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Volume 11
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Catalysts, Volume 11, Issue 12 (December 2021) – 142 articles

Cover Story (view full-size image): Soybean oil deodorizer distillate (SODD) is a lowly exploited byproduct generated in the edible oil deodorization step in oil refining industries, despite its high content on valuable compounds (unsaturated free fatty acids, acylglycerides, phytosterols, tocopherols, scalene, and others). The versatility of a liquid lipase formulation was exploited in sequential hydrolysis and simultaneous esterification/transesterification reactions. The enzyme exhibited an excellent performance in both aqueous and anhydrous media, allowing to prepare fatty acid ethyl esters-rich products (up to 90 wt.%) from low (< 3 wt.%) to high (> 70 wt.%) free acidity SODDs. View this paper
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13 pages, 3017 KiB  
Article
Novel CNT Supported Molybdenum Catalyst for Detection of L-Cysteine in Its Natural Environment
by Kadir Selçuk, Hilal Kivrak and Nahit Aktaş
Catalysts 2021, 11(12), 1561; https://doi.org/10.3390/catal11121561 - 20 Dec 2021
Cited by 4 | Viewed by 2856
Abstract
In this study, novel carbon nanotube-supported Mo (Mo/CNT) catalysts were prepared with the sodium borohydride reduction method for the detection of L-cysteine (L-Cys, L-C). Mo/CNT catalysts were characterized with scanning electron microscopy with elemental dispersion X-ray (EDX-SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance [...] Read more.
In this study, novel carbon nanotube-supported Mo (Mo/CNT) catalysts were prepared with the sodium borohydride reduction method for the detection of L-cysteine (L-Cys, L-C). Mo/CNT catalysts were characterized with scanning electron microscopy with elemental dispersion X-ray (EDX-SEM), X-ray diffraction (XRD), UV-vis diffuse reflectance spectrometry (UV-vis), temperature-programmed reduction (TPR), temperature programmed oxidation (TPO), and temperature-programmed desorption (TPD) techniques. The results of these advanced surface characterization techniques revealed that the catalysts were prepared successfully. Electrochemical measurements were employed to construct a voltammetric L-C sensor based on Mo/CNT catalyst by voltammetric techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Further measurements were carried out with electrochemical impedance spectroscopy (EIS). Mo/CNT/GCE exhibited excellent performance for L-C detection with a linear response in the range of 0–150 µM, with a current sensitivity of 200 mA/μM cm2 (0.0142 μA/μM), the lowest detection limit of 0.25 μM, and signal-to-noise ratio (S/N = 3). Interference studies showed that the Mo/CNT/GCE electrode was not affected by D-glucose, uric acid, L-tyrosine, and L-trytophane, commonly interfering organic structures. Natural sample analysis was also accomplished with acetyl L-C. Mo/CNT catalyst is a promising material as a sensor for L-C detection. Full article
(This article belongs to the Special Issue Electrocatalytic Activity of Nanocomposites Containing Carbon Materials)
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18 pages, 9035 KiB  
Article
The Effect of Catalyst Placement on the Stability of a U-Bend Catalytic Heat-Recirculating Micro-Combustor: A Numerical Investigation
by Niket S. Kaisare and Valeria Di Sarli
Catalysts 2021, 11(12), 1560; https://doi.org/10.3390/catal11121560 - 20 Dec 2021
Cited by 4 | Viewed by 2645
Abstract
This study investigates the combined effect of catalyst placement and solid thermal conductivity on the stability of a U-bend catalytic heat-recirculating micro-combustor. The CFD code ANSYS Fluent 2020 R1 was used for two-dimensional simulations of lean premixed propane/air combustion by varying the inlet [...] Read more.
This study investigates the combined effect of catalyst placement and solid thermal conductivity on the stability of a U-bend catalytic heat-recirculating micro-combustor. The CFD code ANSYS Fluent 2020 R1 was used for two-dimensional simulations of lean premixed propane/air combustion by varying the inlet gas velocity, i.e., the input power. Three configurations were compared at low (3 W/(m K)) and high (30 W/(m K)) wall thermal conductivity: (A) the configuration in which both inner and outer walls are catalyst coated; (B) only the inner wall is catalyst coated; and (C) only the outer wall is catalyst coated. Numerical results show that, at low thermal conductivity, configuration (B) exhibits the same resistance to extinction as configuration (A), whereas at high thermal conductivity, configurations (B) and (C) exhibit much lower resistance to blowout than configuration (A). Accordingly, for low-power systems, which typically lose stability via extinction and thus require low-conductive materials, an optimal catalyst placement can be the partial coating of configuration (B). Conversely, for high-power systems, which are prone to blowout and thus require high-conductivity materials, a full coating of both the inner and outer walls is needed to guarantee higher stability. To elucidate these findings, a detailed analysis of the combustion behavior of the three configurations is presented. Full article
(This article belongs to the Section Catalytic Reaction Engineering)
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17 pages, 2289 KiB  
Article
Technological Aspects of Highly Selective Synthesis of Allyloxyalcohols—New, Greener, Productive Methods
by Magdalena Urbala
Catalysts 2021, 11(12), 1559; https://doi.org/10.3390/catal11121559 - 20 Dec 2021
Viewed by 3423
Abstract
Allyl ethers bearing free hydroxyl groups of CH2=CH-CH-O-A-OH type (hydroxyalkyl allyl ethers, allyloxyalcohols) are valuable chemicals in many environmentally friendly industrial applications. The development of technologically attractive methods for their production is necessary. The two pathways (L-L PTC and [...] Read more.
Allyl ethers bearing free hydroxyl groups of CH2=CH-CH-O-A-OH type (hydroxyalkyl allyl ethers, allyloxyalcohols) are valuable chemicals in many environmentally friendly industrial applications. The development of technologically attractive methods for their production is necessary. The two pathways (L-L PTC and non-catalytic solvent-free conditions) were optimized for the highly selective and yield synthesis of 4-allyloxybutan-1-ol. Improvements in the PTC method (50% NaOH(aq), the equimolar ratio of NaOH to diol, cyclohexane as solvent) with a new highly selective and effective PT catalyst, i.e., Me(n-Oct)3N+Br− (0.3 mol%), resulted in 88% yield and 98% selectivity of 4-allyloxybutan-1-ol with minimal formation of allyl chloride hydrolysis by-products (<1%). In turn, application of non-catalytic solvent-free conditions and the change in the key substrate with an excess of diol and use of solid NaOH solely led to a mono-O-allylation product with an excellent yield of 99% in a relatively short reaction time (3.5 h), with trace amounts of by-products (<0.1%). This sustainable method is perfectly suitable for the synthesis on a larger scale (3 moles of the key substrate) and for the full O-allylation process. Full article
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18 pages, 5438 KiB  
Article
LaFeO3 Modified with Ni for Hydrogen Evolution via Photocatalytic Glucose Reforming in Liquid Phase
by Giuseppina Iervolino, Vincenzo Vaiano, Diana Sannino, Felipe Puga, Josè Antonio Navío and María C. Hidalgo
Catalysts 2021, 11(12), 1558; https://doi.org/10.3390/catal11121558 - 20 Dec 2021
Cited by 9 | Viewed by 3487
Abstract
In this work, the optimization of Ni amount on LaFeO3 photocatalyst was studied in the photocatalytic molecular hydrogen production from glucose aqueous solution under UV light irradiation. LaFeO3 was synthesized via solution combustion synthesis and different amount of Ni were dispersed [...] Read more.
