Next Issue
Volume 11, May
Previous Issue
Volume 11, March
 
 

Catalysts, Volume 11, Issue 4 (April 2021) – 117 articles

Cover Story (view full-size image): Multi-enzyme catalysis has emerged as a new frontier for the synthesis of complex chemicals. At the same time, the in vitro operation of multiple enzymes requires new strategies for increasing the operational performance of enzymatic cascade reactions. Advances in synthetic biology and protein engineering have therefore led to bioinspired co-localization strategies for scaffolding and compartmentalization of enzymes. In the future, genetically encoded co-localization mechanisms could become platforms for autonomously self-organizing biocatalytic systems. Such genetically programmable systems could be produced by cell factories or emerging cell-free systems. View this paper
  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Reader to open them.
Order results
Result details
Section
Select all
Export citation of selected articles as:
22 pages, 4501 KiB  
Review
Research Progress on Catalytic Water Splitting Based on Polyoxometalate/Semiconductor Composites
by Yue Wu and Lihua Bi
Catalysts 2021, 11(4), 524; https://doi.org/10.3390/catal11040524 - 20 Apr 2021
Cited by 15 | Viewed by 4608
Abstract
In recent years, due to the impact of global warming, environmental pollution, and the energy crisis, international attention and demand for clean energy are increasing. Hydrogen energy is recognized as one of the clean energy sources. Water is considered as the largest potential [...] Read more.
In recent years, due to the impact of global warming, environmental pollution, and the energy crisis, international attention and demand for clean energy are increasing. Hydrogen energy is recognized as one of the clean energy sources. Water is considered as the largest potential supplier of hydrogen energy. However, artificial catalytic water splitting for hydrogen and oxygen evolution has not been widely used due to its high energy consumption and high cost during catalytic cracking. Therefore, the exploitation of photocatalysts, electrocatalysts, and photo-electrocatalysts for rapid, cost effective, and reliable water splitting is essentially needed. Polyoxometalates (POMs) are regarded as the potential candidates for water splitting catalysis. In addition to their excellent catalytic properties and reversibly redox activities, POMs can also modify semiconductors to overcome their shortcomings, and improve photoelectric conversion efficiency and photocatalytic activity, which has attracted more and more attention in the field of photoelectric water splitting catalysis. In this review, we summarize the latest applications of POMs and semiconductor composites in the field of photo-electrocatalysis (PEC) for hydrogen and oxygen evolution by catalytic water splitting in recent years and take the latest applications of POMs and semiconductor composites in photocatalysis for water splitting. In the conclusion section, the challenges and strategies of photocatalytic and PEC water-splitting by POMs and semiconductor composites are discussed. Full article
(This article belongs to the Section Photocatalysis)
Show Figures

Figure 1

12 pages, 17383 KiB  
Article
Mechanism of Guaiacol Hydrodeoxygenation on Cu (111): Insights from Density Functional Theory Studies
by Destiny Konadu, Caroline Rosemyya Kwawu, Richard Tia, Evans Adei and Nora Henriette de Leeuw
Catalysts 2021, 11(4), 523; https://doi.org/10.3390/catal11040523 - 20 Apr 2021
Cited by 5 | Viewed by 4315
Abstract
Understanding the mechanism of the catalytic upgrade of bio-oils via the process of hydrodeoxygenation (HDO) is desirable to produce targeted oxygen-deficient bio-fuels. We have used calculations based on the density functional theory to investigate the reaction mechanism of HDO of guaiacol over Cu [...] Read more.
Understanding the mechanism of the catalytic upgrade of bio-oils via the process of hydrodeoxygenation (HDO) is desirable to produce targeted oxygen-deficient bio-fuels. We have used calculations based on the density functional theory to investigate the reaction mechanism of HDO of guaiacol over Cu (111) surface in the presence of H2, leading to the formation of catechol and anisole. Our analysis of the thermodynamics and kinetics involved in the reaction process shows that catechol is produced via direct demethylation, followed by dehydrogenation of –OH and re-hydrogenation of catecholate in a concerted fashion. The de-methylation step is found to be the rate-limiting step for catechol production with a barrier of 1.97 eV. Formation of anisole will also proceed via the direct dehydroxylation of guaiacol followed by hydrogenation. Here, the rate-limiting step is the dehydroxylation step with an energy barrier of 2.07 eV. Thermodynamically, catechol formation is favored while anisole formation is not favored due to the weaker interaction seen between anisole and the Cu (111) surface, where the binding energies of guaiacol, catechol, and anisole are -1.90 eV, −2.18 eV, and −0.72 eV, respectively. The stepwise barriers also show that the Cu (111) surface favors catechol formation over anisole as the rate-limiting barrier is higher for anisole production. For catechol, the overall reaction is downhill, implying that this reaction path is thermodynamically and kinetically preferred and that anisole, if formed, will more easily transform. Full article
(This article belongs to the Section Computational Catalysis)
Show Figures

Graphical abstract

13 pages, 32101 KiB  
Article
Palladium Particles Modified by Mixed-Frequency Square-Wave Potential Treatment to Enhance Electrocatalytic Performance for Formic Acid Oxidation
by Fangchao Li, Bin Liu, Yuanhao Shen, Jie Liu, Cheng Zhong and Wenbin Hu
Catalysts 2021, 11(4), 522; https://doi.org/10.3390/catal11040522 - 20 Apr 2021
Cited by 1 | Viewed by 2079
Abstract
Palladium catalysts have attracted widespread attention as advanced electrocatalysts for the formic acid oxidation (FAO) due to their excellent electrocatalytic activity and relatively high abundance. At present, electrodeposition methods have been widely developed to prepare small-sized and highly-dispersed Pd electrocatalysts. However, the customary [...] Read more.
Palladium catalysts have attracted widespread attention as advanced electrocatalysts for the formic acid oxidation (FAO) due to their excellent electrocatalytic activity and relatively high abundance. At present, electrodeposition methods have been widely developed to prepare small-sized and highly-dispersed Pd electrocatalysts. However, the customary use of surfactants would introduce heterogeneous impurities, which requires complicated removal processes. In this work, we reported a two-step electrochemical method that employed square-wave potential treatment (SWPT) to modify electrodeposited Pd particles without the use of capping agents. Under the SWPT with a mixed frequency, Pd particles show significantly reduced size and more dispersed distribution, exhibiting a high mass activity of 1.43 A mg−1 toward FAO, which is 4.6 times higher than the counterpart of commercial Pd/C. The increase in electrocatalytic activity of FAO is attributed to the highly developed surface of palladium particles uniformly distributed over the support surface. Full article
(This article belongs to the Section Electrocatalysis)
Show Figures

