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Catalysts, Volume 11, Issue 5 (May 2021) – 124 articles

Cover Story (view full-size image): Carbon neutrality is a great challenge of the future, which can be achieved if hydrogen becomes the main energy carrier. However, not being a primary source, hydrogen must be produced from renewable feedstocks, through renewable-energy-source-based production processes. The future is outlined increasingly based on the local production and distribution of hydrogen, in which the energy to sustain the production processes must be generated on site, exploiting the local resources, such as wind power and/or solar power. Briefly, the most promising sustainable hydrogen production processes can be grouped into three main groups: water electrolysis, biomass fermentation and electrified reforming processes of renewables such as biomass. View this paper.
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Editorial
Metal Organic Frameworks for Advanced Applications
Catalysts 2021, 11(5), 648; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050648 - 20 May 2021
Viewed by 537
Abstract
Metal organic frameworks (MOFs) are a class of porous materials with a modular structure [...] Full article
(This article belongs to the Special Issue MOFs for Advanced Applications)
Editorial
Non-Precious Metal Electrocatalysts: Synthesis, Characterization and Application
Catalysts 2021, 11(5), 647; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050647 - 20 May 2021
Viewed by 451
Abstract
Electrocatalysis plays a vital role in many chemical processes and is concentrated on improving their efficiency [...] Full article
Editorial
Recent Advances in Organometallic Chemistry and Catalysis
Catalysts 2021, 11(5), 646; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050646 - 19 May 2021
Viewed by 584
Abstract
The use of organometallic compounds in organic chemistry is one of the cornerstones of the modern synthetic methodology for the activation and generation of new bonds in a molecule [...] Full article
(This article belongs to the Special Issue Recent Advances in Organometallic Chemistry and Catalysis)
Editorial
Ni-Containing Catalysts
Catalysts 2021, 11(5), 645; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050645 - 19 May 2021
Viewed by 464
Abstract
Murray Raney used Nickel for the first time as a hydrogenation catalyst over one century ago [...] Full article
(This article belongs to the Special Issue Ni-Containing Catalysts)
Review
Modified Layered Silicas as Catalysts for Conversion of Nitrogen Pollutants in Flue Gases—A Review
Catalysts 2021, 11(5), 644; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050644 - 19 May 2021
Viewed by 542
Abstract
This paper is focused on the recent achievements in the studies of modified layered zeolites and cationic layered clay minerals. These materials are very promising catalysts in green chemistry processes, such as selective catalytic reduction of NOx with ammonia (NH3-SCR) [...] Read more.
This paper is focused on the recent achievements in the studies of modified layered zeolites and cationic layered clay minerals. These materials are very promising catalysts in green chemistry processes, such as selective catalytic reduction of NOx with ammonia (NH3-SCR) and selective catalytic oxidation of ammonia to dinitrogen (NH3-SCO). Special attention is paid to the roles of the micro- and mesoporous structures of the catalytic materials, the type and location of deposited transition metals, as well as surface acidity in the design of effective catalysts for the NH3-SCR and NH3-SCO processes. The majority of the presented analysis is based on the authors’ research. Full article
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Editorial
Green Chemistry and Environmental Processes
Catalysts 2021, 11(5), 643; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050643 - 19 May 2021
Viewed by 572
Abstract
This Special Issue was designed based on two complementary principles, both aimed at developing environmentally friendly production processes, in which catalysis plays a leading role [...] Full article
(This article belongs to the Special Issue Green Chemistry and Environmental Processes)
Article
Mesoporous Organo-Silica Supported Chromium Oxide Catalyst for Oxidative Dehydrogenation of Ethane to Ethylene with CO2
Catalysts 2021, 11(5), 642; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050642 - 18 May 2021
Viewed by 515
Abstract
Chromium oxide supported on mesoporous organo-silica (MOS) was synthesized with different Cr loading by an incipient method. The catalytic performance of a Cr(x)/MOS catalyst for CO2-based ethane dehydrogenation was investigated. The synthesized catalysts were characterized by XRD, BET, TEM, SEM, XPS, [...] Read more.
Chromium oxide supported on mesoporous organo-silica (MOS) was synthesized with different Cr loading by an incipient method. The catalytic performance of a Cr(x)/MOS catalyst for CO2-based ethane dehydrogenation was investigated. The synthesized catalysts were characterized by XRD, BET, TEM, SEM, XPS, FTIR, and UV–Vis DR measurements. The textural properties of the prepared samples showed that the mesoporous nature of MOS sample was not disturbed by chromium impregnation. Among the prepared samples, Cr(8)/MOS catalyst exhibited good distribution of chromium species along with superior concentration of Cr6+ and the highest recorded Cr6+/Cr3+ ratio. The results revealed that the superior catalytic performance was reached at Cr(8)/MOS, with 50.4% and 90.1% of ethane conversion and ethylene selectivity, respectively. The catalytic activity decreased slowly over reaction time; it declined approximately 22% after 10 h of stream operation. The roles of CO2-based ethane dehydrogenation were also studied, where carbon dioxide can be a source of lattice oxygen and as a hydrogen consumer in reverse water–gas shift (RWGS) reaction. The effect of various catalytic factors, such as catalytic temperature, reaction time, space gas velocity, and CO2 partial pressure on the conversion of ethane, yield, and selectivity to ethylene, were investigated as well. Full article
(This article belongs to the Special Issue Catalytic Applications of Metal or Metal Oxide Nanocomposites)
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Article
Influence of Co-Precipitation Agent on the Structure, Texture and Catalytic Activity of Au-CeO2 Catalysts in Low-Temperature Oxidation of Benzyl Alcohol
Catalysts 2021, 11(5), 641; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050641 - 18 May 2021
Viewed by 705
Abstract
The aim of the study was to establish the influence of a co-precipitation agent (i.e., NaOH–immediate precipitation; hexamethylenetetramine/urea–gradual precipitation and growth of nanostructures) on the properties and catalytic activity of as-synthesized Au-CeO2 nanocomposites. All catalysts were fully characterized with the use of [...] Read more.
