido[4,5-b]indoles Using Ammonium Iodide as the Nitrogen Source

by Yufeng Chen, Ruitong Yang, Fuhong Xiao, Tong Li, Guojiang Mao and Guo-Jun Deng

Catalysts 2023, 13(3), 623; https://doi.org/10.3390/catal13030623 - 20 Mar 2023

Cited by 4 | Viewed by 1441

Abstract

A four-component synthesis of 2-phenyl-9H-pyrimido[4,5-b]indoles was developed using indole-3-carboxaldehydes, aromatic aldehyde and ammonium iodide as the raw materials under transition-metal-free conditions. The pyrimidine ring was formed in one pot through [4 + 2] annulation reaction. Four C–N bonds were [...] Read more.

A four-component synthesis of 2-phenyl-9H-pyrimido[4,5-b]indoles was developed using indole-3-carboxaldehydes, aromatic aldehyde and ammonium iodide as the raw materials under transition-metal-free conditions. The pyrimidine ring was formed in one pot through [4 + 2] annulation reaction. Four C–N bonds were formed in one pot promoted by iodine and iodide additives. This work is highlighted by using two ammonium iodides as the sole nitrogen source. Full article

(This article belongs to the Special Issue Catalytic Annulation Reactions)

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28 pages, 5714 KiB

Open AccessArticle

Quantification of the Microwave Effect in the Synthesis of 5-Hydroxymethylfurfural over Sulfonated MIL-101(Cr)

by Noor Aljammal, Jeroen Lauwaert, Bert Biesemans, Francis Verpoort, Philippe M. Heynderickx and Joris W. Thybaut

Catalysts 2023, 13(3), 622; https://doi.org/10.3390/catal13030622 - 20 Mar 2023

Cited by 2 | Viewed by 2197

Abstract

The potential benefits of microwave irradiation for fructose dehydration into 5 hydroxymethylfurfural (5-HMF) have been quantified over a sulfonated metal–organic framework (MOF), MIL 101(Cr)-SO₃H. The effects of temperature (140–170 °C), batch time (5–300 min), and catalyst-to-substrate ratio (0.1–0.01 g/g) were systematically [...] Read more.

The potential benefits of microwave irradiation for fructose dehydration into 5 hydroxymethylfurfural (5-HMF) have been quantified over a sulfonated metal–organic framework (MOF), MIL 101(Cr)-SO₃H. The effects of temperature (140–170 °C), batch time (5–300 min), and catalyst-to-substrate ratio (0.1–0.01 g/g) were systematically mapped. After 10 min of microwave (MW) irradiation at 140 °C in a DMSO–acetone reaction medium, practically complete fructose conversion was obtained with a 70% yield of 5-HMF. Without MW, i.e., using conventional heating (CH) at the same conditions, the fructose conversion was limited to 13% without any 5-HMF yield. Rather, 90 min of CH was required to reach a similarly high conversion and yield. The profound impact of moving from CH towards MW conditions on the reaction kinetics, also denoted as the microwave effect, has been quantified through kinetic modeling via a change in the Gibbs free energy of the transition state. The modeling results revealed an eight-fold rate coefficient enhancement for fructose dehydration owing to MW irradiation, while the temperature dependence of the various reaction steps almost completely disappeared in the investigated range of operating conditions. Full article

(This article belongs to the Special Issue 10th Anniversary of Catalysts: Feature Papers in Catalytic Reaction Engineering)

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12 pages, 9494 KiB

Open AccessFeature PaperArticle

Coupling the Piezoelectric Effect and the Plasmonic Effect to Enhance the Photocatalytic Degradation of Ciprofloxacin in Au-Ferroelectric Bi₄Ti₃O₁₂ Nanofibers

by Chao Meng, Junfeng Peng, Lei Wang, Hao Han, Kai Yang and Daotong You

Catalysts 2023, 13(3), 621; https://doi.org/10.3390/catal13030621 - 20 Mar 2023

Cited by 1 | Viewed by 1548

Abstract

In this study, ferroelectric Bi₄Ti₃O₁₂ and Au-Bi₄Ti₃O₁₂ nanofibers were synthesized by electrospinning and ion sputtering. The piezoelectric effect of Bi₄Ti₃O₁₂ and the surface plasmon effect of Au were [...] Read more.