Graphical abstract

63 pages, 3027 KiB  
Review
The Role of Catalytic Ozonation Processes on the Elimination of DBPs and Their Precursors in Drinking Water Treatment
by Fernando J. Beltrán, Ana Rey and Olga Gimeno
Catalysts 2021, 11(4), 521; https://doi.org/10.3390/catal11040521 - 20 Apr 2021
Cited by 20 | Viewed by 3604
Abstract
Formation of disinfection byproducts (DBPs) in drinking water treatment (DWT) as a result of pathogen removal has always been an issue of special attention in the preparation of safe water. DBPs are formed by the action of oxidant-disinfectant chemicals, mainly chlorine derivatives (chlorine, [...] Read more.
Formation of disinfection byproducts (DBPs) in drinking water treatment (DWT) as a result of pathogen removal has always been an issue of special attention in the preparation of safe water. DBPs are formed by the action of oxidant-disinfectant chemicals, mainly chlorine derivatives (chlorine, hypochlorous acid, chloramines, etc.), that react with natural organic matter (NOM), mainly humic substances. DBPs are usually refractory to oxidation, mainly due to the presence of halogen compounds so that advanced oxidation processes (AOPs) are a recommended option to deal with their removal. In this work, the application of catalytic ozonation processes (with and without the simultaneous presence of radiation), moderately recent AOPs, for the removal of humic substances (NOM), also called DBPs precursors, and DBPs themselves is reviewed. First, a short history about the use of disinfectants in DWT, DBPs formation discovery and alternative oxidants used is presented. Then, sections are dedicated to conventional AOPs applied to remove DBPs and their precursors to finalize with the description of principal research achievements found in the literature about application of catalytic ozonation processes. In this sense, aspects such as operating conditions, reactors used, radiation sources applied in their case, kinetics and mechanisms are reviewed. Full article
(This article belongs to the Special Issue Photocatalytic Oxidation/Ozonation Processes)
Show Figures

Graphical abstract

13 pages, 1478 KiB  
Article
Efficient Amino Donor Recycling in Amination Reactions: Development of a New Alanine Dehydrogenase in Continuous Flow and Dialysis Membrane Reactors
by David Roura Padrosa, Zoya Nisar and Francesca Paradisi
Catalysts 2021, 11(4), 520; https://doi.org/10.3390/catal11040520 - 20 Apr 2021
Cited by 12 | Viewed by 3183
Abstract
Transaminases have arisen as one of the main biocatalysts for amine production but despite their many advantages, their stability is still a concern for widespread application. One of the reasons for their instability is the need to use an excess of the amino [...] Read more.
Transaminases have arisen as one of the main biocatalysts for amine production but despite their many advantages, their stability is still a concern for widespread application. One of the reasons for their instability is the need to use an excess of the amino donor when trying to synthesise amines with unfavourable equilibria. To circumvent this, recycling systems for the amino donor, such as amino acid dehydrogenases or aldolases, have proved useful to push the equilibria while avoiding high amino donor concentrations. In this work, we report the use of a new alanine dehydrogenase from the halotolerant bacteria Halomonas elongata which exhibits excellent stability to different cosolvents, combined with the well characterised CbFDH as a recycling system of L-alanine for the amination of three model substrates with unfavourable equilibria. In a step forward, the amino donor recycling system has been co-immobilised and used in flow with success as well as re-used as a dialysis enclosed system for the amination of an aromatic aldehyde. Full article
(This article belongs to the Special Issue Overcoming the Challenges in Biocatalytic Applications)
Show Figures

Figure 1

16 pages, 4095 KiB  
Article
Catalytic Combustion of Toluene over Highly Dispersed Cu-CeOx Derived from Cu-Ce-MOF by EDTA Grafting Method
by Wenjie Sun, Yijia Huang, Xiaomin Li, Zhen Huang, Hualong Xu and Wei Shen
Catalysts 2021, 11(4), 519; https://doi.org/10.3390/catal11040519 - 20 Apr 2021
Cited by 13 | Viewed by 4083
Abstract
In this work, Cu-CeOx-MOF catalysts with well-dispersed Cu in different contents were synthesized via the ethylenediaminetetraacetic acid (EDTA) grafting method. EDTA was grafted in Ce-MOF-808 to anchor Cu and then the metal-organic frameworks (MOFs) were utilized as sacrificial template to form [...] Read more.
In this work, Cu-CeOx-MOF catalysts with well-dispersed Cu in different contents were synthesized via the ethylenediaminetetraacetic acid (EDTA) grafting method. EDTA was grafted in Ce-MOF-808 to anchor Cu and then the metal-organic frameworks (MOFs) were utilized as sacrificial template to form highly performed Cu-CeOx-MOF for toluene catalytic combustion. In this series of samples, Cu-CeOx-MOF-0.2 had a higher ratio of Oα/(Oα+Oβ), more oxygen vacancies and performed better low-temperature reducibility. Cu-CeOx-MOF-0.2 showed outstanding catalytic activity and stability. The T90 (temperature when toluene conversion achieved 90%) of Cu-CeOx-MOF-0.2 was 226 °C at 60,000 mL/(gcat∙h). In situ diffuse reflectance infrared transform spectroscopy (in situ DRIFTS) results revealed that the opening of aromatic ring and the deep oxidation of carboxylate were key steps for toluene catalytic combustion over Cu-CeOx-MOF-0.2. Full article
Show Figures

Figure 1

12 pages, 2124 KiB  
Article
Lipase Immobilized on MCFs as Biocatalysts for Kinetic and Dynamic Kinetic Resolution of sec-Alcohols
by Dominika Stradomska, Monika Heba, Aleksandra Czernek, Nikodem Kuźnik, Danuta Gillner, Katarzyna Maresz, Wojciech Pudło, Andrzej Jarzębski and Katarzyna Szymańska
Catalysts 2021, 11(4), 518; https://doi.org/10.3390/catal11040518 - 20 Apr 2021
Cited by 10 | Viewed by 2881
Abstract
Dynamic kinetic resolution (DKR) is one of the most attractive methods for enantioselective synthesis. In the reported studies, lipase B from Candida antarctica (CALB) immobilized on siliceous mesoporous cellular foams (MCF) functionalized with different hydrophobic groups, and two ruthenium complexes with substituted cyclopentadienyl [...] Read more.
Dynamic kinetic resolution (DKR) is one of the most attractive methods for enantioselective synthesis. In the reported studies, lipase B from Candida antarctica (CALB) immobilized on siliceous mesoporous cellular foams (MCF) functionalized with different hydrophobic groups, and two ruthenium complexes with substituted cyclopentadienyl ligands were investigated as catalysts for the chemoenzymatic DKR of (rac)-1-phenylethanol, using Novozym 435 as a benchmark biocatalyst. Studies on the (rac)-1-phenylethanol transesterification reaction showed that CALB supported on MCFs grafted with methyl groups is a promising biocatalyst and isopropenyl acetate is a preferable acylation agent. Both Ru-complexes activated by K3PO4 or t-BuOK, proved to be effective catalysts of the racemization reaction. The final DKR experiments using all catalysts combinations singled out, gave 96% conversion, and (R)-1-phenylethyl acetate enantiomeric excess of 98% in 8 h using K3PO4 activator. Full article
(This article belongs to the Special Issue Advances in Enzyme Immobilization)
Show Figures