The aim of the study was to establish the influence of a co-precipitation agent (i.e., NaOH–immediate precipitation; hexamethylenetetramine/urea–gradual precipitation and growth of nanostructures) on the properties and catalytic activity of as-synthesized Au-CeO2 nanocomposites. All catalysts were fully characterized with the use of XRD, nitrogen physisorption, ICP-OES, SEM, HR-TEM, UV-vis, XPS, and tested in low-temperature oxidation of benzyl alcohol as a model oxidation reaction. The results obtained in this study indicated that the type of co-precipitation agent has a significant impact on the growth of gold species. Immediate co-precipitation of Au-CeO2 nanostructures with the use of NaOH allowed obtainment of considerably smaller and more homogeneous in size gold nanoparticles than those formed by gradual co-precipitation and growth of Au-CeO2 nanostructures in the presence of hexamethylenetetramine or urea. In the catalytic tests, it was established that the key factor promoting high activity in low-temperature oxidation of benzyl alcohol was size of gold nanoparticles. The highest conversion of the alcohol was observed for the catalyst containing the smallest Au particle size (i.e., Au-CeO2 nanocomposite prepared with the use of NaOH as a co-precipitation agent). Full article
(This article belongs to the Special Issue Advance in Selective Alcohol and Polyol Oxidation Catalysis)
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Article
A Three-Component Hybrid Templated by Asymmetric Viologen Exhibiting Visible-Light-Driven Photocatalytic Degradation on Dye Pollutant in Maritime Accident Seawater
Catalysts 2021, 11(5), 640; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050640 - 18 May 2021
Viewed by 563
Abstract
The increasing dangerous chemical pollutants led by shipping accidents call for the new pollutant treatment strategy. In this work, a new three-component hybrid {[(BiI6)I13]·2I3·(H-BPA)4}n (1) can be used in dye degradation in [...] Read more.
The increasing dangerous chemical pollutants led by shipping accidents call for the new pollutant treatment strategy. In this work, a new three-component hybrid {[(BiI6)I13]·2I3·(H-BPA)4}n (1) can be used in dye degradation in seawater. The highly interesting feature of 1 lies in its unique 1-D Z-shape [(BiI6)I13]n6− infinite chain constructed from the I···I contacts between mono-nuclear (BiI6)3− anions and I133− polyiodide anions. Finally, the hydrogen bonds between [(BiI6)I13]n6− polyanions and H-BPA2+ cations contribute to the formation a quasi-3-D network. Specifically, 1 exhibits the wide absorption zone from ultraviolet to visible regions and high charge-separation efficiency, hinting its application in visible-light catalysis. As expected, 1 represents photocatalytic activity for the degradation of rhodamine B in seawater with degradation ratio of 90%, and the photocatalytic performance is stable. This work might provide new photocatalytic material for pollutant treatment in shipping accidents. Full article
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Article
Enzymatic Polymerization of Dihydroquercetin (Taxifolin) in Betaine-Based Deep Eutectic Solvent and Product Characterization
Catalysts 2021, 11(5), 639; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050639 - 17 May 2021
Viewed by 607
Abstract
Deep eutectic solvents (DESs) are an alternative to conventional organic solvents in various biocatalytic reactions. Meanwhile, there have been few studies reporting on synthetic reactions in DESs or DES-containing mixtures involving oxidoreductases. In this work, we have studied the effects of several DESs [...] Read more.
Deep eutectic solvents (DESs) are an alternative to conventional organic solvents in various biocatalytic reactions. Meanwhile, there have been few studies reporting on synthetic reactions in DESs or DES-containing mixtures involving oxidoreductases. In this work, we have studied the effects of several DESs based on betaine as the acceptor of hydrogen bonds on the catalytic activity and stability of laccase from the basidial fungus Trametes hirsuta and performed enzymatic polymerization of the flavonoid dihydroquercetin (DHQ, taxifolin) in a DES–buffer mixture containing 60 vol.% of betaine-glycerol DES (molar ratio 1:2). The use of the laccase redox mediator TEMPO enabled an increased yield of DHQ oligomers (oligoDHQ), with a number average molecular weight of 1800 g mol−1 and a polydispersity index of 1.09. The structure of the synthesized product was studied using different physicochemical methods. NMR spectroscopy showed that oligoDHQ had a linear structure with an average chain length of 6 monomers. A scheme for enzymatic polymerization of DHQ in a DES–buffer mixture was also proposed. Full article
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Review
Recent Advances in Nucleic Acid Modulation for Functional Nanozyme
Catalysts 2021, 11(5), 638; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050638 - 17 May 2021
Viewed by 552
Abstract
Nanozymes have the potential to replace natural enzymes, so they are widely used in energy conversion technologies such as biosensors and signal transduction (converting biological signals of a target into optical, electrical, or metabolic signals). The participation of nucleic acids leads nanozymes to [...] Read more.
