Catalysts

15 pages, 1737 KiB

Open AccessFeature PaperArticle

Thermal Behavior of Heavy Oil Catalytic Pyrolysis and Aquathermolysis

by Mohammed A. Khelkhal, Semen E. Lapuk, Aleksey V. Buzyurov, Nikita E. Ignashev, Elvira I. Shmeleva, Irek I. Mukhamatdinov and Alexey V. Vakhin

Catalysts 2022, 12(4), 449; https://doi.org/10.3390/catal12040449 - 18 Apr 2022

Cited by 31 | Viewed by 2865

Abstract

There is still considerable controversy surrounding the mechanisms, thermodynamics, and kinetics of heavy oil aquathermolysis and pyrolysis processes. The present paper aims to widen our knowledge about the effect of iron tallates on pyrolysis and aquathermolysis of Cuban heavy oil. The obtained SARA [...] Read more.

There is still considerable controversy surrounding the mechanisms, thermodynamics, and kinetics of heavy oil aquathermolysis and pyrolysis processes. The present paper aims to widen our knowledge about the effect of iron tallates on pyrolysis and aquathermolysis of Cuban heavy oil. The obtained SARA (S: saturates, A: aromatics, R: resins, A: asphaltenes) analysis has shown a significant increase in light hydrocarbon content during aquathermolysis. Moreover, the elemental analysis has indicated an increase in C and H content by almost 4% and 6%, respectively, with a significant decrease in S and O content by up to 23% in the presence of iron tallates. These results have been further confirmed by infrared spectrometry. The obtained IR data indicated that asphaltene and resin compounds transform into light hydrocarbons after aquathermolysis. On another hand, the activation energy of heavy oil pyrolysis decreased in the presence of the utilized catalyst; meanwhile, the reaction rate increased, especially in the temperature range of 200–480 °C, which may validate a significant effect of the used catalyst in real conditions. Moreover, the obtained thermodynamic data showed a decrease in the enthalpy and entropy of activation of oil pyrolysis in the presence of iron tallates. Our results are encouraging in terms of energy consumption, optimization, and process control and should be validated by a larger sample size. Full article

(This article belongs to the Special Issue Catalysts for Biofuel and Bioenergy Production)

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14 pages, 3763 KiB

Open AccessArticle

Low-Temperature O₃ Decomposition over Pd-TiO₂ Hybrid Catalysts

by Houcine Touati, Afef Mehri, Fathi Karouia, Frédéric Richard, Catherine Batiot-Dupeyrat, Stéphane Daniele and Jean-Marc Clacens

Catalysts 2022, 12(4), 448; https://doi.org/10.3390/catal12040448 - 18 Apr 2022

Cited by 5 | Viewed by 3352

Abstract

In aircraft and spacecraft, outside air is not directly fed to the passenger because it contains ozone at elevated altitudes. The decomposition of low concentration ozone in the air was carried out at 25 °C by catalytic oxidation on Pd-based catalysts supported on [...] Read more.

In aircraft and spacecraft, outside air is not directly fed to the passenger because it contains ozone at elevated altitudes. The decomposition of low concentration ozone in the air was carried out at 25 °C by catalytic oxidation on Pd-based catalysts supported on a high surface area hybrid TiO₂. The use of these hybrid catalysts has shown a beneficial effect, both on the catalytic activity and on the catalyst stability. Kinetic studies showed that the most promising catalytic phase (Pd/TiO₂_100) was the one obtained from the TiO₂ support containing the lowest content of citrate ligands and leading to small Pd particles (around 4 nm). The effect of catalyst synthesis on the decomposition of O₃ gas (15 ppm) in a dry and humid (HR = 10%) stream in a closed environment such as aircraft or spacecraft was also investigated in this study and further elucidated by detailed characterizations. It was shown that the system could be used as an effective treatment for air coming from outside. Full article

(This article belongs to the Special Issue Environmental Catalysis for Air Pollution Applications)

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21 pages, 4449 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Catalytic Routes to Produce Polyphenolic Esters (PEs) from Biomass Feedstocks

by Antonio Faggiano, Maria Ricciardi and Antonio Proto

Catalysts 2022, 12(4), 447; https://doi.org/10.3390/catal12040447 - 18 Apr 2022

Cited by 9 | Viewed by 3755

Abstract

Polyphenolic esters (PEs) are valuable chemical compounds that display a wide spectrum of activities (e.g., anti-oxidative effects). As a result, their production through catalytic routes is an attractive field of research. The present review aims to discuss recent studies from the literature regarding [...] Read more.

Polyphenolic esters (PEs) are valuable chemical compounds that display a wide spectrum of activities (e.g., anti-oxidative effects). As a result, their production through catalytic routes is an attractive field of research. The present review aims to discuss recent studies from the literature regarding the catalytic production of PEs from biomass feedstocks, namely, naturally occurred polyphenolic compounds. Several synthetic approaches are reported in the literature, mainly bio-catalysis and to a lesser extent acid catalysis. Immobilized lipases (e.g., Novozym 435) are the preferred enzymes thanks to their high reactivity, selectivity and reusability. Acid catalysis is principally investigated for the esterification of polyphenolic acids with fatty alcohols and/or glycerol, using both homogeneous (p-toluensulfonic acid, sulfonic acid and ionic liquids) and heterogeneous (strongly acidic cation exchange resins) catalysts. Based on the reviewed publications, we propose some suggestions to improve the synthesis of PEs with the aim of increasing the greenness of the overall production process. In fact, much more attention should be paid to the use of new and efficient acid catalysts and their reuse for multiple reaction cycles. Full article

(This article belongs to the Special Issue Recent Advances in Catalytic Biomass Conversion to Value-Added Chemicals)

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20 pages, 3361 KiB

Open AccessArticle

Sugarcane Bagasse Ash as a Catalyst Support for Facile and Highly Scalable Preparation of Magnetic Fenton Catalysts for Ultra-Highly Efficient Removal of Tetracycline

by Natthanan Rattanachueskul, Oraya Dokkathin, Decha Dechtrirat, Joongjai Panpranot, Waralee Watcharin, Sulawan Kaowphong and Laemthong Chuenchom

Catalysts 2022, 12(4), 446; https://doi.org/10.3390/catal12040446 - 18 Apr 2022

Cited by 7 | Viewed by 2927

Abstract

Sugarcane bagasse ash, which is waste from the combustion process of bagasse for electricity generation, was utilized as received as a catalyst support to prepare the magnetic sugarcane bagasse ash (MBGA) with different iron-to-ash ratios using a simple co-precipitation method, and the effects [...] Read more.

Sugarcane bagasse ash, which is waste from the combustion process of bagasse for electricity generation, was utilized as received as a catalyst support to prepare the magnetic sugarcane bagasse ash (MBGA) with different iron-to-ash ratios using a simple co-precipitation method, and the effects of NaOH and iron loadings on the physicochemical properties of the catalyst were investigated using various intensive characterization techniques. In addition, the catalyst was used with a low amount of H₂O₂ for the catalytic degradation of a high concentration of tetracycline (800 mg/L) via a Fenton system. The catalyst exhibited excellent degradation activity of 90.43% removal with good magnetic properties and high stabilities and retained good efficiency after four cycles with NaOH as the eluent. Moreover, the hydroxyl radical on the surface of catalyst played a major role in the degradation of TC, and carbon-silica surface of bagasse ash significantly improved the efficiencies. The results indicated that the MBGA catalyst shows the potential to be highly scalable for a practical application, with high performance in the heterogeneous Fenton system. Full article

(This article belongs to the Special Issue Current Advanced Technologies in Catalysts/Catalyzed Reactions)

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28 pages, 15945 KiB

Open AccessReview

A Critical Study of Cu₂O: Synthesis and Its Application in CO₂ Reduction by Photochemical and Electrochemical Approaches

by Sathya Mohan, Brahmari Honnappa, Ashil Augustin, Mariyappan Shanmugam, Chitiphon Chuaicham, Keiko Sasaki, Boopathy Ramasamy and Karthikeyan Sekar

Catalysts 2022, 12(4), 445; https://doi.org/10.3390/catal12040445 - 17 Apr 2022

Cited by 14 | Viewed by 10679

Abstract

Copper oxide (Cu₂O) is a potential material as a catalyst for CO₂ reduction. Cu₂O nanostructures have many advantages, including interfacial charge separation and transportation, enhanced surface area, quantum efficiency, and feasibility of modification via composite development or integration [...] Read more.