In this study, ferroelectric Bi₄Ti₃O₁₂ and Au-Bi₄Ti₃O₁₂ nanofibers were synthesized by electrospinning and ion sputtering. The piezoelectric effect of Bi₄Ti₃O₁₂ and the surface plasmon effect of Au were used to improve the photogenerated electron–hole separation and optical absorption. The results of the characterization showed successful preparation of the orthorhombic Bi₄Ti₃O₁₂ nanofibers, in which the absorption band edge was 426 nm with a 2.91 eV band gap. The piezo-photocatalytic activity of the Bi₄Ti₃O₁₂ was tested through the degradation of the antibiotic ciprofloxacin under three different experimental conditions: light, vibration, and light plus vibration. All of the ciprofloxacin was degraded after 80 min in piezo-photocatalytic conditions, with a piezo-photocatalytic degradation rate of 0.03141 min⁻¹, which is 1.56 and 3.88 times, respectively, that of photocatalysis and piezo-catalysis. After loading Au on the Bi₄Ti₃O₁₂, the degradation efficiency was improved under all three conditions, and the piezoelectric photocatalytic efficiency of Au-Bi₄Ti₃O₁₂ for ciprofloxacin degradation was able to reach 100% in 60 min with a piezo-photocatalytic degradation rate of 0.06157 min⁻¹. The results of the photocurrent and impedance tests indicated that the photocurrent density of Bi₄Ti₃O₁₂ nanofibers loaded with Au is increased from 5.08 × 10⁻⁷ A/cm² to 8.17 × 10⁻⁶ A/cm², which is 16.08 times higher than without loading the Au. This work provides an effective way to improve the conversion efficiency of photocatalysis to degrade organic pollutants by combining the plasmon effect and the piezoelectric effect. Full article

(This article belongs to the Special Issue Engineering Novel Heterojunctions for Photocatalytic Energy and Environmental Applications)

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28 pages, 4168 KiB

Open AccessReview

Nanomaterials Aspects for Photocatalysis as Potential for the Inactivation of COVID-19 Virus

by Samira Bagheri, Nurhidayatullaili Muhd Julkapli, Mohd Rashid Yusof Hamid, Rojin Ziaei and Suresh Sagadevan

Catalysts 2023, 13(3), 620; https://doi.org/10.3390/catal13030620 - 20 Mar 2023

Cited by 5 | Viewed by 2114

Abstract

Coronavirus disease-2019 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is the most difficult recent global outbreak. Semiconducting materials can be used as effective photocatalysts in photoactive technology by generating various reactive oxidative species (ROS), including superoxide (•O₂⁻ [...] Read more.

Coronavirus disease-2019 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and is the most difficult recent global outbreak. Semiconducting materials can be used as effective photocatalysts in photoactive technology by generating various reactive oxidative species (ROS), including superoxide (•O₂⁻) and hydroxyl (•OH) radicals, either by degradation of proteins, DNA, and RNA or by inhibition of cell development through terminating the cellular membrane. This review emphasizes the capability of photocatalysis as a reliable, economical, and fast-preferred method with high chemical and thermal stability for the deactivation and degradation of SARS-CoV-2. The light-generated holes present in the valence band (VB) have strong oxidizing properties, which result in the oxidation of surface proteins and their inactivation under light illumination. In addition, this review discusses the most recent photocatalytic systems, including metals, metal oxides, carbonaceous nanomaterials, and 2-dimensional advanced structures, for efficient SARS-CoV-2 inactivation using different photocatalytic experimental parameters. Finally, this review article summarizes the limitations of these photocatalytic approaches and provides recommendations for preserving the antiviral properties of photocatalysts, large-scale treatment, green sustainable treatment, and reducing the overall expenditure for applications. Full article

