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Catalysts, Volume 12, Issue 3 (March 2022) – 108 articles

Cover Story (view full-size image): Acidic green natural zeolite clinoptilolite was prepared via ammonium ion exchange and calcination. The obtained HCLIN catalyst was highly acidic and catalytically active in the etherification of renewable glycerol with t-butanol. The catalyst was thermally stable. Some reversible loss of Brønsted sites occurred, which was related to the formation of penta-coordinated Al[V], at the expense of tetrahedrally coordinated framework Al[IV]. BS sites were broad distributed. The porosity and specific surface area were high without post-synthesis treatment. The preparation process was highly sustainable. The use of environmentally harmful and corrosive mineral acids and chemicals was avoided. The release of waste water, material loss by acid or post-treatment, and energy consumption were reduced in this process. The produced catalyst is reusable. View this paper
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24 pages, 9962 KiB  
Article
Kinetic Study and Modeling of the Degradation of Aqueous Ammonium/Ammonia Solutions by Heterogeneous Photocatalysis with TiO2 in a UV-C Pilot Photoreactor
by Juan C. García-Prieto, Luis A. González-Burciaga, José B. Proal-Nájera and Manuel García-Roig
Catalysts 2022, 12(3), 352; https://doi.org/10.3390/catal12030352 - 21 Mar 2022
Cited by 5 | Viewed by 2317
Abstract
The degradation mechanism of NH4+/NH3 in aqueous solutions by heterogeneous photocatalysis (TiO2/SiO2) and photolysis in UV-C pilot photoreactor has been studied. Under the conditions used, NH4+/NH3 can be decomposed both by [...] Read more.
The degradation mechanism of NH4+/NH3 in aqueous solutions by heterogeneous photocatalysis (TiO2/SiO2) and photolysis in UV-C pilot photoreactor has been studied. Under the conditions used, NH4+/NH3 can be decomposed both by photolytically and photocatalytically, without disregarding stripping processes. The greatest degradation is achieved at the highest pH studied (pH 11.0) and at higher lamp irradiation power used (25 W) with degradation performances of 44.1% (photolysis) and 59.7% (photocatalysis). The experimental kinetic data fit well with a two parallel reactions mechanism. A low affinity of ammonia for adsorption and surface reaction on the photocatalytic fiber was observed (coverage not higher than 10%), indicating a low influence of surface phenomena on the reaction rate, the homogeneous phase being predominant over the heterogeneous phase. The proposed reaction mechanism was validated, confirming that it is consistent with the photocatalytic and photolytic formation of nitrogen gas, on the one hand, and the formation of nitrate, on the other hand. At the optimal conditions, the rate constants were k3 = 0.154 h−1 for the disappearance of ammonia and k1 = 3.3 ± 0.2 10−5 h−1 and k2 = 1.54 ± 0.07 10−1 h−1 for the appearance of nitrate and nitrogen gas, respectively. Full article
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18 pages, 51040 KiB  
Article
Facile Synthesis of Nanosheet-Stacked Hierarchical ZSM-5 Zeolite for Efficient Catalytic Cracking of n-Octane to Produce Light Olefins
by Peng Wang, Xia Xiao, Yutong Pan, Zhen Zhao, Guiyuan Jiang, Zhongdong Zhang, Fanfang Meng, Yuming Li, Xiaoqiang Fan, Lian Kong and Zean Xie
Catalysts 2022, 12(3), 351; https://doi.org/10.3390/catal12030351 - 21 Mar 2022
Cited by 6 | Viewed by 2599
Abstract
The development of an effective strategy for synthesizing two-dimensional MFI zeolites has attracted more and more attention. Herein, nanosheet-stacked hierarchical ZSM-5 zeolite was obtained by a seed-assisted hydrothermal synthesis route using a small amount of [C18H37-N+(CH3 [...] Read more.
The development of an effective strategy for synthesizing two-dimensional MFI zeolites has attracted more and more attention. Herein, nanosheet-stacked hierarchical ZSM-5 zeolite was obtained by a seed-assisted hydrothermal synthesis route using a small amount of [C18H37-N+(CH3)2-C6H12-N+(CH3)2-C6H12]Br2 (C18-6-6Br2) as a zeolite structure-directing agent and triethylamine (TEA) as a zeolite growth modifier. By varying the molar ratio of C18-6-6Br2/TEA from 2.5/0 to 2.5/40, the morphologies and textural properties of the resultant HZ5-2.5/x catalysts were finely modulated. By increasing x from 5 to 40, the morphology of the HZ5-2.5/x changed from unilamellar assembly with narrow a–c plane to intertwined nanosheets with wide a–c plane and multilamellar nanosheets with house-of-cards morphology. The thickness of these nanosheets was almost 8–10 nm. In addition, selectivity to light olefins reached 70.7% for the HZ5-2.5/10 catalyst, which was 6.6% higher than that for CZSM-5 (64.1%). Furthermore, the MFI zeolite nanosheets exhibited better anticoking stability within the 60 h reaction time compared to conventional ZSM-5 zeolite, which could be attributed to the short diffusion path and hierarchical porosity. This work will provide valuable insights into the rational design of novel zeolite catalysts for the efficient cracking of hydrocarbons. Full article
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10 pages, 1592 KiB  
Article
Efficient Synthesis of Dihydropyrimidines Using a Highly Ordered Mesoporous Functionalized Pyridinium Organosilica
by Fatemeh Rajabi, Mika Sillanpää, Christophe Len and Rafael Luque
Catalysts 2022, 12(3), 350; https://doi.org/10.3390/catal12030350 - 21 Mar 2022
Cited by 3 | Viewed by 2905 | Correction
Abstract
A Brönsted acidic ionic solid pyridinium-functionalized organosilica network (PMO-Py-IL) was demonstrated to efficiently catalyse one-pot Biginelli condensation reaction. The green synthesis of 3,4-dihydro-2(H)-pyrimidinones (DHPMs) with high yield was carried out via one-pot three component condensation of β- dicarbonyls, aldehydes, and urea in the [...] Read more.
A Brönsted acidic ionic solid pyridinium-functionalized organosilica network (PMO-Py-IL) was demonstrated to efficiently catalyse one-pot Biginelli condensation reaction. The green synthesis of 3,4-dihydro-2(H)-pyrimidinones (DHPMs) with high yield was carried out via one-pot three component condensation of β- dicarbonyls, aldehydes, and urea in the presence of a catalytic amount of PMO-Py-IL nanomaterial as an efficient nanocatalyst under solvent free conditions. Furthermore, the catalyst showed outstanding stability and could be easily separated and reused for at least ten reaction runs without significant loss of activity and product selectivity. The green protocol features simple set-up, cost-effectiveness, easy work-up, eco-friendly and mild reaction conditions. Full article
(This article belongs to the Special Issue Exclusive Papers of the Editorial Board Members (EBMs) of Catalysts)
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17 pages, 20809 KiB  
Article
Non-Idealities in Lab-Scale Kinetic Testing: A Theoretical Study of a Modular Temkin Reactor
by Gregor D. Wehinger, Bjarne Kreitz and C. Franklin Goldsmith
Catalysts 2022, 12(3), 349; https://doi.org/10.3390/catal12030349 - 18 Mar 2022
Cited by 9 | Viewed by 2520
Abstract
The Temkin reactor can be applied for industrial relevant catalyst testing with unmodified catalyst particles. It was assumed in the literature that this reactor behaves as a cascade of continuously stirred tank reactors (CSTR). However, this assumption was based only on outlet gas [...] Read more.