Nanozymes have the potential to replace natural enzymes, so they are widely used in energy conversion technologies such as biosensors and signal transduction (converting biological signals of a target into optical, electrical, or metabolic signals). The participation of nucleic acids leads nanozymes to produce richer interface effects and gives energy conversion events more attractive characteristics, creating what are called “functional nanozymes”. Since different nanozymes have different internal structures and external morphological characteristics, functional modulation needs to be compatible with these properties, and attention needs to be paid to the influence of nucleic acids on nanozyme activity. In this review, “functional nanozymes” are divided into three categories, (nanozyme precursor ion)/ (nucleic acid) self-assembly, nanozyme-nucleic acid irreversible binding, and nanozyme-nucleic acid reversible binding, and the effects of nucleic acids on modulation principles are summarized. Then, the latest developments of nucleic acid-modulated nanozymes are reviewed in terms of their use in energy conversion technology, and their conversion mechanisms are critically discussed. Finally, we outline the advantages and limitations of “functional nanozymes” and discuss the future development prospects and challenges in this field. Full article
(This article belongs to the Special Issue State of the Art and Future Trends in Nanostructured Biocatalysis)
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Article
Visible-Light Enhanced Catalytic Wet Peroxide Oxidation of Natural Organic Matter in the Presence of Al/Fe-Pillared Clay
Catalysts 2021, 11(5), 637; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050637 - 16 May 2021
Viewed by 560
Abstract
An Al/Fe-pillared clay catalyst (Al/Fe-PILC) prepared from low cost technical-grade reagents has been investigated in the photocatalytic Wet Peroxide Oxidation (photo-CWPO) of dissolved Natural Organic Matter (NOM) under circumneutral pH. The successful pillaring of the layered clay material was confirmed by X-ray diffraction [...] Read more.
An Al/Fe-pillared clay catalyst (Al/Fe-PILC) prepared from low cost technical-grade reagents has been investigated in the photocatalytic Wet Peroxide Oxidation (photo-CWPO) of dissolved Natural Organic Matter (NOM) under circumneutral pH. The successful pillaring of the layered clay material was confirmed by X-ray diffraction (XRD), N2 adsorption at −196 °C, cation exchange capacity (CEC) and simultaneous thermal analysis (TGA/DSC). High levels of mineralization of the dissolved organic carbon and color removal of a synthetic NOM surrogate solution were achieved even under natural lab’s lighting and ambient temperature and pressure, whereas the absence of radiation (in dark) was found to strongly affect the performance of the degradation. The photo-CWPO of NOM activated by the Al/Fe-PILC clay catalyst under visible light irradiation (LED lamp, 450 and 550 nm peaks) displayed a DOC mineralization of 72% and color removal of 73% in just 210 min of irradiation at neutral pH, whereas both responses decayed under ultraviolet lightning (λ: 365 nm) to 41% and 58%, respectively. This behavior is ascribed to formation of triplet states of natural organic matter (3NOM*) by absorption of visible light, which seems to synergistically improve the rate-determining step of the heterogeneous Fenton process, namely reduction of Fe3+ into Fe2+ on the surface of the clay catalyst. Interestingly, experiments performed at neutral and pH 3.0 showed very similar efficiencies under visible light irradiation; these findings may really facilitate the application of the photo-CWPO process to assist conventional drinking water treatment plants in the removal of NOM before the typical disinfection by chlorine to produce safer drinking water. Full article
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Article
Hydrothermal Sintering and Oxidation of an Alumina-Supported Nickel Methanation Catalyst Studied Using In Situ Magnetometry
Catalysts 2021, 11(5), 636; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050636 - 16 May 2021
Viewed by 503
Abstract
The presented study investigated the effects of temperature (350–650 °C) and gas environment (pure Ar versus a H2O/H2 partial pressure ratio (PH2O/PH2) of 5) on the extent of sintering and oxidation of Al2O3 [...] Read more.
The presented study investigated the effects of temperature (350–650 °C) and gas environment (pure Ar versus a H2O/H2 partial pressure ratio (PH2O/PH2) of 5) on the extent of sintering and oxidation of Al2O3-supported Ni0 nanoparticles (≈4 nm). We note that a PH2O/PH2 of 5 corresponds to a simulated CO conversion of 94% during methanation. Sintering and oxidation were studied using in situ magnetometry, while ex situ TEM analyses confirmed the particle sizes before and after the magnetometry-based experiments. It was found that increasing the temperature from 350 to 650 °C in Ar at atmospheric pressure causes a negligible change to the average size and degree of reduction (DOR) of the starting Ni0 nanoparticles. However, studying the same temperature window under hydrothermal conditions at 10 bar causes significant particle growth (≈9 nm) and the development of a bimodal distribution. Furthermore, the presence of steam decreases the DOR of Ni0 from 86.2% after initial activation to 22.2% due to oxidation. In summary, this study reports on the expected sintering and oxidation of Ni-based catalysts under high CO conversion conditions at elevated temperatures during methanation. Importantly, we were able to demonstrate how magnetometry-based analyses can provide similar size information (and changes thereof) as those observed with TEM but with the added advantage that this information can be obtained in situ. Full article
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Article
The Impact of Lanthanum and Zeolite Structure on Hydrocarbon Storage
Catalysts 2021, 11(5), 635; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050635 - 15 May 2021
Viewed by 608
Abstract
Hydrocarbon traps can be used to bridge the temperature gap from the cold start of a vehicle until the exhaust after-treatment catalyst has reached its operating temperature. In this work, we investigate the effect of zeolite structure (ZSM-5, BEA, SSZ-13) and the effect [...] Read more.