Copper oxide (Cu₂O) is a potential material as a catalyst for CO₂ reduction. Cu₂O nanostructures have many advantages, including interfacial charge separation and transportation, enhanced surface area, quantum efficiency, and feasibility of modification via composite development or integration of the favorable surface functional groups. We cover the current advancements in the synthesis of Cu₂O nanomaterials in various morphological dimensions and their photochemical and electrochemical applications, which complies with the physical enrichment of their enhanced activity in every application they are employed in. The scope of fresh designs, namely composites or the hierarchy of copper oxide nanostructures, and various ways to improve CO₂ reduction performance are also discussed in this review. Photochemical and electrochemical CO₂ transformations have received tremendous attention in the last few years, thanks to the growing interest in renewable sources of energy and green facile chemistry. The current review provides an idea of current photochemical and electrochemical carbon dioxide fixing techniques by using Cu₂O-based materials. Carboxylation and carboxylative cyclization, yield valuable chemicals such as carboxylic acids and heterocyclic compounds. Radical ions, which are induced by photo- and electrochemical reactions, as well as other high-energy organic molecules, are regarded as essential mid-products in photochemical and electrochemical reactions with CO₂. It has also been claimed that CO₂ can be activated to form radical anions. Full article

(This article belongs to the Special Issue Advanced Functional Materials for Photo/Electro-Catalysts for Environmental and Energy Applications)

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16 pages, 4471 KiB

Open AccessArticle

Spherical ZVI/Mn-C Bimetallic Catalysts for Efficient Fenton-like Reaction under Mild Conditions

by Lu Qin, Xin Yu, Kang Wang and Xitao Wang

Catalysts 2022, 12(4), 444; https://doi.org/10.3390/catal12040444 - 15 Apr 2022

Cited by 10 | Viewed by 2667

Abstract

The heterogeneous Fenton-like reaction has been receiving increasing attention for its inexpensiveness and high efficiency in water treatment. In this study, a novel strategy was proposed for preparing spherical ZVI/Mn-C bimetallic catalysts with a high activity for a Fenton-like reaction by using the [...] Read more.

The heterogeneous Fenton-like reaction has been receiving increasing attention for its inexpensiveness and high efficiency in water treatment. In this study, a novel strategy was proposed for preparing spherical ZVI/Mn-C bimetallic catalysts with a high activity for a Fenton-like reaction by using the ammonium alginate assisted sol–gel method coupled with a carbothermic reduction. The results showed that the obtained ZVI/Mn-C spheres had a uniform size, smooth surface and good sphericity, and the particle size of ZVI was limited to about 30 nm by the carbon layer. Among all catalysts, the ZVI/Mn-C-31 catalyst exhibited the highest phenol degradation efficiency in the Fenton-like process, and almost 100% phenol degradation efficiency was achieved under neutral pH at room temperature within 5 min. Moreover, the ZVI/Mn-C-31/H₂O₂ system showed a 100% degradation efficiency for removing a wide range of aromatic pollutants, including catechol, resorcinol and o-nitrophenol. Moreover, the radicals-scavenging experiment illustrated that the ·OH played a key factor in mineralizing the organic matters, and the ·O₂⁻ generated from the MnO-H₂O₂ system accelerated the conversion rate of ferric iron to ferrous iron. Due to the synergistic effects between ZVI and MnO, the ZVI/Mn-C-31 catalyst performed excellently in the Fenton-like reaction at an extended pH range. Full article

(This article belongs to the Section Environmental Catalysis)

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20 pages, 5978 KiB

Open AccessFeature PaperArticle

The Preparation of g-C₃N₄/CoAl-LDH Nanocomposites and Their Depollution Performances in Cement Mortars under UV-Visible Light

by Mengya Huang, Zhengxian Yang, Lin Lu, Jiankun Xu, Wencheng Wang and Can Yang

Catalysts 2022, 12(4), 443; https://doi.org/10.3390/catal12040443 - 15 Apr 2022

Cited by 16 | Viewed by 3021

Abstract

In this study, new organic-inorganic g-C₃N₄/CoAl-LDH nanocomposites were prepared and introduced to fabricate photocatalytic cement mortars by internal mixing, coating, and spraying. The photocatalytic depollution of both g-C₃N₄/CoAl-LDH and cement mortars was assessed by NO [...] Read more.

In this study, new organic-inorganic g-C₃N₄/CoAl-LDH nanocomposites were prepared and introduced to fabricate photocatalytic cement mortars by internal mixing, coating, and spraying. The photocatalytic depollution of both g-C₃N₄/CoAl-LDH and cement mortars was assessed by NO_x degradation reaction under UV-visible light irradiation. The study results suggested that the degradation efficiency of g-C₃N₄/CoAl-LDH nanocomposites improved with an increase in g-C₃N₄ content. The g-C₃N₄/CoAl-LDH_1.5 nanocomposite displayed the highest NO_x degradation capacity, which was about 1.23 and 3.21 times that of pure g-C₃N₄ and CoAl-LDH, respectively. The photocatalytic cement mortars which were all fabricated using different approaches could effectively degrade the target pollutants and exhibited significant compatibility between g-C₃N₄/CoAl-LDH and cementitious substrate. Among them, the coated mortars showed strong resistance to laboratory-simulated wearing and abrasion with a small decrease in degradation rate. Full article

(This article belongs to the Special Issue Photocatalytic Building Materials: From Fundamentals to Sustainable Applications)

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10 pages, 2426 KiB

Open AccessArticle

Catalytic Conversion of High Fructose Corn Syrup to Methyl Lactate with CoO@silicalite-1

by Yuxi Jiang, Xilei Lyu, Hao Chen, Xiwen Wei, Zihao Zhang and Xiuyang Lu

Catalysts 2022, 12(4), 442; https://doi.org/10.3390/catal12040442 - 14 Apr 2022

Cited by 2 | Viewed by 2339

Abstract

Methyl lactate (MLA), a versatile biomass platform, was typically produced from the catalytic conversion of high-priced fructose. High fructose corn syrup (HFCS) is a mixture of glucose, fructose, water, etc., which is viewed as an economical substitute for fructose to produce MLA due [...] Read more.