The Temkin reactor can be applied for industrial relevant catalyst testing with unmodified catalyst particles. It was assumed in the literature that this reactor behaves as a cascade of continuously stirred tank reactors (CSTR). However, this assumption was based only on outlet gas composition or inert residence time distribution measurements. The present work theoretically investigates the catalytic CO2 methanation as a test case on different catalyst geometries, a sphere, and a ring, inside a single Temkin reaction chamber under isothermal conditions. Axial gas-phase species profiles from detailed computational fluid dynamics (CFD) are compared with a CSTR and 1D plug-flow reactor (PFR) model using a sophisticated microkinetic model. In addition, a 1D chemical reactor network (CRN) model was developed, and model parameters were adjusted based on the CFD simulations. Whereas the ideal reactor models overpredict the axial product concentrations, the CRN model results agree well with the CFD simulations, especially under low to medium flow rates. This study shows that complex flow patterns greatly influence species fields inside the Temkin reactor. Although residence time measurements suggest CSTR-like behavior, the reactive flow cannot be described by either a CSTR or PFR model but with the developed CRN model. Full article
(This article belongs to the Special Issue Catalysts: Reactor Modeling Using Computational Fluid Dynamics)
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16 pages, 3076 KiB  
Article
Selective and Efficient Reduction of Nitrate to Gaseous Nitrogen from Drinking Water Source by UV/Oxalic Acid/Ferric Iron Systems: Effectiveness and Mechanisms
by Zhiyuan Shi, Falu Wang, Qian Xiao, Shuili Yu and Xingli Ji
Catalysts 2022, 12(3), 348; https://doi.org/10.3390/catal12030348 - 18 Mar 2022
Cited by 6 | Viewed by 2026
Abstract
Nitrate (NO3) reduction in water has been receiving increasing attention in water treatment due to its carcinogenic and endocrine-disrupting properties. This study employs a novel advanced reduction process, the UV/oxalic acid/ferric iron systems (UV/C2O42−/Fe3+ [...] Read more.
Nitrate (NO3) reduction in water has been receiving increasing attention in water treatment due to its carcinogenic and endocrine-disrupting properties. This study employs a novel advanced reduction process, the UV/oxalic acid/ferric iron systems (UV/C2O42−/Fe3+ systems), in reducing NO3 due to its high reduction efficiency, excellent selectivity, and low treatment cost. The UV/C2O42−/Fe3+ process reduced NO3 with pseudo-first-order reaction rate constants of 0.0150 ± 0.0013 min−1, minimizing 91.4% of 60 mg/L NO3 and reaching 84.2% of selectivity for gaseous nitrogen after 180 min at pHini. 7.0 and 0.5 mg/L dissolved oxygen (DO). Carbon dioxide radical anion (CO2•−) played a predominant role in reducing NO3. Gaseous nitrogen and NH4+, as well as CO2, were the main nitrogen- and carbon-containing products, respectively, and reduction pathways were proposed accordingly. A suitable level of oxalic acids (3 mM) and NO3 (60 mg/L) was recommended; increasing initial iron concentrations and UV intensity increased NO3 reduction. Instead, increasing the solution pH decreased the reduction, and 0.5–8.0 mg/L DO negligibly affected the process. Moreover, UV/C2O42−/Fe3+ systems were not retarded by 0.1–10 mM SO42− or Cl or 0.1–1.0 mM HCO3 but were prohibited by 10 mM HCO3 and 30 mg-C/L humic acids. There was a lower reduction of NO3 in simulated groundwater (72.8%) than deionized water after 180 min at pHini. 7.0 and 0.5 mg/L DO, which meets the drinking water standard (<10 mg/L N-NO3). Therefore, UV/C2O42−/Fe3+ systems are promising approaches to selectively and efficiently reduce NO3 in drinking water. Full article
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24 pages, 1272 KiB  
Article
Kinetics of the Direct DME Synthesis: State of the Art and Comprehensive Comparison of Semi-Mechanistic, Data-Based and Hybrid Modeling Approaches
by Nirvana Delgado Otalvaro, Pembe Gül Bilir, Karla Herrera Delgado, Stephan Pitter and Jörg Sauer
Catalysts 2022, 12(3), 347; https://doi.org/10.3390/catal12030347 - 18 Mar 2022
Cited by 4 | Viewed by 2358
Abstract
Hybrid kinetic models represent a promising alternative to describe and evaluate the effect of multiple variables in the performance of complex chemical processes, since they combine system knowledge and extrapolability of the (semi-)mechanistic models in a wide range of reaction conditions with the [...] Read more.
Hybrid kinetic models represent a promising alternative to describe and evaluate the effect of multiple variables in the performance of complex chemical processes, since they combine system knowledge and extrapolability of the (semi-)mechanistic models in a wide range of reaction conditions with the adaptability and fast convergence of data-based approaches (e.g., artificial neural networks—ANNs). For the first time, a hybrid kinetic model for the direct DME synthesis was developed consisting of a reactor model, i.e., balance equations, and an ANN for the reaction kinetics. The accuracy, computational time, interpolation and extrapolation ability of the new hybrid model were compared to those of a lumped and a data-based model with the same validity range, using both simulations and experiments. The convergence of parameter estimation and simulations with the hybrid model is much faster than with the lumped model, and the predictions show a greater degree of accuracy within the models’ validity range. A satisfactory dimension and range extrapolation was reached when the extrapolated variable was included in the knowledge module of the model. This feature is particularly dependent on the network architecture and phenomena covered by the underlying model, and less on the experimental conditions evaluated during model development. Full article
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17 pages, 5642 KiB  
Article
Effect of Plating Variables on Oxygen Evolution Reaction of Ni–Zn–Fe Electrodes for Alkaline Water Electrolysis
by Su-han Lee, Ji Eun Kim, Hyunku Joo, Chu-sik Park, Seong-uk Jeong, Kwangjin Jung, Young-ho Kim and Kyoung-soo Kang
Catalysts 2022, 12(3), 346; https://doi.org/10.3390/catal12030346 - 18 Mar 2022
Cited by 2 | Viewed by 2762
Abstract
In this study, we investigated the oxygen evolution reaction (OER) characteristics of Ni–Zn–Fe electrodes by varying plating current density and Ni:Fe ratio in a plating bath. The activity of the OER increased up to the plating current density of 160 mA/cm2, [...] Read more.