In this work, the optimization of Ni amount on LaFeO3 photocatalyst was studied in the photocatalytic molecular hydrogen production from glucose aqueous solution under UV light irradiation. LaFeO3 was synthesized via solution combustion synthesis and different amount of Ni were dispersed on LaFeO3 surface through deposition method in aqueous solution and using NaBH4 as reducing agent. The prepared samples were characterized with different techniques: Raman spectroscopy, UltraViolet-Visible Diffuse Reflectance Spettroscopy (UV–Vis-DRS), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), X-ray Fluorescence (XRF), Transmission Electron microscopy (TEM), and Scanning Electron microscopy (SEM) analyses. For all the investigated photocatalysts, the presence of Ni on perovskite surface resulted in a better activity compared to pure LaFeO3. In particular, it is possible to identify an optimal amount of Ni for which it is possible to obtain the best hydrogen production. Specifically, the results showed that the optimal Ni amount was equal to nominal 0.12 wt% (0.12Ni/LaFeO3), for which the photocatalytic H2 production was equal to 2574 μmol/L after 4 h of UV irradiation. The influence of different of photocatalyst dosage and initial glucose concentration was also evaluated. The results of the optimization of operating parameters indicated that the highest molecular hydrogen production was achieved on 0.12Ni/LaFeO3 sample with 1.5 g/L of catalyst dosage and 1000 ppm initial glucose concentration. To determine the reactive species that play the most significant role in the photocatalytic hydrogen production, photocatalytic tests in the presence of different radical scavengers were performed. The results showed that •OH radical plays a significant role in the photocatalytic conversion of glucose in H2. Moreover, photocatalytic tests carried out with D2O instead of H2O evidenced the role of water molecules in the photocatalytic production of molecular hydrogen in glucose aqueous solution. Full article
(This article belongs to the Special Issue Recent Advances on Photocatalytic and Electro-photocatalytic Hydrogen Production)
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20 pages, 3063 KiB  
Review
Advances in Oxidative Desulfurization of Fuel Oils over MOFs-Based Heterogeneous Catalysts
by Hongsi Luo, Yulong Gu, Daqing Liu and Yinyong Sun
Catalysts 2021, 11(12), 1557; https://doi.org/10.3390/catal11121557 - 20 Dec 2021
Cited by 25 | Viewed by 4782
Abstract
Catalytic oxidative desulfurization (ODS) of fuel oils is considered one of the most promising non-hydrodesulfurization technologies due to the advantages of mild reaction conditions, low cost and easy removal of aromatic sulfur compounds. Based on this reason, the preparation of highly efficient ODS [...] Read more.
Catalytic oxidative desulfurization (ODS) of fuel oils is considered one of the most promising non-hydrodesulfurization technologies due to the advantages of mild reaction conditions, low cost and easy removal of aromatic sulfur compounds. Based on this reason, the preparation of highly efficient ODS catalysts has been a hot research topic in this field. Recently, metal-organic frameworks (MOFs) have attracted extensive attention due to the advantages involving abundant metal centers, high surface area, rich porosity and varied pore structures. For this, the synthesis and catalytic performance of the ODS catalysts based on MOFs materials have been widely studied. Until now, many research achievements have been obtained along this direction. In this article, we will review the advances in oxidative desulfurization of fuel oils over MOFs-based heterogeneous catalysts. The catalytic ODS performance over various types of catalysts is compared and discussed. The perspectives for future work are proposed in this field. Full article
(This article belongs to the Special Issue Frontiers in Heterogeneous Catalysts for Desulfurization of Fuel Oil)
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23 pages, 4109 KiB  
Article
Investigations of the Effect of H2 in CO Oxidation over Ceria Catalysts
by Arantxa Davó-Quiñonero, Sergio López-Rodríguez, Cristian Chaparro-Garnica, Iris Martín-García, Esther Bailón-García, Dolores Lozano-Castelló, Agustín Bueno-López and Max García-Melchor
Catalysts 2021, 11(12), 1556; https://doi.org/10.3390/catal11121556 - 20 Dec 2021
Cited by 4 | Viewed by 3488
Abstract
The preferential CO oxidation (so-called CO-PROX) is the selective CO oxidation amid H2-rich atmospheres, a process where ceria-based materials are consolidated catalysts. This article aims to disentangle the potential CO–H2 synergism under CO-PROX conditions on the low-index ceria surfaces (111), [...] Read more.
The preferential CO oxidation (so-called CO-PROX) is the selective CO oxidation amid H2-rich atmospheres, a process where ceria-based materials are consolidated catalysts. This article aims to disentangle the potential CO–H2 synergism under CO-PROX conditions on the low-index ceria surfaces (111), (110) and (100). Polycrystalline ceria, nanorods and ceria nanocubes were prepared to assess the physicochemical features of the targeted surfaces. Diffuse reflectance infrared Fourier-transformed spectroscopy (DRIFTS) shows that ceria surfaces are strongly carbonated even at room temperature by the effect of CO, with their depletion related to the CO oxidation onset. Conversely, formate species formed upon OH + CO interaction appear at temperatures around 60 °C and remain adsorbed regardless the reaction degree, indicating that these species do not take part in the CO oxidation. Density functional theory calculations (DFT) reveal that ceria facets exhibit high OH coverages all along the CO-PROX reaction, whilst CO is only chemisorbed on the (110) termination. A CO oxidation mechanism that explains the early formation of carbonates on ceria and the effect of the OH coverage in the overall catalytic cycle is proposed. In short, hydroxyl groups induce surface defects on ceria that increase the COx–catalyst interaction, revealed by the CO adsorption energies and the stabilization of intermediates and readsorbed products. In addition, high OH coverages are shown to facilitate the hydrogen transfer to form less stable HCOx products, which, in the case of the (110) and (100), is key to prevent surface poisoning. Altogether, this work sheds light on the yet unclear CO–H2 interactions on ceria surfaces during CO-PROX reaction, providing valuable insights to guide the design of more efficient reactors and catalysts for this process. Full article
(This article belongs to the Special Issue Metal Supported Catalysts for Preferential Carbon Monoxide Oxidation (CO-PROX))
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6 pages, 1074 KiB  
Communication
Photocatalytic Alkylation of α-(Trifluoromethyl)Styrenes with Potassium Xanthogenates
by Vyacheslav I. Supranovich and Alexander D. Dilman
Catalysts 2021, 11(12), 1555; https://doi.org/10.3390/catal11121555 - 20 Dec 2021
Cited by 9 | Viewed by 2860
Abstract
A protocol for the coupling of potassium xanthogenates with α-(trifluoromethyl)styrenes in the presence of triethyl phosphite is reported. The reaction is carried out under blue light irradiation in the presence of organic photocatalyst 3DPAFIPN. The reaction proceeds via formation of alkyl radicals from [...] Read more.