(This article belongs to the Special Issue Application of Nanosystems in Catalysis)

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18 pages, 5117 KiB

Open AccessArticle

Fe Single Atoms Reduced by NaBH₄ Mediate g-C₃N₄ Electron Transfer and Effectively Remove 2-Mercaptobenzothiazole

by Chen Yang, Xuefeng Hu, Yaxing Bai, Beichuan Cai and Yujie Li

Catalysts 2023, 13(3), 619; https://doi.org/10.3390/catal13030619 - 20 Mar 2023

Cited by 5 | Viewed by 2307

Abstract

In this study, a simple and low-energy synthesis scheme of Fe single-atom anchored carbon nitride was reported to improve the photocatalytic performance of g-C₃N₄. Synthesized Fe single-atom doped graphite carbon nitride (Fe-SACs/g-C₃N₄) showed high activity [...] Read more.

In this study, a simple and low-energy synthesis scheme of Fe single-atom anchored carbon nitride was reported to improve the photocatalytic performance of g-C₃N₄. Synthesized Fe single-atom doped graphite carbon nitride (Fe-SACs/g-C₃N₄) showed high activity and stability for the degradation of 2-mercaptobenzothiazole (MBT); under visible light irradiation, 99% of MBT could be degraded within 35 min, and the degradation ability basically did not decline after five cycles, mainly due to the synergistic effect of the Fe single atoms and carbon nitride. The results of X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), and density functional theory calculations show that the single-atom Fe forms Fe-N₄ coordination with pyridine nitrogen to generate a new electron transfer channel, which can significantly improve the in-plane separation and transfer of carriers, finally enhancing the generation of superoxide radicals. This is confirmed by time-resolved photoluminescence, photoelectron chemistry, and electron spin resonance measurements. The main intermediates of MBT degradation were determined using a liquid chromatograph–mass spectrometer (LC-MS), and a possible photocatalytic mechanism based on the quenching experiment and electron paramagnetic resonance (EPR) test was proposed. A deep understanding of the contribution of Fe single-atom sites with clear local coordination structures will help to design effective catalysts for photocatalytic performance. Full article

(This article belongs to the Special Issue UV/Vis/NIR Photocatalysis and Optical Properties)

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21 pages, 10582 KiB

Open AccessArticle

Investigating the Performance of Lithium-Doped Bismuth Ferrite [BiFe_1−xLi_xO₃]-Graphene Nanocomposites as Cathode Catalyst for the Improved Power Output in Microbial Fuel Cells

by Tenzin Pema, Ankit Kumar, Babita Tripathi, Soumya Pandit, Sunil Chauhan, Satyendra Singh, Pritam Kumar Dikshit, Abhilasha Singh Mathuriya, Piyush Kumar Gupta, Dibyajit Lahiri, Ram Chandra Singh, Jigisha Anand and Kundan Kumar Chaubey

Catalysts 2023, 13(3), 618; https://doi.org/10.3390/catal13030618 - 20 Mar 2023

Cited by 4 | Viewed by 1988

Abstract

In this study, multifunctional lithium-doped bismuth ferrite [BiFe_1−xLi_xO₃]-graphene nanocomposites (x = 0.00, 0.02, 0.04, 0.06) were synthesized by a sol-gel and ultrasonication assisted chemical reduction method. X-ray diffraction and FESEM electron microscopy techniques disclosed the nanocomposite phase [...] Read more.