Graphical abstract

17 pages, 3468 KiB  
Article
In Situ IR Studies on the Mechanism of Dimethyl Carbonate Synthesis from Methanol and Carbon Dioxide
by Khalid A. Almusaiteer, Sulaiman I. Al-Mayman, Aghaddin Mamedov and Yousef S. Al-Zeghayer
Catalysts 2021, 11(4), 517; https://doi.org/10.3390/catal11040517 - 20 Apr 2021
Cited by 5 | Viewed by 2377
Abstract
The synthesis of dimethyl carbonate (DMC) from methanol and Carbon dioxide (CO2) has been investigated over 5% Rh/Al2O3 catalyst. Diffuse Reflectance Infrared Fourier Transfer Spectroscopy (DRIFTS) was used to probe the reaction adsorbates which showed that activation of [...] Read more.
The synthesis of dimethyl carbonate (DMC) from methanol and Carbon dioxide (CO2) has been investigated over 5% Rh/Al2O3 catalyst. Diffuse Reflectance Infrared Fourier Transfer Spectroscopy (DRIFTS) was used to probe the reaction adsorbates which showed that activation of methanol and CO2 involves generation of intermediate methoxy species and formate ingredients, participating in elementary steps of DMC formation. Formation of DMC involves parallel routes comprising interaction of the OH group of Al2O3 through an acid/base mechanism and formate pathway with participation of metal sites. DMC in acid/base pathway is formed via methoxy species to form methoxy carbonate (CH3O)CO2 (active adsorbate), which then reacts with the methyl species to form DMC. The pathway involving metal Rh sites generates an additional elementary step for the involvement of CO2 in the reaction through active formate species. The synergy of parallel pathways determines the performance of the 5% Rh/Al2O3 catalyst. Further improvement of catalyst performance should be based on such a feature of the reaction mechanism. Full article
(This article belongs to the Special Issue Catalysts for Advanced Synthesis)
Show Figures

Graphical abstract

19 pages, 6934 KiB  
Article
Self-Assembled Hybrid ZnO Nanostructures as Supports for Copper-Based Catalysts in the Hydrogenolysis of Glycerol
by Lama Omar, Noémie Perret and Stephane Daniele
Catalysts 2021, 11(4), 516; https://doi.org/10.3390/catal11040516 - 20 Apr 2021
Cited by 11 | Viewed by 2121
Abstract
This study describes the use of new ZnO/PAAH hybrid nanomaterials (PAAH = polyacrylic acid) as copper catalyst supports for the hydrogenolysis of glycerol. A study of the synthesis parameters (washing process, temperatures of synthesis and calcination) of these hybrid supports has allowed us [...] Read more.
This study describes the use of new ZnO/PAAH hybrid nanomaterials (PAAH = polyacrylic acid) as copper catalyst supports for the hydrogenolysis of glycerol. A study of the synthesis parameters (washing process, temperatures of synthesis and calcination) of these hybrid supports has allowed us to vary their morphology and specific surface area and ultimately the sizes and dispersion of the copper nanoparticles, and to perform a general analysis of their effects on the catalytic performance of the materials. All catalysts were synthesized by the urea deposition-precipitation method (DPU) and were fully characterized to establish a structure–activity relationship. Optimization of the synthesis and catalytic conditions allowed remarkable yields/conversions of the order of 70% for selectivities in 1,2 propanediol of 90%. Full article
(This article belongs to the Special Issue Catalytic Valorization of Glycerol: Strategies and Perspectives)
Show Figures

Figure 1

12 pages, 1984 KiB  
Article
Facile Synthesis of Flower-Like TiO2-Based Composite for Adsorption–Photocatalytic Degradation of High-Chroma Methylene Blue
by Mengqi Tian, Jingjing Wang, Runjun Sun, Mu Yao and Lianbi Li
Catalysts 2021, 11(4), 515; https://doi.org/10.3390/catal11040515 - 20 Apr 2021
Cited by 4 | Viewed by 1813
Abstract
A flower-like TiO2-based composite (denoted as Zn-Ti-6) was prepared using a flower-like zinc oxide template for adsorption–photocatalytic degradation of high-chroma methylene blue. The reaction took place in an alkaline environment following hydrochloric acid treatment to remove the template and form TiO [...] Read more.
A flower-like TiO2-based composite (denoted as Zn-Ti-6) was prepared using a flower-like zinc oxide template for adsorption–photocatalytic degradation of high-chroma methylene blue. The reaction took place in an alkaline environment following hydrochloric acid treatment to remove the template and form TiO2-based composite. Sodium hydroxide played both roles of morphology-directing agent and reactive etchant. The possible mechanism for the formation of flower-like Zn-Ti-6 was proposed. The adsorption and photocatalytic degradation behavior of Zn-Ti-6 on methylene blue (MB) removal was also investigated. The results revealed that Zn-Ti-6 showed better adsorption and photocatalytic degradation performance than TiO2 nanoparticles owing to its much larger specific surface area, more abundant hydroxyls, and lower photoluminescence intensity. The adsorption and photocatalytic degradation data of Zn-Ti-6 were well fitted to the pseudo-second-order and pseudo-first-order kinetics models, respectively. The excellent adsorption performance of Zn-Ti-6 is largely beneficial to the subsequent photocatalytic degradation performance for high-chroma wastewater treatment. Overall, this study contributes a facile fabrication strategy for flower-like TiO2-based composite to achieve the adsorption–photocatalytic degradation of high-chroma wastewater. Full article
(This article belongs to the Special Issue Novel Catalysts for Environmental Green Chemistry Application)
Show Figures

Graphical abstract

20 pages, 4399 KiB  
Article
Magnetite-Based Catalyst in the Catalytic Wet Peroxide Oxidation for Different Aqueous Matrices Spiked with Naproxen–Diclofenac Mixture
by Ysabel Huaccallo-Aguilar, Silvia Álvarez-Torrellas, Johanny Martínez-Nieves, Jonathan Delgado-Adámez, María Victoria Gil, Gabriel Ovejero and Juan García
Catalysts 2021, 11(4), 514; https://doi.org/10.3390/catal11040514 - 19 Apr 2021
Cited by 10 | Viewed by 2204
Abstract
Magnetite supported on multiwalled carbon nanotubes catalysts were synthesized by co-precipitation and hydrothermal treatment. The magnetic catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectrometry, thermogravimetric analysis and N2 physisorption. The catalysts were then tested for their ability to remove diclofenac (DCF) and [...] Read more.
Magnetite supported on multiwalled carbon nanotubes catalysts were synthesized by co-precipitation and hydrothermal treatment. The magnetic catalysts were characterized by X-ray diffraction, Fourier-transform infrared spectrometry, thermogravimetric analysis and N2 physisorption. The catalysts were then tested for their ability to remove diclofenac (DCF) and naproxen (NAP) from an aqueous solution at different conditions (pH, temperature, and hydrogen peroxide) to determine the optimum conditions for chemical oxidation. The optimization of the process parameters was conducted using response surface methodology (RSM) coupled with Box–Behnken design (BBD). By RSM–BBD methodology, the optimal parameters (1.75 mM H2O2 dosage, 70 °C and pH 6.5) were determined, and the removal percentages of NAP and DCF were 19 and 54%, respectively. The NAP–DCF degradation by catalytic wet peroxide oxidation (CWPO) was caused by •OH radicals. In CWPO of mixed drug solutions, DCF and NAP showed competitive oxidation. Hydrophobic interactions played an important role during the CWPO process. On the other hand, the magnetic catalyst reduced its activity after the second cycle of reuse. In addition, proof of concept and disinfection tests performed at the operating conditions showed results following the complexity of the water matrices. In this sense, the magnetic catalyst in CWPO has adequate potential to treat water contaminated with NAP–DCF mixtures. Full article
(This article belongs to the Special Issue Environmental Catalysis for Water Remediation)
Show Figures