A protocol for the coupling of potassium xanthogenates with α-(trifluoromethyl)styrenes in the presence of triethyl phosphite is reported. The reaction is carried out under blue light irradiation in the presence of organic photocatalyst 3DPAFIPN. The reaction proceeds via formation of alkyl radicals from readily available xanthogenate salts via oxidative desulfurization and cleavage of the carbon–oxygen bond assisted by triethyl phosphite. Full article
(This article belongs to the Section Photocatalysis)
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19 pages, 6450 KiB  
Article
Pentamethylcyclopentadienyl Molybdenum(V) Complexes Derived from Iodoanilines: Synthesis, Structure, and ROP of ε-Caprolactone
by Tian Xing, Mark R. J. Elsegood, Sophie H. Dale and Carl Redshaw
Catalysts 2021, 11(12), 1554; https://doi.org/10.3390/catal11121554 - 20 Dec 2021
Cited by 2 | Viewed by 2686
Abstract
The reaction of [Mo(η-C5Me5)Cl4] with the ortho-, meta-, or para-iodo-functionalized anilines 2-IC6H4NH2, 3-IC6H4NH2, 4-IC6H4NH2 yields imido or [...] Read more.
The reaction of [Mo(η-C5Me5)Cl4] with the ortho-, meta-, or para-iodo-functionalized anilines 2-IC6H4NH2, 3-IC6H4NH2, 4-IC6H4NH2 yields imido or amine products of the type [Mo(η-C5Me5)Cl2(IC6H4N)] (2-I, 1, 3-I, 3, 4-I, 5) or [Mo(η-C5Me5)Cl4(IC6H4NH2)] (3-I, 2, 4-I, 4), respectively, depending on the reaction stoichiometry/conditions; we were unable to isolate an amine complex of the 2-I derivative. The reaction of [Mo(η-C5Me5)Cl4] with one equivalent of 2-I,4-FC6H3NH2 in the presence of Et3N afforded [Mo(η-C5Me5)Cl2(2-I,4-FC6H3N)]·MeCN (6·MeCN), which, upon exposure to air, afforded the Mo(VI) imido complex [Mo(η-C5Me5)Cl3(2-I,4-FC6H3N)] (7). For comparative studies, the structure of the aniline (C6H5NH2)-derived complex [Mo(η-C5Me5)Cl2(2-C6H3N)] (8) has also been prepared. The molecular structures of 1–8 have been determined and reveal packing in the form of zig-zag chains or ladders. The complexes catalyze, in the presence of benzyl alcohol under N2, the ring-opening polymerization (ROP) of ε-caprolactone affording relatively low molecular weight products. The MALDI-ToF spectra indicate that a number of polymer series bearing a variety of end groups are formed. Conducting the ROPs as melts or under air results in the isolation of higher molecular weight products, again bearing a variety of end groups. Kinetic studies reveal the aniline-derived imido complex 8 performs best, whilst a meta-iodo substituent and a Mo(V) centre are also found to be beneficial. The structures of the side products 2-IC6H4NH3Cl and 3-IC6H4NH3Cl are also reported. Full article
(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)
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18 pages, 3005 KiB  
Review
Insights into the Influence of Key Preparation Parameters on the Performance of MoS2/Graphene Oxide Composites as Active Materials in Supercapacitors
by Catalin Alexandru Salagean, Codrut Costinas, Liviu Cosmin Cotet and Lucian Baia
Catalysts 2021, 11(12), 1553; https://doi.org/10.3390/catal11121553 - 20 Dec 2021
Cited by 8 | Viewed by 3454
Abstract
Advances in energy storage and energy conversion play an essential role nowadays because the energy demands are becoming greater than ever. To overcome the actual performances of the materials used to build supercapacitors, a combination of transition metal dichalcogenides (TMDCs) and graphene oxide [...] Read more.
Advances in energy storage and energy conversion play an essential role nowadays because the energy demands are becoming greater than ever. To overcome the actual performances of the materials used to build supercapacitors, a combination of transition metal dichalcogenides (TMDCs) and graphene oxide (GO) or reduced graphene oxide (rGO) as graphene-based structures are often studied for their excellent properties, such as high specific area and good electrical conductivity. Nevertheless, synthesis pathways and parameters play key roles in obtaining better materials as components for supercapacitors with higher technical performances. Driven by the desire to understand the influence of the structural and morphological particularities on the performances of supercapacitors based on MoS2/graphene oxide (GO) composites, a survey of the literature was performed by pointing out the alterations induced by different synthesis pathways and key parameters to the above-mentioned particularities. Full article
(This article belongs to the Special Issue Advanced Nanomaterials for a Green World)
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8 pages, 1682 KiB  
Article
Dehydration of Xylose to Furfural over Imidazolium-Based Ionic Liquid with Phase Separation
by Derun Hua, Hao Ding, Yunfeng Liu, Jian Li and Baojun Han
Catalysts 2021, 11(12), 1552; https://doi.org/10.3390/catal11121552 - 20 Dec 2021
Cited by 6 | Viewed by 2726
Abstract
An environmentally friendly catalyst and task-specific ionic liquid (IL), 1-(4-sulfonic acid) butyl-3-cetyl-2-methyl imidazolium hydrogen sulfate, was applied to the dehydration of xylose to furfural. Its structure was determined by FT-IR, 1H NMR technologies. The solubility of IL in water changed with the [...] Read more.
An environmentally friendly catalyst and task-specific ionic liquid (IL), 1-(4-sulfonic acid) butyl-3-cetyl-2-methyl imidazolium hydrogen sulfate, was applied to the dehydration of xylose to furfural. Its structure was determined by FT-IR, 1H NMR technologies. The solubility of IL in water changed with the temperature, and had the advantages of homogeneous and heterogeneous catalysts. At the given conditions, xylose conversion of 95.3% and furfural yield of 67.5% were achieved over IL. Full article
(This article belongs to the Special Issue Catalytic Conversion of Carbohydrates)
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21 pages, 18931 KiB  
Article
The Potency of Fungal-Fabricated Selenium Nanoparticles to Improve the Growth Performance of Helianthus annuus L. and Control of Cutworm Agrotis ipsilon
by Mohamed A. Amin, Mohamed A. Ismail, Ali A. Badawy, Mohamed A. Awad, Mohammed F. Hamza, Mohamed F. Awad and Amr Fouda
Catalysts 2021, 11(12), 1551; https://doi.org/10.3390/catal11121551 - 19 Dec 2021
Cited by 54 | Viewed by 4450
Abstract
The application of green nanotechnology in agriculture has been receiving substantial attention, especially in the development of new nano-fertilizers and nano-insecticides. Herein, the metabolites secreted by the fungal strain Penicillium chrysogenum are used as a reducing agent for selenium ions to form selenium [...] Read more.
The application of green nanotechnology in agriculture has been receiving substantial attention, especially in the development of new nano-fertilizers and nano-insecticides. Herein, the metabolites secreted by the fungal strain Penicillium chrysogenum are used as a reducing agent for selenium ions to form selenium nanoparticles (Se-NPs). The synthesized Se-NPs were characterized using color change, UV-Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), and dynamic light scattering (DLS). The biomass filtrate of the fungal strain changed from colorless to a ruby red color after mixing with sodium selenite with a maximum surface plasmon resonance at 262 nm. Data exhibits the successful formation of spherical, amorphous Se-NPs with sizes ranging between 3–15 nm and a weight percentage of 38.52%. The efficacy of Se-NPs on the growth performance of sunflower (Helianthus annuus L.) and inhibition of cutworm Agrotis ipsilon was investigated. The field experiment revealed the potentiality of Se-NPs to enhance the growth parameters and carotenoid content in sunflower, especially at 20 ppm. The chlorophylls, carbohydrates, proteins, phenolic compounds, and free proline contents were markedly promoted in response to Se-NPs concentrations. The antioxidant enzymes (peroxidase, catalase, superoxide dismutase, and polyphenol oxidase) were significantly decreased compared with the control. Data analysis showed that the highest mortality for the 1st, 2nd, 3rd, 4th, and 5th instar larvae of Agrotis ipsilon was achieved at 25 ppm with percentages of 89.7 ± 0.3, 78.3 ± 0.3, 72.3 ± 0.6, 63.7 ± 0.3, and 68.7 ± 0.3 respectively after 72 h. Full article
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10 pages, 3946 KiB  
Article
N, S, P-Codoped Graphene-Supported Ag-MnFe2O4 Heterojunction Nanoparticles as Bifunctional Oxygen Electrocatalyst with High Efficiency
by Hongzhou Dong, Yingjie Chen, Chong Gong, Lina Sui, Qiong Sun, Kangle Lv and Lifeng Dong
Catalysts 2021, 11(12), 1550; https://doi.org/10.3390/catal11121550 - 19 Dec 2021
Cited by 4 | Viewed by 3195
Abstract
Due to slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharging and charging processes, it is essential to rationally design and synthesize non-precious metal bifunctional electrocatalysts with good performance for metal-air batteries. Herein, Ag-MnFe2O4 heterojunction [...] Read more.