In this study, we investigated the oxygen evolution reaction (OER) characteristics of Ni–Zn–Fe electrodes by varying plating current density and Ni:Fe ratio in a plating bath. The activity of the OER increased up to the plating current density of 160 mA/cm2, as the Fe content of the deposited electrode increased and electrochemical surface area (ECSA) increased after Zn dealloying. However, for the plated electrode with higher than 160 mA/cm2 of current density, the change in composition caused by underpotential deposition led to decreased activity due to decreasing Fe content and diminishing Zn dealloying. Moreover, when the Ni:Fe ratio in the plating bath was varied, outstanding OER activity was observed at Ni:Fe = 2:1. When the Fe content of the bath increased beyond this ratio, Fe could not restrain Ni oxidation and formed Fe oxides in OER reaction, and oxygen vacancy decreased. These caused a degradation of the OER activity. Full article
(This article belongs to the Section Electrocatalysis)
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4 pages, 190 KiB  
Editorial
Metallic or Metallic Oxide (Photo)catalysts for Environmental Applications
by Julien G. Mahy and Sophie Hermans
Catalysts 2022, 12(3), 345; https://doi.org/10.3390/catal12030345 - 18 Mar 2022
Cited by 1 | Viewed by 1372
Abstract
During the last century, industrialization intensified in a growing number of countries around the world, and in various industries, particularly in the chemical, pharmaceutical, cosmetics, horticulture, food, and petroleum sectors [...] Full article
31 pages, 2617 KiB  
Review
Heterogeneous Advanced Oxidation Processes: Current Approaches for Wastewater Treatment
by Gabriela Lama, Jessica Meijide, Angeles Sanromán and Marta Pazos
Catalysts 2022, 12(3), 344; https://doi.org/10.3390/catal12030344 - 17 Mar 2022
Cited by 33 | Viewed by 4745
Abstract
Nowadays, water pollution is one of the most dangerous environmental problems in the world. The presence of the so-called emerging pollutants in the different water bodies, impossible to eliminate through conventional biological and physical treatments used in wastewater treatment plants due to their [...] Read more.
Nowadays, water pollution is one of the most dangerous environmental problems in the world. The presence of the so-called emerging pollutants in the different water bodies, impossible to eliminate through conventional biological and physical treatments used in wastewater treatment plants due to their persistent and recalcitrant nature, means that pollution continues growing throughout the world. The presence of these emerging pollutants involves serious risks to human and animal health for aquatic and terrestrial organisms. Therefore, in recent years, advanced oxidation processes (AOPs) have been postulated as a viable, innovative and efficient technology for the elimination of these types of compounds from water bodies. The oxidation/reduction reactions triggered in most of these processes require a suitable catalyst. The most recent research focuses on the use and development of different types of heterogeneous catalysts, which are capable of overcoming some of the operational limitations of homogeneous processes such as the generation of metallic sludge, difficult separation of treated water and narrow working pH. This review details the current advances in the field of heterogeneous AOPs, Fenton processes and photocatalysts for the removal of different types of emerging pollutants. Full article
(This article belongs to the Special Issue Photo/Electrocatalysis for Wastewater Treatment)
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20 pages, 3909 KiB  
Article
Systematic Functional and Computational Analysis of Glucose-Binding Residues in Glycoside Hydrolase Family GH116
by Meng Huang, Salila Pengthaisong, Ratana Charoenwattanasatien, Natechanok Thinkumrob, Jitrayut Jitonnom and James R. Ketudat Cairns
Catalysts 2022, 12(3), 343; https://doi.org/10.3390/catal12030343 - 17 Mar 2022
Cited by 6 | Viewed by 2249
Abstract
Glycoside hydrolases (GH) bind tightly to the sugar moiety at the glycosidic bond being hydrolyzed to stabilize its transition state conformation. We endeavored to assess the importance of glucose-binding residues in GH family 116 (GH116) β-glucosidases, which include human β-glucosylceramidase 2 (GBA2), by [...] Read more.
Glycoside hydrolases (GH) bind tightly to the sugar moiety at the glycosidic bond being hydrolyzed to stabilize its transition state conformation. We endeavored to assess the importance of glucose-binding residues in GH family 116 (GH116) β-glucosidases, which include human β-glucosylceramidase 2 (GBA2), by mutagenesis followed by kinetic characterization, X-ray crystallography, and ONIOM calculations on Thermoanaerobacterium xylanolyticum TxGH116, the structural model for GH116 enzymes. Mutations of residues that bind at the glucose C3OH and C4OH caused 27–196-fold increases in KM for p-nitrophenyl-β-D-glucoside, and significant decreases in the kcat, up to 5000-fold. At the C6OH binding residues, mutations of E777 decreased the kcat/KM by over 60,000-fold, while R786 mutants increased both the KM (40-fold) and kcat (2–4-fold). The crystal structures of R786A and R786K suggested a larger entrance to the active site could facilitate their faster rates. ONIOM binding energy calculations identified D452, H507, E777, and R786, along with the catalytic residues E441 and D593, as strong electrostatic contributors to glucose binding with predicted interaction energies > 15 kcal mol−1, consistent with the effects of the D452, H507, E777 and R786 mutations on enzyme kinetics. The relative importance of GH116 active site residues in substrate binding and catalysis identified in this work improves the prospects for the design of inhibitors for GBA2 and the engineering of GH116 enzymes for hydrolytic and synthetic applications. Full article
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18 pages, 3638 KiB  
Article
Regulating Crystal Facets of MnO2 for Enhancing Peroxymonosulfate Activation to Degrade Pollutants: Performance and Mechanism
by Juncong Fu, Peng Gao, Lu Wang, Yongqing Zhang, Yuhui Deng, Renfeng Huang, Shuaifei Zhao, Zebin Yu, Yuancheng Wei, Guangzhao Wang and Shaoqi Zhou
Catalysts 2022, 12(3), 342; https://doi.org/10.3390/catal12030342 - 17 Mar 2022
Cited by 15 | Viewed by 2842
Abstract
On the catalyst surface, crystal facets with different surface atom arrangements and diverse physicochemical properties lead to distinct catalytic activity. Acquiring a highly reactive facet through surface regulation is an efficient strategy to promote the oxidative decomposition of wastewater organic pollutants via peroxymonosulfate [...] Read more.