Methyl lactate (MLA), a versatile biomass platform, was typically produced from the catalytic conversion of high-priced fructose. High fructose corn syrup (HFCS) is a mixture of glucose, fructose, water, etc., which is viewed as an economical substitute for fructose to produce MLA due to the much lower cost of separation and drying processes. However, the transformation of HFCS to MLA is still a challenge due to its complex components and the presence of water. In this work, the catalytic conversion of HFCS to MLA over CoO@silicalite-1 catalyst synthesized via a straightforward post citric acid treatment approach was reported. The maximum MLA yield reached 43.8% at 180 °C for 18 h after optimizing the reaction conditions and Co loading. Interestingly, adding extra 3% water could further increase the MLA yield, implying that our CoO@silicalite-1 catalyst is also capable for upgrading wet HFCS. As a result, the costly drying process of wet HFCS can be avoided. Moreover, the activity of CoO@silicalite-1 catalyst can be regenerated for at least four cycles via facile calcination in air. This study, therefore, will provide a new opportunity to not only solve the HFCS-overproduction issues but also produce value-added MLA. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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12 pages, 2109 KiB

Open AccessFeature PaperArticle

Expanding the Range: AuCu Metal Aerogels from H₂O and EtOH

by Maximilian Georgi, Johannes Kresse, Karl Hiekel, René Hübner and Alexander Eychmüller

Catalysts 2022, 12(4), 441; https://doi.org/10.3390/catal12040441 - 14 Apr 2022

Cited by 4 | Viewed by 2523

Abstract

Due to their self-supporting and nanoparticulate structure, metal aerogels have emerged as excellent electrocatalysts, especially in the light of the shift to renewable energy cycles. While a large number of synthesis parameters have already been studied in depth, only superficial attention has been [...] Read more.

Due to their self-supporting and nanoparticulate structure, metal aerogels have emerged as excellent electrocatalysts, especially in the light of the shift to renewable energy cycles. While a large number of synthesis parameters have already been studied in depth, only superficial attention has been paid to the solvent. In order to investigate the influence of this parameter with respect to the gelation time, crystallinity, morphology, or porosity of metal gels, Au_xCu_y aerogels were prepared in water and ethanol. It was shown that although gelation in water leads to highly porous gels (60 m²g⁻¹), a CuO phase forms during this process. The undesired oxide could be selectively removed using a post-washing step with formic acid. In contrast, the solvent change to EtOH led to a halving of the gelation time and the suppression of Cu oxidation. Thus, pure Cu aerogels were synthesized in addition to various bimetallic Au₃X (X = Ni, Fe, Co) gels. The faster gelation, caused by the lower permittivity of EtOH, led to the formation of thicker gel strands, which resulted in a lower porosity of the Au_xCu_y aerogels. The advantage given by the solvent choice simplifies the preparation of metal aerogels and provides deeper knowledge about their gelation. Full article

(This article belongs to the Special Issue Metal-Based Aerogels and Porous Composites as Efficient Catalysts: Synthesis and Catalytic Performance)

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14 pages, 2774 KiB

Open AccessArticle

Synergetic Effects of Mixed-Metal Polyoxometalates@Carbon-Based Composites as Electrocatalysts for the Oxygen Reduction and the Oxygen Evolution Reactions

by Inês S. Marques, Bruno Jarrais, Israël-Martyr Mbomekallé, Anne-Lucie Teillout, Pedro de Oliveira, Cristina Freire and Diana M. Fernandes

Catalysts 2022, 12(4), 440; https://doi.org/10.3390/catal12040440 - 14 Apr 2022

Cited by 8 | Viewed by 2922

Abstract

The smart choice of polyoxometalates (POMs) and the design of POM@carbon-based composites are promising tools for producing active electrocatalysts for both the oxygen reduction (ORR) and the oxygen evolution reactions (OER). Hence, herein, we report the preparation, characterization and application of three composites [...] Read more.

The smart choice of polyoxometalates (POMs) and the design of POM@carbon-based composites are promising tools for producing active electrocatalysts for both the oxygen reduction (ORR) and the oxygen evolution reactions (OER). Hence, herein, we report the preparation, characterization and application of three composites based on doped, multi-walled carbon nanotubes (MWCNT_N6) and three different POMs (Na₁₂[(FeOH₂)₂Fe₂(As₂W₁₅O₅₆)₂]·54H₂O, Na₁₂[(NiOH₂)₂Ni₂(As₂W₁₅O₅₆)₂]·54H₂O and Na₁₄[(FeOH₂)₂N_i2(As₂W₁₅O₅₆)₂]·55H₂O) as ORR and OER electrocatalysts in alkaline medium (pH = 13). Overall, the three POM@MWCNT_N6 composites showed good ORR performance with onset potentials between 0.80 and 0.81 V vs. RHE and diffusion-limiting current densities ranging from −3.19 to −3.66 mA cm⁻². Fe₄@MWCNT_N6 and Fe₂Ni₂@MWCNT_N6 also showed good stability after 12 h (84% and 80% of initial current). The number of electrons transferred per O₂ molecule was close to three, suggesting a mixed regime. Moreover, the Fe₂Ni₂@MWCNT_N6 presented remarkable OER performance with an overpotential of 0.36 V vs. RHE (for j = 10 mA cm⁻²), a j_max close to 135 mA cm⁻² and fast kinetics with a Tafel slope of 45 mV dec⁻¹. More importantly, this electrocatalyst outperformed not only most POM@carbon-based composites reported so far but also the state-of-the-art RuO₂ electrocatalyst. Thus, this work represents a step forward towards bifunctional electrocatalysts using less expensive materials. Full article

(This article belongs to the Special Issue Advances in Sustainable Electrocatalytic Processes using Carbon and Metal Oxide Nanomaterials)

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9 pages, 1167 KiB

Open AccessCommunication

Isospecific Polymerization of Halide- and Amino-Substituted Styrenes Using a Bis(phenolate) Titanium Catalyst

by Qiyuan Wang, Zhen Zhang, Yang Jiang, Yanfeng Zhang, Shihui Li and Dongmei Cui

Catalysts 2022, 12(4), 439; https://doi.org/10.3390/catal12040439 - 13 Apr 2022

Cited by 2 | Viewed by 2635

Abstract

Isospecific polymerization of polar styrenes is a challenge of polymer science. Particularly challenging are monomers bearing electron-withdrawing substituents or bulky substituents. Here, we report the coordination polymerization of halide- and amino-functionalized styrenes including para-fluorostyrene (pFS), para-chlorostyrene (pClS), [...] Read more.

Isospecific polymerization of polar styrenes is a challenge of polymer science. Particularly challenging are monomers bearing electron-withdrawing substituents or bulky substituents. Here, we report the coordination polymerization of halide- and amino-functionalized styrenes including para-fluorostyrene (pFS), para-chlorostyrene (pClS), para-bromostyrene (pBrS), and para-(N,N-diethylamino)styrene (DMAS) using 2,2′-sulfur-bridged bis(phenolate) titanium precursor (1). The combination of 1 and [Ph₃C][B(C₆F₅)₄] and AlⁱBu₃ provides crystalline poly(pFS)s with perfect isotacticity (mmmm > 95%) and high molecular weights (≤16.0 × 10⁴ g mol⁻¹). Upon activation with a large excess of DMAO, 1 reaches polymerization activity of 5.58 × 10⁵ g mol_Ti⁻¹ h⁻¹ producing isotactic poly(pFS)s featuring higher molecular weights (≤39.6 × 10⁴ g mol⁻¹). The distinguished performance of the 1/DMAO system has been extended to the polymerization of pClS and pBrS, both usually involve halogen abstraction during the polymerization, to produce isotactic and high molecular weight (M_n = 32.2 × 10⁴ vs. 13.7 × 10⁴ g mol⁻¹) polymers in good activities (2.18 × 10⁵ vs. 1.31 × 10⁵ g mol_Ti⁻¹ h⁻¹). Surprisingly, 1/DMAO is nearly inactive for DMAS polymerization, on contrary, the system 1/[Ph₃C][B(C₆F₅)₄]/AlⁱBu₃ displays isoselectivity (mmmm > 95%) albeit in a moderate activity. Full article

(This article belongs to the Special Issue Advanced Catalysts for Polyolefin Production)

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14 pages, 24719 KiB

Open AccessArticle

DFT Study on the Combined Catalytic Removal of N₂O, NO, and NO₂ over Binuclear Cu-ZSM-5

by Congru Gao, Jianwei Li, Jie Zhang and Xiuliang Sun

Catalysts 2022, 12(4), 438; https://doi.org/10.3390/catal12040438 - 13 Apr 2022

Cited by 3 | Viewed by 2791

Abstract

The large amount of nitrogen oxides (N₂O, NO, NO₂, etc.) contained in the flue gas of industrial adipic acid production will seriously damage the environment. A designed binuclear Cu-ZSM-5 catalyst can be applied to decompose N₂O and [...] Read more.