Due to slow kinetics of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) during discharging and charging processes, it is essential to rationally design and synthesize non-precious metal bifunctional electrocatalysts with good performance for metal-air batteries. Herein, Ag-MnFe2O4 heterojunction nanoparticles supported on N, S, P-codoped graphene (NSPG) are developed with enhanced ORR and OER bifunctional electrocatalytic activities and stability. In contrast, S, P-doped graphene (SPG) and N, P-doped graphene (NPG) show less stabilization for the heterojunction particles. For example, under alkaline conditions, the ORR half-wave potential of Ag-MnFe2O4/NSPG can reach 0.831 V, and the over potential for OER is 0.56 V at the current density 10 mA·cm−2. Furthermore, Ag-MnFe2O4/NSPG shows better methanol resistance and durability than Pt/C catalysts. Full article
(This article belongs to the Topic Electromaterials for Environment & Energy)
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51 pages, 5160 KiB  
Review
Thermochemical and Catalytic Conversion Technologies for the Development of Brazilian Biomass Utilization
by Caroline Carriel Schmitt, Frederico Gomes Fonseca, Mariana M. Campos Fraga, Alberto Wisniewski, Jr., Susan Karp, Álvaro Henrique Mello José, Rita C. L. B. Rodrigues, Renata Moreira, Danilo Eiji Hirayama, Klaus Raffelt and Nicolaus Dahmen
Catalysts 2021, 11(12), 1549; https://doi.org/10.3390/catal11121549 - 19 Dec 2021
Cited by 7 | Viewed by 4554
Abstract
The social, economic, and environmental impacts of climate change have been shown to affect poorer populations throughout the world disproportionally, and the COVID-19 pandemic of 2020–2021 has only exacerbated the use of less sustainable energy, fuel, and chemical sources. The period of economic [...] Read more.
The social, economic, and environmental impacts of climate change have been shown to affect poorer populations throughout the world disproportionally, and the COVID-19 pandemic of 2020–2021 has only exacerbated the use of less sustainable energy, fuel, and chemical sources. The period of economic and social recovery following the pandemic presents an unprecedented opportunity to invest in biorefineries based on the pyrolysis of agricultural residues. These produce a plethora of sustainable resources while also contributing to the economic valorization of first-sector local economies. However, biomass-derived pyrolysis liquid is highly oxygenated, which hinders its long-term stability and usability. Catalytic hydrogenation is a proposed upgrading method to reduce this hindrance, while recent studies on the use of nickel and niobium as low-cost catalysts, both abundant in Brazil, reinforce the potential synergy between different economic sectors within the country. This review gathers state-of-the-art applications of these technologies with the intent to guide the scientific community and lawmakers alike on yet another alternative for energy and commodities production within an environmentally sustainable paradigm. Full article
(This article belongs to the Special Issue Catalysis for Sustainable Refinery and Bio-Refinery)
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16 pages, 1476 KiB  
Article
Kinetics and Mechanism of Aniline and Chloroanilines Degradation Photocatalyzed by Halloysite-TiO2 and Halloysite-Fe2O3 Nanocomposites
by Beata Szczepanik, Piotr Słomkiewicz, Dariusz Wideł, Marianna Czaplicka and Laura Frydel
Catalysts 2021, 11(12), 1548; https://doi.org/10.3390/catal11121548 - 19 Dec 2021
Cited by 12 | Viewed by 3146
Abstract
The kinetics of photocatalytic degradation of aniline, 2-chloroaniline, and 2,6-dichloroaniline in the presence of halloysite-TiO2 and halloysite-Fe2O3 nanocomposites, halloysite containing naturally dispersed TiO2, Fe2O3, commercial TiO2, P25, and α-Fe2O3 [...] Read more.
The kinetics of photocatalytic degradation of aniline, 2-chloroaniline, and 2,6-dichloroaniline in the presence of halloysite-TiO2 and halloysite-Fe2O3 nanocomposites, halloysite containing naturally dispersed TiO2, Fe2O3, commercial TiO2, P25, and α-Fe2O3 photocatalysts, were investigated with two approaches: the Langmuir–Hinshelwood and first-order equations. Adsorption equilibrium constants and adsorption enthalpies, photodegradation rate constants, and activation energies for photocatalytic degradation were calculated for all studied amines photodegradation. The photodegradation mechanism was proposed according to organic intermediates identified by mass spectrometry and electrophoresis methods. Based on experimental results, it can be concluded that after 300 min of irradiation, aniline, 2-chloro-, and 2,6-dichloroaniline were completely degraded in the presence of used photocatalysts. Research results allowed us to conclude that higher adsorption capacity and immobilization of TiO2 and Fe2O3 on the halloysite surface in the case of halloysite-TiO2 and halloysite-Fe2O3 nanocomposites significantly increases photocatalytic activity of these materials in comparison to the commercial photocatalyst: TiO2, Fe2O3, and P25. Full article
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9 pages, 4200 KiB  
Communication
Cost-Effective 1T-MoS2 Grown on Graphite Cathode Materials for High-Temperature Rechargeable Aluminum Ion Batteries and Hydrogen Evolution in Water Splitting
by Shivaraj B. Patil, Ji-Yao An, Zhi-Jie Li, Yu-Cheng Wu, Swathi M. Gowdru, Han-Hsuan Hsieh, Zhen Chen and Di-Yan Wang
Catalysts 2021, 11(12), 1547; https://doi.org/10.3390/catal11121547 - 19 Dec 2021
Cited by 5 | Viewed by 2825
Abstract
The high dependence on and high cost of lithium has led to a search for alternative materials. Aluminum ion batteries (AIBs) have gained interest due to their abundance, low cost, and high capacity. However, the use of the expensive 1-ethyl-3-methylimidazolium chloride (EMIC) electrolyte [...] Read more.