Figure 1

12 pages, 1791 KiB  
Article
Unconventional Gold-Catalyzed One-Pot/Multicomponent Synthesis of Propargylamines Starting from Benzyl Alcohols
by Stephany Zárate-Roldán, María Concepción Gimeno and Raquel P. Herrera
Catalysts 2021, 11(4), 513; https://doi.org/10.3390/catal11040513 - 19 Apr 2021
Cited by 6 | Viewed by 2441
Abstract
A formal homogeneous gold-catalyzed A3-coupling, starting from benzyl alcohols, is reported for the straightforward synthesis of propargylamines. This is the first process where these highly valuable compounds have been synthesized, starting from the corresponding alcohols in a one-pot oxidation procedure using [...] Read more.
A formal homogeneous gold-catalyzed A3-coupling, starting from benzyl alcohols, is reported for the straightforward synthesis of propargylamines. This is the first process where these highly valuable compounds have been synthesized, starting from the corresponding alcohols in a one-pot oxidation procedure using MnO2, followed by a HAuCl4·3H2O catalyzed multicomponent reaction. The final products are obtained with very good yields in short reaction times, which is of fundamental interest for the synthesis of pharmaceuticals. The usefulness and efficiency of our methodology is successfully compared against the same reaction starting from aldehydes. Full article
(This article belongs to the Special Issue Catalytic Approaches to Selective Elaboration of Organic Molecules)
Show Figures

Figure 1

15 pages, 1589 KiB  
Article
Microbial Removal of Pb(II) Using an Upflow Anaerobic Sludge Blanket (UASB) Reactor
by Jeremiah Chimhundi, Carla Hörstmann, Evans M. N. Chirwa and Hendrik G. Brink
Catalysts 2021, 11(4), 512; https://doi.org/10.3390/catal11040512 - 19 Apr 2021
Cited by 8 | Viewed by 2374
Abstract
The main objective of this study was to achieve the continuous biorecovery and bioreduction of Pb(II) using an industrially obtained consortia as a biocatalyst. An upflow anaerobic sludge blanket reactor was used in the treatment process. The bioremediation technique that was applied made [...] Read more.
The main objective of this study was to achieve the continuous biorecovery and bioreduction of Pb(II) using an industrially obtained consortia as a biocatalyst. An upflow anaerobic sludge blanket reactor was used in the treatment process. The bioremediation technique that was applied made use of a yeast extract as the microbial substrate and Pb(NO3)2 as the source of Pb(II). The UASB reactor exhibited removal efficiencies of between 90 and 100% for the inlet Pb concentrations from 80 to 2000 ppm and a maximum removal rate of 1948.4 mg/(L·d) was measured. XRD and XPS analyses of the precipitate revealed the presence of Pb0, PbO, PbS and PbSO4. Supporting experimental work carried out included growth measurements, pH, oxidation–reduction potentials and nitrate levels. Full article
(This article belongs to the Special Issue Biocatalysis for Green Chemistry)
Show Figures

Figure 1

14 pages, 1483 KiB  
Article
Do Gas Nanobubbles Enhance Aqueous Photocatalysis? Experiment and Analysis of Mechanism
by Weijia Yu, Jiaying Chen, Mohamed Ateia, Ezra L. Cates and Matthew S. Johnson
Catalysts 2021, 11(4), 511; https://doi.org/10.3390/catal11040511 - 19 Apr 2021
Cited by 10 | Viewed by 3335
Abstract
The performance of photocatalytic advanced oxidation must be improved in order for the technology to make the jump from academic research to widespread use. Research is needed on the factors that cause photocatalysis to become self-limiting. In this study, we introduced, for the [...] Read more.
The performance of photocatalytic advanced oxidation must be improved in order for the technology to make the jump from academic research to widespread use. Research is needed on the factors that cause photocatalysis to become self-limiting. In this study, we introduced, for the first time, nanobubbles continuously into a running photocatalytic reactor. Synthetic air, O2, and N2 bubbles in the size range of 40 to 700 nm were added to a reaction system comprising P25 TiO2 photocatalyst in stirred aqueous solution excited by UV-A lamps, with methyl orange as a target contaminant. The removal of methyl orange was tested under conditions of changing pH and with the addition of different radical scavengers. Results indicated that the oxygen and air nanobubbles improved the photocatalytic degradation of methyl orange—the removal efficiency of methyl orange increased from 58.2 ± 3.5% (N2 aeration) to 71.9 ± 0.6% (O2 aeration). Dissolved oxygen (DO) of 14.93 ± 0.13 mg/L was achieved using O2 nanobubbles in comparison to 8.43 ± 0.34 mg/L without aeration. The photodegradation of methyl orange decreased from 70.8 ± 0.4% to 53.9 ± 0.5% as pH increased from 2 to 10. Experiments using the scavengers showed that O2 was the main reactive species in photocatalytic degradation under highly dissolved oxygen conditions, which also accounted for the observation that the removal efficiency for methyl orange decreased at higher pH. However, without photocatalyst, nanobubbles alone did not improve the removal of methyl orange, and nanobubbles also did not increase the degradation of methyl orange by only photolysis. These experiments show that oxygen and air nanobubbles can act as environmentally friendly catalysts for boosting the performance of photocatalytic water treatment systems. Full article
Show Figures

Graphical abstract

18 pages, 3660 KiB  
Article
Effective Separation of Prime Olefins from Gas Stream Using Anion Pillared Metal Organic Frameworks: Ideal Adsorbed Solution Theory Studies, Cyclic Application and Stability
by Majeda Khraisheh, Fares Almomani and Gavin Walker
Catalysts 2021, 11(4), 510; https://doi.org/10.3390/catal11040510 - 18 Apr 2021
Cited by 2 | Viewed by 2576
Abstract
The separation of C3H4/C3H6 is one of the most energy intensive and challenging operations, requiring up to 100 theoretical stages, in traditional cryogenic distillation. In this investigation, the potential application of two MOFs (SIFSIX-3-Ni and NbOFFIVE-1-Ni) [...] Read more.
The separation of C3H4/C3H6 is one of the most energy intensive and challenging operations, requiring up to 100 theoretical stages, in traditional cryogenic distillation. In this investigation, the potential application of two MOFs (SIFSIX-3-Ni and NbOFFIVE-1-Ni) was tested by studying the adsorption-desorption behaviors at a range of operational temperatures (300–360 K) and pressures (1–100 kPa). Dynamic adsorption breakthrough tests were conducted and the stability and regeneration ability of the MOFs were established after eight consecutive cycles. In order to establish the engineering key parameters, the experimental data were fitted to four isotherm models (Langmuir, Freundlich, Sips and Toth) in addition to the estimation of the thermodynamic properties such as the isosteric heats of adsorption. The selectivity of the separation was tested by applying ideal adsorbed solution theory (IAST). The results revealed that SIFSIX-3-Ni is an effective adsorbent for the separation of 10/90 v/v C3H4/C3H6 under the range of experimental conditions used in this study. The maximum adsorption reported for the same combination was 3.2 mmol g−1. Breakthrough curves confirmed the suitability of this material for the separation with a 10-min gab before the lighter C3H4 is eluted from the column. The separated C3H6 was obtained with a 99.98% purity. Full article
(This article belongs to the Special Issue MOFs for Advanced Applications)
Show Figures