On the catalyst surface, crystal facets with different surface atom arrangements and diverse physicochemical properties lead to distinct catalytic activity. Acquiring a highly reactive facet through surface regulation is an efficient strategy to promote the oxidative decomposition of wastewater organic pollutants via peroxymonosulfate (PMS) activation. However, the mechanism through which crystal facets affect PMS activation is still unclear. In this study, three facet-engineered α-MnO2 with different exposed facets were prepared via a facile hydrothermal route. The prepared 310-MnO2 exhibited superior PMS activation performance to 100-MnO2 and 110-MnO2. Moreover, the 310-MnO2/PMS oxidative system was active over a wide pH range and highly resistant to interfering substances from wastewater. These advantages of the 310-MnO2/PMS system make it highly promising for practical wastewater treatment. Based on quenching experiments, electron paramagnetic resonance (EPR) analysis, solvent exchange, and electrochemical measurements, mediated electron transfer was found to be the dominant nonradical pathway for p-chloroaniline (PCA) degradation. A sulfhydryl group (-SH) masking experiment showed that the highly exposed Mn atoms on the 310-MnO2 surface were sites of PMS activation. In addition, density functional theory (DFT) calculations confirmed that the dominant {310} facet promoted adsorption/activation of PMS, which favored the formation of more metastable complexes on the α-MnO2 surface. The reaction mechanism obtained here clarifies the relationship between PMS activation and crystal facets. This study provides significant insights into the rational design of high-performance catalysts for efficient water remediation. Full article
(This article belongs to the Special Issue Advanced Catalysts for Persulfate Activation)
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17 pages, 1501 KiB  
Review
Low-Temperature SCR Catalyst Development and Industrial Applications in China
by Hongtai Zhu, Liyun Song, Kai Li, Rui Wu, Wenge Qiu and Hong He
Catalysts 2022, 12(3), 341; https://doi.org/10.3390/catal12030341 - 17 Mar 2022
Cited by 15 | Viewed by 4172
Abstract
In recent years, low-temperature SCR (Selective Catalytic Reduction) denitrification technology has been popularized in non-power industries and has played an important role in the control of industrial flue gas NOx emissions in China. Currently, the most commonly used catalysts in industry are [...] Read more.
In recent years, low-temperature SCR (Selective Catalytic Reduction) denitrification technology has been popularized in non-power industries and has played an important role in the control of industrial flue gas NOx emissions in China. Currently, the most commonly used catalysts in industry are V2O5-WO3(MoO3)/TiO2, MnO2-based catalysts, CeO2-based catalysts, MnO2-CeO2 catalysts and zeolite SCR catalysts. The flue gas emitted during industrial combustion usually contains SO2, moisture and alkali metals, which can affect the service life of SCR catalysts. This paper summarizes the mechanism of catalyst poisoning and aims to reduce the negative effect of NH4HSO4 on the activity of the SCR catalyst at low temperatures in industrial applications. It also presents the outstanding achievements of domestic companies in denitrification in the non-power industry in recent years. Much progress has been made in the research and application of low-temperature NH3-SCR, and with the renewed demand for deeper NOx treatments, new technologies with lower energy consumption and more functions need to be developed. Full article
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16 pages, 2790 KiB  
Article
Impact of Sintering Temperature on the Electrical Properties of La0.9Sr0.1MnO3 Manganite
by Wided Hizi, Hedi Rahmouni, Nima E. Gorji, Ahlem Guesmi, Naoufel Ben Hamadi, Lotfi Khezami, Essebti Dhahri, Kamel Khirouni and Malek Gassoumi
Catalysts 2022, 12(3), 340; https://doi.org/10.3390/catal12030340 - 17 Mar 2022
Cited by 12 | Viewed by 2452
Abstract
La0.9Sr0.1MnO3 nanoparticles were prepared using the citrate–gel route and sintered at different temperatures (TS = 600 °C, 800 °C, and 1000 °C). The x-day diffraction patterns reveal that the samples exhibit a single phase with a rhombohedral [...] Read more.
La0.9Sr0.1MnO3 nanoparticles were prepared using the citrate–gel route and sintered at different temperatures (TS = 600 °C, 800 °C, and 1000 °C). The x-day diffraction patterns reveal that the samples exhibit a single phase with a rhombohedral (R3¯C) structure. The transmission electron microscopy technique shows an increase in the grain size when the sintering temperature (TS) rises. The obtained values are approximately similar to that of crystallite size calculated from x-ray diffraction patterns. The impact of sintering temperature (TS) on the electrical properties of La0.9Sr0.1MnO3manganite is examined using the impedance spectroscopy technique. A metal-semi-conductor transition at a specific temperature (TM-SC) is observed for all samples. Indeed, the sintering temperature increase induces the shift of this transition temperature toward higher temperatures. Such a behavior is explained by the increase in the grain size. An agreement between the metal-semi-conductor transition values coming from the DC resistivity and the grain boundaries analyses is observed. This agreement proves the contribution of the grain boundaries in the electrical properties of the studied samples. In addition, the presence of the relaxation phenomenon is confirmed. The fitted Nyquist plots show the correlation between the microstructure of the material and the electrical properties using an electrical equivalent circuit model. The DC resistivity and the impedance analyses reveal the thermal activation of the transport properties in the investigated system. Full article
(This article belongs to the Topic Nanomaterials for Sustainable Energy Applications)
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14 pages, 8727 KiB  
Communication
Continuous Flow Biocatalysis: Synthesis of Coumarin Carboxamide Derivatives by Lipase TL IM from Thermomyces lanuginosus
by Li-Hua Du, Meng-Jie Yang, Yue Pan, Ling-Yan Zheng, Shi-Yi Zhang, Zhi-Kai Sheng, Ping-Feng Chen and Xi-Ping Luo
Catalysts 2022, 12(3), 339; https://doi.org/10.3390/catal12030339 - 17 Mar 2022
Cited by 3 | Viewed by 2112
Abstract
Coumarin carboxamide derivatives are important building blocks for organic synthesis and chemical biology due to their excellent biopharmaceutical properties. In this paper, we demonstrate for the first time a two-step enzymatic synthesis of coumarin carboxamide derivatives. Salicylaldehyde and dimethyl malonate were reacted to [...] Read more.
Coumarin carboxamide derivatives are important building blocks for organic synthesis and chemical biology due to their excellent biopharmaceutical properties. In this paper, we demonstrate for the first time a two-step enzymatic synthesis of coumarin carboxamide derivatives. Salicylaldehyde and dimethyl malonate were reacted to obtain coumarin carboxylate methyl derivatives, which were then reacted with various amines under the catalysis of lipase TL IM from Thermomyces lanuginosus to obtain coumarin carboxamide derivatives in continuous flow reactors. We studied various reaction parameters on the yields. The important features of this method include mild reaction conditions, a short reaction time (40 min), reduced environmental pollution, higher productivity (STY = 31.2941 g L−1 h−1) and enzymes being relatively easy to obtain. Full article
(This article belongs to the Topic Bioreactors: Control, Optimization and Applications)
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17 pages, 1355 KiB  
Article
Removal of Organics from Landfill Leachate by Heterogeneous Fenton-like Oxidation over Copper-Based Catalyst
by Sajid Hussain, Eleonora Aneggi, Alessandro Trovarelli and Daniele Goi
Catalysts 2022, 12(3), 338; https://doi.org/10.3390/catal12030338 - 16 Mar 2022
Cited by 16 | Viewed by 2132
Abstract
Landfill leachates are a mixture of high concentration organic and inorganic contaminants and need to be appropriately treated due to their toxicity and severe adverse effects on the environment. Here, we studied the treatment of landfill leachate through a heterogeneous Fenton-like oxidation process [...] Read more.