In this study, multifunctional lithium-doped bismuth ferrite [BiFe_1−xLi_xO₃]-graphene nanocomposites (x = 0.00, 0.02, 0.04, 0.06) were synthesized by a sol-gel and ultrasonication assisted chemical reduction method. X-ray diffraction and FESEM electron microscopy techniques disclosed the nanocomposite phase and nanocrystalline nature of [BiFe_1−xLi_xO₃]-graphene nanocomposites. The FESEM images and the EDX elemental mapping revealed the characteristic integration of BiFe_1−xLi_xO₃ nanoparticles (with an average size of 95 nm) onto the 2D graphene layers. The Raman spectra of the [BiFe_1−xLi_xO₃]-graphene nanocomposites evidenced the BiFe_1−xLi_xO₃ and graphene nanostructures in the synthesized nanocomposites. The photocatalytic performances of the synthesized nanocomposites were assessed for ciprofloxacin (CIP) photooxidation under UV-visible light illumination. The photocatalytic efficiencies of [BiFe_1−xLi_xO₃]-graphene nanocomposites were measured to be 42%, 47%, 43%, and 10%, for x = 0.00, 0.02, 0.04, 0.06, respectively, within 120 min illumination, whereas the pure BiFeO₃ nanoparticles were 21.0%. BiFe_1−xLi_xO₃ nanoparticles blended with graphene were explored as cathode material and tested in a microbial fuel cell (MFC). The linear sweep voltammetry (LSV) analysis showed that the high surface area of BiFeO₃ was attributed to efficient oxygen reduction reaction (ORR) activity. The increasing loading rates of (0.5–2.5 mg/cm²) [BiFe_1−xLi_xO₃]-graphene composite on the cathode surface showed increasing power output, with 2.5 and 2 mg/cm² achieving the maximum volumetric power density of 8.2 W/m³ and 8.1 W/m³, respectively. The electrochemical impedance spectroscopy (EIS) analysis showed that among the different loading rates used in this study, BiFeO₃, with a loading rate of 2.5 mg/cm², showed the lowest charge transfer resistance (R_ct). The study results showed the potential of [BiFe_1−xLi_xO₃]-graphene composite as a cost-effective alternative for field-scale MFC applications. Full article

(This article belongs to the Special Issue Recent Advances on Nano-Catalysts for Biological Processes II)

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15 pages, 3131 KiB

Open AccessArticle

Scale-Up Lipase Production and Development of Methanol Tolerant Whole-Cell Biocatalyst from Magnusiomyces spicifer SPB2 in Stirred-Tank Bioreactor and Its Application for Biodiesel Production

by Purimprat Srimhan and Tipparat Hongpattarakere

Catalysts 2023, 13(3), 617; https://doi.org/10.3390/catal13030617 - 20 Mar 2023

Cited by 3 | Viewed by 1785

Abstract

This study aimed to economically develop the yeast whole-cell biocatalyst from the lipase-secreting Magnusiomyces spicifer SPB2 to serve green biodiesel production. The scaled-up productions of lipases were optimized using a 5-L stirred-tank bioreactor. The maximum extracellular lipase and cell-bound lipase (CBL) yields of [...] Read more.

This study aimed to economically develop the yeast whole-cell biocatalyst from the lipase-secreting Magnusiomyces spicifer SPB2 to serve green biodiesel production. The scaled-up productions of lipases were optimized using a 5-L stirred-tank bioreactor. The maximum extracellular lipase and cell-bound lipase (CBL) yields of 1189.65 U/L and 5603.74 U/L were achieved at 24 h and 60 h, respectively, in the modified IMY medium (pH 5.0) containing 2% of soybean oil as a carbon source and 0.2% Gum Arabic as an emulsifying agent. The optimized cultivation was initiated with an inoculum size of 1 × 10⁷ cells/mL and conducted under an aeration rate of 0.75 vvm with an agitation speed of 400 rpm. The obtained whole-cell biocatalyst of M. spicifer SPB2 was applied to catalyze the transesterification reaction using palm oil and methanol as substrates. The greatest yield of 97.93% fatty acid methyl ester (FAME) was reached at 72 h using a palm oil/methanol ratio of 1:7, indicating high methanol stability of the biocatalyst. Moreover, substrate homogenization accelerated the reaction to achieve FAME production of 97.01% at 48 h and remained stable afterwards. Without homogenization, the highest FAME of 98.20% was obtained at 60 h. The whole-cell biocatalyst prepared from lipase-secreting M. spicifer SPB2 at an up-scaled level greatly enhanced efficiency and feasibility for commercial biodiesel production through a green conversion process. Full article