Graphical abstract

4 pages, 171 KiB  
Editorial
Non-Thermal Plasma-Assisted Catalytic Reactions for Environmental Protection
by Vincenzo Vaiano and Giuseppina Iervolino
Catalysts 2021, 11(4), 509; https://doi.org/10.3390/catal11040509 - 18 Apr 2021
Cited by 3 | Viewed by 1596
Abstract
“Non-thermal plasma technology” (NTP) has notably increased [...] Full article
11 pages, 1986 KiB  
Article
One-Step Preparation of Biochar Electrodes and Their Applications in Sediment Microbial Electrochemical Systems
by Kui You, Zihan Zhou, Chao Gao and Qiao Yang
Catalysts 2021, 11(4), 508; https://doi.org/10.3390/catal11040508 - 17 Apr 2021
Cited by 8 | Viewed by 2521
Abstract
Biochar is a kind of carbon-rich material formed by pyrolysis of biomass at high temperature in the absence or limitation of oxygen. It has abundant pore structure and a large surface area, which could be considered the beneficial characteristics for electrodes of microbial [...] Read more.
Biochar is a kind of carbon-rich material formed by pyrolysis of biomass at high temperature in the absence or limitation of oxygen. It has abundant pore structure and a large surface area, which could be considered the beneficial characteristics for electrodes of microbial electrochemical systems. In this study, reed was used as the raw material of biochar and six biochar-based electrode materials were obtained by three methods, including one-step biochar cathodes (BC 800 and BC 700), biochar/polyethylene composite cathodes (BP 5:5 and BP 6:4), and biochar/polyaniline/hot-melt adhesive composite cathode (BPP 5:1:4 and BPP 4:1:5). The basic physical properties and electrochemical properties of the self-made biochar electrode materials were characterized. Selected biochar-based electrode materials were used as the cathode of sediment microbial electrochemical reactors. The reactor with pure biochar electrode (BC 800) achieves a maximum output power density of 9.15 ± 0.02 mW/m2, which increases the output power by nearly 80% compared with carbon felt. When using a biochar/polyaniline/hot-melt adhesive (BPP 5:1:4) composite cathode, the output power was increased by 2.33 times. Under the premise of ensuring the molding of the material, the higher the content of biochar, the better the electrochemical performance of the electrodes. The treatment of reed powder before pyrolysis is an important factor for the molding of biochar. The one-step molding biochar cathode had satisfactory performance in sediment microbial electrochemical systems. By exploring the biochar-based electrode, waste biomass could be reused, which is beneficial for the environment. Full article
(This article belongs to the Section Electrocatalysis)
Show Figures

Figure 1

16 pages, 6744 KiB  
Article
Polyaniline/Ag2S–CdS Nanocomposites as Efficient Electrocatalysts for Triiodide Reduction in Dye-Sensitized Solar Cells
by Meng Kuo, Tsung-Chia Cheng, Huai-Kai Ye, Tzong-Liu Wang, Tzu-Ho Wu, Chi-Ching Kuo and Rong-Ho Lee
Catalysts 2021, 11(4), 507; https://doi.org/10.3390/catal11040507 - 17 Apr 2021
Cited by 4 | Viewed by 2310
Abstract
In this study, an Ag2S–CdS nanocomposite (AC11) was prepared through chemical co-precipitation of silver nitrate and cadmium acetate in an aqueous solution of thiourea. We then synthesized PACI, a nanocomposite of polyaniline (PANI) and AC11, through in situ polymerization of aniline [...] Read more.
In this study, an Ag2S–CdS nanocomposite (AC11) was prepared through chemical co-precipitation of silver nitrate and cadmium acetate in an aqueous solution of thiourea. We then synthesized PACI, a nanocomposite of polyaniline (PANI) and AC11, through in situ polymerization of aniline in an AC11-containing solution, resulting in uniform embedding of the AC11 nanoparticles in the PANI fibers. Moreover, we synthesized the nanocomposite PACO through deposition of the AC11 nanoparticles on the surface of the PANI fibers. PANI, PACI, and PACO were then spin-coated onto conducting glasses to form PANI-S, PACI-S, and PACO-S counter electrodes, respectively, for dye-sensitized solar cells (DSSCs). Cyclic voltammetry revealed that the electrochemical catalytic activity of the PACI-S electrode was much higher than those of the PANI-S and PACO-S electrodes. Furthermore, the photovoltaic properties of the PACI-S-based DSSC were much better than those of the PANI-S- and PACO-S-based DSSCs. Indeed, the highest short-circuit current density (12.06 mA/cm2), open-circuit voltage (0.72 V), fill factor (0.58), and photoenergy conversion efficiency (5.04%) were those of the DSSC featuring PACI-S as the counter electrode. Full article
Show Figures

Graphical abstract

11 pages, 3112 KiB  
Article
Removal of VOCs by Ozone: n-Alkane Oxidation under Mild Conditions
by Alina I. Mytareva, Igor S. Mashkovsky, Sergey A. Kanaev, Dmitriy A. Bokarev, Galina N. Baeva, Alexander V. Kazakov and Alexander Yu. Stakheev
Catalysts 2021, 11(4), 506; https://doi.org/10.3390/catal11040506 - 16 Apr 2021
Cited by 10 | Viewed by 2800
Abstract
Volatile organic compounds (VOCs) have a negative effect on both humans and the environment; therefore, it is crucial to minimize their emission. The conventional solution is the catalytic oxidation of VOCs by air; however, in some cases this method requires relatively high temperatures. [...] Read more.
Volatile organic compounds (VOCs) have a negative effect on both humans and the environment; therefore, it is crucial to minimize their emission. The conventional solution is the catalytic oxidation of VOCs by air; however, in some cases this method requires relatively high temperatures. Thus, the oxidation of short-chain alkanes, which demonstrate the lowest reactivity among VOCs, starts at 250–350 °C. This research deals with the ozone catalytic oxidation (OZCO) of alkanes at temperatures as low as 25–200 °C using an alumina-supported manganese oxide catalyst. Our data demonstrate that oxidation can be significantly accelerated in the presence of a small amount of O3. In particular, it was found that n-C4H10 can be readily oxidized by an air/O3 mixture over the Mn/Al2O3 catalyst at temperatures as low as 25 °C. According to the characterization data (SEM-EDX, XRD, H2-TPR, and XPS) the superior catalytic performance of the Mn/Al2O3 catalyst in OZCO stems from a high concentration of Mn2O3 species and oxygen vacancies. Full article
Show Figures