Hydrocarbon traps can be used to bridge the temperature gap from the cold start of a vehicle until the exhaust after-treatment catalyst has reached its operating temperature. In this work, we investigate the effect of zeolite structure (ZSM-5, BEA, SSZ-13) and the effect of La addition to H-BEA and H-ZSM-5 on the hydrocarbon storage capacity by temperature-programmed desorption and DRIFT spectroscopy. The results show that the presence of La has a significant effect on the adsorption characteristics of toluene on the BEA-supported La materials. A low loading of La onto zeolite BEA (2% La-BEA) improves not only the toluene adsorption capacity but also the retention of toluene. However, a higher loading of La results in a decrease in the adsorbed amount of toluene, which likely is due to partial blocking of the pore of the support. High loadings of La in BEA result in a contraction of the unit cell of the zeolite as evidenced by XRD. A synergetic effect of having simultaneously different types of hydrocarbons (toluene, propene, and propane) in the feed is found for samples containing ZSM-5, where the desorption temperature of propane increases, and the quantity that desorbed increases by a factor of four. This is found to be due to the interaction between toluene and propane inside the structure of the zeolite. Full article
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Article
Kinetic Study of 17α-Estradiol Activity in Comparison with 17β-Estradiol and 17α-Ethynylestradiol
Catalysts 2021, 11(5), 634; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050634 - 14 May 2021
Viewed by 537
Abstract
17α-estradiol (αE2), an endogenous stereoisomer of the hormone 17β-estradiol (E2), is capable of binding to estrogen receptors (ER). We aimed to mathematically describe, using experimental data, the possible interactions between αE2 and sperm ER during the process of sperm capacitation and to develop [...] Read more.
17α-estradiol (αE2), an endogenous stereoisomer of the hormone 17β-estradiol (E2), is capable of binding to estrogen receptors (ER). We aimed to mathematically describe, using experimental data, the possible interactions between αE2 and sperm ER during the process of sperm capacitation and to develop a kinetic model. The goal was to compare the suggested kinetic model with previously published results of ER interactions with E2 and 17α-ethynylestradiol (EE2). The HPLC-MS/MS method was developed to monitor the changes of αE2 concentration during capacitation. The calculated relative concentrations Bt were used for kinetic analysis. Rate constants k and molar ratio n were optimized and used for the construction of theoretical B(t) curves. Modifications in αE2–ER interactions were discovered during comparison with models for E2 and EE2. These new interactions displayed autocatalytic formation of an unstable adduct between the hormone and the cytoplasmic receptors. αE2 accumulates between the plasma membrane lipid bilayer with increasing potential, and when the critical level is reached, αE2 penetrates through the inner layer of the plasma membrane into the cytoplasm. It then rapidly reacts with the ER and creates an unstable adduct. The revealed dynamics of αE2–ER action may contribute to understanding tissue rejuvenation and the cancer-related physiology of αE2 signaling. Full article
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Article
Characterization and Structure Elucidation of Binary Zr:Ti MEL Structure; Simultaneous Photodegradation/Removal of Organic–Inorganic Pollutants
Catalysts 2021, 11(5), 633; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050633 - 14 May 2021
Viewed by 476
Abstract
The preparation of a series of different Ti/Zr MEL structure was performed successfully. Full characterization of the prepared materials was done using XRD, IR, DR, and SEM. The results show that the prepared materials contain only one crystalline phase (ZSM-11). The affinity of [...] Read more.
The preparation of a series of different Ti/Zr MEL structure was performed successfully. Full characterization of the prepared materials was done using XRD, IR, DR, and SEM. The results show that the prepared materials contain only one crystalline phase (ZSM-11). The affinity of Zr to form the crystalline phase alone in a binary Zr/Ti synthesizing mixture was approved by SEM and elemental analysis results. The percentage of each active site was calculated. DR spectra were deconvoluted, and three active sites were supposed and quantified (tetragonal, octahedral, and crystalline). The mutual effect of ions (lead, copper, cobalt, and nickel) and methylene blue dye on the removal efficiency with and without ultraviolet irradiation was examined and fully characterized. The ions largely influence the photodegradation process, and a mechanism was formulated. Meanwhile, the presence of dye showed a negligible effect on the removal of ions. Full article
(This article belongs to the Special Issue Catalysts for Advanced Synthesis)
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Article
Ionic Liquid-Derived Carbon-Supported Metal Electrocatalysts as Anodes in Direct Borohydride-Peroxide Fuel Cells
Catalysts 2021, 11(5), 632; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050632 - 14 May 2021
Viewed by 580
Abstract
Three different carbon-supported metal (gold, platinum, nickel) nanoparticle (M/c-IL) electrocatalysts are prepared by template-free carbonization of the corresponding ionic liquids, namely [Hmim][AuCl4], [Hmim]2[PtCl4], and [C16mim]2[NiCl4], as confirmed by X-ray diffraction analysis, [...] Read more.
