Chemistry Proceedings

Other

343 KiB

Open AccessProceeding Paper

Noble Metals-Based Catalysts for Hydrogen Production via Bioethanol Reforming in a Fluidized Bed Reactor

by Concetta Ruocco, Vincenzo Palma, Marta Cortese and Marco Martino

Chem. Proc. 2020, 2(1), 1; https://doi.org/10.3390/ECCS2020-07543 - 9 Nov 2020

Cited by 1 | Viewed by 1199

In this work, Pt-Ni/CeO₂-SiO_2, as well as Ru-Ni/CeO₂-SiO₂ catalysts, were obtained at different loadings of the noble metal (in the interval 0–3 wt%) and tested for oxidative steam reforming of ethanol. Stability performance was evaluated at 500 [...] Read more.

In this work, Pt-Ni/CeO₂-SiO_2, as well as Ru-Ni/CeO₂-SiO₂ catalysts, were obtained at different loadings of the noble metal (in the interval 0–3 wt%) and tested for oxidative steam reforming of ethanol. Stability performance was evaluated at 500 °C for 25 h under a steam to ethanol ratio of 4 and an oxygen to ethanol ratio of 0.5. The weight hourly space velocity was fixed to 60 h⁻¹, which is considerably higher than the typical values selected for such processes. All the catalysts deactivated with time-on-stream, due to the severe operative conditions selected. However, the highest ethanol conversion (above 95%) and hydrogen yield (30%) at the end of the test were recorded over the 2 wt%Pt-10 wt%Ni/CeO₂-SiO₂ catalyst, which also displayed a limited carbon formation rate (1.5 × 10⁻⁶ g_coke·g_catalyst⁻¹·g_carbon,fed⁻¹·h⁻¹, reduced almost 5 times compared to the samples that had a Pt or Ru content of 0.5 wt%). Thus, the latter catalyst was identified as a promising candidate for future tests under real bioethanol mixture. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

1063 KiB

Open AccessProceeding Paper

Electrocatalysis of Ethanol and Methanol Electrooxidation by Composite Electrodes with NiOOH/FeOOH Supported on Reduced Graphene Oxide onto Composite Electrodes

by João Pedro Jenson de Oliveira, Acelino Cardoso de Sá and Leonardo Lataro Paim

Chem. Proc. 2020, 2(1), 2; https://doi.org/10.3390/ECCS2020-07523 - 9 Nov 2020

Cited by 1 | Viewed by 1301

Abstract

This paper presents graphite/paraffin composite electrodes modified with microparticles of nickel (Ni) and Ni-Fe alloy anchored in reduced graphene oxide (rGO); these electrodes were made by electrosynthesis. Firstly, the electrodeposition of reduced graphene oxide was made by cyclic voltammetry (CV) onto the graphite/paraffin [...] Read more.

This paper presents graphite/paraffin composite electrodes modified with microparticles of nickel (Ni) and Ni-Fe alloy anchored in reduced graphene oxide (rGO); these electrodes were made by electrosynthesis. Firstly, the electrodeposition of reduced graphene oxide was made by cyclic voltammetry (CV) onto the graphite/paraffin electrodes’ surface. After electrodeposition of the rGO, iron and nickel were electrodeposited by CV with successive scans. Finally, the formation of iron-nickel oxyhydroxide on the electrode surface was performed by cyclic voltammetry in alkaline medium. The composites were investigated by field emission gun scanning electron microscopy (FEG-SEM); it was observed that the Ni microparticles had spherical shapes, while the Ni-Fe alloy did not present a defined shape. The composite electrodes were used to analysis ethanol and methanol electrooxidation in an alkaline medium of 0.10 mol L⁻¹ of NaOH in a potential range of from −0.20 to 1.0 V (vs. Ag/AgCl) at 50 mV s⁻¹ by CV. The electrodes were able to make the electrooxidation of ethanol at a potential of around 0.57 V for the electrode constituted by the Ni-Fe alloy and around 0.61 V for the electrode modified with Ni, and for methanol in a potential around 0.57 V for the Ni-Fe alloy and around 0.66 V for the Ni electrode. The Ni-Fe alloy electrodes showed the electrocatalysis of the alcohols in relation to Ni electrodes. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

725 KiB

Open AccessProceeding Paper

Selection of the Optimal Medium for Adsorption of Plant Proteases

by Victoria Koroleva, Svetlana Olshannikova, Marina Holyavka, Alexander Pashkov and Valeriy Artyukhov

Chem. Proc. 2020, 2(1), 3; https://doi.org/10.3390/ECCS2020-07525 - 9 Nov 2020

Viewed by 1042

Abstract

Immobilized enzymes are the most sought-after preparations in the global market. They are used in medicine, veterinary medicine, the food industry, winemaking and brewing. The simplest method for immobilizing biocatalysts on insoluble carriers is the simple adsorption method. Its advantage is that it [...] Read more.

Immobilized enzymes are the most sought-after preparations in the global market. They are used in medicine, veterinary medicine, the food industry, winemaking and brewing. The simplest method for immobilizing biocatalysts on insoluble carriers is the simple adsorption method. Its advantage is that it preserves the natural conformation of the enzyme, which slightly reduces its catalytic ability compared to the native form. In our study, we carried out the selection of optimal conditions for adsorption immobilization of acid-soluble chitosan (Mr = 350 kDa) enzymes of plant origin (ficin, papain and bromelain) on a matrix. Ficin (EC 3.4.22.3), papain (EC 3.4.22.2) and bromelain (EC 3.4.22.4) (Sigma) were chosen as the objects of study, azocasein (Sigma) was used as a substrate for hydrolysis and an acid-soluble high-molecular-weight chitosan (350 kDa) was used as an immobilization matrix, synthesized by Bioprogress CJSC. Suitable buffer systems for immobilization were identified by the optimal ratio of protein content and total and specific activity. Ficin is immobilized on a chitosan matrix using glycine buffer with a pH of 8.6. Glycine buffer with a pH of 8.6–10.5 is an optimal medium for sorption of papain on chitosan. Bromelain is immobilized on a chitosan matrix under Tris-glycine buffer with pH 8.5 conditions. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

1165 KiB

Open AccessProceeding Paper

Distribution of Charged and Hydrophobic Amino Acids on the Surfaces of Two Types of Beta-Fructosidase from Thermotoga Maritima

by Farkhat Sakibaev, Marina Holyavka, Victoria Koroleva and Valeriy Artyukhov

Chem. Proc. 2020, 2(1), 4; https://doi.org/10.3390/ECCS2020-07550 - 9 Nov 2020

Viewed by 997

Abstract

Thermotoga maritima beta-fructosidases are enzymes that release beta-D-fructose from sucrose, raffinose, and fructan polymers such as inulin. The surfaces of beta-fructosidases 1UYP and 1W2T from Thermotoga maritima were studied in this work. It was showed that amino acids are not distributed equally on [...] Read more.