Figure 1

10 pages, 3428 KiB  
Article
g-C3N4-Stabilised Organic–Inorganic Halide Perovskites for Efficient Photocatalytic Selective Oxidation of Benzyl Alcohol
by Menglong Zhang, Weizhe Wang, Fangliang Gao and Dongxiang Luo
Catalysts 2021, 11(4), 505; https://doi.org/10.3390/catal11040505 - 16 Apr 2021
Cited by 5 | Viewed by 2216
Abstract
The outstanding optoelectronic performance and facile synthetic approach of metal halide perovskites has inspired additional applications well beyond efficient solar cells and light emitting diodes (LEDs). Herein, we present an alternative option available for the optimisation of selective and efficient oxidation of benzylic [...] Read more.
The outstanding optoelectronic performance and facile synthetic approach of metal halide perovskites has inspired additional applications well beyond efficient solar cells and light emitting diodes (LEDs). Herein, we present an alternative option available for the optimisation of selective and efficient oxidation of benzylic alcohols through photocatalysis. The materials engineering of hybrids based on formamidine lead bromide (FAPbBr3) and graphic carbon nitride (g-C3N4) is achieved via facile anti-solvent approach. The photocatalytic performance of the hybrids is highly reliant on weight ratio between FAPbBr3 and g-C3N4. Besides, the presence of g-C3N4 dramatically enhances the long-term stability of the hybrids, compared to metal oxides hybrids. Detailed optical, electrical and thermal studies reveal the proposed novel photocatalytic and stability behaviours arising in FAPbBr3 and g-C3N4 hybrid materials. Full article
(This article belongs to the Special Issue Solar Fuels Production by Artificial Photosynthesis)
Show Figures

Figure 1

30 pages, 7540 KiB  
Review
Metal Oxide-Based Photocatalytic Paper: A Green Alternative for Environmental Remediation
by Daniela Nunes, Ana Pimentel, Rita Branquinho, Elvira Fortunato and Rodrigo Martins
Catalysts 2021, 11(4), 504; https://doi.org/10.3390/catal11040504 - 16 Apr 2021
Cited by 42 | Viewed by 6335
Abstract
The interest in advanced photocatalytic technologies with metal oxide-based nanomaterials has been growing exponentially over the years due to their green and sustainable characteristics. Photocatalysis has been employed in several applications ranging from the degradation of pollutants to water splitting, CO2 and [...] Read more.
The interest in advanced photocatalytic technologies with metal oxide-based nanomaterials has been growing exponentially over the years due to their green and sustainable characteristics. Photocatalysis has been employed in several applications ranging from the degradation of pollutants to water splitting, CO2 and N2 reductions, and microorganism inactivation. However, to maintain its eco-friendly aspect, new solutions must be identified to ensure sustainability. One alternative is creating an enhanced photocatalytic paper by introducing cellulose-based materials to the process. Paper can participate as a substrate for the metal oxides, but it can also form composites or membranes, and it adds a valuable contribution as it is environmentally friendly, low-cost, flexible, recyclable, lightweight, and earth abundant. In term of photocatalysts, the use of metal oxides is widely spread, mostly since these materials display enhanced photocatalytic activities, allied to their chemical stability, non-toxicity, and earth abundance, despite being inexpensive and compatible with low-cost wet-chemical synthesis routes. This manuscript extensively reviews the recent developments of using photocatalytic papers with nanostructured metal oxides for environmental remediation. It focuses on titanium dioxide (TiO2) and zinc oxide (ZnO) in the form of nanostructures or thin films. It discusses the main characteristics of metal oxides and correlates them to their photocatalytic activity. The role of cellulose-based materials on the systems’ photocatalytic performance is extensively discussed, and the future perspective for photocatalytic papers is highlighted. Full article
Show Figures

Graphical abstract

15 pages, 1892 KiB  
Article
Lipase Catalyzed Synthesis of Enantiopure Precursors and Derivatives for β-Blockers Practolol, Pindolol and Carteolol
by Morten Andre Gundersen, Guro Buaas Austli, Sigrid Sløgedal Løvland, Mari Bergan Hansen, Mari Rødseth and Elisabeth Egholm Jacobsen
Catalysts 2021, 11(4), 503; https://doi.org/10.3390/catal11040503 - 16 Apr 2021
Cited by 9 | Viewed by 2816
Abstract
Sustainable methods for producing enantiopure drugs have been developed. Chlorohydrins as building blocks for several β-blockers have been synthesized in high enantiomeric purity by chemo-enzymatic methods. The yield of the chlorohydrins increased by the use of catalytic amount of base. The reason for [...] Read more.
Sustainable methods for producing enantiopure drugs have been developed. Chlorohydrins as building blocks for several β-blockers have been synthesized in high enantiomeric purity by chemo-enzymatic methods. The yield of the chlorohydrins increased by the use of catalytic amount of base. The reason for this was found to be the reduced formation of the dimeric by-products compared to the use of higher concentration of the base. An overall reduction of reagents and reaction time was also obtained compared to our previously reported data of similar compounds. The enantiomers of the chlorohydrin building blocks were obtained by kinetic resolution of the racemate in transesterification reactions catalyzed by Candida antarctica Lipase B (CALB). Optical rotations confirmed the absolute configuration of the enantiopure drugs. The β-blocker (S)-practolol ((S)-N-(4-(2-hydroxy-3-(isopropylamino)propoxy)phenyl)acetamide) was synthesized with 96% enantiomeric excess (ee) from the chlorohydrin (R)-N-(4-(3-chloro-2 hydroxypropoxy)phenyl)acetamide, which was produced in 97% ee and with 27% yield. Racemic building block 1-((1H-indol-4-yl)oxy)-3-chloropropan-2-ol for the β-blocker pindolol was produced in 53% yield and (R)-1-((1H-indol-4-yl)oxy)-3-chloropropan-2-ol was produced in 92% ee. The chlorohydrin 7-(3-chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one, a building block for a derivative of carteolol was produced in 77% yield. (R)-7-(3-Chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one was obtained in 96% ee. The S-enantiomer of this carteolol derivative was produced in 97% ee in 87% yield. Racemic building block 5-(3-chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one, building block for the drug carteolol, was also produced in 53% yield, with 96% ee of the R-chlorohydrin (R)-5-(3-chloro-2-hydroxypropoxy)-3,4-dihydroquinolin-2(1H)-one. (S)-Carteolol was produced in 96% ee with low yield, which easily can be improved. Full article
Show Figures

Figure 1

14 pages, 28487 KiB  
Article
UV Stimulated Manganese Dioxide for the Persulfate Catalytic Degradation of Bisphenol A
by Guihua Dong, Bing Chen, Bo Liu, Stanislav R. Stoyanov, Yiqi Cao, Min Yang and Baiyu Zhang
Catalysts 2021, 11(4), 502; https://doi.org/10.3390/catal11040502 - 16 Apr 2021
Cited by 18 | Viewed by 3172
Abstract
One of the most commonly produced industrial chemicals worldwide, bisphenol A (BPA), is used as a precursor in plastics, resins, paints, and many other materials. It has been proved that BPA can cause long-term adverse effects on ecosystems and human health due to [...] Read more.
One of the most commonly produced industrial chemicals worldwide, bisphenol A (BPA), is used as a precursor in plastics, resins, paints, and many other materials. It has been proved that BPA can cause long-term adverse effects on ecosystems and human health due to its toxicity as an endocrine disruptor. In this study, we developed an integrated MnO2/UV/persulfate (PS) process for use in BPA photocatalytic degradation from water and examined the reaction mechanisms, degradation pathways, and toxicity reduction. Comparative tests using MnO2, PS, UV, UV/MnO2, MnO2/PS, and UV/PS processes were conducted under the same conditions to investigate the mechanism of BPA catalytic degradation by the proposed MnO2/UV/PS process. The best performance was observed in the MnO2/UV/PS process in which BPA was completely removed in 30 min with a reduction rate of over 90% for total organic carbon after 2 h. This process also showed a stable removal efficiency with a large variation of pH levels (3.6 to 10.0). Kinetic analysis suggested that 1O2 and SO4 played more critical roles than •OH for BPA degradation. Infrared spectra showed that UV irradiation could stimulate the generation of –OH groups on the MnO2 photocatalyst surface, facilitating the PS catalytic degradation of BPA in this process. The degradation pathways were further proposed in five steps, and thirteen intermediates were identified by gas chromatography-mass spectrometry. The acute toxicity was analyzed during the treatment, showing a slight increase (by 3.3%) in the first 30 min and then a decrease by four-fold over 2 h. These findings help elucidate the mechanism and pathways of BPA degradation and provide an effective PS catalytic strategy. Full article
(This article belongs to the Special Issue Photocatalysis in the Wastewater Treatment)
Show Figures