The large amount of nitrogen oxides (N₂O, NO, NO₂, etc.) contained in the flue gas of industrial adipic acid production will seriously damage the environment. A designed binuclear Cu-ZSM-5 catalyst can be applied to decompose N₂O and reduce NO and NO_2, purifying the air environment. Using the density functional theory method, the catalytic decomposition mechanisms of N₂O, NO_X-NH₃-SCR, and NO_X-assisted N₂O decomposition is simulated over the Cu-ZSM-5 model. The results indicate that N₂O can be catalytically decomposed over the binuclear Cu active site in the sinusoidal channel. The speed-limiting step is the second N₂O molecule activation process. After the decomposition of the first N₂O molecule, a stable extra-frame [Cu-O-Cu]²⁺ structure will generate. The subsequent discussion proved that the NO_X-NH₃-SCR reaction can be realized over the [Cu-O-Cu]²⁺ active site. In addition, it proved that the decomposition reaction of NO and NO₂ can be carried out over the [Cu-O-Cu]²⁺ active site, and NO can greatly reduce the energy barrier for the conversion of the active site from [Cu-O-Cu]²⁺ to the binuclear Cu form, while NO₂ can be slightly reduced. Through discussion, it is found that the binuclear Cu-ZSM-5 can realize the combined removal of N₂O and NO_X from adipic acid flue gas, hoping to provide a theoretical basis for the development of a dual-functional catalyst. Full article

(This article belongs to the Special Issue Kinetics and Mechanism of Catalytic Reactions—Integrity of Experiment and Theory)

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19 pages, 4476 KiB

Open AccessArticle

Whole-Genome Sequence and Comparative Analysis of Trichoderma asperellum ND-1 Reveal Its Unique Enzymatic System for Efficient Biomass Degradation

by Fengzhen Zheng, Tianshuo Han, Abdul Basit, Junquan Liu, Ting Miao and Wei Jiang

Catalysts 2022, 12(4), 437; https://doi.org/10.3390/catal12040437 - 13 Apr 2022

Cited by 10 | Viewed by 3017

Abstract

The lignocellulosic enzymes of Trichoderma asperellum have been intensely investigated toward efficient conversion of biomass into high-value chemicals/industrial products. However, lack of genome data is a remarkable hurdle for hydrolase systems studies. The secretory enzymes of newly isolated T. asperellum ND-1 during lignocellulose [...] Read more.

The lignocellulosic enzymes of Trichoderma asperellum have been intensely investigated toward efficient conversion of biomass into high-value chemicals/industrial products. However, lack of genome data is a remarkable hurdle for hydrolase systems studies. The secretory enzymes of newly isolated T. asperellum ND-1 during lignocellulose degradation are currently poorly known. Herein, a high-quality genomic sequence of ND-1, obtained by both Illumina HiSeq 2000 sequencing platforms and PacBio single-molecule real-time, has an assembly size of 35.75 Mb comprising 10,541 predicted genes. Secretome analysis showed that 895 proteins were detected, with 211 proteins associated with carbohydrate-active enzymes (CAZymes) responsible for biomass hydrolysis. Additionally, T. asperellum ND-1, T. atroviride IMI 206040, and T. virens Gv-298 shared 801 orthologues that were not identified in T. reesei QM6a, indicating that ND-1 may play critical roles in biological-control. In-depth analysis suggested that, compared with QM6a, the genome of ND-1 encoded a unique enzymatic system, especially hemicellulases and chitinases. Moreover, after comparative analysis of lignocellulase activities of ND-1 and other fungi, we found that ND-1 displayed higher hemicellulases (particularly xylanases) and comparable cellulases activities. Our analysis, combined with the whole-genome sequence information, offers a platform for designing advanced T. asperellum ND-1 strains for industrial utilizations, such as bioenergy production. Full article

(This article belongs to the Topic Advances in Enzymes and Protein Engineering)

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14 pages, 7128 KiB

Open AccessArticle

Sustainable Synthesis of N/S-Doped Porous Carbon from Waste-Biomass as Electroactive Material for Energy Harvesting

by Suguna Perumal, Somasundaram Chandra Kishore, Raji Atchudan, Ashok K. Sundramoorthy, Muthulakshmi Alagan and Yong Rok Lee

Catalysts 2022, 12(4), 436; https://doi.org/10.3390/catal12040436 - 13 Apr 2022

Cited by 15 | Viewed by 2831

Abstract

It is absolutely essential to convert biomass waste into usable energy in a rational manner. This investigation proposes the economical synthesis of heteroatom (N and S)-doped carbon (ATC) from Aesculus turbinata seed as a natural precursor by carbonization at 800 °C. The final [...] Read more.

It is absolutely essential to convert biomass waste into usable energy in a rational manner. This investigation proposes the economical synthesis of heteroatom (N and S)-doped carbon (ATC) from Aesculus turbinata seed as a natural precursor by carbonization at 800 °C. The final product obtained was characterized using field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, high-resolution transmittance electron microscopy, X-ray diffraction, Raman spectroscopy, nitrogen adsorption-desorption isotherms, attenuated total reflectance Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy in order to investigate its structural property and chemical composition. The porous carbon achieved by this method contained oxygen, nitrogen, and sulfur from Aesculus turbinata seed and had pores rich in micropores and mesopores. Crystalline ATC obtained with a high surface area (560 m² g⁻¹) and pore size (3.8 nm) were exploited as electrode material for the supercapacitor. The electrochemical studies revealed a specific capacitance of 142 F g⁻¹ at a current density of 0.5 A g⁻¹ using 1 M H₂SO₄ as an electrolyte. ATC had exceptional cycling stability, and the capacitance retention was 95% even after 10,000 charge-discharge cycles. The findings show that ATC derived from biomass proved to be a potential energy storage material by converting waste biomass into a high-value-added item, a supercapacitor. Full article

(This article belongs to the Special Issue Recent Advances of Electrocatalysis in Fuel Cells)

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12 pages, 1976 KiB

Open AccessArticle

Protonated Chiral 1,2-Diamine Organocatalysts for N-Selective Nitroso Aldol Reaction

by Jae Ho Shim, Ji Yeon Lee, Hyeon Soo Kim and Deok-Chan Ha

Catalysts 2022, 12(4), 435; https://doi.org/10.3390/catal12040435 - 13 Apr 2022

Cited by 2 | Viewed by 2952

Abstract

The introduction of nitrogen to carbonyl groups is considered both challenging and highly desirable by those who work in the field of organic synthesis. In this study, a diphenylethylenediamine-derived catalyst demonstrating N-selectivity was designed using a quantum calculation for the nitroso aldol [...] Read more.