Landfill leachates are a mixture of high concentration organic and inorganic contaminants and need to be appropriately treated due to their toxicity and severe adverse effects on the environment. Here, we studied the treatment of landfill leachate through a heterogeneous Fenton-like oxidation process using a zirconia supported copper catalyst (Cu/ZrO2). Reaction conditions such as pH, amount of catalyst, oxidant dose, temperature, and reaction time were investigated and their effects on pollutant abatement discussed. AOS (average oxidation state) and COS (carbon oxidation state) parameters were used for the evaluation of the degree of oxidation of the process, obtaining some insight into the formation of oxidized intermediates (partial oxidation) and the total oxidation (mineralization) of the leachate during the reaction. A two-step oxidation process enhanced the overall performance of the reaction with an abatement of organic compounds of 92% confirming the promising activity of a copper-based catalyst for the treatment of liquid waste. Higher catalytic activity was achieved when the following reaction conditions were applied: 70 °C, pH 5, 200 mg/L of catalyst, 30 mL/L of H2O2 dose, and 150 min. In addition, durability of the catalyst under optimized reaction conditions was verified by repeated reaction cycles. Full article
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23 pages, 9257 KiB  
Review
Advanced Nickel-Based Catalysts for Urea Oxidation Reaction: Challenges and Developments
by Yaming Ma, Chenxiang Ma, Yingche Wang and Ke Wang
Catalysts 2022, 12(3), 337; https://doi.org/10.3390/catal12030337 - 16 Mar 2022
Cited by 35 | Viewed by 5947
Abstract
The electrochemical urea oxidation reaction (UOR) is crucial for determining industrial and commercial applications of urea-based energy conversion devices. However, the performance of UOR is limited by the dynamic complex of the six-electron transfer process. To this end, it is essential to develop [...] Read more.
The electrochemical urea oxidation reaction (UOR) is crucial for determining industrial and commercial applications of urea-based energy conversion devices. However, the performance of UOR is limited by the dynamic complex of the six-electron transfer process. To this end, it is essential to develop efficient UOR catalysts. Nickel-based materials have been extensively investigated owing to their high activity, easy modification, stable properties, and cheap and abundant reserves. Various material designs and strategies have been investigated in producing highly efficient UOR catalysts including alloying, doping, heterostructure construction, defect engineering, micro functionalization, conductivity modulation, etc. It is essential to promptly review the progress in this field to significantly inspire subsequent studies. In this review, we summarized a comprehensive investigation of the mechanisms of oxidation or poisoning and UOR processes on nickel-based catalysts as well as different approaches to prepare highly active catalysts. Moreover, challenges and prospects for future developments associated with issues of UOR in urea-based energy conversion applications were also discussed. Full article
(This article belongs to the Special Issue Advanced Catalysts for Electrochemical Energy Storage and Conversion)
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1 pages, 154 KiB  
Retraction
Retraction: Manzoor et al. Experimental Study of CO2 Conversion into Methanol by Synthesized Photocatalyst (ZnFe2O4/TiO2) Using Visible Light as an Energy Source. Catalysts 2020, 10, 163
by Numair Manzoor, Muhammad Sadiq, Muhammad Naqvi, Umair Sikandar and Salman Raza Naqvi
Catalysts 2022, 12(3), 336; https://doi.org/10.3390/catal12030336 - 16 Mar 2022
Viewed by 1437
Abstract
The journal retracts the article, “Experimental Study of CO2 Conversion into Methanol by Synthesized Photocatalyst (ZnFe2O4/TiO2) Using Visible Light as an Energy Source” [...] Full article
10 pages, 619 KiB  
Article
Studies toward the Use of Ionic Liquids and Supercritical CO2 for the Recovery and Separation of Praseodymium from Waste Streams
by Rene Rodriguez, Donna Baek, Mary Case and Robert Fox
Catalysts 2022, 12(3), 335; https://doi.org/10.3390/catal12030335 - 16 Mar 2022
Viewed by 1482
Abstract
Waste streams from the incineration of metal-containing materials like such as computer processor boards and batteries may contain critical rare earth elements like praseodymium. Data on the solubility of Pr compounds and on their distribution coefficients in supercritical CO2/ionic liquid two-phase [...] Read more.
Waste streams from the incineration of metal-containing materials like such as computer processor boards and batteries may contain critical rare earth elements like praseodymium. Data on the solubility of Pr compounds and on their distribution coefficients in supercritical CO2/ionic liquid two-phase systems are important to determine if an ionic liquid/supercritical CO2 two-phase approach is feasible toward the recovery of a particular metal. This work provides data on the solubility of various praseodymium compounds in butyl-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyTf2N) ionic liquid and on the distribution coefficients of these praseodymium compounds in the supercritical CO2 phase of the two-phase BMPyTf2N ionic liquid/supercritical CO2 system, with and without a tributyl phosphate additive. Full article
(This article belongs to the Special Issue Ionic Liquids for Green Catalysis and Separation)
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15 pages, 19109 KiB  
Article
Biosynthesized Bimetallic (ZnOSnO2) Nanoparticles for Photocatalytic Degradation of Organic Dyes and Pharmaceutical Pollutants
by Louisah M. Mahlaule-Glory, Sarah Mathobela and Nomso C. Hintsho-Mbita
Catalysts 2022, 12(3), 334; https://doi.org/10.3390/catal12030334 - 16 Mar 2022
Cited by 9 | Viewed by 2188
Abstract
The quest for eco-friendly synthetic routes that can be used for the development of multifunctional materials, in particular for water treatment, has reinforced the use of plant extracts as replacement solvents. In this study, bimetallic ZnOSnO2 nanoparticles of different ratios were synthesized [...] Read more.
The quest for eco-friendly synthetic routes that can be used for the development of multifunctional materials, in particular for water treatment, has reinforced the use of plant extracts as replacement solvents. In this study, bimetallic ZnOSnO2 nanoparticles of different ratios were synthesized using the Sutherlandia frutescens (S. frutescens) plant and tested for the degradation of methylene blue dye and the antibiotics sulfisoxazole and sulfamethoxazole. From the analysis, FTIR confirmed the formation of bimetallic nanoparticles in all ratios within the fingerprint region. SEM revealed homogenous and heterostructures of tubular and spherical structures, with the size distribution ranging from 5–60 nm, respectively. XRD confirmed the formation and the crystallinity of the bimetallic nanoparticles, UV-Vis confirmed the optical properties of the materials and the bandgap values were found between 3.08 and 3.3 eV. From the surface area analysis, type III isotherm and mesoporous structures were confirmed. The photocatalytic activity of these ratios was investigated against MB dye and the antibiotics SSX and SMX. The highest degradation of 88% for MB was obtained using the 50:50 loading ratio at 150 min with a fast kinetic rate of 0.0008 min−1. Furthermore, the holes were the species found to be responsible for the degradation of MB. The SSX and SMX antibiotics exhibited a 66% and 70% degradation, respectively. From this analysis, it can be noted that it is possible to synthesize environmentally safe materials that can be used to degrade various pollutants in our water streams. Full article
(This article belongs to the Special Issue Nanomaterials for Photocatalysis and Piezo-Photocatalysis)
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10 pages, 1762 KiB  
Article
Electrocatalytic Isomerization of Allylic Alcohols: Straightforward Preparation of β-Aryl-Ketones
by Anding Li, Nan Zheng, Kai Guo, Zhongchao Zhang and Zhen Yang
Catalysts 2022, 12(3), 333; https://doi.org/10.3390/catal12030333 - 16 Mar 2022
Viewed by 2422
Abstract
Electrochemical synthesis has been rapidly developing over the past few years. Here, we report a practical and eco-friendly electrocatalytic isomerization of allylic alcohols to their corresponding carbonyl compounds. This reaction can be carried out in undivided cells without the addition of external chemical [...] Read more.