The high dependence on and high cost of lithium has led to a search for alternative materials. Aluminum ion batteries (AIBs) have gained interest due to their abundance, low cost, and high capacity. However, the use of the expensive 1-ethyl-3-methylimidazolium chloride (EMIC) electrolyte in AIBs curtails its wide application. Recently, high-temperature batteries have also gained much attention owing to their high demand by industries. Herein, we introduce cost-effective 1T molybdenum sulfide grown on SP-1 graphite powder (1T-MoS2/SP-1) as a cathode material for high-temperature AIBs using the AlCl3-urea eutectic electrolyte (1T-MoS2/SP-1–urea system). The AIB using the 1T-MoS2/SP-1–urea system exhibited a capacity as high as 200 mAh/g with high efficiency of 99% over 100 cycles at 60 °C when cycled at the rate of 100 mA/g. However, the AIB displayed a capacity of 105 mAh/g when cycled at room temperature. The enhanced performance of the 1T-MoS2/SP-1–urea system is attributed to reduced viscosity of the AlCl3-urea eutectic electrolyte at higher temperatures with high compatibility of 1T-MoS2 with SP-1. Moreover, the electrocatalytic lithiation of 1T-MoS2 and its effect on the hydrogen evolution reaction were also investigated. We believe that our work can act as a beacon for finding alternative, cost-effective, and high-temperature batteries. Full article
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20 pages, 2410 KiB  
Article
Effect of Calcination Conditions on the Properties and Photoactivity of TiO2 Modified with Biuret
by Aleksandra Piątkowska and Sylwia Mozia
Catalysts 2021, 11(12), 1546; https://doi.org/10.3390/catal11121546 - 18 Dec 2021
Cited by 3 | Viewed by 2700
Abstract
A simple wet impregnation-calcination method was used to obtain a series of novel non-metal doped TiO2 photocatalysts. Biuret was applied as C and N source, while raw titanium dioxide derived from sulfate technology process was used as TiO2 and S source. [...] Read more.
A simple wet impregnation-calcination method was used to obtain a series of novel non-metal doped TiO2 photocatalysts. Biuret was applied as C and N source, while raw titanium dioxide derived from sulfate technology process was used as TiO2 and S source. The influence of the modification with biuret and the effect of the atmosphere (air or argon) and temperature (500–800 °C) of calcination on the physicochemical properties and photocatalytic activity of the photocatalysts towards ketoprofen decomposition under simulated solar light was investigated. Moreover, selected photocatalysts were applied for ketoprofen photodecomposition under visible and UV irradiation. Crucial features affecting the photocatalytic activity were the anatase to rutile phase ratio, anatase crystallites size and non-metals content. The obtained photocatalysts revealed improved activity in the photocatalytic ketoprofen decomposition compared to the crude TiO2. The best photoactivity under all irradiation types exhibited the photocatalyst calcined in the air atmosphere at 600 °C, composed of 96.4% of anatase with 23 nm crystallites, and containing 0.11 wt% of C, 0.05 wt% of N and 0.77 wt% of S. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts—Feature Papers in Photocatalysis)
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41 pages, 24699 KiB  
Review
Vinylogous and Arylogous Stereoselective Base-Promoted Phase-Transfer Catalysis
by Assunta D’Amato and Giorgio Della Sala
Catalysts 2021, 11(12), 1545; https://doi.org/10.3390/catal11121545 - 18 Dec 2021
Cited by 6 | Viewed by 3535
Abstract
Vinylogous enolate and enolate-type carbanions, generated by deprotonation of α,β-unsaturated compounds and characterized by delocalization of the negative charge over two or more carbon atoms, are extensively used in organic synthesis, enabling functionalization and C–C bond formation at remote positions. Similarly, reactions with [...] Read more.
Vinylogous enolate and enolate-type carbanions, generated by deprotonation of α,β-unsaturated compounds and characterized by delocalization of the negative charge over two or more carbon atoms, are extensively used in organic synthesis, enabling functionalization and C–C bond formation at remote positions. Similarly, reactions with electrophiles at benzylic and heterobenzylic position are performed through generation of arylogous and heteroarylogous enolate-type nucleophiles. Although widely exploited in metal-catalysis and organocatalysis, it is only in recent years that the vinylogy and arylogy principles have been translated fruitfully in phase-transfer catalyzed processes. This review provides an overview of the methods developed to date, involving vinylogous and (hetero)arylogous carbon nucleophiles under phase-transfer catalytic conditions, highlighting main mechanistic aspects. Full article
(This article belongs to the Special Issue Design and Applications of Phase Transfer Catalysis)
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13 pages, 4741 KiB  
Review
Microporous Volumes from Nitrogen Adsorption at 77 K: When to Use a Different Standard Isotherm?
by João Pires, Rafaela Fernandes, Moisés L. Pinto and Mary Batista
Catalysts 2021, 11(12), 1544; https://doi.org/10.3390/catal11121544 - 18 Dec 2021
Cited by 10 | Viewed by 3729
Abstract
This work reviews the application of various standard isotherms to evaluate the micropore volume in a range of microporous materials. The selected materials have quite different surface chemistry, and are relevant due to their properties for adsorption and catalysis: zeolites, activated carbons, clay-based [...] Read more.
This work reviews the application of various standard isotherms to evaluate the micropore volume in a range of microporous materials. The selected materials have quite different surface chemistry, and are relevant due to their properties for adsorption and catalysis: zeolites, activated carbons, clay-based materials and MOFs. Some cases were analysed before and after being used as supports in the heterogenization of homogeneous catalysts. The discussion is centred, but not limited, to the three standard isotherms that are mostly employed in the literature (t-curve, non-porous carbon and non-porous hydroxylated silica) for the assessment of the micropore volume. For a given material the values of the micropore volumes from the different standard isotherms were compared, particularly against the values from the largely used t-curve. The cases where major discrepancies were found could normally be ascribed to samples that have a broad micropore size distribution. Full article
(This article belongs to the Section Catalytic Materials)
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32 pages, 5825 KiB  
Review
Removal of Organic Dyes from Water and Wastewater Using Magnetic Ferrite-Based Titanium Oxide and Zinc Oxide Nanocomposites: A Review
by António B. Mapossa, Washington Mhike, José L. Adalima and Shepherd Tichapondwa
Catalysts 2021, 11(12), 1543; https://doi.org/10.3390/catal11121543 - 18 Dec 2021
Cited by 34 | Viewed by 5511
Abstract
Heterogeneous photocatalysis using titanium dioxide (TiO2) and zinc oxide (ZnO) has been widely studied in various applications, including organic pollutant remediation in aqueous systems. The popularity of these materials is based on their high photocatalytic activity, strong photosensitivity, and relatively low [...] Read more.
Heterogeneous photocatalysis using titanium dioxide (TiO2) and zinc oxide (ZnO) has been widely studied in various applications, including organic pollutant remediation in aqueous systems. The popularity of these materials is based on their high photocatalytic activity, strong photosensitivity, and relatively low cost. However, their commercial application has been limited by their wide bandgaps, inability to absorb visible light, fast electron/hole recombination, and limited recyclability since the nanomaterial is difficult to recover. Researchers have developed several strategies to overcome these limitations. Chief amongst these is the coupling of different semi-conductor materials to produce heterojunction nanocomposite materials, which are both visible-light-active and easily recoverable. This review focuses on the advances made in the development of magnetic ferrite-based titanium oxide and zinc oxide nanocomposites. The physical and magnetic properties of the most widely used ferrite compounds are discussed. The spinel structured material had superior catalytic and magnetic performance when coupled to TiO2 and ZnO. An assessment of the range of synthesis methods is also presented. A comprehensive review of the photocatalytic degradation of various priority organic pollutants using the ferrite-based nanocomposites revealed that degradation efficiency and magnetic recovery potential are dependent on factors such as the chemical composition of the heterojunction material, synthesis method, irradiation source, and structure of pollutant. It should be noted that very few studies have gone beyond the degradation efficiency studies. Very little information is available on the extent of mineralization and the subsequent formation of intermediate compounds when these composite catalysts are used. Additionally, potential degradation mechanisms have not been adequately reported. Full article
(This article belongs to the Special Issue Recent Advances in Photocatalysis for Wastewater Treatment: Synthesis of the Materials and Photocatalytic Reactors)
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18 pages, 9176 KiB  
Article
Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance
by Mohamad Rasid Shera Farisya, Ramli Irmawati, Ishak Nor Shafizah, Yun Hin Taufiq-Yap, Ernee Noryana Muhamad, Siew Ling Lee and Nurrulhidayah Salamun
Catalysts 2021, 11(12), 1542; https://doi.org/10.3390/catal11121542 - 17 Dec 2021
Cited by 10 | Viewed by 4108
Abstract
In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, [...] Read more.