(This article belongs to the Special Issue Lipase: A Multi-Purpose Biocatalyst at the Forefront of Biotechnology)

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13 pages, 2418 KiB

Open AccessArticle

Effect of Urea as a Shape-Controlling Agent on the Properties of Bismuth Oxybromides

by Viktória Márta, Zsolt Pap, Enikő Bárdos, Tamás Gyulavári, Gábor Veréb and Klara Hernadi

Catalysts 2023, 13(3), 616; https://doi.org/10.3390/catal13030616 - 20 Mar 2023

Viewed by 1951

Abstract

Bismuth oxybromides were prepared via a solvothermal method by applying different urea amounts during synthesis. The effects of the urea ratio on the morpho–structural properties and photocatalytic activity of the samples were investigated. X-ray diffraction, diffuse reflectance spectroscopy, infrared spectroscopy, Raman spectroscopy, scanning [...] Read more.

Bismuth oxybromides were prepared via a solvothermal method by applying different urea amounts during synthesis. The effects of the urea ratio on the morpho–structural properties and photocatalytic activity of the samples were investigated. X-ray diffraction, diffuse reflectance spectroscopy, infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and surface tension measurements were carried out to characterize the samples. Their photoactivity was evaluated by the photocatalytic degradation of rhodamine B and ibuprofen under UV and visible light irradiations. The urea ratio notably influenced morphology, particle size distribution, and photoactivity. However, it only had a limited effect on the crystalline composition, primary crystallite size, and band gap of bismuth oxybromides. The formation of Bi-based complexes and degraded urea-based products were observed, which were deduced to influence band gap energies and hence, photoactivity. Predominantly, samples prepared at low urea ratios proved to be the best for both rhodamine B and ibuprofen degradations under both irradiations. Full article

(This article belongs to the Special Issue Ecofriendly Catalytic Materials in Environmental Catalysis for Water Protection)

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27 pages, 11345 KiB

Open AccessArticle

Polymer-Supported Oxidovanadium(IV) Complexes and Their Catalytic Applications in One-Pot Multicomponent Reactions Producing Biologically Active 2,4,5-Trisubstituted-1H-imidazoles

by Mannar R. Maurya, Monojit Nandi, Akhil Patter, Fernando Avecilla and Kaushik Ghosh

Catalysts 2023, 13(3), 615; https://doi.org/10.3390/catal13030615 - 19 Mar 2023

Cited by 7 | Viewed by 2240

Abstract

Two new monobasic tridentate O⁀N⁀N donor ligands, HL₁ (I) and HL₂ (II) have been obtained in two steps by reacting phenylhydrazine and salicylaldehyde or 3,5-di-tert-butylsalicylaldehyde and then reacting the resulting compounds with 2-chloromethylbenzimidazole in the [...] Read more.

Two new monobasic tridentate O⁀N⁀N donor ligands, HL₁ (I) and HL₂ (II) have been obtained in two steps by reacting phenylhydrazine and salicylaldehyde or 3,5-di-tert-butylsalicylaldehyde and then reacting the resulting compounds with 2-chloromethylbenzimidazole in the presence of triethylamine. The reaction of [V^IVO(acac)₂] with these ligands in a 1:1 molar ratio in dry methanol led to the formation of homogeneous oxidovanadium(IV) complexes [V^IVO(acac)L₁] (1) and [V^IVO(acac)L₂] (2). Immobilization of these complexes on chloromethylated polystyrene (PS-Cl) cross-linked with divinyl benzene resulted in corresponding polymer-supported heterogeneous complexes PS-[V^IVO(acac)L₁] (3) and PS-[V^IVO(acac)L₂] (4). Ligands (I and II), homogeneous complexes (1 and 2) and heterogeneous complexes (3 and 4) have been characterized using elemental analysis and various spectroscopic techniques. A single crystal X-ray diffraction study of I and 1 further confirms their structures. The oxidation state IV of vanadium in these complexes was assured by recording their EPR spectra while heterogeneous complexes were further characterized using field emission-scanning electron microscopy (FE-SEM) combined with energy dispersive X-ray analysis (EDS) and atomic force microscopy (AFM). All vanadium complexes have been explored for their catalytic potential to one-pot-three-component reactions (reagents: benzil, ammonium acetate and various aromatic aldehydes) for the efficient synthesis of 2,4,5-triphenyl-1H-imidazole derivatives (nine examples). Various reaction conditions have been optimized to obtain a maximum yield (up to 96%) of catalytic products. It has been found that heterogeneous complexes show excellent catalytic activity and are recyclable up to five catalytic cycles. Full article