Electrochemical synthesis has been rapidly developing over the past few years. Here, we report a practical and eco-friendly electrocatalytic isomerization of allylic alcohols to their corresponding carbonyl compounds. This reaction can be carried out in undivided cells without the addition of external chemical oxidants and metal catalysts. Moreover, this reaction features a broad substrate scope including challenging allylic alcohols bearing tri- and tetra-substituted olefins and affords straightforward access to diverse β-aryl-ketones. Mechanistic investigations suggest that the reactions proceed through a radical process. This study represents a unique example in which electrochemistry enables hydrogen atom transfer in organic allylic alcohol substrates using a simple organocatalyst. Full article
(This article belongs to the Section Electrocatalysis)
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16 pages, 5216 KiB  
Article
A Theoretical Study of the Oxygen Release Mechanisms of a Cu-Based Oxygen Carrier during Chemical Looping with Oxygen Uncoupling
by Minjun Wang, Shixiong Zhang, Ming Xia and Mengke Wang
Catalysts 2022, 12(3), 332; https://doi.org/10.3390/catal12030332 - 15 Mar 2022
Cited by 6 | Viewed by 2064
Abstract
The Cu-based oxygen carrier is a promising material in the chemical looping with oxygen uncoupling (CLOU) process, while its performance in the CLOU is significantly dependent on the oxygen release properties. However, the study of oxygen release mechanisms in CLOU is not comprehensive [...] Read more.
The Cu-based oxygen carrier is a promising material in the chemical looping with oxygen uncoupling (CLOU) process, while its performance in the CLOU is significantly dependent on the oxygen release properties. However, the study of oxygen release mechanisms in CLOU is not comprehensive enough. In this work, the detailed oxygen release mechanisms of CuO(110) and CuO(111) are researched at an atomic level using the density functional theory (DFT) method, including the formation of O2, the desorption of O2 and the diffusion of O anion, as well as the analysis of the density of states. The results show that (1) the most favorable pathway for O2 formation and desorption occurs on the CuO(110) surface of O-terminated with energy barriers of 1.89 eV and 3.22 eV, respectively; (2) the most favorable pathway for O anion diffusion occurs in the CuO(110) slab with the lowest energy barrier of 0.24 eV; and (3) the total density of states for the O atoms in the CuO(110) slab shifts to a lower energy after an O vacancy formation. All of the above results clearly demonstrate that the CuO(110) surface plays a significantly important role in the oxygen release reaction, and the oxygen vacancy defect should be conducive to the reactivity of oxygen release in a Cu-based oxygen carrier. Full article
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12 pages, 2135 KiB  
Article
Uncovering the Mechanism of the Hydrogen Poisoning on Ru Nanoparticles via Density Functional Theory Calculations
by David S. Rivera Rocabado, Mika Aizawa, Tomohiro G. Noguchi, Miho Yamauchi and Takayoshi Ishimoto
Catalysts 2022, 12(3), 331; https://doi.org/10.3390/catal12030331 - 14 Mar 2022
Cited by 7 | Viewed by 2332
Abstract
Although hydrogen plays a crucial role in ammonia synthesis, very little is known about its poisoning of Ru catalysts. In this study, density functional theory calculations of H2 and N2 dissociations, and H atom binding on Ru153 were performed to [...] Read more.
Although hydrogen plays a crucial role in ammonia synthesis, very little is known about its poisoning of Ru catalysts. In this study, density functional theory calculations of H2 and N2 dissociations, and H atom binding on Ru153 were performed to provide a fundamental understanding of hydrogen poisoning. Because of the kinetic dominance of the H2 dissociation over N2 (vertically or horizontally adsorbed) splitting, the dissociated H atoms block the active sites required for horizontal (less energetically demanding dissociation) N2 adsorption to occur either from the gas phase or after its geometrical transformation from being adsorbed vertically. Additionally, the dissociated H atoms withdraw electrons from the surface, which reduces the ability of the neighboring Ru atoms to donate electrons for N2 activation, hindering its dissociation and suppressing ammonia synthesis. Full article
(This article belongs to the Special Issue Role of Defects and Disorder in Catalysis)
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22 pages, 5789 KiB  
Article
Photocatalytic Efficacy of Heterocyclic Base Grafted Chitosan Magnetite Nanoparticles on Sorption of Pb(II); Application on Mining Effluent
by Mohammed F. Hamza, Adel E.-S. Goda, Shunyan Ning, Hamed I. Mira, Adel A.-H. Abdel-Rahman, Yuezhou Wei, Toyohisa Fujita, Hamada H. Amer, Saad H. Alotaibi and Amr Fouda
Catalysts 2022, 12(3), 330; https://doi.org/10.3390/catal12030330 - 14 Mar 2022
Cited by 11 | Viewed by 2516
Abstract
Development of bio-based sorbents (i.e., chitosan moieties) at nanoscale size for the removal of metal contaminants is the main target of this research. Grafting with thiazole heterocyclic derivative gives fast kinetics sorption, highly metal loading, and good recyclability for mining leaching solution. Different [...] Read more.
Development of bio-based sorbents (i.e., chitosan moieties) at nanoscale size for the removal of metal contaminants is the main target of this research. Grafting with thiazole heterocyclic derivative gives fast kinetics sorption, highly metal loading, and good recyclability for mining leaching solution. Different analyses tools including (thermogravimetric analysis (TGA), scanning electron microscope and energy dispersive spectroscopy (SEM-EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR), BET surface area (nitrogen sorption desorption), titration, and TEM (transmission electron microscopy)) were used to investigate the chemical and textural properties of the functionalized sorbent. The sorption was measured in normal visible light and under UV emission. The highest capacity was measured at pH 5, which reached 0.251 mmol Pb g−1 in visible light compared with 0.346 mmol Pb g−1 under UV for the pristine crosslinked chitosan (MCc). The sorption performances were improved by functionalization; (0.7814 and 1.014 mmol Pb g−1) for the functionalized sorbent (MCa-ATA) under visible light and UV, respectively. PFORE (pseudo-first-order rate equation) and RIDE (resistance to intraparticle diffusion) fit kinetics, the Sips equation is the most fit profile for the sorption isotherms for the MCc in either light and UV processes, while PFORE and RIDE for kinetics under light and UV for MCa-ATA and Sips in light and Sips and Langmuir under the UV emission. Finally, the sorbent was investigated toward a raffinate solution from ore processing and shows promising extraction tools for the most interesting elements. Full article
(This article belongs to the Special Issue Nanomaterials for Photocatalysis)
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15 pages, 4445 KiB  
Article
Degradation of Ibuprofen by the Electro/Fe3+/Peroxydisulfate Process: Reactive Kinetics, Degradation Products and Mechanism
by Na Qiu, Chanchan Shen, Yongxia Liu, Xiuqing Li, Guangyin Jia, Jingping Qin and Xinglei Wang
Catalysts 2022, 12(3), 329; https://doi.org/10.3390/catal12030329 - 13 Mar 2022
Cited by 4 | Viewed by 2256
Abstract
Ibuprofen (IBU), a nonsteroidal anti-inflammatory drug, is one of the most widely used and frequently detected pharmaceuticals and personal care products in water bodies. This study examined the IBU degradation in aquatic solutions via ferric ion activated peroxydisulfate (PDS) coupled with electro-oxidation (EC/Fe [...] Read more.