Thermotoga maritima beta-fructosidases are enzymes that release beta-D-fructose from sucrose, raffinose, and fructan polymers such as inulin. The surfaces of beta-fructosidases 1UYP and 1W2T from Thermotoga maritima were studied in this work. It was showed that amino acids are not distributed equally on the surfaces of the enzymes. Several clusters of charged and hydrophobic residues were detected at pH 7.0. Such clusters were detected by calculation of the distances between them. It was determined that on surfaces of beta-fructosidases PDB ID: 1UYP and PDB ID: 1W2T, 96% and 95% of charged amino acids and also 50% and 42% of hydrophobic amino acids form clusters, respectively. Six clusters of charged amino acids on the surface of beta-fructosidase 1UYP and five clusters on the surface of beta-fructosidase 1W2T were detected. The composition of such clusters is presented. Both types of beta-fructosidase have three clusters of hydrophobic amino acids on their surface. These facts should be considered when choosing immobilization conditions. It was shown that a charged matrix is more promising for the immobilization of beta-fructosidases 1UYP and 1W2T from Thermotoga maritima due to the possibility of binding without any significant loss of activity due to their overlapping active center. Hydrophobic carriers are less promising due to the probable active site overlap. Such binding may have a loss of enzyme activity as a result. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

346 KiB

Open AccessProceeding Paper

Divers Transformations Leading to New Potent GPx Mimetics

by Jacek Ścianowski, Agata J. Pacuła-Miszewska, Magdalena Obieziurska-Fabisiak and Anna Laskowska

Chem. Proc. 2020, 2(1), 5; https://doi.org/10.3390/ECCS2020-07546 - 9 Nov 2020

Viewed by 928

Abstract

Designing a highly active and selective Se-therapeutic that mimics the activity of the antioxidant enzyme glutathione peroxidase (GPx) still remains a challenge. Since the discovery of ebselen (N-phenyl-1,2-benzisoselenazol-3(2H)-one) and its ability to act as a GPx mimetic, the search for more [...] Read more.

Designing a highly active and selective Se-therapeutic that mimics the activity of the antioxidant enzyme glutathione peroxidase (GPx) still remains a challenge. Since the discovery of ebselen (N-phenyl-1,2-benzisoselenazol-3(2H)-one) and its ability to act as a GPx mimetic, the search for more effective peroxide scavengers has become a “hot topic” in this field of research. Herein, we present several modifications of the benzisoselenazolone core that enable improving the antioxidant and anticancer potential of the basic ebselen structure. These transformations include (a) the installation of chiral terpene skeletons, from p-menthane, pinane, and carane systems, on the nitrogen atom; (b) exchange of the carbonyl oxygen atom for sulfur to obtain thiocarbonyl derivatives; (c) oxidation of the selenium moiety resulting in a series of benzenoselenenic acids and their further transformation to corresponding water-soluble potassium salts; and (d) attachment of an additional phenyl group leading to variously N-substituted unsymmetrical phenylselenides with an o-amido function. All of the synthetized compounds were tested as antioxidants and antiproliferative agents. Conclusions concerning the structure–activity correlation, including the difference in the reactivity of specific Se-moieties (-Se-N-, -SeOOH, -SeOOK, -SePh), N-substituents (the influence of bulky aliphatic moiety and the three-dimensional orientation of atoms), and incorporated heteroatoms (-C=O, -C=S) are presented. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Scheme 1

383 KiB

Open AccessProceeding Paper

Paradoxical Behavior of Organodiselenides: Pro-Oxidant to Antioxidant

by Vishwa V. Gandhi, K. I. Priyadarsini and A. Kunwar

Chem. Proc. 2020, 2(1), 6; https://doi.org/10.3390/ECCS2020-07552 - 9 Nov 2020

Cited by 1 | Viewed by 1045

Abstract

Over the years, organodiselenides have emerged as the biologically relevant class of molecules. On the one hand, such compounds are known for pro-oxidant effects leading to toxicity in biological systems. On the other hand, there are growing evidences about their bio-mimetic activities as [...] Read more.

Over the years, organodiselenides have emerged as the biologically relevant class of molecules. On the one hand, such compounds are known for pro-oxidant effects leading to toxicity in biological systems. On the other hand, there are growing evidences about their bio-mimetic activities as catalysts such as glutathione peroxidase (GPx)-like activity. Our recent work has explored this paradoxical behavior of diselenides in developing antioxidants and/or anticancer agents. For this purpose, a number of alkyl and aryl diselenides have been evaluated in different biological models. The results have shown that aryl diselenides, in particular pyridinediselenides, altered the ratio of the intracellular thiol redox pairs of glutathione (GSH) and glutathione disulfide (GSSG) towards reduction (antioxidant) rather than oxidation (pro-oxidant) to protect normal cells against radiation damage and to induce cytotoxicity in tumor cells. Further, these studies have also postulated that the intracellular redox state, the level of thioredoxin reductase (TrxR), and reductive intermediates (e.g., selenol and/or selone) might play a very important role in the manifestation of the toxicities of aryl diselenides in cells. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

513 KiB

Open AccessProceeding Paper

Covalent Immobilization of Thiol Proteinases on Chitosan

by Svetlana Olshannikova, Victoria Koroleva, Marina Holyavka, Alexander Pashkov and Valeriy Artyukhov

Chem. Proc. 2020, 2(1), 7; https://doi.org/10.3390/ECCS2020-07527 - 9 Nov 2020

Cited by 2 | Viewed by 988

Abstract

Plant enzymes such as ficin (EC 3.4.22.3), papain (EC 3.4.22.2) and bromelain (EC 3.4.22.4) are obtained from tropical plants. These biocatalysts belong to thiol proteases, in the active center of which cysteine is contained. Ficin, papain and bromelain have a wide substrate specificity, [...] Read more.

Plant enzymes such as ficin (EC 3.4.22.3), papain (EC 3.4.22.2) and bromelain (EC 3.4.22.4) are obtained from tropical plants. These biocatalysts belong to thiol proteases, in the active center of which cysteine is contained. Ficin, papain and bromelain have a wide substrate specificity, which provides a demand for their use in various industries. Enzymes in the free state are less commonly used; immobilized biocatalysts are the preferred form. The aim of this work was to determine the optimal concentration of a crosslinking agent in the covalent immobilization of ficin, papain and bromelain on a chitosan matrix. Ficin, papain and bromelain (Sigma) were chosen as objects of study. An acid-soluble chitosan (350 kDa, Bioprogress CJSC) was used as an immobilization carrier. The concentration range of glutaraldehyde (crosslinking agent) ranged from 1 to 25%. Suitable concentrations of glutaraldehyde for covalent immobilization were identified by the optimal ratio of protein content (mg per g of carrier), total activity (in units per ml of solution) and specific activity (in units per mg of protein). It was shown that for covalent immobilization of ficin and bromelain on a chitosan matrix, it is most promising to use 10% glutaraldehyde. For immobilization of papain on chitosan by covalent means, the concentration of glutaraldehyde equal to 20% is optimal. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

330 KiB

Open AccessProceeding Paper

Eco-Friendly Catalytic Aminoselenation of Alkenes: A Green Alternative for Obtaining Potentially Active Compounds

by Luana S. Gomes, Rafaella G. Angelino, José S. S. Neto, Iris di Leo, Claudio Santi and Vanessa Nascimento

Chem. Proc. 2020, 2(1), 8; https://doi.org/10.3390/ECCS2020-07580 - 9 Nov 2020

Viewed by 1273

Abstract

In this work, a new ecological approach to the selenofunctionalization of alkenes has been described using I₂ as catalyst, DMSO as oxidant, under microwave irradiation (MW) in a solvent- and metal-free method. The general idea is to combine organoselenium compounds and triazole [...] Read more.

In this work, a new ecological approach to the selenofunctionalization of alkenes has been described using I₂ as catalyst, DMSO as oxidant, under microwave irradiation (MW) in a solvent- and metal-free method. The general idea is to combine organoselenium compounds and triazole nuclei to obtain molecules capable of becoming a powerful class due to their potential pharmacological activity. However, most methods that involve the functionalization of alkenes are generally mediated by the use of transition metals or reagents in large stoichiometric quantities. Thus, the development of direct, clean and environmentally appropriate procedures, which are in accordance with the principles of green chemistry, for the synthesis of these compounds remains highly desirable. Thus, the present work developed the synthesis of β-amino selenides with only 20 minutes of reaction time, following the conditions previously mentioned. In addition, encouraged by these results, the scope of the reaction was expanded using also diorganoil disulfides and ditellurides, obtaining molecules with good to excellent yields. Finally, compared to traditional methods, our methodology is a lightweight, metal-free, simple and practical tool for the selenofunctionalization of alkenes and is considered a promising alternative in the development of new drugs with potential biological activities. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

247 KiB

Open AccessProceeding Paper

Benzeneseleninic Acid in the Photo-Catalyzed Hydroxy-Selenylation of Styrenes

by Filipe Penteado, Luana Bettanin, Kethelyn Machado and Eder J. Lenardão

Chem. Proc. 2020, 2(1), 9; https://doi.org/10.3390/ECCS2020-07758 - 10 Nov 2020

Viewed by 1232

Abstract

We established a new visible-light-mediated protocol for the regioselective β-hydroxyselenylation of olefins, employing benzeneseleninic acid as substrate. Regarding a novel approach, the benzeneseleninic acid emerges as an efficient and affordable reagent to be used as an electrophilic selenium source that can be [...] Read more.