In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, respectively. The synthesized catalysts were characterized using FTIR, XRD, TGA, BET, NH3-TPD, XRF, and SEM-EDX. The synthesized catalysts were tested on glycerol acetylation reaction at conditions: 0.5 g catalyst loading, 100–120 °C temperature, 1:6 glycerol/acetic acid molar ratios, and 2–4 h reaction time. The final product obtained was analysed using GC-FID. An increment in sulfuric acid concentration reduces the surface area, pore volume, and particles size. However, the increment has increased the number of active sites (Lewis acid) and strong acid strength. 15SA catalyst exhibited excellent glycerol conversion (>90%) and the highest selectivity of triacetin (42%). Besides sufficient surface area (1.9 m2 g−1) and good porosity structure, the great performance of the 15SA catalyst was attributed to its high acid site density (342.6 µmol g−1) and the high active site of metal oxide (95%). Full article
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30 pages, 7245 KiB  
Review
Synthesis of Mesoporous Zeolites and Their Opportunities in Heterogeneous Catalysis
by Bhupendra Kumar Singh, Yongseok Kim, Seungdon Kwon and Kyungsu Na
Catalysts 2021, 11(12), 1541; https://doi.org/10.3390/catal11121541 - 17 Dec 2021
Cited by 26 | Viewed by 6726
Abstract
Currently, zeolites are one of the most important classes of heterogeneous catalysts in chemical industries owing to their unique structural characteristics such as molecular-scale size/shape-selectivity, heterogenized single catalytic sites in the framework, and excellent stability in harsh industrial processes. However, the microporous structure [...] Read more.
Currently, zeolites are one of the most important classes of heterogeneous catalysts in chemical industries owing to their unique structural characteristics such as molecular-scale size/shape-selectivity, heterogenized single catalytic sites in the framework, and excellent stability in harsh industrial processes. However, the microporous structure of conventional zeolite materials limits their applications to small-molecule reactions. To alleviate this problem, mesoporous zeolitic frameworks were developed. In the last few decades, several methods have been developed for the synthesis of mesoporous zeolites; these zeolites have demonstrated greater lifetime and better performance than their bulk microporous counterparts in many catalytic processes, which can be explained by the rapid diffusion of reactant species into the zeolite framework and facile accessibility to bulky molecules through the mesopores. Mesoporous zeolites provide versatile opportunities not only in conventional chemical industries but also in emerging catalysis fields. This review presents many state-of-the-art mesoporous zeolites, discusses various strategies for their synthesis, and details their contributions to catalytic reactions including catalytic cracking, isomerization, alkylation and acylation, alternative fuel synthesis via methanol-to-hydrocarbon (MTH) and Fischer–Tropsch synthesis (FTS) routes, and different fine-chemical syntheses. Full article
(This article belongs to the Special Issue State-of-the-Art Nanostructured Catalysts in Asia)
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14 pages, 3597 KiB  
Article
Enhancing Methane Conversion by Modification of Zn States in Co-Reaction of MTA
by Yue Yu, Zhixiang Xi, Bingjie Zhou, Binbo Jiang, Zuwei Liao, Yao Yang, Jingdai Wang, Zhengliang Huang, Jingyuan Sun and Yongrong Yang
Catalysts 2021, 11(12), 1540; https://doi.org/10.3390/catal11121540 - 17 Dec 2021
Cited by 2 | Viewed by 2396
Abstract
Limited by harsh reaction conditions, the activation and utilization of methane were regarded as holy grail reaction. Co-reaction with methanol, successfully realizing mild conversion below 450 °C, provides practical strategies for methane conversion on metal-loaded ZSM-5 zeolites, especially for highly efficient Zn loaded [...] Read more.
Limited by harsh reaction conditions, the activation and utilization of methane were regarded as holy grail reaction. Co-reaction with methanol, successfully realizing mild conversion below 450 °C, provides practical strategies for methane conversion on metal-loaded ZSM-5 zeolites, especially for highly efficient Zn loaded ones. However, Zn species, regarded as active acid sites on the zeolite, have not been sufficiently studied. In this paper, Zn-loaded ZSM-5 zeolite was prepared, and Zn was modified by capacity, loading strategy, and treating atmosphere. Apparent methane conversion achieves 15.3% for 1.0Zn/Z-H2 (16.8% as calculated net conversion) with a significantly reduced loading of 1.0 wt.% against deactivation, which is among the best within related zeolite materials. Besides, compared to the MTA reaction, the addition of methane promotes the high-valued aromatic production from 49.4% to 54.8%, and inhibits the C10+ production from 7.8% to 3.6%. Notably, Zn2+ is found to be another active site different from the reported ZnOH+. Medium strong acid sites are proved to be beneficial for methane activation. This work provides suggestions for the modification of the Zn active site, in order to prepare highly efficient catalysts for methane activation and BTX production in co-reaction with methanol. Full article
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19 pages, 5780 KiB  
Article
Gram-Scale Synthesis of CoO/C as Base for PtCo/C High-Performance Catalysts for the Oxygen Reduction Reaction
by Dmitry Mauer, Sergey Belenov, Vladimir Guterman, Anatoly Nikolsky, Alexey Kozakov, Alexey Nikulin, Danil Alexeenko and Olga Safronenko
Catalysts 2021, 11(12), 1539; https://doi.org/10.3390/catal11121539 - 17 Dec 2021
Cited by 6 | Viewed by 3021
Abstract
The composition, structure, catalytic activity in the ORR and stability of PtCo/C materials, obtained in two stages and compared with commercial Pt/C analogs, were studied. At the first stage of the synthesis performed by electrodeposition of cobalt on a carbon support, a CoO [...] Read more.
The composition, structure, catalytic activity in the ORR and stability of PtCo/C materials, obtained in two stages and compared with commercial Pt/C analogs, were studied. At the first stage of the synthesis performed by electrodeposition of cobalt on a carbon support, a CoOx/C composite containing 8% and 25 wt% cobalt oxide was successfully obtained. In the second step, PtCoOx/C catalysts of Pt1.56Co and Pt1.12Co composition containing 14 and 30 wt% Pt, respectively, were synthesized based on the previously obtained composites. According to the results of the composition and structure analysis of the obtained PtCoOx/C catalysts by X-ray diffraction (XRD), X-ray fluorescence analysis (XRF), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) methods, the formation of small bimetallic nanoparticles on the carbon support surface has been proved. The resulting catalysts demonstrated up to two times higher specific catalytic activity in the ORR and high stability compared to commercial Pt/C analogs. Full article
(This article belongs to the Special Issue Pt-M (M = Ni,Co,Cu, etc.)/C Electrocatalysts)
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12 pages, 2857 KiB  
Article
Synthesis of Thin Titania Coatings onto the Inner Surface of Quartz Tubes and Their Photoactivity in Decomposition of Methylene Blue and Rhodamine B
by Stanislav D. Svetlov, Dmitry A. Sladkovskiy, Kirill V. Semikin, Alexander V. Utemov, Rufat Sh. Abiev and Evgeny V. Rebrov
Catalysts 2021, 11(12), 1538; https://doi.org/10.3390/catal11121538 - 16 Dec 2021
Cited by 5 | Viewed by 2765
Abstract
An evaporation-deposition coating method for coating the inner surface of long (>1 m) quartz tubes of small diameter has been studied by the introduction of two-phase (gas-liquid) flow with the gas core flowing in the middle and a thin liquid film of synthesis [...] Read more.