Three different carbon-supported metal (gold, platinum, nickel) nanoparticle (M/c-IL) electrocatalysts are prepared by template-free carbonization of the corresponding ionic liquids, namely [Hmim][AuCl4], [Hmim]2[PtCl4], and [C16mim]2[NiCl4], as confirmed by X-ray diffraction analysis, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy and Raman spectroscopy. The electrochemical investigation of borohydride oxidation reaction (BOR) at the three electrocatalysts by cyclic voltammetry reveals different behavior for each material. BOR is found to be a first-order reaction at the three electrocatalysts, with an apparent activation energy of 10.6 and 13.8 kJ mol−1 for Pt/c-IL and Au/c-IL electrocatalysts, respectively. A number of exchanged electrons of 5.0, 2.4, and 2.0 is obtained for BOR at Pt/c-IL, Au/c-IL, and Ni/c-IL electrodes, respectively. Direct borohydride-peroxide fuel cell (DBPFC) tests done at temperatures in the 25–65 °C range show ca. four times higher power density when using a Pt/c-IL anode than with an Au/c-IL anode. Peak power densities of 40.6 and 120.5 mW cm−2 are achieved at 25 and 65 °C, respectively, for DBPFC with a Pt/c-IL anode electrocatalyst. Full article
(This article belongs to the Special Issue Innovative Electrocatalysts for Fuel Cell and Battery Applications)
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Article
Alternative Routes for the Production of Natural 4-Vinylguaiacol from Sugar Beet Fiber Using Basidiomycetous Enzymes
Catalysts 2021, 11(5), 631; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050631 - 14 May 2021
Cited by 1 | Viewed by 467
Abstract
Traditional smoking generates not only the impact flavor compound 4-vinylguaiacol, but concurrently many unwanted and potent toxic compounds such as polycyclic aromatic hydrocarbons. Enzyme technology provides a solution without any side-product formation. A feruloyl esterase from Rhizoctonia solani (RspCAE) liberated ferulic acid from [...] Read more.
Traditional smoking generates not only the impact flavor compound 4-vinylguaiacol, but concurrently many unwanted and potent toxic compounds such as polycyclic aromatic hydrocarbons. Enzyme technology provides a solution without any side-product formation. A feruloyl esterase from Rhizoctonia solani (RspCAE) liberated ferulic acid from low-priced sugar beet fiber. Decarboxylation of ferulic acid to 4-vinylguaiacol was achieved by a second enzyme from Schizophyllum commune (ScoFAD). Both enzymes were covalently immobilized on agarose to enable reusability in a fixed-bed approach. The two enzyme cascades showed high conversion rates with yields of 0.8 and 0.95, respectively, and retained activity for nearly 80 h of continuous operation. The overall productivity of the model process with bed volumes of 300 µL and a substrate flow rate of 0.25 mL min−1 was 3.98 mg 4-vinylguaiacol per hour. A cold online solid phase extraction using XAD4 was integrated into the bioprocess and provided high recovery rates during multiple elution steps. Attempting to facilitate the bioprocess, a fused gene coding for the two enzymes and a set of different linker lengths and properties was constructed and introduced into Komagataella phaffii. Longer and rigid linkers resulted in higher activity of the fusion protein with a maximum of 67 U L−1. Full article
(This article belongs to the Special Issue Enzyme Immobilization and Biocatalysis)
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Review
Waste Animal Bones as Catalysts for Biodiesel Production; A Mini Review
Catalysts 2021, 11(5), 630; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050630 - 13 May 2021
Cited by 1 | Viewed by 741
Abstract
Slaughterhouse waste is considered to be an emerging issue because of its disposal cost. As an alternative, it would be a great prospect for the bioeconomy society to explore new usages of these leftover materials. As per food safety rules mentioned by EU [...] Read more.
Slaughterhouse waste is considered to be an emerging issue because of its disposal cost. As an alternative, it would be a great prospect for the bioeconomy society to explore new usages of these leftover materials. As per food safety rules mentioned by EU legislation, all bone waste generated by slaughterhouses ought to be disposed of by rendering. The huge quantity of worldwide bone waste generation (130 billion kilograms per annum) is an environmental burden if not properly managed. The waste animal bones can be efficiently employed as a heterogeneous catalyst to produce biodiesel. This mini review summarized the recent literature reported for biodiesel generation using waste animal bones derived heterogeneous catalyst. It discusses the sources of bone waste, catalyst preparation methods, particularly calcination and its effects, and important characteristics of bones derived catalyst. It suggests that catalysts extracted from waste animal bones have suitable catalytic activity in transesterification of different oil sources to generate a good quality biodiesel. Full article
(This article belongs to the Special Issue Heterogeneous Catalysis in Green Chemistry)
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Review
Lipase Immobilization in Mesoporous Silica Nanoparticles for Biofuel Production
Catalysts 2021, 11(5), 629; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050629 - 13 May 2021
Cited by 1 | Viewed by 504
Abstract
Lipases are ubiquitous enzymes whose physiological role is the hydrolysis of triacylglycerol into fatty acids. They are the most studied and industrially interesting enzymes, thanks to their versatility to promote a plethora of reactions on a wide range of substrates. In fact, depending [...] Read more.