We established a new visible-light-mediated protocol for the regioselective β-hydroxyselenylation of olefins, employing benzeneseleninic acid as substrate. Regarding a novel approach, the benzeneseleninic acid emerges as an efficient and affordable reagent to be used as an electrophilic selenium source that can be easily converted to selenium-based radical species under visible-light conditions. In this sense, the photocatalytically formed PhSe• radical can react directly with unsaturated substrates, including alkenes, to access a new C–Se bond and a carbon-centered radical intermediate, which finally is trapped by a hydroxyl radical species, delivering the β-hydroxyselanyl compounds. Thus, despite the versatile utilities in organic synthesis, such as building blocks, the β-hydroxyselanyl compounds have demonstrated important biological activities. Based on that, we concentrated our efforts on developing a robust, effective, and environmentally benign methodology for their preparation. The optimal condition involves the reaction between styrene and 1.0 equivalent of phenylseleninic acid, in the presence of 5.0 mol% of eosin Y, as a cheap and easily available photocatalyst, with DMSO promoting the reaction medium. Satisfactorily, the system was irradiated with blue LED light for 2 h, to deliver the desired products in good yields. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

677 KiB

Open AccessProceeding Paper

Coke-Resistant Rh and Ni Catalysts Supported on γ-Al₂O₃ and CeO₂ for Biogas Oxidative Steam Reforming

by Simona Renda, Antonio Ricca and Vincenzo Palma

Chem. Proc. 2020, 2(1), 10; https://doi.org/10.3390/ECCS2020-07588 - 9 Nov 2020

Cited by 1 | Viewed by 1109

Abstract

The depletion of fossil fuels and the growing concerns related to the environmental impact of their processing has progressively switched the interest towards the utilization of biomass-derived materials for a large variety of processes. Among them, biogas, which is a CH₄-rich [...] Read more.

The depletion of fossil fuels and the growing concerns related to the environmental impact of their processing has progressively switched the interest towards the utilization of biomass-derived materials for a large variety of processes. Among them, biogas, which is a CH₄-rich gas deriving from anaerobic digestion of biomass, has acquired a lot of interest as a feedstock for reforming processes. The main issue in employing biogas is related to the carbon deposition and active metal sintering, which are both responsible for the deactivation of the catalyst. In this work, bimetallic and monometallic Rh- and Ni-based formulations were supported on alumina and ceria with the aim of evaluating their activity and stability in biogas oxidative steam reforming. The Rh addition to the monometallic Ni/^γ-Al₂O₃ formulation enhances its catalytic performances; nevertheless, this induces a higher coke deposition, thus suggesting a preferential coke formation on Rh sites. The initial activity of the CeO₂-supported catalysts was found to be lower than the Al₂O₃-supported catalysts, but the 5%Ni/CeO₂ sample showed a very good stability during the test and, despite the lower activity, 0.5%Rh-5%Ni/CeO₂ did not show coke deposition. The results suggest that the promotion of Ni/CeO₂ catalysts with other active metals could lead to the selection of a highly stable and performing formulation for biogas oxidative steam reforming. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

562 KiB

Open AccessProceeding Paper

Microkinetic Modeling of the Water-Gas Shift Reaction over Cobalt Catalysts Supported on Multi-Walled Carbon Nanotubes

by Fabio Machado Cavalcanti, Jeroen Poissonnier, Tom Vandevyvere, Reinaldo Giudici, Rita Maria Brito Alves, Martin Schmal and Joris W. Thybaut

Chem. Proc. 2020, 2(1), 11; https://doi.org/10.3390/ECCS2020-07581 - 9 Nov 2020

Viewed by 1438

Abstract

The development of microkinetic models allows gaining an understanding of fundamental catalyst surface phenomena in terms of elementary reaction steps without a priori defining a rate-determining step, yielding more meaningful and physically reliable reaction rates. This work aimed at developing such a microkinetic [...] Read more.

The development of microkinetic models allows gaining an understanding of fundamental catalyst surface phenomena in terms of elementary reaction steps without a priori defining a rate-determining step, yielding more meaningful and physically reliable reaction rates. This work aimed at developing such a microkinetic model that accurately describes the Water-Gas Shift (WGS) reaction, i.e., one of the major routes for hydrogen production, over cobalt (Co) catalysts supported on multi-walled carbon nanotubes (MWCNTs). Co is known for its sulfur-tolerance and the functionalized MWCNT support has exceptional conductivity properties and defects that facilitate electron transfer on its surface. The model was formulated based on a well-known mechanism for the WGS reaction involving the highly reactive carboxyl (COOH*) intermediate. The kinetic parameters were computed by a combination of calculation via theoretical prediction models (such as the Collision and Transition-State theory) and via regression to the experimental data. The derived system of differential-algebraic equations was solved using the DDAPLUS package available in the Athena VISUAL Studio. The developed model was capable of simulating the experimental data (R² = 0.96), presenting statistically significant kinetic parameters. Furthermore, some of the catalyst descriptors in the model have been related to the catalyst properties as determined by characterization techniques, such as the specific surface area (S_P = 22,000 m²/kg_cat) and the density of active sites (σ = 0.012 mol_Act.Surf./kg_cat). The modelling and characterization efforts allowed identifying the COOH* formation reaction (CO* + OH* → COOH* + *) as the surface reaction with the highest activation energy. Optimal catalyst performance, resulting in a CO conversion exceeding 85%, was simulated at elevated temperatures (350–450 °C) and space times (70–80 kg·s/mol), in agreement with the experimental observations. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

829 KiB

Open AccessProceeding Paper

Electrocatalytic Properties of Co Nanoconical Structured Electrode Produced by One-Step and Two-Step Methods

by Katarzyna Skibinska, Karolina Kolczyk-Siedlecka, Dawid Kutyla, Anna Jedraczka and Piotr Zabinski

Chem. Proc. 2020, 2(1), 12; https://doi.org/10.3390/ECCS2020-07573 - 9 Nov 2020

Viewed by 996

Abstract

One-dimensional (1D) nanostructures, such as nanotubes, nanopores, nanodots and nanocones, are characterized by better catalytic properties than bulk materials due to their large active surface area and small geometrical size. There are several methods of synthesis for these structures, including the one- and [...] Read more.