The introduction of nitrogen to carbonyl groups is considered both challenging and highly desirable by those who work in the field of organic synthesis. In this study, a diphenylethylenediamine-derived catalyst demonstrating N-selectivity was designed using a quantum calculation for the nitroso aldol reaction. The reductive monoalkylation of (R,R)-(+)-1,2-diphenylethylenediamine afforded an organic chiral diamine catalyst in high yield. The expected reaction mechanism for the nitroso aldol reaction was determined, and the product and solvent conditions were optimized through quantum calculations. The calculation results revealed that the enantioselectivity is determined by the hydrogen bond between the alkyl substituent of the chiral diamine and the oxygen of the aromatic aldehyde on the ammonium moiety. The reaction was found to proceed optimally in the presence of 5 mol % catalyst at −10 °C in brine. Using these conditions, an eco-friendly nitroso aldol reaction was performed in which the organic catalyst and cyclohexanone formed enamine. Nitrosobenzene, activated by hydrogen bonding with an ammonium catalyst, was used to minimize the steric hindrance between the catalyst and the reactant, resulting in high enantioselectivity. A nitroso aldol product with high N-selectivity and enantioselectivity (98% ee) was obtained in 95% yield. The catalyst developed in this study provides a less expensive and more environmentally friendly alternative for the nitroso aldol reaction. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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16 pages, 3832 KiB

Open AccessArticle

Highly Hydrophilic Ti−Beta Zeolite with Ti−Rich Exterior as Efficient Catalyst for Cyclohexene Epoxidation

by Huang Pan, Rusi Peng, Zhiguo Zhu, Hao Xu, Mingyuan He and Peng Wu

Catalysts 2022, 12(4), 434; https://doi.org/10.3390/catal12040434 - 12 Apr 2022

Cited by 5 | Viewed by 2310

Abstract

Nanocrystalline Ti−Beta zeolite with high hydrophilicity and a Ti−rich exterior was successfully prepared via a dissolution–recrystallization method. With the post−treatment of tetraethylammonium hydroxide (TEAOH) solution at elevated temperature, the Si and Ti species within the Ti−Beta matrix were partially dissolved and recrystallized on [...] Read more.

Nanocrystalline Ti−Beta zeolite with high hydrophilicity and a Ti−rich exterior was successfully prepared via a dissolution–recrystallization method. With the post−treatment of tetraethylammonium hydroxide (TEAOH) solution at elevated temperature, the Si and Ti species within the Ti−Beta matrix were partially dissolved and recrystallized on the outer surface of crystals, resulting in the Ti−rich exterior and higher hydrophilicity, which improved the accessibility of the active Ti sites and the enrichment of H₂O₂. Simultaneously, some of the closed Ti(OSi)₄ species were transformed to more active open Ti(OSi)₃OH or Ti(OSi)₂(H₂O)₂(OH)₂ species. The modified Ti−Beta zeolite exhibited greatly enhanced catalytic performance in the epoxidation of cyclohexene in comparison to the parent Ti−Beta. Full article

(This article belongs to the Section Catalytic Materials)

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12 pages, 1928 KiB

Open AccessArticle

Hybrid Catalysts from Copper Biosorbing Bacterial Strains and Their Recycling for Catalytic Application in the Asymmetric Addition Reaction of B₂(pin)₂ on α,β-Unsaturated Chalcones

by Raffaella Gandolfi, Giorgio Facchetti, Lucia Cavalca, Stefania Mazzini, Milena Colombo, Giulia Coffetti, Gigliola Borgonovo, Leonardo Scaglioni, Sarah Zecchin and Isabella Rimoldi

Catalysts 2022, 12(4), 433; https://doi.org/10.3390/catal12040433 - 11 Apr 2022

Cited by 6 | Viewed by 2377

Abstract

The recycling of heavy metal contaminants from wastewater as a source of valuable products perfectly fits with the principles of a Circular Economy system in view of restoring pollutants back into the system endowed with new social and economic benefits. Heavy metals are [...] Read more.

The recycling of heavy metal contaminants from wastewater as a source of valuable products perfectly fits with the principles of a Circular Economy system in view of restoring pollutants back into the system endowed with new social and economic benefits. Heavy metals are often present in such a low concentration that it makes the removal efficiency difficult to realize through the conventional physicochemical methods with high selectivity. Biosorption, conversely, by EPSs (extracellular polymeric substances) produced by several bacterial cells’ strains, is gaining a great deal of attention as an economic, efficient and sustainable depolluting process of wastewater from metal cations such as copper. Metal coordination to EPS components was thus deeply investigated by ¹H NMR titration experiments. The 1,10–Phenanthroline–copper complex was exploited for quantifying the ability of different strains to sequester copper by a practical UV-Vis spectrophotometric method. The obtained data distinguished Serratia plymuthica strain SC5II as the bacterial strain displaying copper-adsorbing properties higher than any other, with Stenotrophomonas sp. strain 13a resulting in the worst one. Different analytical techniques, i.e., Dynamic Light Scattering (DLS), FT-IR analysis and SEM spectroscopy were thus employed to rationalize these results. Finally, the obtained copper chelates were successfully employed as hybrid catalysts in the asymmetric boron addition to α,β-unsaturated chalcones for the synthesis of valuable pharmaceutical intermediates, thus placing waste management in a new circular perspective. Full article

(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)

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15 pages, 4038 KiB

Open AccessArticle

Fabrication of Stable Cu-Ce Catalyst with Active Interfacial Sites for NO_x Elimination by Flame Spray Pyrolysis

by Xin Tong, Jiafeng Yu, Ling Zhang and Jian Sun

Catalysts 2022, 12(4), 432; https://doi.org/10.3390/catal12040432 - 11 Apr 2022

Cited by 2 | Viewed by 2041

Abstract

The complete conversion of NO_x to harmless N₂ without N₂O formation is crucial for the control of air pollution, especially at low temperatures. Cu-based catalysts are promising materials due to their low cost and high activity in NO dissociation, [...] Read more.

The complete conversion of NO_x to harmless N₂ without N₂O formation is crucial for the control of air pollution, especially at low temperatures. Cu-based catalysts are promising materials due to their low cost and high activity in NO dissociation, even comparable to noble metals; however, they suffer from low stability. Here, we established a Cu-Ce catalyst in one step with strong metal–support interaction by the flame spray pyrolysis (FSP) method. Almost 100% NO conversion was achieved at 100 °C, and they completely transferred into N₂ at a low temperature (200 °C) for the FSP-CuCe catalyst, exhibiting excellent performance in NO reduction by CO reaction. Moreover, the catalytic performance can stay stable, while 23% NO conversion was lost in the same condition for the one made by the co-precipitation (CP) method. This can be attributed to the synergistic effect of abundant active interfacial sites and more flexible surface oxygen created during the FSP process. The flame technology developed here provides an efficient way to fabricate strong metal–support interactions, exhibiting notable potential in the design of stable Cu-based catalysts. Full article

(This article belongs to the Section Catalytic Materials)

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13 pages, 3802 KiB

Open AccessArticle

Synthesis and Application of Egg Shell Biochar for As(V) Removal from Aqueous Solutions

by Asma Akram, Shazma Muzammal, Muhammad Bilal Shakoor, Sajid Rashid Ahmad, Asim Jilani, Javed Iqbal, Abdullah G. Al-Sehemi, Abul Kalam and Samia Faisal O. Aboushoushah

Catalysts 2022, 12(4), 431; https://doi.org/10.3390/catal12040431 - 11 Apr 2022

Cited by 11 | Viewed by 3994

Abstract

Arsenic in water bodies has increased to toxic levels and become a major issue worldwide. Among various treatment methods, the removal of As from polluted water with low-cost and environmental-friendly sorbents such as biochar is considered a promising technique nowadays. In a recent [...] Read more.