An evaporation-deposition coating method for coating the inner surface of long (>1 m) quartz tubes of small diameter has been studied by the introduction of two-phase (gas-liquid) flow with the gas core flowing in the middle and a thin liquid film of synthesis sol flowing near the hot tube wall. The operational window for the deposition of continuous titania coatings has been obtained. The temperature range for the deposition of continuous titania coatings is limited to 105–120 °C and the gas flow rate is limited to the range of 0.4–1.0 L min−1. The liquid flow rate in the annular flow regime allows to control the coating thickness between 3 and 10 micron and the coating porosity between 10% and 20%. By increasing the liquid flow rate, the coating porosity can be substantially reduced. The coatings were characterized by X-ray diffraction, N2 chemisorption, thermogravimetric analysis, and scanning electron microscopy. The coatings were tested in the photocatalytic decomposition of methylene blue and rhodamine B under UV-light and their activity was similar to that of a commercial P25 titania catalyst. Full article
(This article belongs to the Special Issue Metallic or Metallic Oxide (Photo)catalysts for Environmental Applications)
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23 pages, 28630 KiB  
Article
Valorization of Solketal Synthesis from Sustainable Biodiesel Derived Glycerol Using Response Surface Methodology
by Gayathri Arun, Muhammad Ayoub, Zulqarnain, Umesh Deshannavar, Mohd Hizami Mohd Yusoff, Sarah Farrukh and Farooq Sher
Catalysts 2021, 11(12), 1537; https://doi.org/10.3390/catal11121537 - 16 Dec 2021
Cited by 17 | Viewed by 3542
Abstract
Biodiesel production has gained considerable importance over the last few decades due to the increase in fossil fuel prices as well as toxic emissions of oxygen and nitrogen. The production of biodiesel via catalytic transesterification produces crude glycerol as a co-product along with [...] Read more.
Biodiesel production has gained considerable importance over the last few decades due to the increase in fossil fuel prices as well as toxic emissions of oxygen and nitrogen. The production of biodiesel via catalytic transesterification produces crude glycerol as a co-product along with biodiesel, amounting to 10% of the total biodiesel produced. Glycerol has a low value in its impure form, and the purification of glycerol requires sophisticated technologies and is an expensive process. The conversion of crude glycerol into value-added chemicals such as solketal is the best way to improve the sustainability of biodiesel synthesis using the transesterification reaction. Therefore, the conversion of crude glycerol into the solketal was investigated in a batch reactor simulation model developed by the Aspen Plus V11.0. The non-random two liquid theory (NRTL) method was used as a thermodynamic property package to study the effect of four input ketalization parameters. The model was validated with the findings of previous experimental studies of solketal synthesis using sulfuric acid as a catalyst. The influence of the following operating parameters was investigated: reaction time of 10,000 to 60,000 s, reaction temperature of 303 to 323 K, acetone to glycerol molar ratio of 2:1 to 10:1, and catalyst concentration of 0.005 to 0.03 wt %. The optimum solketal yield of 81.36% was obtained at the optimized conditions of 313 K, 9:1, 0.03 wt %, and 40,000 s. The effect of each input parameter on the ketalization process and interaction between input and output parameters was investigated by using the response surface methodology (RSM) optimizer. The relationship between independent and response variables developed by RSM fit most of the simulation data, which showed the accuracy of the model. A second-order differential equation fit the simulation data well and showed an R2 value of 0.99. According to the findings of RSM, the influence of catalyst amount, acetone to glycerol molar ratio, and reaction time were more significant on solketal yield. The effect of temperature on the performance of the reaction was not found to be significant because of the exothermic nature of the process. The findings of this study showed that biodiesel-derived glycerol can be effectively utilized to produce solketal, which can be used for a wider range of applications such as a fuel additive. However, further work is required to enhance the solketal yield by developing new heterogeneous catalysts so that the industrial implementation of its production can be made possible. Full article
(This article belongs to the Special Issue Catalytic Valorization of Glycerol: Strategies and Perspectives)
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11 pages, 7129 KiB  
Article
Synthesis, Characterization and Enhanced Visible Light Photocatalytic Performance of ZnWO4-NPs@rGO Nanocomposites
by Norah Alhokbany, Saad M. Alshehri and Jahangeer Ahmed
Catalysts 2021, 11(12), 1536; https://doi.org/10.3390/catal11121536 - 16 Dec 2021
Cited by 13 | Viewed by 2773
Abstract
ZnWO4 nanoparticles on reduced graphene oxide (ZnWO4-NPs@rGO) nanocomposites were synthesized using the hydrothermal method. Structural, morphological, optical, and photocatalytic studies of the ZnWO4-NPs@rGO nanocomposites were successfully investigated. Photo-catalytic performances of the ZnWO4-NPs@rGO nanocomposites were examined for [...] Read more.
ZnWO4 nanoparticles on reduced graphene oxide (ZnWO4-NPs@rGO) nanocomposites were synthesized using the hydrothermal method. Structural, morphological, optical, and photocatalytic studies of the ZnWO4-NPs@rGO nanocomposites were successfully investigated. Photo-catalytic performances of the ZnWO4-NPs@rGO nanocomposites were examined for the degradation of hazardous methylene blue dye (HMBD) in a neutral medium. ZnWO4-NPs@rGO nanocomposites show superior photo-catalytic performances over pure ZnWO4 nanoparticles. ZnWO4-NPs@rGO nanocomposites degrade ~98% dye while pure ZnWO4 nanoparticles degrade ~53% dye in 120 min. The prepared nanocomposites also show excellent recycled photo-catalytic efficiencies over multiple cycles. Full article
(This article belongs to the Special Issue The Importance of Shape-Tailoring at Nano- and Micro-Levels in Catalytic and Photocatalytic Applications)
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15 pages, 5277 KiB  
Article
TiCl4/MgCl2/MCM-41 Bi-Supported Ziegler–Natta Catalyst: Effects of Catalyst Composition on Ethylene/1-Hexene Copolymerization
by Xiaoyu Liu, Wenqi Guo, Xueer Wang, Yintian Guo, Biao Zhang, Zhisheng Fu, Qi Wang and Zhiqiang Fan
Catalysts 2021, 11(12), 1535; https://doi.org/10.3390/catal11121535 - 16 Dec 2021
Cited by 5 | Viewed by 3505
Abstract
TiCl4/MgCl2/MCM-41 type bi-supported Ziegler-Natta catalysts with different MgCl2/MCM-41 ratios were synthesized by adsorbing TiCl4 onto MgCl2 crystallites anchored in mesopores of MCM-41 (mesoporous silica with 3.4 nm pore size). Ethylene/1-hexene copolymerization with the catalysts was [...] Read more.