(This article belongs to the Special Issue Multicomponent Catalytic Reactions under Green Conditions)

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20 pages, 3119 KiB

Open AccessArticle

Influence of HB₂Nb₃O₁₀-Based Nanosheet Photocatalysts (B = Ca, Sr) Preparation Method on Hydrogen Production Efficiency

by Sergei A. Kurnosenko, Vladimir V. Voytovich, Oleg I. Silyukov, Ivan A. Rodionov, Ekaterina N. Malygina and Irina A. Zvereva

Catalysts 2023, 13(3), 614; https://doi.org/10.3390/catal13030614 - 18 Mar 2023

Cited by 4 | Viewed by 1531

Abstract

Photocatalytic activity of HB₂Nb₃O₁₀ perovskite nanosheets (B = Ca, Sr) has been systematically investigated in the reactions of hydrogen production, depending on the method of the photocatalyst preparation: using the pristine nanosheets in the parent suspension without reassembly, [...] Read more.

Photocatalytic activity of HB₂Nb₃O₁₀ perovskite nanosheets (B = Ca, Sr) has been systematically investigated in the reactions of hydrogen production, depending on the method of the photocatalyst preparation: using the pristine nanosheets in the parent suspension without reassembly, filtered nanosheets as well as nanosheets restacked by hydrochloric acid. Photocatalytic measurements were organized in such a way as to control a wide range of parameters, including the hydrogen generation rate, quantum efficiency of the reaction, potential dark activity of the sample as well as stability and pH of the reaction suspension. Exfoliation of the niobates into nanosheets allowed obtaining efficient photocatalysts surpassing the initial bulk materials in the activity up to 55 times and providing apparent quantum efficiency up to 20.8% after surface decoration with a Pt cocatalyst. Among the reassembled samples, greater hydrogen evolution activity was exhibited by simply filtered nanosheets that, unlike the HCl-restacked ones, were found to possess much lower specific surface area in a dry state but contain a perceptible amount of tetrabutylammonium cations on the surface. The activity difference, potentially, is associated with the fact that the filtered nanosheets undergo ultrasonic disaggregation before photocatalytic tests much easier than their HCl-restacked counterparts and, thanks to this, have greater active surface in the reaction suspension. In addition, the enhanced activity of the filtered nanosheets may be due to the presence of tetrabutylammonium as an organic modifier on their surface, which is consistent with the high photocatalytic performance of organically modified layered perovskites considered in our previous reports. Full article

(This article belongs to the Special Issue Catalysts for Sustainable Hydrogen Production: Preparation, Applications and Process Integration, 2nd Edition)

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13 pages, 5083 KiB

Open AccessArticle

Manganese-Based Metal-Organic Frameworks Photocatalysts for Visible Light-Driven Oxidative Coupling of Benzylamine under Atmospheric Oxygen: A Comparative Study

by Lamia A. Siddig, Reem H. Alzard, Abdalla S. Abdelhamid and Ahmed Alzamly

Catalysts 2023, 13(3), 613; https://doi.org/10.3390/catal13030613 - 18 Mar 2023

Cited by 2 | Viewed by 2352

Abstract

Research on the utilization of sustainable and renewable energy sources has increased as a result of the world’s expanding energy demand. In this regard, we report the photocatalytic performance of two synthesized Mn-MOFs: Mn^II₃(tp)_6/2(bpy)₂.(dmf) (C₄₇ [...] Read more.