Graphical abstract

19 pages, 6922 KiB  
Article
Continuous 2-Methyl-3-butyn-2-ol Selective Hydrogenation on Pd/γ-Al2O3 as a Green Pathway of Vitamin A Precursor Synthesis
by Antonio J. Fernández-Ropero, Bartosz Zawadzki, Emil Kowalewski, Izabela S. Pieta, Mirosław Krawczyk, Krzysztof Matus, Dmytro Lisovytskiy and Anna Śrębowata
Catalysts 2021, 11(4), 501; https://doi.org/10.3390/catal11040501 - 15 Apr 2021
Cited by 10 | Viewed by 2443
Abstract
In this work, the effect of pretreatment conditions (10% H2/Ar flow rate 25 mL/min and 400 °C, 3 h or 600 °C, 17 h) on the catalytic performance of 1 wt.% Pd/γ-Al2O3 has been evaluated for hydrogenation of [...] Read more.
In this work, the effect of pretreatment conditions (10% H2/Ar flow rate 25 mL/min and 400 °C, 3 h or 600 °C, 17 h) on the catalytic performance of 1 wt.% Pd/γ-Al2O3 has been evaluated for hydrogenation of 2-methyl-3-butyn-2-ol in continuous-flow mode. Two palladium catalysts have been tested under different conditions of pressure and temperature and characterized using various physicochemical techniques. The catalytic performance of red(400 °C)-Pd/γ-Al2O3 and red(600 °C)-Pd/γ-Al2O3 are affected by the coexistence of several related factors like the competition between PdH and PdCx formation during the reaction, structure sensitivity, hydrogen spillover to the alumina support and presence or absence of Pd–Al species. High-temperature reduction leads to formation of Pd–Al species in addition to pure Pd. The Pd–Al species which reveal unique electronic properties by decreasing the Pdδ− surface concentration via electron transfer from Pd to Al, leading to a weaker Pd–Alkyl bonding, additionally assisted by the hydrogen spillover, are the sites of improved semi-hydrogenation of 2-methyl-3-butyn-2-ol towards 2-methyl-3-buten-2-ol (97%)—an important intermediate for vitamin A synthesis. Full article
Show Figures

Graphical abstract

14 pages, 2024 KiB  
Article
NiCo Nanoneedles on 3D Carbon Nanotubes/Carbon Foam Electrode as an Efficient Bi-Functional Catalyst for Electro-Oxidation of Water and Methanol
by Tung Ngoc Pham, Ajaikumar Samikannu, Solomon Tesfalidet, Thomas Wågberg and Jyri-Pekka Mikkola
Catalysts 2021, 11(4), 500; https://doi.org/10.3390/catal11040500 - 15 Apr 2021
Cited by 5 | Viewed by 2694
Abstract
In this study, we report a 3D structured carbon foam electrode assembled from a bi-functional NiCo catalyst, carbon nanotubes (CNT), and a monolith 3D structured carbon foam (CF) as a highly active and stable electrode for oxygen evolution reaction (OER) and methanol oxidation [...] Read more.
In this study, we report a 3D structured carbon foam electrode assembled from a bi-functional NiCo catalyst, carbon nanotubes (CNT), and a monolith 3D structured carbon foam (CF) as a highly active and stable electrode for oxygen evolution reaction (OER) and methanol oxidation reaction (MOR). When the NiCo@CNTs/CF electrode was used as an anode in OER, after the anodization step, the electrode required a small overpotential of 320 mV to reach the current density of 10 mA cm−2 and demonstrated excellent stability over a long testing time (total 30 h) in 1 M KOH. The as-prepared NiCo@CNTs/CF electrode also exhibited a good performance towards methanol oxidation reaction (MOR) with high current density, 100 mA cm−2 at 0.6 V vs. Ag/AgCl, and good stability in 1 M KOH plus 0.5 M CH3OH electrolyte. The NiCo@CNTs/CF catalyst/electrode provides a potential for application as an anode in water electrolysis and direct methanol fuel cells. Full article
(This article belongs to the Special Issue Design and Applications of Bifunctional Catalysts)
Show Figures

Figure 1

11 pages, 4625 KiB  
Article
Rapid Synthesis of Asymmetric Methyl-Alkyl Carbonates Catalyzed by α-KMgPO4 in a Sealed-Vessel Reactor Monowave 50
by Tiefeng Wang, Xu Li, Xiaosheng Zhang and Jinxiang Dong
Catalysts 2021, 11(4), 499; https://doi.org/10.3390/catal11040499 - 15 Apr 2021
Viewed by 2049
Abstract
Dimethyl-carbonate (DMC) is a green carboxymethylation agent for synthesis of the versatile long-chain alkyl carbonates through base-catalyzed transesterification with aliphatic alcohols. Herein, we demonstrated the facile preparation of a novel heterogeneous base catalyst α-KMgPO4 using commercially cheap metal salts via hydrothermal-calcination procedure. [...] Read more.
Dimethyl-carbonate (DMC) is a green carboxymethylation agent for synthesis of the versatile long-chain alkyl carbonates through base-catalyzed transesterification with aliphatic alcohols. Herein, we demonstrated the facile preparation of a novel heterogeneous base catalyst α-KMgPO4 using commercially cheap metal salts via hydrothermal-calcination procedure. The combination of temperature programmed desorption (TPD) and FTIR measurements with CO2 pre-adsorbed revealed the presence of weak and medium base sites on α-KMgPO4. Furthermore, α-KMgPO4 catalyzed transesterification of DMC and n-octanol was performed in a sealed-vessel reactor (Monowave 50). The results show that the reaction was completed in only 10 min with the 97.5% conversion of n-octanol and >99% selectivity to asymmetric methyl-octyl carbonate under the optimal conditions. Additionally, the possible catalytic mechanism is proposed. As an extended contribution, the tribology performance of the asymmetric methyl-alkyl carbonates was further evaluated. Full article
Show Figures