One-dimensional (1D) nanostructures, such as nanotubes, nanopores, nanodots and nanocones, are characterized by better catalytic properties than bulk materials due to their large active surface area and small geometrical size. There are several methods of synthesis for these structures, including the one- and two-step methods. In the one-step method, a crystal modifier is added to the solution in order to limit the horizontal direction of structures growing during electrodeposition. In this work, cobalt nanoconical structures were obtained from an electrolyte containing CoCl₂, H₃BO₃ and NH₄Cl as the crystal modifier. Another method of production of 1D nanocones is electrodeposition of the metal into porous anodic alumina oxide (AAO) templates. This method is called the two-step method. In this case, an AAO template was obtained using two-step anodization. Then, electrodeposition of cobalt was performed from an electrolyte containing CoSO₄ and H₃BO₃. Nanocones obtained by the two-step method show smaller geometrical size. The bulk sample was electrodeposited from the same electrolyte. The electrocatalytic properties of materials fabricated by the one-step and two-step methods were measured in 1M NaOH and compared with bulk materials. Co cones obtained by the one-step method show the worst electrocatalytic properties. The hydrogen evolution reaction started the earliest for Co nanocones electrodeposited in the templates. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

382 KiB

Open AccessProceeding Paper

Synthesis and Characterization of Pd over Novel TiO₂ Mixtures: Insights on Metal–Support Interactions

by Matías G. Rinaudo, Ana M. Beltrán, María A. Fernández, Luis E. Cadús and Maria R. Morales

Chem. Proc. 2020, 2(1), 13; https://doi.org/10.3390/ECCS2020-07529 - 9 Nov 2020

Viewed by 1333

Abstract

Palladium nanoparticles were supported on unusual mixtures of anatase, TiO₂ (II) and rutile titania phases by wet impregnation, obtaining catalysts with metal contents of ca. 0.25 wt % labeled Pd/Ti5, Pd/Ti45, and Pd/Ti120. Crystalline structures were confirmed by X-ray diffraction. Pd particle [...] Read more.

Palladium nanoparticles were supported on unusual mixtures of anatase, TiO₂ (II) and rutile titania phases by wet impregnation, obtaining catalysts with metal contents of ca. 0.25 wt % labeled Pd/Ti5, Pd/Ti45, and Pd/Ti120. Crystalline structures were confirmed by X-ray diffraction. Pd particle sizes in the range of 4–20 nm were observed by scanning-transmission electron Microscopy. External surface areas (S_BET) in the range 10–17 m² g⁻¹ were higher enough to achieve a good distribution of palladium over titanium oxide outer surface, as evidenced by energy-dispersive X-ray spectroscopy elemental profiles. Pd⁰/Pd^δ+ atomic ratio measured by X-ray photoelectron spectroscopy showed a decrease from Pd/Ti5 to Pd/Ti120, in line with the decrease in anatase phase present in the catalysts. This behavior suggested that palladium tended to form more TiPd_xO structures in Pd/Ti5 whilst PdO_x structures were more likely to be present on supports with greater amounts of TiO₂ (II) and rutile, due to the distinct metal–support interactions. An increase in reducibility and oxygen mobility from Pd/Ti5 to Pd/Ti120 was observed by temperature programmed measurements and associated to the different high-energy ball milled supports. Catalysts with improved properties reported herein could exhibit an excellent performance in oxidation reactions, e.g., glycerol selective oxidation. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

1121 KiB

Open AccessProceeding Paper

Highly Active Pandanus Nanocellulose-Supported Poly(amidoxime) Copper (II) Complex for Ullmann Cross-Coupling Reaction

by Choong Jian Fui, Tang Xin Ting, Mohd Sani Sarjadi and Md Lutfor Rahman

Chem. Proc. 2020, 2(1), 14; https://doi.org/10.3390/ECCS2020-07530 - 9 Nov 2020

Viewed by 1092

Abstract

The transition metal-catalyzed chemical transformation of organic electrophiles, and organometallic reagents have turned up as an exceedingly robust synthetic tool. The evolution of transition metal catalysts has attained a stage of civilization that authorizes for an extensive scope of chemical bonds formation partners [...] Read more.

The transition metal-catalyzed chemical transformation of organic electrophiles, and organometallic reagents have turned up as an exceedingly robust synthetic tool. The evolution of transition metal catalysts has attained a stage of civilization that authorizes for an extensive scope of chemical bonds formation partners to be combined efficiently. The applications of Cu-based nanoparticles have received great attention owing to the earth-abundant, low toxicity and inexpensive. Due to these characteristics, copper nanoparticles have generated a great deal of interest especially in the field of catalysis. In this study, poly(acrylonitrile) was synthesized by undergoes free-radical initiation process and followed by Beckmann rearrangement with hydroxylamine solution converted into the poly(amidoxime) ligand and anchored the copper onto poly(amidoxime). Cu(II)@PAM was characterized using different techniques such as FTIR, FESEM, EDX, TEM, TGA, DSC, ICP-OES, and XPS analyses. The Cu(II)@PAM showed high stability and high catalytic activity in a wide variety of electrophilic substituted phenols with substituted aryl/benzyl halides. 0.15 mol%, ±3 mg of Cu(II)@PAM could efficiently promote Ullmann reaction to give the corresponding coupling product up to 99 % yields. The complex was easy separated and recovered from the reaction mixture by simple filtration. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

576 KiB

Open AccessProceeding Paper

Structural Investigation of the Carbon Deposits on Ni/Al₂O₃ Catalyst Modified by CaO-MgO for the Biogas Dry Reforming Reaction

by Nikolaos D. Charisiou, Georgios I. Siakavelas, Victor Sebastian, Steven J. Hinder, Mark A. Baker, Vagelis G. Papadakis, Wen Wang, Kyriaki Polychronopoulou and Maria A. Goula

Chem. Proc. 2020, 2(1), 15; https://doi.org/10.3390/ECCS2020-07569 - 9 Nov 2020

Cited by 3 | Viewed by 1376

Abstract

Ni catalysts based on Al₂O₃ and Al₂O₃ modified with CaO-MgO were tested for the dry reforming of biogas (BDR). Time-on-stream experiments were carried out between 600 and 800 °C, and the spent catalysts were examined using a [...] Read more.

Ni catalysts based on Al₂O₃ and Al₂O₃ modified with CaO-MgO were tested for the dry reforming of biogas (BDR). Time-on-stream experiments were carried out between 600 and 800 °C, and the spent catalysts were examined using a variety of characterization techniques including, N₂ adsorption/desorption, thermogravimetric analysis (TGA), Raman spectroscopy, electron microscopy (STEM-HAADF and HR-TEM), and X-ray photoelectron spectroscopy (XPS). It was revealed that the carbon deposits consisted of carbon nanotubes and amorphous carbon for both samples. XPS studies showed the presence of Ni⁰on both catalysts and Ni₂O₃/NiAl₂O₄ on the Ni/Al₂O₃ sample. The time-on-stream experiments showed that the Ni/CaO-MgO-Al₂O₃ catalyst is more resistant to deactivation and more active and selective for all temperatures under investigation. It was concluded that doping Al₂O₃ with CaO-MgO enhances catalytic performance as: (a) it helps to maintain highly dispersed Ni⁰ during the BDR as the interaction between metal and support is a stronger one, (b) it leads to the formation of carbon structures that are easier to oxidize, and (c) it facilitates the gasification of the carbon deposits because its increased surface basic sites enhance the adsorption of carbon dioxide. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

253 KiB

Open AccessProceeding Paper

One-Pot Green Catalytic Preparation of 3-Aminobenzoic Acid in the Presence of Carbonaceous Bio-Based Materials in Subcritical Water

by Sarra Tadrent and Christophe Len

Chem. Proc. 2020, 2(1), 16; https://doi.org/10.3390/ECCS2020-07541 - 9 Nov 2020

Viewed by 1086

Abstract

A green and sustainable approach for the production of 3-aminobenzoic acid (3-ABA) from 3-nitrobenzaldehyde promoted by NORIT GAC 12-40 as a carbonaceous bio-based material was successfully achieved in subcritical water. The process involves two successive reactions: reduction of the nitro group and oxidation [...] Read more.