Ibuprofen (IBU), a nonsteroidal anti-inflammatory drug, is one of the most widely used and frequently detected pharmaceuticals and personal care products in water bodies. This study examined the IBU degradation in aquatic solutions via ferric ion activated peroxydisulfate (PDS) coupled with electro-oxidation (EC/Fe3+/PDS). The degradation mechanisms involved three synergistic reactions in the EC/Fe3+/PDS system, including: (1) the electro-oxidation; (2) SO4 generated from the activation of PDS by ferrous ions formed via cathodic reduction; (3) SO4 generated from the electron transfer reaction. The radical scavenging experiments indicated that SO4 and •OH dominated the oxidation process. The effects of the applied current density, PDS concentration, Fe3+ dosage, initial IBU concentration and initial pH as well as inorganic anions and humic acid on the degradation efficiency, were studied, and the degradation process of IBU followed the pseudo-first-order kinetic model. About 99.37% of IBU was removed in 60 min ((Fe3+ concentration) = 2.0 mM, (PDS concentration) = 12 mM, (initial IBU concentration) = 30 mg/L, current density = 15 mA/cm2, initial pH = 3). Finally, seven intermediate compounds were identified and probable IBU degradation pathways in the EC/Fe3+/PDS system were speculated. Full article
(This article belongs to the Special Issue Advanced Functional Materials for Environmental Catalysis)
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14 pages, 3030 KiB  
Article
Facile Synthesis, Characterization, and Photocatalytic Activity of Hydrothermally Grown Cu2+-Doped ZnO–SnS Nanocomposites for MB Dye Degradation
by Govinda Dharmana, Thirumala Rao Gurugubelli, Prabhakara Srinivasa Rao Masabattula, Bathula Babu and Kisoo Yoo
Catalysts 2022, 12(3), 328; https://doi.org/10.3390/catal12030328 - 13 Mar 2022
Cited by 11 | Viewed by 2366
Abstract
The morphology, chemical composition, and doping process of metal oxides and sulfides play a significant role in their photocatalytic performance under solar light illumination. We synthesized Cu2+-doped ZnO–SnS nanocomposites at 220 °C for 10 h, using hydrothermal methods. These nanocomposites were [...] Read more.
The morphology, chemical composition, and doping process of metal oxides and sulfides play a significant role in their photocatalytic performance under solar light illumination. We synthesized Cu2+-doped ZnO–SnS nanocomposites at 220 °C for 10 h, using hydrothermal methods. These nanocomposites were structurally, morphologically, and optically characterized using various techniques, including powder X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-visible absorption spectroscopy. Their photocatalytic activity (PCA) on methylene blue (MB) pollutant dye was examined under 150 W solar light illumination. Mixed-phase abundances with hexagonal ZnO and orthorhombic SnS structures were observed. TEM micrographs showed changes in morphology from spherical to nano-flake structures with an increasing doping concentration. XPS indicated the chemical states of the constituent elements in the nanocomposites. UV-visible absorption spectroscopy showed a decrease in the bandgap with an increasing doping concentration. Strong PCA was observed due to the separation of charge carriers, a change in bandgap, and a high light absorption ability under solar light irradiation. The measured photodegradation efficiency of the MB dye was approximately 97% after 2 h. The movement of the charge carriers and the bandgap alignment of the synthesized composites are briefly discussed. Full article
(This article belongs to the Special Issue Semiconductor Photocatalysis and Quantum Dots Photocatalysis)
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23 pages, 6661 KiB  
Article
Influence of the Support on Propene Oxidation over Gold Catalysts
by Ewoud J. J. de Boed, Bryan J. Folmer, Min Tang, Baira Donoeva and Petra E. de Jongh
Catalysts 2022, 12(3), 327; https://doi.org/10.3390/catal12030327 - 11 Mar 2022
Cited by 4 | Viewed by 2518
Abstract
The epoxidation of propene without forming a substantial amount of byproducts is one of the holy grails of catalysis. Supported Cu, Ag and Au catalysts are studied for this reaction and the activity of the supported metals is generally well understood. On the [...] Read more.
The epoxidation of propene without forming a substantial amount of byproducts is one of the holy grails of catalysis. Supported Cu, Ag and Au catalysts are studied for this reaction and the activity of the supported metals is generally well understood. On the contrary, limited information is available on the influence of the support on the epoxide selectivity. The reaction of propene with equal amounts of hydrogen and oxygen was tested over gold nanoparticles deposited onto CeO2, TiO2, WO3, γ-Al2O3, SiO2, TiO2-SiO2 and titanosilicate-1. Several metal oxide supports caused further conversion of the synthesized propene oxide. Strongly acidic supports, such as WO3 and titanosilicate-1, catalyzed the isomerization of propene oxide towards propanal and acetone. Key factors for achieving high PO selectivity are having inert or neutralized surface sites, a low specific surface and/or a low density of surface -OH groups. This work provides insights and practical guidelines to which metal oxide support properties lead to which products in the reaction of propene in the presence of oxygen and hydrogen over supported gold catalysts. Full article
(This article belongs to the Special Issue Catalytic Epoxidation Reaction)
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25 pages, 3719 KiB  
Review
Nanoparticle Engineered Photocatalytic Paints: A Roadmap to Self-Sterilizing against the Spread of Communicable Diseases
by Vijay S. Mohite, Milind M. Darade, Rakesh K. Sharma and Shivaji H. Pawar
Catalysts 2022, 12(3), 326; https://doi.org/10.3390/catal12030326 - 11 Mar 2022
Cited by 11 | Viewed by 2941
Abstract
Applications of visible-light photocatalytic engineered nanomaterials in the preparation of smart paints are of recent origin. The authors have revealed a great potential of these new paints for self-sterilizing of the surfaces in hospitals and public places simply with visible light exposure and [...] Read more.