Graphical abstract

22 pages, 5026 KiB  
Article
Eco-Friendly and Sustainable Process for Converting Hydrous Bioethanol to Butanol
by Miron V. Landau, Tomy Hos, Roxana Vidruk Nehemya, George Nomikos and Moti Herskowitz
Catalysts 2021, 11(4), 498; https://doi.org/10.3390/catal11040498 - 14 Apr 2021
Cited by 2 | Viewed by 2847
Abstract
The purpose of the study was the development of water-resistant catalyst and catalytic processes for the conversion of hydrous ethanol to 1-butanol. Water, in hydrous ethanol, strongly inhibits conversion to 1-butanol on solid catalysts. In this study, the nonstoichiometric P-deficient hydroxyapatite containing carbonate [...] Read more.
The purpose of the study was the development of water-resistant catalyst and catalytic processes for the conversion of hydrous ethanol to 1-butanol. Water, in hydrous ethanol, strongly inhibits conversion to 1-butanol on solid catalysts. In this study, the nonstoichiometric P-deficient hydroxyapatite containing carbonate anions (C-HAP), Ca10−x/2(PO4)6−x(CO3)x(OH)2, displayed good performance in the Guerbet condensation of hydrated ethanol to 1-butanol, after proper stabilization of reaction conditions. Hydrous ethanol (96 wt%) was converted on C-HAP formed as extrudates with silica binder at 400 °C and weight hour space velocity (WHSV) = 0.5–1.0 h−1 to yield 21–23% 1-butanol and 73–74% selectivity. It displayed stable operation for up to 170 h on streams conducted in bench and mini-pilot rigs with catalyst loadings of 2 and 50 cm3, respectively. The process simulation employed the recycling of ethanol without laboratory verification to reach 68% theoretical yield of 1-butanol. The techno-economic analysis demonstrated the feasibility of this process, showing that it may be profitable depending on the prices of hydrated ethanol and 1-butanol. Full article
(This article belongs to the Section Catalytic Materials)
Show Figures

Graphical abstract

45 pages, 5154 KiB  
Review
From Enzyme Stability to Enzymatic Bioelectrode Stabilization Processes
by Charlène Beaufils, Hiu-Mun Man, Anne de Poulpiquet, Ievgen Mazurenko and Elisabeth Lojou
Catalysts 2021, 11(4), 497; https://doi.org/10.3390/catal11040497 - 14 Apr 2021
Cited by 26 | Viewed by 6836
Abstract
Bioelectrocatalysis using redox enzymes appears as a sustainable way for biosensing, electricity production, or biosynthesis of fine products. Despite advances in the knowledge of parameters that drive the efficiency of enzymatic electrocatalysis, the weak stability of bioelectrodes prevents large scale development of bioelectrocatalysis. [...] Read more.
Bioelectrocatalysis using redox enzymes appears as a sustainable way for biosensing, electricity production, or biosynthesis of fine products. Despite advances in the knowledge of parameters that drive the efficiency of enzymatic electrocatalysis, the weak stability of bioelectrodes prevents large scale development of bioelectrocatalysis. In this review, starting from the understanding of the parameters that drive protein instability, we will discuss the main strategies available to improve all enzyme stability, including use of chemicals, protein engineering and immobilization. Considering in a second step the additional requirements for use of redox enzymes, we will evaluate how far these general strategies can be applied to bioelectrocatalysis. Full article
(This article belongs to the Special Issue Enzymatic Bioelectrocatalysis)
Show Figures

Figure 1

11 pages, 2360 KiB  
Article
Hexagonal WO3·0.33H2O Hierarchical Microstructure with Efficient Photocatalytic Degradation Activity
by Wei Li, Tingting Wang, Dongdong Huang, Chan Zheng, Yuekun Lai, Xueqing Xiao, Shuguang Cai and Wenzhe Chen
Catalysts 2021, 11(4), 496; https://doi.org/10.3390/catal11040496 - 14 Apr 2021
Cited by 9 | Viewed by 2209
Abstract
Structural design and morphological control of semiconductors is considered to be one of the most effective ways to improve their photocatalytic degradation properties. In the present work, a hexagonal WO3·0.33H2O hierarchical microstructure (HWHMS) composed of nanorods was successfully prepared [...] Read more.
Structural design and morphological control of semiconductors is considered to be one of the most effective ways to improve their photocatalytic degradation properties. In the present work, a hexagonal WO3·0.33H2O hierarchical microstructure (HWHMS) composed of nanorods was successfully prepared by the hydrothermal method. The morphology of the HWHMS was confirmed by field-emission scanning electron microscopy, and X-ray diffraction, Raman spectroscopy, and thermogravimetric analysis demonstrated that the synthesized product was orthorhombic WO3·0.33H2O. Owing to the unique hierarchical microstructure, the HWHMS showed larger Brunauer–Emmett–Teller (BET) surface and narrower bandgap (1.53 eV) than the isolated WO3·0.33H2O nanorods. Furthermore, the HWHMS showed enhanced photocatalytic activity for degradation of methylene blue under visible-light irradiation compared with the isolated nanorods, which can be ascribed to the narrower bandgap, larger BET specific surface area, and orthorhombic phase structure of the HWHMS. This work provides a potential protocol for construction of tungsten trioxide counterparts and materials similar to tungsten trioxide for application in gas sensors, photocatalysts, electrochromic devices, field-emission devices, and solar-energy devices. Full article
(This article belongs to the Special Issue Metal Nanoparticle Catalysis)
Show Figures

Figure 1

12 pages, 8064 KiB  
Article
Nickel-Fe3O4 Magnetic Nanoparticles Supported on Multiwalled Carbon Nanotubes: Effective Catalyst in Suzuki Cross Coupling Reactions
by Sojeong K. Folsom, Destiny J. Ivey, Frank S. McNair and Ali R. Siamaki
Catalysts 2021, 11(4), 495; https://doi.org/10.3390/catal11040495 - 13 Apr 2021
Cited by 11 | Viewed by 2667
Abstract
Nickel-Fe3O4 nanoparticles supported on multi-walled carbon nanotubes (Ni-Fe3O4/MWCNTs) were synthesized by mechanical grinding of a sample of nickel salt, Fe3O4 and MWCNTs using a ball-mill mixer. The preparation method allows for bulk production [...] Read more.
Nickel-Fe3O4 nanoparticles supported on multi-walled carbon nanotubes (Ni-Fe3O4/MWCNTs) were synthesized by mechanical grinding of a sample of nickel salt, Fe3O4 and MWCNTs using a ball-mill mixer. The preparation method allows for bulk production of Ni-Fe3O4 nanoparticles at room temperature without the necessity of any solvent or chemical reagent. The nanoparticles prepared by this method exhibit small particles size of 5–8 nm with uniform dispersion of nickel nanoparticles on the surface of multi-walled carbon nanotubes. The Ni-Fe3O4/MWCNTs demonstrated remarkable catalytic activity for Suzuki cross coupling reactions of functionalized aryl halides and phenylboronic acids with excellent turnover number and turnover frequency (e.g., 76,000 h−1) using Monowave 50 conventional heating reactor at 120 °C within a very short reaction time of 15 min. The catalyst is air-stable and exhibits easy removal from the reaction mixture due to its magnetic properties, recyclability with no loss of activity, and significantly better performance than the other well-known commercial nickel catalyst. The Ni-Fe3O4/MWCNTs nanoparticles were fully characterized by a variety of spectroscopic techniques including X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy (XPS). Since nickel offers similar properties to other more expensive transition metals including the most widely used palladium counterpart in cross coupling catalysis, this work demonstrates a promising lower-cost, air-moisture stable and efficient alternative catalyst based on nickel nanoparticles for cross coupling reactions. Full article
(This article belongs to the Special Issue Metal Nanoparticle Catalysis)
Show Figures

Graphical abstract

Previous Issue
Next Issue
Back to TopTop