A green and sustainable approach for the production of 3-aminobenzoic acid (3-ABA) from 3-nitrobenzaldehyde promoted by NORIT GAC 12-40 as a carbonaceous bio-based material was successfully achieved in subcritical water. The process involves two successive reactions: reduction of the nitro group and oxidation of the formyl group. At 300 °C under 90 bar for 6 h, the yield of 3-ABA is 59%. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Scheme 1

969 KiB

Open AccessProceeding Paper

UV Sensitivity of Free and Immobilized on Chitosan Matrix Proteases

by Svetlana Pankova, Marina Holyavka and Valeriy Artyukhov

Chem. Proc. 2020, 2(1), 17; https://doi.org/10.3390/ECCS2020-07610 - 9 Nov 2020

Viewed by 1145

Abstract

UV irradiation is an essential factor in natural and artificial climate in modern environmental conditions, which has a constant effect on living systems. Collagenase, bromelain, ficin, papain (Sigma-Aldrich: St. Louis, MO, USA) and trypsin (MP biomedicals: Santa Ana, CA, USA) were the objects [...] Read more.

UV irradiation is an essential factor in natural and artificial climate in modern environmental conditions, which has a constant effect on living systems. Collagenase, bromelain, ficin, papain (Sigma-Aldrich: St. Louis, MO, USA) and trypsin (MP biomedicals: Santa Ana, CA, USA) were the objects of this study. The substrate for hydrolysis was BSA (Sigma-Aldrich: St. Louis, MO, USA), the carriers for immobilization were chitosans (<100, 200 and 350 kDa) and chitosan succinate (Bioprogress: Shchyolkovo, Russia). The protease immobilization was carried out by the adsorption. The determination of the protein amount in samples and their catalytic activity was carried out by the modified Lowry method. UV irradiation of proteases was performed using doses 151–6040 J/m². By the degree of photosensitivity, hydrolases can be arranged in the next row: collagenase → bromelain → ficin → papain → trypsin. Adsorption on a chitosan and succinate of chitosan leads to an increase in the stability to ultraviolet light of heterogeneous (immobilized) biocatalysts compared to free enzymes. Photoprotective effect of the chitosan may be due to the following reasons: enzyme interact with the chitosan to form photo resistant complexes; сhitosan screens active free-radicals, preventing the photooxidation of a certain number of amino acids, including the active centers of the studied enzymes under the influence of UV irradiation. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

352 KiB

Open AccessProceeding Paper

Activated Biochar-Based Metal Catalysts for Steam Reforming of Pyrolysis Bio-Oil Model Compound

by Christian Di Stasi, Marta Cortese, Gianluca Greco, Belén González, Vincenzo Palma and Joan J. Manyà

Chem. Proc. 2020, 2(1), 18; https://doi.org/10.3390/ECCS2020-07536 - 9 Nov 2020

Viewed by 1143

Abstract

In this work, different biochar-based metal catalysts were tested for mid-temperature (400−600 °C) acetic acid steam reforming. K, Co, Ce, Fe and Ni were chosen as active phases for the production of the studied catalysts. Their performance was evaluated in terms of acetic [...] Read more.

In this work, different biochar-based metal catalysts were tested for mid-temperature (400−600 °C) acetic acid steam reforming. K, Co, Ce, Fe and Ni were chosen as active phases for the production of the studied catalysts. Their performance was evaluated in terms of acetic acid conversion, hydrogen yield, acetone yield, and stability. The best outcomes were obtained for the nickel-based catalysts, which exhibited high conversion (>90%) along with insignificant deactivation rates. Nevertheless, for relatively low nickel loadings, a certain extent of coke deposition was deduced from the observed fluctuations in pressure drop. A 10 wt.% nickel loading appeared to be a reasonable tradeoff between activity and coke production. After the identification of the optimal loading, four bimetallic catalysts were produced with the aim of improving the original activity of the nickel-based one. The cobalt–nickel catalysts showed the most stable behavior with a constant conversion degree (98%) in the range of 475–600 °C. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

462 KiB

Open AccessProceeding Paper

Photochemical Treatment of Blue-Indigo Using a TiO₂-Sunlight System in Heterogeneous Conditions

by Erick Fabian Mosquera Quiñonez, Juan Enrique Tacoronte Morales and Mirna Geraldine Cevallos Mina

Chem. Proc. 2020, 2(1), 19; https://doi.org/10.3390/ECCS2020-07526 - 9 Nov 2020

Cited by 1 | Viewed by 1484

Abstract

Ecuador is one of the countries in the Latin American region with a high textile production. However, chemical treatment strategies in the Ambato, Tungurahua and Quito areas are inefficient and not systematically applied, and the volumes of dyes and pigment-type contaminants generate serious [...] Read more.

Ecuador is one of the countries in the Latin American region with a high textile production. However, chemical treatment strategies in the Ambato, Tungurahua and Quito areas are inefficient and not systematically applied, and the volumes of dyes and pigment-type contaminants generate serious environmental problems. The treatments of indigo textile wastewater and related indigo derivatives are very complex. Taking these into consideration, a simple photochemical protocol in heterogeneous conditions was developed, for degrading “blue-indigo” (Ambato textile group) in solution, using TiO₂ (Degussa P25, with a purity of ≈99% and BET surface area 50 ± 15 m²/g) and solar light at lab scale. The photocatalytic oxidation of “blue-indigo” in aqueous solution was assessed by solar irradiation, in the presence of TiO₂ particles. The effect of indigo concentrations, pH and TiO₂ loading for maximum degree of degradation were evaluated. The mineralization of “blue-indigo” was reported by measuring COD-i and COD-f of the solution that was irradiated with sunlight under optimized conditions. The results enable the re-designing of strategies for controlling contamination in textile wastewaters in eco-sustainable conditions for Ecuador. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

4 pages, 285 KiB

Open AccessProceeding Paper

Efficient Eco-Friendly Solvent-Free Obtaining Bis-Selenium-Alkenes with High Biological Potential

by Pâmella Cordeiro, Matheus Silva Prado, José Neto and Vanessa Nascimento

Chem. Proc. 2020, 2(1), 20; https://doi.org/10.3390/ECCS2020-07566 - 9 Dec 2020

Viewed by 1962

Abstract

Organocalcogenides, in particular, organoselenium compounds, have been widely studied due to their large number of synthetic and biological applications. Among organoselenium compounds, a class of bis-selenide-alkene derivatives has attracted attention. Recently, some studies have been developed for the synthesis of vinyl chalcogen derivatives, [...] Read more.

Organocalcogenides, in particular, organoselenium compounds, have been widely studied due to their large number of synthetic and biological applications. Among organoselenium compounds, a class of bis-selenide-alkene derivatives has attracted attention. Recently, some studies have been developed for the synthesis of vinyl chalcogen derivatives, since these are also highly valuable intermediates in several synthetic applications. However, the methodologies developed so far have extensive reaction times, and use toxic solvents as well as heavy metals. Therefore, there is an emerging need to develop protocols for the synthesis of these molecules that are in accordance with the principles of green chemistry. In this work, we developed an alternative synthesis of bis-selenium-alkene derivatives, through an environmentally appropriate methodology. Reaction optimization was evaluated from the diphenylacetylene and diphenyl diselenide, using I₂/DMSO as a catalytic system under microwave irradiation or conventional heating. The variations of these conditions were carried out through different equivalences between the reagents, the amount of catalyst (I₂), temperature, DMSO and the reaction process (Microwave or conventional). Even now, it was found that the best established condition was using diphenylacetylene, diphenyl diselenide, 30 mol% I₂ in DMSO, under microwave irradiation at 100 °C for 10 min. In this condition, the product was obtained in 82% yield and its characterization was performed using 1H and 13C NMR spectroscopy. Therefore, the methodology that is being developed, in addition to perfectly attending to the principles of green chemistry, will allow to evaluate the reaction scope using different alkenes and diselenides or even disulfides and ditellurides. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

344 KiB

Open AccessProceeding Paper

Chalcogen–Nitrogen Bond: Insights into a Key Chemical Motif

by Marco Bortoli, Andrea Madabeni, Pablo Andrei Nogara, Folorunsho B. Omage, Giovanni Ribaudo, Davide Zeppilli, Joao Batista Teixeira Rocha and Laura Orian

Chem. Proc. 2020, 2(1), 21; https://doi.org/10.3390/ECCS2020-07589 - 9 Nov 2020

Cited by 2 | Viewed by 1459

Abstract

Chalcogen–nitrogen chemistry deals with systems in which sulfur, selenium or tellurium is linked to a nitrogen nucleus. This chemical motif is a key component of different functional structures, ranging from inorganic materials and polymers to rationally designed catalysts, to bioinspired molecules and enzymes. [...] Read more.