Arsenic in water bodies has increased to toxic levels and become a major issue worldwide. Among various treatment methods, the removal of As from polluted water with low-cost and environmental-friendly sorbents such as biochar is considered a promising technique nowadays. In a recent experiment, the treatment of As-contaminated water using egg shell biochar was studied. Various parameters affecting the sorption, such as pH, contact time, sorbent dose, As(V) concentration and the effects of anions, were also examined. The results revealed that at a pH of 4.5, a maximum sorption of 6.3 mg g⁻¹ was observed, and the As(V) removal was 96% with an As concentration of 0.6 mg L⁻¹ and a sorbent dose of 0.9 g L⁻¹. At a contact time of 2 h (120 min), a maximum sorption of 6.3 mg g⁻¹ was noted with a removal percentage of 96%. The sorption of As(V) was obtained at an optimal sorbent dose of 0.9 g L⁻¹. The SEM-EDS data illustrated that biochar consisted of a large number of active sites for As(V) adsorption, and As appeared on the biochar surface after the sorption experiments. Moreover, XPS analyses also confirmed the presence of As(V) on the biochar surface after treatment with As-contaminated water. In a nutshell, the results of this study demonstrate that egg shell biochar has notable efficiency in the removal of As(V) from aqueous solution and that egg shell biochar could be a cost-effective and environmental-friendly sorbent for the treatment of As(V)-contaminated water, specifically in developing countries. Full article

(This article belongs to the Special Issue Environmental Catalysis for Water Remediation)

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13 pages, 7890 KiB

Open AccessArticle

Inactivation of Escherichia coli Using Biogenic Silver Nanoparticles and Ultraviolet (UV) Radiation in Water Disinfection Processes

by Ljubica Tasic, Danijela Stanisic, Caio H. N. Barros, Letícia Khater Covesi and Erick R. Bandala

Catalysts 2022, 12(4), 430; https://doi.org/10.3390/catal12040430 - 11 Apr 2022

Cited by 5 | Viewed by 2684

Abstract

This work tested the antimicrobial activity of three different biogenic silver nanoparticles (AgNPs) against Escherichia coli (E. coli) for water disinfection processes. The influence of different AgNP capping or stabilizing agents (e.g., protein or carbohydrate capped) and the use of ultraviolet [...] Read more.

This work tested the antimicrobial activity of three different biogenic silver nanoparticles (AgNPs) against Escherichia coli (E. coli) for water disinfection processes. The influence of different AgNP capping or stabilizing agents (e.g., protein or carbohydrate capped) and the use of ultraviolet (UV) radiation on the disinfection process were also assessed. The use of UV radiation was found to enhance the antimicrobial effects of AgNPs on E. coli. The antibacterial effects of AgNPs depended on the type of the capping biomolecules. Protein-capped nanoparticles showed greater antimicrobial effects compared with carbohydrate-capped (cellulose nanofibers, CNF) nanoparticles. Those capped with the fungal secretome proteins were the most active in E. coli inactivation. The least E. coli inactivation was observed for CNF-capped AgNPs. The size of the tested AgNPs also showed an expected effect on their anti-E. coli activity, with the smallest particles being the most active. The antimicrobial effects of biogenic AgNPs on E. coli make them an effective, innovative, and eco-friendly alternative for water disinfection processes, which supports further research into their use in developing sustainable water treatment processes. Full article

(This article belongs to the Special Issue Photo/Electrocatalysis for Wastewater Treatment)

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14 pages, 2172 KiB

Open AccessArticle

Effect of Ceria Doping in Different Impregnation Steps on Ni-Based Catalysts Loading on TiO₂-SiC for CO Methanation

by Chen Liu, Qin Zheng and Yusheng Zhang

Catalysts 2022, 12(4), 429; https://doi.org/10.3390/catal12040429 - 11 Apr 2022

Viewed by 2092

Abstract

A series of TiO₂-SiC supported Ni-based catalysts with and without ceria doping were prepared by a traditional impregnation method. CeO₂ was introduced into the catalyst in different steps of the impregnation process. All the samples were characterized by N₂ [...] Read more.

A series of TiO₂-SiC supported Ni-based catalysts with and without ceria doping were prepared by a traditional impregnation method. CeO₂ was introduced into the catalyst in different steps of the impregnation process. All the samples were characterized by N₂ physisorption, XRD, TPR, and TGA, and were tested for the performance of CO methanation in a fixed-bed reactor under atmospheric conditions through the steam of H₂/CO = 3 without diluent gas. All the Ni-based catalysts supported by TiO₂-SiC exhibited the property of anti-sintering and could efficiently avoid carbon deposition occurring on catalysts. The experimental results show that the performance of all CeO₂ doping samples (more than 80% of CO conversion) was better than the sample without CeO₂ (around 20% of CO conversion). Introducing CeO₂ after the dry step of impregnation achieved complete CO conversion at a lower temperature compared with its introduction through doping at the co-impregnation and step-impregnation methods. The results of further characterization indicate that the addition of CeO₂ in different impregnation steps affected the dispersion of nickel on support, made the size of metal particles smaller, and changed the reducibility of catalysts. Full article

(This article belongs to the Topic Catalysis: Homogeneous and Heterogeneous)

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26 pages, 1444 KiB

Open AccessReview

The Influence of Synthesis Methods and Experimental Conditions on the Photocatalytic Properties of SnO₂: A Review

by Jéssica Luisa Alves do Nascimento, Lais Chantelle, Iêda Maria Garcia dos Santos, André Luiz Menezes de Oliveira and Mary Cristina Ferreira Alves

Catalysts 2022, 12(4), 428; https://doi.org/10.3390/catal12040428 - 11 Apr 2022

Cited by 27 | Viewed by 3986

Abstract

Semiconductors based on transition metal oxides represent an important class of materials used in emerging technologies. For this, the performance of these materials strongly depends on the size and morphology of particles, surface charge characteristics, and the presence of bulk and surface defects [...] Read more.

Semiconductors based on transition metal oxides represent an important class of materials used in emerging technologies. For this, the performance of these materials strongly depends on the size and morphology of particles, surface charge characteristics, and the presence of bulk and surface defects that are influenced by the synthesis method and the experimental conditions the materials are prepared. In this context, the present review aims to report the importance of choosing the synthesis methods and experimental conditions to modify structural, morphological, and electronic characteristics of semiconductors, more specifically, tin oxide (SnO₂), since these parameters may be a determinant for better performance in various applications, including photocatalysis. SnO₂ is an n-type semiconductor with a band gap between 3.6 and 4.0 eV, whose intrinsic characteristics are responsible for its electrical conductivity, good optical characteristics, high thermal stability, and other qualities. Such characteristics have provided excellent results in advanced oxidative processes, i.e., heterogeneous photocatalysis applications. This process involves semiconductors in the production of hydroxyl radicals via activation by light absorption, and it is considered as an emerging and promising technology for domestic-industrial wastewater treatment. In our review article, we focused on the photodegradation of different organic dyes and types of persistent organic pollutants using SnO₂-based photocatalysts, and how the efficiency of these materials can be impacted by synthesis methods and experimental conditions employed to prepare them. Full article

(This article belongs to the Topic Advanced Oxidation Process: Applications and Prospects)

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15 pages, 4736 KiB

Open AccessFeature PaperArticle

Metal Embedded Porous Carbon for Efficient CO₂ Cycloaddition under Mild Conditions

by Chen Qi, Somboon Chaemchuen, Meng Liu, Jichao Wang, Serge Zhuiykov and Francis Verpoort

Catalysts 2022, 12(4), 427; https://doi.org/10.3390/catal12040427 - 11 Apr 2022

Cited by 10 | Viewed by 2801

Abstract

Nitrogen-doped porous carbon material was generated via thermal pyrolysis of zeolitic imidazole frameworks (ZIFs). The structure of the ZIF templates was tuned, so that the obtained product was an N-doped porous carbon-containing encapsulated metal nanoparticle. The hierarchical structural and unique properties of pyrolyzed [...] Read more.