Lipases are ubiquitous enzymes whose physiological role is the hydrolysis of triacylglycerol into fatty acids. They are the most studied and industrially interesting enzymes, thanks to their versatility to promote a plethora of reactions on a wide range of substrates. In fact, depending on the reaction conditions, they can also catalyze synthesis reactions, such as esterification, acidolysis and transesterification. The latter is particularly important for biodiesel production. Biodiesel can be produced from animal fats or vegetable oils and is considered as a biodegradable, non-toxic and renewable energy source. The use of lipases as industrial catalysts is subordinated to their immobilization on insoluble supports, to allow multiple uses and use in continuous processes, but also to stabilize the enzyme, intrinsically prone to denaturation with consequent loss of activity. Among the materials that can be used for lipase immobilization, mesoporous silica nanoparticles represent a good choice due to the combination of thermal and mechanical stability with controlled textural characteristics. Moreover, the presence of abundant surface hydroxyl groups allows for easy chemical surface functionalization. This latter aspect has the main importance since lipases have a high affinity with hydrophobic supports. The objective of this work is to provide an overview of the recent progress of lipase immobilization in mesoporous silica nanoparticles with a focus on biodiesel production. Full article
(This article belongs to the Special Issue Enzyme Immobilization and Biocatalysis)
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Article
Highly Efficient MOF Catalyst Systems for CO2 Conversion to Bis-Cyclic Carbonates as Building Blocks for NIPHUs (Non-Isocyanate Polyhydroxyurethanes) Synthesis
Catalysts 2021, 11(5), 628; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050628 - 12 May 2021
Viewed by 842
Abstract
The present paper describes a greener sustainable route toward the synthesis of NIPHUs. We report a highly efficient solvent-free process to produce [4,4′-bi(1,3-dioxolane)]-2,2′-dione (BDC), involving CO2, as renewable feedstock, and bis-epoxide (1,3-butadiendiepoxide) using only metal–organic frameworks (MOFs) as catalysts and cetyltrimethyl-ammonium [...] Read more.
The present paper describes a greener sustainable route toward the synthesis of NIPHUs. We report a highly efficient solvent-free process to produce [4,4′-bi(1,3-dioxolane)]-2,2′-dione (BDC), involving CO2, as renewable feedstock, and bis-epoxide (1,3-butadiendiepoxide) using only metal–organic frameworks (MOFs) as catalysts and cetyltrimethyl-ammonium bromide (CTAB) as a co-catalyst. This synthetic procedure is evaluated in the context of reducing global emissions of waste CO2 and converting CO2 into useful chemical feedstocks. The reaction was carried out in a pressurized reactor at pressures of 30 bars and controlled temperatures of around 120–130 °C. This study examines how reaction parameters such as catalyst used, temperature, or reaction time can influence the molar mass, yield, or reactivity of BDC. High BDC reactivity is essential for producing high molar mass linear non-isocyanate polyhydroxyurethane (NIPHU) via melt-phase polyaddition with aliphatic diamines. The optimized Al-OH-fumarate catalyst system described in this paper exhibited a 78% GC-MS conversion for the desired cyclic carbonates, in the absence of a solvent and a 50 wt % chemically fixed CO2. The cycloaddition reaction could also be carried out in the absence of CTAB, although lower cyclic carbonate yields were observed. Full article
(This article belongs to the Special Issue Applications of Nanoporous Materials in Catalysis)
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Article
Atmospheric Pressure Tornado Plasma Jet of Polydopamine Coating on Graphite Felt for Improving Electrochemical Performance in Vanadium Redox Flow Batteries
Catalysts 2021, 11(5), 627; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050627 - 12 May 2021
Viewed by 498
Abstract
The intrinsic hydrophobicity of graphite felt (GF) is typically altered for the purpose of the surface wettability and providing active sites for the enhancement of electrochemical performance. In this work, commercial GF is used as the electrodes. The GF electrode with a coated-polydopamine [...] Read more.
The intrinsic hydrophobicity of graphite felt (GF) is typically altered for the purpose of the surface wettability and providing active sites for the enhancement of electrochemical performance. In this work, commercial GF is used as the electrodes. The GF electrode with a coated-polydopamine catalyst is achieved to enhance the electrocatalytic activity of GF for the redox reaction of vanadium ions in vanadium redox flow battery (VRFB). Materials characteristics proved that a facile coating via atmospheric pressure plasma jet (APPJ) to alter the surface superhydrophilicity and to deposit polydopamine on GF for providing the more active sites is feasibly achieved. Due to the synergistic effects of the presence of more active sites on the superhydrophilic surface of modified electrodes, the electrochemical performance toward VO2+/VO2+ reaction was evidently improved. We believed that using the APPJ technique as a coating method for electrocatalyst preparation offers the oxygen-containing functional groups on the substrate surface on giving a hydrogen bonding with the grafted functional polymeric materials. Full article
(This article belongs to the Special Issue Catalysts and Electrode Functionalization for Redox Flow Battery)
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Article
Photoelectrochemical Water Oxidation by Cobalt Cytochrome C Integrated-ATO Photoanode
Catalysts 2021, 11(5), 626; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050626 - 12 May 2021
Viewed by 728
Abstract
Here, we report the immobilization of Co-protoporphyrin IX (Co-PPIX) substituted cytochrome c (Co-cyt c) on Antimony-doped Tin Oxide (ATO) as a catalyst for photoelectrochemical oxidation of water. Under visible light irradiation (λ > 450 nm), the ATO-Co-cyt c photoanode displays ~6-fold enhancement [...] Read more.