TiCl4/MgCl2/MCM-41 type bi-supported Ziegler-Natta catalysts with different MgCl2/MCM-41 ratios were synthesized by adsorbing TiCl4 onto MgCl2 crystallites anchored in mesopores of MCM-41 (mesoporous silica with 3.4 nm pore size). Ethylene/1-hexene copolymerization with the catalysts was conducted at different 1-hexene concentrations and ethylene pressures. MgCl2/MCM-41 composite supports and the catalysts were characterized by X-ray diffraction (XRD), nitrogen adsorption analysis (BET), and elemental analysis. The copolymers were fractionated by extraction with boiling n-heptane, and comonomer contents of the fractions were determined. Under 4 bar ethylene pressure, the bi-supported catalysts showed higher activity and a stronger comonomer activation effect than the TiCl4/MgCl2 catalyst. In comparison with the TiCl4/MgCl2 catalyst, the bi-supported catalysts produced much less copolymer fraction of low molecular weight and high 1-hexene content, meaning that the active center distribution of the catalyst was significantly changed by introducing MCM-41 in the support. The copolymer produced by the bi-supported catalysts showed similar melting temperature to that produced by TiCl4/MgCl2 under the same polymerization conditions. The space confinement effect of the mesopores of MCM-41 on the size and structure of MgCl2 crystallites is proposed as the main reason for the special active center distribution of the bi-supported catalysts. Full article
(This article belongs to the Special Issue Advances in Ziegler-Natta Type Catalysts for Olefin Polymerization)
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19 pages, 6136 KiB  
Article
Effects of Preparation Conditions on the Efficiency of Visible-Light-Driven Hydrogen Generation Based on Cd0.25Zn0.75S Photocatalysts
by Maali-Amel Mersel, Lajos Fodor, Péter Pekker, Miklós Jakab, Éva Makó and Ottó Horváth
Catalysts 2021, 11(12), 1534; https://doi.org/10.3390/catal11121534 - 16 Dec 2021
Cited by 5 | Viewed by 2653
Abstract
Photocatalytic H2 production utilizing H2S, an industrial side-product, is regarded as an environmentally friendly process to produce clean energy through direct solar energy conversion. For this purpose, sulfide-based materials, such as photocatalysts, have been widely used due to their good [...] Read more.
Photocatalytic H2 production utilizing H2S, an industrial side-product, is regarded as an environmentally friendly process to produce clean energy through direct solar energy conversion. For this purpose, sulfide-based materials, such as photocatalysts, have been widely used due to their good solar response and high photocatalytic activity. In this work, a ZnS–CdS composite was studied, and special attention was dedicated to the influence of the preparation parameters on its H2 production activity. The ZnS–CdS composite, with an enhanced photoactivity for H2 production, was synthesized both from ammine complexes and, in a conventional way, directly from acetates at various pH values. Deviating from the traditional method, the photoactivity of ZnS–CdS prepared from ammine complexes was not affected by the pH. Besides, the hydrothermal treatment and the ammonia content strongly influenced the rate of H2 production in this system. DRS, TEM, SEM, XRD, and quantum yield measurements prove the dependence of the photoactivity of these catalysts on the structural and morphological properties determined by the preparation conditions. The promising photocatalytic efficiency achieved with the application of these ZnS–CdS catalysts, prepared without any metal deposition, encourages further investigations to enhance the rate of hydrogen generation by optimization of the reaction conditions for practical utilization. Full article
(This article belongs to the Special Issue 10th Anniversary of Catalysts—Feature Papers in Photocatalysis)
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18 pages, 9355 KiB  
Article
Self-Supporting g-C3N4 Nanosheets/Ag Nanoparticles Embedded onto Polyester Fabric as “Dip-Catalyst” for Synergic 4-Nitrophenol Hydrogenation
by Abdallah Amedlous, Mohammed Majdoub, Zakaria Anfar and Elhassan Amaterz
Catalysts 2021, 11(12), 1533; https://doi.org/10.3390/catal11121533 - 16 Dec 2021
Cited by 16 | Viewed by 2877
Abstract
Herein, we report the design of a cost-effective catalyst with excellent recyclability, simple recuperation and facile recovery, and the examination between the reaction cycles via the development of self-supporting g-C3N4 nanosheets/Ag NPs polyester fabric (PES) using a simple, facile and [...] Read more.
Herein, we report the design of a cost-effective catalyst with excellent recyclability, simple recuperation and facile recovery, and the examination between the reaction cycles via the development of self-supporting g-C3N4 nanosheets/Ag NPs polyester fabric (PES) using a simple, facile and efficient approach. PES fabrics were coated via a sono-coating method with carbon nitride nanosheets (GCNN) along with an in situ setting of Ag nanoparticles on PES coated GCNN surface producing PES-GCNN/Ag0. The elaborated textile-based materials were fully characterized using FTIR, 13C NMR, XRD, TGA, SEM, EDX, etc. Catalytic performance of the designed “Dip-Catalyst” demonstrated that the as-prepared PES-GCCN/Ag0 has effectively catalyzed the hydrogenation of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) in the presence of NaBH4. The 3 × 3 cm2 PES-GCNN/Ag0 showed the best catalytic activity, displaying an apparent rate constant (Kapp) equal to 0.43 min−1 and more than 10 reusability cycles, suggesting that the prepared catalyst-based PES fabric can be a strong nominee for sustainable chemical catalysis. Moreover, the coated fabrics exhibited appreciable antibacterial capacity against Staphylococcus epidermidis (S. epidermidis) and Escherichia coli (E. coli). The present study opens up new opportunities for the future design of a low cost and large-scale process of functional fabrics. Full article
(This article belongs to the Special Issue Advanced Functional Nanomaterials for Catalysis and Environmental Applications: Trends and Outlooks)
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12 pages, 4340 KiB  
Article
Hollow TiO2 Microsphere/Graphene Composite Photocatalyst for CO2 Photoreduction
by Yi-Chen Chung, Pei-Jie Xie, Yi-Wei Lai and An-Ya Lo
Catalysts 2021, 11(12), 1532; https://doi.org/10.3390/catal11121532 - 16 Dec 2021
Cited by 5 | Viewed by 2563
Abstract
In an attempt to improve the photocatalytic activity of anatase TiO2, we developed a composite photocatalyst composed of hollow TiO2 microspheres (hTS) and graphene. The hTS were prepared through a two-step hydrothermal process, where SiO2 microspheres with desirable diameters [...] Read more.
In an attempt to improve the photocatalytic activity of anatase TiO2, we developed a composite photocatalyst composed of hollow TiO2 microspheres (hTS) and graphene. The hTS were prepared through a two-step hydrothermal process, where SiO2 microspheres with desirable diameters of 100–400 nm were used as sacrificial templates. Accordingly, the effect of the hTS cavity size on the activity of the catalyst in wet CO2 photoreduction (CO2PR) was studied. Furthermore, it was established that the hydrothermal pH value crucially influences the photocatalytic activity of the hTS photocatalyst, as well as its composition and microstructure. The hTS photocatalyst was also combined with graphene (0–90 wt%) to improve its photocatalytic activity. This study provides insight into the optimal microsphere diameter, hydrothermal pH value, and graphene/hTSx ratio required for designing hollow microsphere-based photocatalysts with enhanced CO2PR performances. Full article
(This article belongs to the Special Issue Organic-Inorganic Hybrid Catalysts for Energy Applications)
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