Nitrogen-doped porous carbon material was generated via thermal pyrolysis of zeolitic imidazole frameworks (ZIFs). The structure of the ZIF templates was tuned, so that the obtained product was an N-doped porous carbon-containing encapsulated metal nanoparticle. The hierarchical structural and unique properties of pyrolyzed materials are involved in further application, including catalysis. The as-synthesized porous carbon materials were applied as a catalyst for CO₂ fixation on cyclic carbonates under near ambient pressure without solvent and co-catalyst. The zinc dispersion in highly porous carbon material, deriving from ZIF-8, exhibited a superior catalytic performance among the synthesized materials. The acid sites (Zn species) and the incorporated basic sites (N-species) present in the porous carbon material are essential for a high affinity for gas adsorption and CO₂ conversion. Additionally, the catalyst was found to be very robust and stable during recycling studies as the catalytic performance remained high for seven cycles. Full article

(This article belongs to the Special Issue State-of-the-Art Catalytical Technology in South Korea II)

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12 pages, 3299 KiB

Open AccessArticle

Boosted Catalytic Activity toward the Hydrolysis of Ammonia Borane by Mixing Co- and Cu-Based Catalysts

by Jinyun Liao, Yujie Wu, Yufa Feng, Haotao Hu, Lixuan Zhang, Jingchun Qiu, Junhao Li, Quanbing Liu and Hao Li

Catalysts 2022, 12(4), 426; https://doi.org/10.3390/catal12040426 - 11 Apr 2022

Cited by 5 | Viewed by 2154

Abstract

Promoting the activity of heterogeneous catalysts in the hydrolysis of ammonia borane for hydrogen production is still a challenging topic for researchers in the hydrogen energy and catalysis fields. Herein, we present a universal, simple and efficient strategy to boost the catalytic performance [...] Read more.

Promoting the activity of heterogeneous catalysts in the hydrolysis of ammonia borane for hydrogen production is still a challenging topic for researchers in the hydrogen energy and catalysis fields. Herein, we present a universal, simple and efficient strategy to boost the catalytic performance toward AB hydrolysis by mixing Co- and Cu-based catalysts for the first time. Synergistic catalysts with remarkably enhanced activity can be obtained by mixing a Co-based catalyst and a Cu-based catalyst together, such as Co₃O₄ and Cu₃(MoO₄)₂(OH)₂, Co₃O₄ and Cu₃(PO₄)_2, Co₃(PO₄)₂ and Cu₃(MoO₄)₂(OH)₂, Co₃(PO₄)₂ and Cu₃(PO₄)₂, and CuO and Co₃O₄. For example, the turnover frequency (TOF) for the mixture catalyst of Co₃O₄ and Cu₃(MoO₄)₂(OH)₂ with a mass ratio of 4:1 is up to 77.3 min⁻¹, which is approximately 11.5 times higher than that of the sum of Co₃O₄ and Cu₃(MoO₄)₂(OH)₂. The reasons for these findings are discussed in detail. The observations and conclusions in this work may provide a guideline for promoting the hydrolysis of ammonia borane through a simple and effective approach. Full article

(This article belongs to the Section Catalytic Materials)

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18 pages, 3038 KiB

Open AccessArticle

Mechanistic Insights into the Effect of Sulfur on the Selectivity of Cobalt-Catalyzed Fischer–Tropsch Synthesis: A DFT Study

by Yagmur Daga and Ali Can Kizilkaya

Catalysts 2022, 12(4), 425; https://doi.org/10.3390/catal12040425 - 10 Apr 2022

Cited by 6 | Viewed by 2826

Abstract

Sulfur is a common poison for cobalt-catalyzed Fischer–Tropsch Synthesis (FTS). Although its effects on catalytic activity are well documented, its effects on selectivity are controversial. Here, we investigated the effects of sulfur-covered cobalt surfaces on the selectivity of FTS using density functional theory [...] Read more.

Sulfur is a common poison for cobalt-catalyzed Fischer–Tropsch Synthesis (FTS). Although its effects on catalytic activity are well documented, its effects on selectivity are controversial. Here, we investigated the effects of sulfur-covered cobalt surfaces on the selectivity of FTS using density functional theory (DFT) calculations. Our results indicated that sulfur on the surface of Co(111) resulted in a significant decrease in the adsorption energies of CO, HCO and acetylene, while the binding of H and CH species were not significantly affected. These findings indicate that sulfur increased the surface H/CO coverage ratio while inhibiting the adsorption of carbon chains. The elementary reactions of H-assisted CO dissociation, carbon and oxygen hydrogenation and CH coupling were also investigated on both clean and sulfur-covered Co(111). The results indicated that sulfur decreased the activation barriers for carbon and oxygen hydrogenation, while increasing the barriers for CO dissociation and CH coupling. Combining the results on elementary reactions with the modification of adsorption energies, we concluded that the intrinsic effect of sulfur on the selectivity of cobalt-catalyzed FTS is to increase the selectivity to methane and saturated short-chain hydrocarbons, while decreasing the selectivity to olefins and long-chain hydrocarbons. Full article

(This article belongs to the Special Issue Mechanism/Kinetic Modeling Study of Catalytic Reactions)

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14 pages, 5132 KiB

Open AccessArticle

Effect of UV Irradiation on the Structural Variation of Metal Oxide-Silica Nanocomposites for Enhanced Removal of Erythromycin at Neutral pH

by Yasaman Ghaffari, Soyoung Beak, Jiyeol Bae, Md Saifuddin and Kwang Soo Kim

Catalysts 2022, 12(4), 424; https://doi.org/10.3390/catal12040424 - 10 Apr 2022

Cited by 7 | Viewed by 2739

Abstract

In this study, the effect of UV treatment on the physicochemical properties and structural variation of metal oxide-silica nanocomposites (Mn₂O₃-Fe₂O₃@SiO₂) has been investigated. Based on the results, UV irradiation significantly affects the nanocomposite [...] Read more.

In this study, the effect of UV treatment on the physicochemical properties and structural variation of metal oxide-silica nanocomposites (Mn₂O₃-Fe₂O₃@SiO₂) has been investigated. Based on the results, UV irradiation significantly affects the nanocomposite structure, where SiO₂ network reconfiguration, change in surface OH group density, and surface area were observed. Erythromycin (ERY) has been chosen as a module pollutant to compare the performance of the pristine and UV-treated nanocomposites. The pristine nanocomposite had a high adsorption efficiency (99.47%) and photocatalytic activity (99.57%) at neutral pH for ERY in the first cycle, and this efficiency decreased significantly for the multiple cycles. However, different results have been observed for the UV-treated nanocomposite, where it retained its performance for ten consecutive cycles. This enhanced performance is attributed to the structural modifications after UV exposure, where increased surface area, pore volume, and OH group density resulted in an increased number of the possible mechanisms responsible for the adsorption/oxidation of ERY. Moreover, oxidation of adsorbed molecules by UV light after each cycle can also be another reason for enhanced removal. For the first time, the fate of ERY is studied using regenerated nanocomposites after the last cycle. LC/MS/MS results showed that ERY degraded in 20 min, and the produced reaction by-products were adsorbed by nanocomposites. This study could be a foundation research for the practical approaches for the regeneration of nanomaterials and the successful removal of organic pollutants from aquatic environments. Full article

(This article belongs to the Topic Synthesis, Characterization and Performance of Materials for a Sustainable Future)

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22 pages, 5542 KiB

Open AccessFeature PaperArticle

Sustainable Synthesis of a Highly Stable and Coke-Free Ni@CeO₂ Catalyst for the Efficient Carbon Dioxide Reforming of Methane

by Seung Bo Kim, Ahmed Al-Shahat Eissa, Min-Jae Kim, Emad S. Goda, Jae-Rang Youn and Kyubock Lee

Catalysts 2022, 12(4), 423; https://doi.org/10.3390/catal12040423 - 9 Apr 2022

Cited by 12 | Viewed by 2857

Abstract

A facile and green synthetic strategy is developed in this paper for the construction of an efficient catalyst for the industrially important carbon dioxide reforming of methane, which is also named the dry reforming of methane (DRM). Through controlling the synthetic strategy and [...] Read more.