Here, we report the immobilization of Co-protoporphyrin IX (Co-PPIX) substituted cytochrome c (Co-cyt c) on Antimony-doped Tin Oxide (ATO) as a catalyst for photoelectrochemical oxidation of water. Under visible light irradiation (λ > 450 nm), the ATO-Co-cyt c photoanode displays ~6-fold enhancement in photocurrent density relative to ATO-Co-PPIX at 0.25 V vs. RHE at pH 5.0. The light-induced water oxidation activity of the system was demonstrated by detecting evolved stoichiometric oxygen by gas chromatography, and incident photon to current efficiency was measured as 4.1% at 450 nm. The faradaic efficiency for the generated oxygen was 97%, with a 671 turnover number (TON) for oxygen. The current density had a slow decay over the course of 6 h of constant irradiation and applied potential, which exhibits the robustness of catalyst-ATO interaction. Full article
(This article belongs to the Special Issue Cobalt Catalysis: Recent Progress and Developments)
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Article
CuO-Fe2O3 Nanoparticles Supported on SiO2 and Al2O3 for Selective Hydrogenation of 2-Methyl-3-Butyn-2-ol
Catalysts 2021, 11(5), 625; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050625 - 12 May 2021
Viewed by 453
Abstract
In this study, novel SiO2- and Al2O3-supported Cu-Fe catalysts are developed for selective hydrogenation of 2-methyl-3-butyne-2-ol to 2-methyl-3-butene-2-ol under mild reaction conditions. TEM, XRD, and FTIR studies of adsorbed CO and TPR-H2 are performed to characterize [...] Read more.
In this study, novel SiO2- and Al2O3-supported Cu-Fe catalysts are developed for selective hydrogenation of 2-methyl-3-butyne-2-ol to 2-methyl-3-butene-2-ol under mild reaction conditions. TEM, XRD, and FTIR studies of adsorbed CO and TPR-H2 are performed to characterize the morphology, nanoparticle size, and particle distribution, as well as electronic state of deposited metals in the prepared catalysts. The deposition of Fe and Cu metal particles on the aluminum oxide carrier results in the formation of a mixed oxide phase with a strong interaction between the Fe and Cu precursors during the calcination. The highly dispersed nanoparticles of Fe2O3 and partially reduced CuOx, with an average size of 3.5 nm and with strong contact interactions between the metals in 5Cu-5Fe/Al2O3 catalysts, provide a high selectivity of 93% toward 2-methyl-3-butene-2-ol at complete conversion of the unsaturated alcohol. Full article
(This article belongs to the Special Issue Mono- and Bimetallic Nanoparticles in Catalysis)
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Article
Photocatalytic Degradation of Sulfolane Using a LED-Based Photocatalytic Treatment System
Catalysts 2021, 11(5), 624; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050624 - 12 May 2021
Cited by 3 | Viewed by 449
Abstract
Sulfolane is an emerging industrial pollutant detected in the environments near many oil and gas plants in North America. So far, numerous advanced oxidation processes have been investigated to treat sulfolane in aqueous media. However, there is only a few papers that discuss [...] Read more.
Sulfolane is an emerging industrial pollutant detected in the environments near many oil and gas plants in North America. So far, numerous advanced oxidation processes have been investigated to treat sulfolane in aqueous media. However, there is only a few papers that discuss the degradation of sulfolane using photocatalysis. In this study, photocatalytic degradation of sulfolane using titanium dioxide (TiO2) and reduced graphene oxide TiO2 composite (RGO-TiO2) in a light-emitting diode (LED) photoreactor was investigated. The impact of different waters (ultrapure water, tap water, and groundwater) and type of irradiation (UVA-LED and mercury lamp) on photocatalytic degradation of sulfolane were also studied. In addition, a reusability test was conducted for the photocatalyst to examine the degradation of sulfolane in three consecutive cycles with new batches of sulfolane-contaminated water. The results show that LED-based photocatalysis was effective in degrading sulfolane in waters even after three photocatalytic cycles. UVA-LEDs displayed more efficient use of photon energy when compared with the mercury lamps as they have a narrow emission spectrum coinciding with the absorption of TiO2. The combination of UVA-LED and TiO2 yielded better performance than UVA-LED and RGO-TiO2 for the degradation of sulfolane. Much lower sulfolane degradation rates were observed in tap water and groundwater than ultrapure water. Full article
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Article
Electrocatalysis for Oxygen Reduction Reaction on EDTAFeNa and Melamine co-Derived Self-Supported Fe-N-C Materials
Catalysts 2021, 11(5), 623; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050623 - 12 May 2021
Viewed by 490
Abstract
To explore high-performing alternatives to platinum-based catalysts is highly desirable for lowering costs and thus promoting fuel cell commercialization. Herein, self-supported Fe-N-C materials were prepared by the pyrolysis of dual precursors including EDTA ferric sodium (EDTAFeNa) and melamine (MA), followed by acid-leaching and [...] Read more.