Research on the utilization of sustainable and renewable energy sources has increased as a result of the world’s expanding energy demand. In this regard, we report the photocatalytic performance of two synthesized Mn-MOFs: Mn^II₃(tp)_6/2(bpy)₂.(dmf) (C₄₇H₃₅Mn₃N₅O₁₃) and Mn₂(tpa)₂(dmf)₂ (C₂₂H₂₂Mn₂N₂O₁₀). The two MOFs were characterized using different spectroscopic and analytical techniques: powder X-ray diffraction, thermogravimetric analysis, diffuse reflectance spectroscopy, Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. Mn^II₃(tp)_6/2(bpy)₂.(dmf) possesses a band gap value of 2.5 eV, which exhibits significant photocatalytic activity when exposed to simulated visible light irradiation. Mn₂(tpa)₂(dmf)₂ shows a larger band gap of 3.16 eV, which renders the photocatalytic performance under visible light. The oxidation of benzylamine to N,N-benzylidenebenzylamine by a photocatalytic reaction was selected to evaluate the photocatalytic activities of Mn^II₃(tp)_6/2(bpy)₂.(dmf) and Mn₂(tpa)₂(dmf)₂ in the visible region. In addition to its high photocatalytic performance, Mn^II₃(tp)_6/2(bpy)₂.(dmf) also showed high thermal stability up to 430 °C. Accordingly, the strategy of designing frameworks possessing mixed ligands provides stability to the frameworks as well as enhancing the photocatalytic performance of frameworks containing bipyridine ligands such as Mn^II₃(tp)_6/2(bpy)₂.(dmf). Full article

(This article belongs to the Special Issue Design and Application of Metal-Organic Framework-Based/-Derived Catalysts)

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17 pages, 2791 KiB

Open AccessArticle

Comprehensive Study on Environmental Behaviour and Degradation by Photolytic/Photocatalytic Oxidation Processes of Pharmaceutical Memantine

by Sandra Babić, Davor Ljubas, Dragana Mutavdžić Pavlović, Martina Biošić, Lidija Ćurković and Dario Dabić

Catalysts 2023, 13(3), 612; https://doi.org/10.3390/catal13030612 - 17 Mar 2023

Cited by 1 | Viewed by 1768

Abstract

Memantine is a pharmaceutical used to treat memory loss, one of the main symptoms of dementia and Alzheimer’s disease. The use of memantine is expected to continue to grow due to the increasing proportion of the elderly population worldwide. The aim of this [...] Read more.

Memantine is a pharmaceutical used to treat memory loss, one of the main symptoms of dementia and Alzheimer’s disease. The use of memantine is expected to continue to grow due to the increasing proportion of the elderly population worldwide. The aim of this work was to conduct a comprehensive study on the behaviour of memantine in the environment and the possibilities of its removal from wastewater. Abiotic elimination processes (hydrolysis, photolysis and sorption) of memantine in the environment were investigated. Results showed that memantine is stable in the environment and easily leached from river sediment. Therefore, further investigation was focused on memantine removal by advanced oxidation processes that would prevent its release into the environment. For photolytic and photocatalytic degradation of memantine, ultraviolet (UV) lamps with the predominant radiation wavelengths of 365 nm (UV-A) and 254/185 nm (UV-C) were used as a source of light. TiO₂ in the form of a nanostructured film deposited on the borosilicate glass wall of the reactor was used for photocatalytic experiments. Photodegradation of memantine followed pseudo-first-order kinetics. The half-life of photocatalytic degradation by UV-A light was much higher (46.3 min) than the half-life obtained by UV-C light (3.9 min). Processes degradation efficiencies and evaluation of kinetic constants were based on the results of HPLC-MS/MS analyses, which also enable the identification of memantine oxidation products. The acute toxicity of the reaction mixture during the oxidation was evaluated by monitoring the inhibition of the luminescence of Vibrio fischeri bacteria. The results showed that memantine and its oxidation products were not harmful to Vibrio fischeri. Full article

(This article belongs to the Special Issue Industrial Applications of Advanced Oxidation Technologies: Past and Future)

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