Chalcogen–nitrogen chemistry deals with systems in which sulfur, selenium or tellurium is linked to a nitrogen nucleus. This chemical motif is a key component of different functional structures, ranging from inorganic materials and polymers to rationally designed catalysts, to bioinspired molecules and enzymes. The formation of a selenium–nitrogen bond, and its disruption, are rather common events in organic Se-catalyzed processes. In nature, along the mechanistic path of glutathione peroxidase, evidence of the formation of a Se–N bond in highly oxidizing conditions has been reported and interpreted as a strategy to protect the selenoenzyme from overoxidation. Selenium is also bonded to nitrogen in the well-known ebselen, a selenenylamide with antioxidant, antimicrobic and cytoprotective activity and its formation/disruption has a crucial role for its pharmacological action. Focusing on examples taken from selenium organic chemistry and biochemistry, the selenium–nitrogen bond is described, and its strength and reactivity are quantified using accurate computational methods applied to model molecular systems. Significant trends show up when comparing to sulfur/tellurium–nitrogen bonds, also reaffirming the peculiar and valuable role of selenium in chemistry and life in this context. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

608 KiB

Open AccessProceeding Paper

Synthesis of New Selenides-1,2,3-Triazoles with Potential Activity against Trypanossoma cruzi

by Beatrice Brasil, Ingrid Chipoline and Vanessa Nascimento

Chem. Proc. 2020, 2(1), 22; https://doi.org/10.3390/ECCS2020-07757 - 10 Nov 2020

Viewed by 1270

Abstract

Chagas disease, considered by the World Health Organization as a neglected tropical disease, is responsible for the deaths of more than 10,000 people annually. The main drugs used to overcome the disease, Benzonidazole and Nifurtimox, besides being old, have limitations regarding the adverse [...] Read more.

Chagas disease, considered by the World Health Organization as a neglected tropical disease, is responsible for the deaths of more than 10,000 people annually. The main drugs used to overcome the disease, Benzonidazole and Nifurtimox, besides being old, have limitations regarding the adverse effects related to the treatment time and, consequently, their toxicity. Therefore, the need for a new drug to be used against this disease becomes evident. The classes of organoselenium and aromatic heterocycles 1,2,3-triazoles are promising for the issue of the profile of both classes for further evaluation against Trypanossoma cruzi, since the known chemistry and antiparasitic activity of both have already been described. In this work, the molecular hybridization technique was used in order to combine the individual bioactive protozoan that causes Chagas disease. The methodology used was based on works described in the literature. Initially, benzene azides were synthesized from commercial anilines, while ethynyl(phenyl)selane came from different aromatic diselenides. With these intermediates, a 1,3-dipolar cycle-addition was performed to obtain the new target molecules 1-phenyl-4-(phenylselanyl)-1H-1,2,3-triazoles, with moderate to good yields ranging from 52 to 75%. The characterization of the final molecules is in process and, when finished, they will be sent for evaluation of biological activity. It is possible to conclude that the method used is simple and easy to access, an important factor for potential drugs against neglected diseases. After the assessment of bioactivity, it will be possible to identify the efficiency of these substances, as well as, if necessary, the optimization of their structure. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

786 KiB

Open AccessProceeding Paper

Combined DFT and Operando Spectroscopic Study of the Water-Gas Shift Reaction over Ceria-Based Catalysts: The Role of the Noble Metal and Ceria Faceting

by Marc Ziemba, Danny Stark and Christian Hess

Chem. Proc. 2020, 2(1), 23; https://doi.org/10.3390/ECCS2020-07531 - 9 Nov 2020

Cited by 2 | Viewed by 1649

Abstract

Ceria loaded with noble metals (Cu, Au) is a highly active material for the low-temperature water-gas shift reaction (LT-WGSR), but nevertheless details of the metal support interaction as well as the role of the ceria surface termination and the metal loading are still [...] Read more.

Ceria loaded with noble metals (Cu, Au) is a highly active material for the low-temperature water-gas shift reaction (LT-WGSR), but nevertheless details of the metal support interaction as well as the role of the ceria surface termination and the metal loading are still unclear. Using operando Raman and UV/Vis spectroscopy combined with theoretical density functional theory (DFT) calculations, we aim at a molecular-level understanding of LT-WGSR catalysts. In particular, by using this combined approach, we are able to draw conclusions about the reducibility state of the ceria support during reaction conditions. Our results show that the defect formation energy of the support does not play a major role for the WGSR, but rather other reaction steps such as the dissociation of water or the desorption of CO₂. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

527 KiB

Open AccessProceeding Paper

Nanoparticle Conjugates of Selenium Compounds: Preparation, Characterisation and Electron Transfer

by Kavirayani Indira Priyadarsini, Beena G. Singh, Prasad P. Phadnis, Kanhu Charan Barick and Puthusserickal Abdulrahiman Hassan

Chem. Proc. 2020, 2(1), 24; https://doi.org/10.3390/ECCS2020-07545 - 9 Nov 2020

Viewed by 1496

Abstract

One of the important features influencing the biological applications of organoselenium compounds is their redox state, which in turn is affected by their interactions with nearby heteroatoms. To modulate the biological action of selenium in such compounds, researchers have designed new structural motifs [...] Read more.

One of the important features influencing the biological applications of organoselenium compounds is their redox state, which in turn is affected by their interactions with nearby heteroatoms. To modulate the biological action of selenium in such compounds, researchers have designed new structural motifs and also developed new formulations using inorganic nanoparticles. Metal nanoparticles such as gold nanoparticles (GNPs) and magnetic nanoparticles (MNPs) like iron oxide (Fe₃O₄) have been extensively studied for conjugation with many heteroatoms (sulphur, nitrogen and oxygen) containing ligands. Selenium, being more polarisable than sulphur, can induce significant surface passivation, thereby providing easy modulations with physico-chemical properties. Considering this, we investigated the physico-chemical properties of a few selenium compounds conjugated to GNPs and MNPs. The GNP conjugates were characterised by spectroscopic and microscopic tools, such as optical absorption, Raman spectroscopy, dynamic light scattering (DLS), the zeta potential and transmission electron microscopy (TEM). The results confirmed that the selenium atom was covalently conjugated to GNPs and this conjugation not only increased their electron transfer ability, but also their antioxidant ability. In another study, asymmetric phenyl selenides were conjugated with MNPs and characterised byX-ray diffraction (XRD), TEM, DLS and zeta potential. The radical scavenging ability of the selenium compounds improved upon conjugation with the MNPs. Therefore, the above studies confirmed that the redox activities of selenium compounds can be modulated upon conjugation with inorganic nanoparticles, such as GNPs and MNPs, which in turn provides new avenues for delivering organoselenium compounds. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

441 KiB

Open AccessProceeding Paper

Intramolecular Tandem Seleno-Michael/Aldol Reaction—Novel Strategy in Carbasugars Synthesis

by Piotr Banachowicz, Natalia Biduś and Szymon Buda

Chem. Proc. 2020, 2(1), 25; https://doi.org/10.3390/ECCS2020-07571 - 9 Nov 2020

Viewed by 1620

Abstract

Carbasugars are a wide group of carbohydrate mimetics in which the ring oxygen is replaced by a methylene group. The high importance of these compounds is related to their interesting biological and pharmacological properties which are the matter of current studies. In our [...] Read more.