A facile and green synthetic strategy is developed in this paper for the construction of an efficient catalyst for the industrially important carbon dioxide reforming of methane, which is also named the dry reforming of methane (DRM). Through controlling the synthetic strategy and Ni content, a high-performance Ni@CeO₂ catalyst was successfully fabricated. The catalyst showed superb efficiency for producing the syngas with high and stable conversions at prolonged operating conditions. Incorporating Ni during the ceria (CeO₂) crystallization resulted in a more stable structure and smaller nanoparticle (NP) size with a more robust interaction with the support than loading Ni on CeO₂ supports by the conventional impregnation method. The H₂/CO ratio was almost 1.0, indicating the promising applicability of utilizing the obtained syngas for the Fischer–Tropsch process to produce worthy chemicals. No carbon deposits were observed over the as-synthesized catalyst after operating the DRM reaction for 50.0 h, even at a more coke-favoring temperature (700 °C). Owing to the superb resistance to coke and sintering, control of the size of the Ni-NPs, uniform dispersion of the active phase, and potent metal interaction with the support, the synthesized catalyst achieved a magnificent catalytic activity and durability during serving for the DRM reaction for extended operating periods. Full article

(This article belongs to the Special Issue Research Progress of Reforming Catalysts)

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11 pages, 2530 KiB

Open AccessArticle

Exploring the Potential of Water-Soluble Cu(II) Complexes with MPA–CdTe Quantum Dots for Photoinduced Electron Transfer

by Niharika Krishna Botcha, Rithvik R. Gutha, Seyed M. Sadeghi and Anusree Mukherjee

Catalysts 2022, 12(4), 422; https://doi.org/10.3390/catal12040422 - 9 Apr 2022

Cited by 2 | Viewed by 1873

Abstract

Three water-soluble copper complexes based on the amine/pyridine functionalities were investigated, along with quantum dots, as a catalyst–photosensitizer assembly, respectively, for fundamental understanding of photoinduced electron transfer. Luminescence quenching and lifetime measurements were performed to try and establish the actual process that leads [...] Read more.

Three water-soluble copper complexes based on the amine/pyridine functionalities were investigated, along with quantum dots, as a catalyst–photosensitizer assembly, respectively, for fundamental understanding of photoinduced electron transfer. Luminescence quenching and lifetime measurements were performed to try and establish the actual process that leads to the quenching, such as electron transfer, energy transfer, or complex formation (static quenching). Cyclic voltammetry and dynamic light scattering experiments were also performed. Irrespective of the similar reduction potentials of the three complexes, very different photoluminescence properties were observed. Full article

(This article belongs to the Special Issue Advances in Water-Splitting Activity of Highly Efficient Cocatalyst/Photocatalyst Composites)

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12 pages, 13043 KiB

Open AccessArticle

Oxidation of Toluene by Ozone over Surface-Modified γ-Al₂O₃: Effect of Ag Addition

by Kandukuri Bhargavi, Debjyoti Ray, Piu Chawdhury, Sairam Malladi, Thatikonda Shashidhar and Challapalli Subrahmanyam

Catalysts 2022, 12(4), 421; https://doi.org/10.3390/catal12040421 - 8 Apr 2022

Cited by 6 | Viewed by 2500

Abstract

In this study, the ability of ozone to oxidise toluene present in low levels into CO and CO₂ was studied. The catalytic ozonation of toluene was carried out in a micro-fixed bed reactor. The oxidation was done in two steps: toluene adsorption [...] Read more.

In this study, the ability of ozone to oxidise toluene present in low levels into CO and CO₂ was studied. The catalytic ozonation of toluene was carried out in a micro-fixed bed reactor. The oxidation was done in two steps: toluene adsorption on the catalyst followed by sequential ozone desorption. Toluene breakdown by ozone at low temperature and atmospheric pressure was achieved using γ-Al₂O₃ supported transition metal oxides impregnated with a reduced noble metal. The catalyst Ag–CoO_x/γ-Al₂O₃ efficiently oxidised and transformed toluene into products (52.4% CO_x yield). This catalyst has a high surface area, more acidic sites, and lattice oxygens for better toluene oxidation. The addition of Ag to the CoO_x/γ-Al₂O₃ catalyst surface improved toluene adsorption on the catalyst surface, resulting in improved product yield, selectivity, and carbon balance. Full article

(This article belongs to the Special Issue Metal-Support Interactions for Advanced Catalysis)

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11 pages, 5001 KiB

Open AccessArticle

Preparation and Properties of Magnesium Cement-Based Photocatalytic Materials

by Yongle Fang, Chang Shu, Lu Yang, Cheng Xue, Ping Luo and Xingang Xu

Catalysts 2022, 12(4), 420; https://doi.org/10.3390/catal12040420 - 8 Apr 2022

Cited by 5 | Viewed by 2135

Abstract

Photocatalytic oxidation is a technology developed in recent years for the degradation of indoor air pollutants. In this study, magnesium cement-based photocatalytic material (MPM) was prepared by loading TiO₂ photocatalysts onto a SiO₂-modified basic magnesium chloride whisker (BMCW) surface, and [...] Read more.

Photocatalytic oxidation is a technology developed in recent years for the degradation of indoor air pollutants. In this study, magnesium cement-based photocatalytic material (MPM) was prepared by loading TiO₂ photocatalysts onto a SiO₂-modified basic magnesium chloride whisker (BMCW) surface, and was subsequently sprayed evenly on the surface of putty powder to form a photocatalytic functional wall coating (PFWC) material. Then, by introducing Ag, visible light photocatalytic functional wall coating (VPFWC) materials were also prepared. The results show that TiO₂ and SiO₂ form Ti–O–Si bonds on the BMCW surface, and the PFWC presents a promising degradation effect, with a photocatalytic removal rate of 46% for gaseous toluene, under ultraviolet light for 3 h, and an MPM coating concentration of 439 g/m². This is related to the surface structure of the functional coating, which is formed using putty powder and MPM. The visible light photocatalytic efficiency of the VPFWC increased as the spraying amount of the AgNO₃ solution increased, up to 16.62 g/m², and then decreased with further increasing. The gaseous toluene was degraded by 28% and 73% in 3 h, by the VPFWC, under visible light and ultraviolet light irradiation, respectively. In addition, the photocatalytic performance of the PFWC/VPFWC also showed excellent durability after being reused five times. Full article

(This article belongs to the Special Issue Photocatalytic Building Materials: From Fundamentals to Sustainable Applications)

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