Applications of visible-light photocatalytic engineered nanomaterials in the preparation of smart paints are of recent origin. The authors have revealed a great potential of these new paints for self-sterilizing of the surfaces in hospitals and public places simply with visible light exposure and this is reported for the first time in this review. A recent example of a communicable disease such as COVID-19 is considered. With all precautions and preventions taken as suggested by the World Health Organization (WHO), COVID-19 has remained present for a longer time compared to other diseases. It has affected millions of people worldwide and the significant challenge remains of preventing infections due to SARS-CoV-2. The present review is focused on revealing the cause of this widespread disease and suggests a roadmap to control the spread of disease. It is understood that the transmission of SARS-CoV-2 virus takes place through contact surfaces such as doorknobs, packaging and handrails, which may be responsible for many preventable and nosocomial infections. In addition, due to the potent transmissibility of SARS-CoV-2, its ability to survive for longer periods on common touch surfaces is also an important reason for the spread of COVID-19. The existing antimicrobial cleaning technologies used in hospitals are not suitable, viable or economical to keep public places free from such infections. Hence, in this review, an innovative approach of coating surfaces in public places with visible-light photocatalytic nanocomposite paints has been suggested as a roadmap to self-sterilizing against the spread of communicable diseases. The formulations of different nanoparticle engineered photocatalytic paints with their ability to destroy pathogens using visible light, alongwith the field trials are also summarized and reported in this review. The potential suggestions for controlling the spread of communicable diseases are also listed at the end of the review. Full article
(This article belongs to the Special Issue Photocatalytic Nanomaterials for Abatement of Microorganisms)
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10 pages, 2747 KiB  
Communication
Preparation Strategy Using Pre-Nucleation Coupled with In Situ Reduction for a High-Performance Catalyst towards Selective Hydrogen Production from Formic Acid
by Qinglei Meng, Xiaolong Yang, Xian Wang, Meiling Xiao, Kui Li, Zhao Jin, Junjie Ge, Changpeng Liu and Wei Xing
Catalysts 2022, 12(3), 325; https://doi.org/10.3390/catal12030325 - 11 Mar 2022
Cited by 3 | Viewed by 1845
Abstract
Formic acid decomposition (FAD) is one of the most promising routes for rapid hydrogen (H2) production. Extensive efforts have been taken to develop efficient catalysts, which calls for the simultaneous regulation of the electronic structure and particle size of the catalyst. [...] Read more.
Formic acid decomposition (FAD) is one of the most promising routes for rapid hydrogen (H2) production. Extensive efforts have been taken to develop efficient catalysts, which calls for the simultaneous regulation of the electronic structure and particle size of the catalyst. The former factor determines the intrinsic performance, while the latter corresponds to the active site utilization. Here, an effective preparation strategy, pre-nucleation coupled with in situ reduction, is developed to realize and well-tune both surface electronic states and particle size of the pallidum (Pd) catalyst. Benefiting from the structural merits, the as-prepared catalyst exhibits high mass-specific activity of 8.94 molH2/(gPd·h) with few carbon monoxide (CO) molecules, and the activation energy could reach a value as small as 33.1 kJ/mol. The work not only affords a highly competitive FAD catalyst but also paves a new avenue to the synthesis of ultra-fine metal nanoparticles with tailorable electronic structures. Full article
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16 pages, 21446 KiB  
Review
Formic Acid Dehydrogenation Using Noble-Metal Nanoheterogeneous Catalysts: Towards Sustainable Hydrogen-Based Energy
by Abbas Al-Nayili, Hasan Sh. Majdi, Talib M. Albayati and Noori M. Cata Saady
Catalysts 2022, 12(3), 324; https://doi.org/10.3390/catal12030324 - 11 Mar 2022
Cited by 53 | Viewed by 5099
Abstract
The need for sustainable energy sources is now more urgent than ever, and hydrogen is significant in the future of energy. However, several obstacles remain in the way of widespread hydrogen use, most of which are related to transport and storage. Dilute formic [...] Read more.
The need for sustainable energy sources is now more urgent than ever, and hydrogen is significant in the future of energy. However, several obstacles remain in the way of widespread hydrogen use, most of which are related to transport and storage. Dilute formic acid (FA) is recognized asa a safe fuel for low-temperature fuel cells. This review examines FA as a potential hydrogen storage molecule that can be dehydrogenated to yield highly pure hydrogen (H2) and carbon dioxide (CO2) with very little carbon monoxide (CO) gas produced via nanoheterogeneous catalysts. It also present the use of Au and Pd as nanoheterogeneous catalysts for formic acid liquid phase decomposition, focusing on the influence of noble metals in monometallic, bimetallic, and trimetallic compositions on the catalytic dehydrogenation of FA under mild temperatures (20–50 °C). The review shows that FA production from CO2 without a base by direct catalytic carbon dioxide hydrogenation is far more sustainable than existing techniques. Finally, using FA as an energy carrier to selectively release hydrogen for fuel cell power generation appears to be a potential technique. Full article
(This article belongs to the Topic Catalysis for Sustainable Chemistry and Energy)
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19 pages, 5510 KiB  
Article
Temperature-Dependent Activity of Gold Nanocatalysts Supported on Activated Carbon in Redox Catalytic Reactions: 5-Hydroxymethylfurfural Oxidation and 4-Nitrophenol Reduction Comparison
by Stefano Scurti, Alessandro Allegri, Francesca Liuzzi, Elena Rodríguez-Aguado, Juan Antonio Cecilia, Stefania Albonetti, Daniele Caretti and Nikolaos Dimitratos
Catalysts 2022, 12(3), 323; https://doi.org/10.3390/catal12030323 - 11 Mar 2022
Cited by 5 | Viewed by 2380
Abstract
In this study, the temperature-dependent activity of Au/AC nanocatalysts in redox catalytic reactions was investigated. To this end, a series of colloidal gold catalysts supported on activated carbon and titania were prepared by the sol immobilization method employing polyvinyl alcohol as a polymeric [...] Read more.
In this study, the temperature-dependent activity of Au/AC nanocatalysts in redox catalytic reactions was investigated. To this end, a series of colloidal gold catalysts supported on activated carbon and titania were prepared by the sol immobilization method employing polyvinyl alcohol as a polymeric stabilizer at different hydrolysis degrees. The as-synthesized materials were widely characterized by spectroscopic analysis (XPS, XRD, and ATR-IR) as well as TEM microscopy and DLS/ELS measurements. Furthermore, 5-hydroxymethylfurfural (HMF) oxidation and 4-nitrophenol (4-NP) reduction were chosen to investigate the catalytic activity as a model reaction for biomass valorization and wastewater remediation. In particular, by fitting the hydrolysis degree with the kinetic data, volcano plots were obtained for both reactions, in which the maximum of the curves was represented relative to hydrolysis intermediate values. However, a comparison of the catalytic performance of the sample Au/AC_PVA-99 (hydrolysis degree of the polymer is 99%) in the two reactions showed a different catalytic behavior, probably due to the detachment of polymer derived from the different reaction temperature chosen between the two reactions. For this reason, several tests were carried out to investigate deeper the observed catalytic trend, focusing on studying the effect of the reaction temperature as well as the effect of support (metal–support interaction) by immobilizing Au colloidal nanoparticles on commercial titania. The kinetic data, combined with the characterization carried out on the catalysts, confirmed that changing the reaction conditions, the PVA behavior on the surface of the catalysts, and, therefore, the reaction outcome, is modified. Full article
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