Carbasugars are a wide group of carbohydrate mimetics in which the ring oxygen is replaced by a methylene group. The high importance of these compounds is related to their interesting biological and pharmacological properties which are the matter of current studies. In our work, a concise synthesis of carbasugars from naturally occurring D-pentoses is presented. The one-pot seleno-Michael reaction connected with intramolecular aldol reaction is a key step of the carbasugar core asymmetric synthesis. Further transformation of obtained carbasugar moiety led to different bioactive compounds. Tandem seleno-Michael reaction conjugated with oxidation/elimination step of in situ generated nucleophile was described a few years ago in the intermolecular variant. In our work, we present the first example of this reaction in an intramolecular way which leads to a previously inaccessible cyclic product of Morita–Baylis–Hillman reaction. Conducted experiments allowed us to obtain cyclic products with high yields and good diastereoisomeric excesses. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

1012 KiB

Open AccessProceeding Paper

Integrating Diphenyl Diselenide and Its Mehg⁺ Detoxificant Mechanism on a Conceptual DFT Framework

by Folorunsho Bright Omage, Cláudia S. Oliveira, Laura Orian and Joao Batista Teixeira Rocha

Chem. Proc. 2020, 2(1), 26; https://doi.org/10.3390/ECCS2020-07577 - 9 Nov 2020

Viewed by 1382

Abstract

Methylmercury (MeHg⁺) is an important environmental contaminant and its toxicity is associated with its interaction with selenium (e.g., selenol groups of selenoproteins or HSe⁻, which is the pivotal metabolite for Se incorporation into selenoproteins). We hypothesized that (PhSe)₂ [...] Read more.

Methylmercury (MeHg⁺) is an important environmental contaminant and its toxicity is associated with its interaction with selenium (e.g., selenol groups of selenoproteins or HSe⁻, which is the pivotal metabolite for Se incorporation into selenoproteins). We hypothesized that (PhSe)₂ mediated MeHg⁺ detoxification could be indirectly altered by its open or closed conformation. The two conformations of (PhSe)₂ were located on the potential energy surface (PES) computed at ZORA-OPBE-D3(BJ)/ZORA-def2-TZVP level of theory. HPLC analysis indicated that (PhSe)₂ did not react with MeHg⁺, but its reduced intermediate formed a stable complex with MeHg⁺. The nudged elastic band (NEB) method revealed conformational changes from closed to open state with an H⁻ (2 electrons) transfer from NaBH₄, forming a reactant complex-like transition state (TS). The UV-Vis spectrophotometer used in combination with the time-dependent density functional theory (TD-DFT) indicated that the signal of (PhSe)₂ at 239 nm was possibly the open conformer’s signal with oscillator strength 0.1 and a π → π * electron transfer character. The experimental band gap energy of (PhSe)₂ at 5.20 eV matched to the excitation energy of the open conformation. The local softness (S⁻) on the selenium atoms almost doubles, as state changes from closed to open. The theoretical results have indicated that the open conformation of (PhSe)₂ is likely the one that reacts with NaBH₄to form the PhSeH, which can react with MeHg⁺. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

403 KiB

Open AccessProceeding Paper

Removal of Hydrogen Sulfide (H₂S) Using MOFs: A Review of the Latest Developments

by Amvrosios G. Georgiadis, Nikolaos D. Charisiou, Ioannis V. Yentekakis and Maria A. Goula

Chem. Proc. 2020, 2(1), 27; https://doi.org/10.3390/ECCS2020-07586 - 9 Nov 2020

Cited by 2 | Viewed by 3191

Abstract

The removal of hydrogen sulfide (H₂S) from gas streams with varying overall pressure and H₂S concentrations is a long-standing challenge faced by the oil and gas industries. The present work focuses on H₂S capture using metal–organic frameworks [...] Read more.

The removal of hydrogen sulfide (H₂S) from gas streams with varying overall pressure and H₂S concentrations is a long-standing challenge faced by the oil and gas industries. The present work focuses on H₂S capture using metal–organic frameworks (MOFs), in an effort to shed light on their potential as adsorbents in the field of gas storage and separation. MOFs hold great promise as they make possible the design of structures from organic and inorganic units, but also, they have provided an answer to a long-time challenging issue, i.e., how to design extended structures of materials. Moreover, the functionalization of the MOF’s surface can result in increased H₂S uptake. For example, the insertion of 1% of a fluorinated linker in MIL-101(Cr)-4F(1%) allows for enhanced H₂S capture. Although noticeable efforts have been made in studying the adsorption capacity of H₂S using MOFs, there is a clear need for gaining a deeper understanding in terms of their thermal conductivities and specific heats in order to design more stable adsorption beds, experiencing high exothermicity. Simply put, the exothermic nature of adsorption means that sharp rises in temperature can negatively affect the bed stability in the absence of sufficient heat transfer. The work presented herein provides a detailed discussion by thoroughly combining the existing literature on new developments in MOFs for H₂S removal, and tries to provide insight into new areas for further research. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

587 KiB

Open AccessProceeding Paper

Improved Catalytic Transfer Hydrogenation of Levulinate Esters with Alcohols over ZrO₂ Catalyst

by Tommaso Tabanelli, Paola Blair Vásquez, Emilia Paone, Rosario Pietropaolo, Nikolaos Dimitratos, Fabrizio Cavani and Francesco Mauriello

Chem. Proc. 2020, 2(1), 28; https://doi.org/10.3390/ECCS2020-07585 - 9 Nov 2020

Cited by 2 | Viewed by 1707

Abstract

Levulinic acid (LA) and its esters (alkyl levulinates) are polyfunctional molecules that can be obtained from lignocellulosic biomass. Herein, the catalytic conversion of methyl and ethyl levulinates into γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) by using methanol, ethanol, and 2-propanol as the [...] Read more.

Levulinic acid (LA) and its esters (alkyl levulinates) are polyfunctional molecules that can be obtained from lignocellulosic biomass. Herein, the catalytic conversion of methyl and ethyl levulinates into γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) by using methanol, ethanol, and 2-propanol as the H-donor/solvent, was investigated under both batch and gas-flow conditions. In particular, high-surface-area, tetragonal zirconia has proven to be a suitable catalyst for this reaction. Isopropanol was found to be the best H-donor under batch conditions, with ethyl levulinate providing the highest yield in GVL. However, long reaction times and high autogenic pressures are needed in order to work in the liquid-phase at high temperature with light alcohols. The reactions occurring under continuous gas-flow conditions, at atmospheric pressure and a relatively low contact time (1 s), were found to be much more efficient, also showing excellent GVL yields when EtOH was used as the reducing agent (GVL yield of around 70% under optimized conditions). The reaction has also been tested using a true bio-ethanol, derived from agricultural waste. These results represent the very first examples of the CTH of alkyl levulinates under continuous gas-flow conditions reported in the literature. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

209 KiB

Open AccessProceeding Paper

Selenocyanation of Indoles Promoted by Visible Light

by Luana Bettanin, Filipe Penteado, Luiz H. Dapper and Eder J. Lenardão

Chem. Proc. 2020, 2(1), 29; https://doi.org/10.3390/ECCS2020-07562 - 9 Nov 2020

Viewed by 1148

Abstract

We developed a promising synthetic methodology for the regioselective photocatalyzed 3-selenocyanation of indoles, employing potassium selenocyanate (KSeCN) and a blue LED light. The 3-selanylindoles have been emerging as a potentially bioactive class of compounds and already have demonstrated anti-inflammatory, antinociceptive and anticancer properties. [...] Read more.