To explore high-performing alternatives to platinum-based catalysts is highly desirable for lowering costs and thus promoting fuel cell commercialization. Herein, self-supported Fe-N-C materials were prepared by the pyrolysis of dual precursors including EDTA ferric sodium (EDTAFeNa) and melamine (MA), followed by acid-leaching and final annealing. Towards an oxygen reduction reaction (ORR) in 0.1 M KOH, the as-prepared MA/EDTAFeNa-HT2 delivered onset (Eonset) and half-wave (E1/2) potentials of 0.97 and 0.84 V vs. RHE, respectively, identical with that of a state-of-the-art Pt/C catalyst, accompanied with predominantly a four-electron pathway. The introduction of MA and extension of acid-leaching promoted a positive shift of 50 mV for E1/2 relative to that of only the EDTAFeNa-derived counterpart. It was revealed that the enhancement of ORR activity is attributed to a decrease in magnetic Fe species and increase in pyridinic/quanternary nitrogen content whilst nearly excluding effects of the graphitization degree, variety of crystalline iron species, and mesoscopic structure. The usage of dual precursors exhibited great potential for the large-scale production of inexpensive and efficient Fe-N-C materials. Full article
(This article belongs to the Special Issue Electro-Catalysts for Energy Conversion and Storage Devices)
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Review
A Review on the Catalytic Decomposition of NO by Perovskite-Type Oxides
Catalysts 2021, 11(5), 622; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050622 - 12 May 2021
Viewed by 483
Abstract
Direct catalytic decomposition of NO has the advantages of being a simple process, producing no secondary pollution, and being good for the economy, which has attracted extensive research in recent years. Perovskite-type mixed oxides, with an ABO3 or A2BO4 [...] Read more.
Direct catalytic decomposition of NO has the advantages of being a simple process, producing no secondary pollution, and being good for the economy, which has attracted extensive research in recent years. Perovskite-type mixed oxides, with an ABO3 or A2BO4 structure, are promising materials as catalysts for NO decomposition due to their low cost, high thermal stability, and, of course, their good catalytic performances. In this review, the influence factors, such as A-site substitution, B-site substitution and reaction conditions on the catalytic performance of catalysts have been expounded. The reaction mechanisms of direct NO decomposition are also discussed. Finally, major conclusions are drawn and some research challenges are highlighted. Full article
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Article
The Isocyanurate-Carbamate-Bridged Hybrid Mesoporous Organosilica: An Exceptional Anchor for Pd Nanoparticles and a Unique Catalyst for Nitroaromatics Reduction
Catalysts 2021, 11(5), 621; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050621 - 12 May 2021
Viewed by 502
Abstract
Hybridisation of mesoporous organosilicas (MO) to reinforce the surface capability in adsorption and stabilisation of noble metal nanoparticles is of great attention in generating/supporting noble metal within their matrices and transforming them into efficient heterogeneous catalysts. Here, we used a unique hybrid of [...] Read more.
Hybridisation of mesoporous organosilicas (MO) to reinforce the surface capability in adsorption and stabilisation of noble metal nanoparticles is of great attention in generating/supporting noble metal within their matrices and transforming them into efficient heterogeneous catalysts. Here, we used a unique hybrid of organic-inorganic mesoporous silica in which pore profile pattern was similar to the well-known mesoporous silica, SBA-15 for catalysis. This hybrid mesoporous organosilica was further engaged as a support in the synthesis and stabilisation of Pd nanoparticles on its surface, and then, the obtained Pd-supported MO was employed as a heterogeneous green catalyst in the conversion of aqueous p-nitrophenol (PNP) to p-aminophenol (PAP) at room temperature with efficient recyclability. Full article
(This article belongs to the Special Issue Nanoporous and Layered Materials in (Photo)(Bio)Catalysis)
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Review
Isoquinolone Syntheses by Annulation Protocols
Catalysts 2021, 11(5), 620; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050620 - 11 May 2021
Viewed by 496
Abstract
Isoquinolones (isoquinolin-1(2H)-ones) are one of the important nitrogen-heterocyclic compounds having versatile biological and physiological activities, and their synthetic methods have been recently developed greatly. This short review illustrates the significant advances in the construction of isoquinolone ring with atom- and step-economy, [...] Read more.
Isoquinolones (isoquinolin-1(2H)-ones) are one of the important nitrogen-heterocyclic compounds having versatile biological and physiological activities, and their synthetic methods have been recently developed greatly. This short review illustrates the significant advances in the construction of isoquinolone ring with atom- and step-economy, focusing on the intermolecular annulation protocols and intramolecular cyclization in the presence of a variety of catalyst systems. The syntheses of isoquinolone-fused rings are also included. Full article
(This article belongs to the Special Issue Catalysts for the Synthesis of Heterocyclic Compounds)
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Article
Steel Slag as New Catalyst for the Synthesis of Fames from Soybean Oil
Catalysts 2021, 11(5), 619; https://0-doi-org.brum.beds.ac.uk/10.3390/catal11050619 - 11 May 2021
Viewed by 429
Abstract
For the first time, secondary steel slag, the material directly coming from ladle treatments, is used as a catalyst for the biodiesel production without undergoing any preliminary chemical or thermal modifications. Catalytic material 1, which has been pre-ground to sizes below 230 [...] Read more.
For the first time, secondary steel slag, the material directly coming from ladle treatments, is used as a catalyst for the biodiesel production without undergoing any preliminary chemical or thermal modifications. Catalytic material 1, which has been pre-ground to sizes below 230 mesh, has been characterized for the surface textural properties and used as a catalyst in the transesterification of triglycerides of soybean oil to produce biodiesel. Reaction conditions were optimized by DOE method, revealing no interdependence between reaction parameters and results, and showed a catalytic activity comparable with that of an analogous slag-deriving catalyst reported in the literature. Full article
(This article belongs to the Special Issue Bioeconomy Driven Catalytic Reactions)
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