We developed a promising synthetic methodology for the regioselective photocatalyzed 3-selenocyanation of indoles, employing potassium selenocyanate (KSeCN) and a blue LED light. The 3-selanylindoles have been emerging as a potentially bioactive class of compounds and already have demonstrated anti-inflammatory, antinociceptive and anticancer properties. There are in the literature several methodologies for their preparation; for example, applying intermolecular cyclization with Se-based electrophilic species. Therefore, it is of interest to seek innovative and effective methodologies to selectively access this class of molecules. Furthermore, the photocatalytically formed NCSe· radical can react directly with the N-heterocycle unsaturated substrates, affording the desired compound more effectively than other electrophilic selenium species. In addition, the 3-selenocyanato-1H-indole derivatives can be employed as precursor to obtaining diselenides, through a reduction–oxidation reaction sequence. The new method employs indole as unsaturated N-heterocycle substrate, and 1.3 equiv. of potassium selenocyanate as a selenium source, in the presence of 5.0 mol% of eosin Y, an organic photocatalyst, and 1.0 mL of acetonitrile. The system was stirred and irradiated with a blue LED light for 5 h, and the crude was purified using column chromatography. Thus, as a result, we developed an efficient and smoothly methodology to prepare 3-selenocyanato-1H-indole derivatives, in good yields. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

387 KiB

Open AccessProceeding Paper

Cux/ZnO-y Catalysts. Effect of Support Modification by High Energy Milling on the Metal-Support Interaction

by María K. López González, Luis E. Cadús and Maria R. Morales

Chem. Proc. 2020, 2(1), 30; https://doi.org/10.3390/ECCS2020-07570 - 9 Nov 2020

Viewed by 1034

Abstract

Commercial ZnO was subjected to high-energy milling to introduce structural modifications, which can result in a different metal-support interaction. The milling time (0 to 960 min) and vial material and mill balls (WC and ZnO₂), were modified. The supports were characterized [...] Read more.

Commercial ZnO was subjected to high-energy milling to introduce structural modifications, which can result in a different metal-support interaction. The milling time (0 to 960 min) and vial material and mill balls (WC and ZnO₂), were modified. The supports were characterized by XRD, Scherrer, S_BET and Raman Spectroscopy. With the increase in milling time, an increase in the accrued kinetic energy (E_cum) was observed. For the same E_cum, with ZrO₂, twice the area was obtained in just 6 min. Cu was deposited on both, the milled support (ZnO-z) and unmilled support (ZnO-0) in three compositions; x = 0.2, 0.5, and 1.0 (%wt). Atomic Absorption Spectroscopy (AAS) measurements showed Cu compositions similar to the theoretical ones. XRD studies, Rietveld modelling and Raman Spectroscopy confirmed that Cu²⁺ cations could be localized, either by substituting the Zn²⁺ ions or interstitially in the network, depending on the metal content. The TPR profiles showed two types of copper species, which interact differently with the support. Likewise, the analysis of the XPS results showed that, with the increase in Cu content, for Cux/ZnO-0, there is a decrease in the metal-support interaction. However, for Cux/ZnO-z the interaction increases, which can be associated with the introduction of structural defects accompanied by superficial energy changes. For both systems, different catalytic behaviours are expected in the hydrogenolysis reaction of glycerol in liquid phase, regarding selectivity and stability, as a result of the metal-support interaction achieved. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

500 KiB

Open AccessProceeding Paper

New High-Throughput Reactor for Biomass Valorization

by Irene Malpartida, Pedro Maireles-Torres, Valentin Lair, Samy Halloumi, Julien Thiel and François Lacoste

Chem. Proc. 2020, 2(1), 31; https://doi.org/10.3390/ECCS2020-07583 - 9 Nov 2020

Cited by 1 | Viewed by 1348

Abstract

The development of an innovative and sustainable high-throughput reaction platform allows optimizing a wide range of chemical processes (materials synthesis and catalysis, among others) to tackle the Green Deal. This tool unifies, for the first time, the benefits of mechanical energy, thermal and [...] Read more.

The development of an innovative and sustainable high-throughput reaction platform allows optimizing a wide range of chemical processes (materials synthesis and catalysis, among others) to tackle the Green Deal. This tool unifies, for the first time, the benefits of mechanical energy, thermal and pressure activation in continuous flow with an induction in situ heating system, facilitating the incorporation of inputs (liquids, solids and gases) with controlled pressure. As a result of the synergistic effect of this simultaneous activation, this technology will: (i) shorten reaction times; (ii) decrease temperature; (iii) improve reactions kinetics as mass transfer limitations are reduced; (iv) minimize the use of solvents; (v) decrease the reaction steps; (vi) increase the volume treated, enabling a real scale-up; and (vii) enhance the yields and/or selectivity. This new high-throughput reactor is used for the synthesis of calcium diglyceroxide (CaDG), minimizing the reaction steps and cost, to obtain a pure CaDG. This heterogeneous catalyst is used for biodiesel production and valorization of the glycerol generated as a by-product. An efficient synthesis protocol of CaDG has been developed, requiring shorter time, without heating, and no need for a solvent. This new process facilitates oil–methanol mixing in the transesterification process, thus minimizing the mass transfer limitations associated with the immiscibility of reactants. In addition, this process has been optimized by using CaDG as a solid catalyst. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

1563 KiB

Open AccessProceeding Paper

Fenton Degradation of Ofloxacin Using a Montmorillonite-Fe₃O₄ Composite

by Alamri Rahmah Dhahawi Ahmad, Saifullahi Shehu Imam, Wen Da Oh and Rohana Adnan

Chem. Proc. 2020, 2(1), 32; https://doi.org/10.3390/ECCS2020-07528 - 10 Nov 2020

Viewed by 1159

Abstract

In this work, FeM composites consisting of montmorillonite and variable amounts of Fe₃O₄ were successfully synthesized via a facile co-precipitation process. They were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), [...] Read more.

In this work, FeM composites consisting of montmorillonite and variable amounts of Fe₃O₄ were successfully synthesized via a facile co-precipitation process. They were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), N₂ adsorption-desorption, and Fourier transform infrared spectroscopy (FT-IR) techniques to explain the effect of Fe₃O₄ content on the physicochemical properties of the Fe₃O₄-montmorillonite (FeM) composites. The FeM composites were subsequently used as heterogeneous Fenton catalysts to activate green oxidant (H₂O₂) for the subsequent degradation of ofloxacin (OFL) antibiotic. The efficiency of the FeM composites was studied by varying various parameters of Fe₃O₄ loading on montmorillonite, catalyst dosage, initial solution pH, initial OFL concentration, different oxidants, H₂O₂ dosage, reaction temperature, inorganic salts, and solar irradiation. Under the conditions of 0.75 g/L FeM-10, 5 mL/L H₂O₂, and natural pH, almost 81% of 50 mg/L of OFL was removed within 120 min in the dark, while total organic carbon (TOC) reduction was about 56%. Moreover, the FeM-10 composite maintained high efficiency and was stable even after four continuous cycles, making it a promising candidate in real wastewater remediation. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

621 KiB

Open AccessProceeding Paper

Discovery and Biochemical Characterization of a Novel Polyesterase for the Degradation of Synthetic Plastics

by Efstratios Nikolaivits, Phaedra Dimopoulou, Veselin Maslak, Jasmina Nikodinovic-Runic and Evangelos Topakas

Chem. Proc. 2020, 2(1), 33; https://doi.org/10.3390/ECCS2020-07572 - 9 Nov 2020

Cited by 1 | Viewed by 1998

Abstract

Plastic waste poses an enormous environmental problem as a result of soil and ocean contamination, causing the release of microplastics that end up in humans through the food web. Enzymatic degradation of plastics has emerged as an alternative to traditional recycling processes. In [...] Read more.

Plastic waste poses an enormous environmental problem as a result of soil and ocean contamination, causing the release of microplastics that end up in humans through the food web. Enzymatic degradation of plastics has emerged as an alternative to traditional recycling processes. In the present work, we used bioinfomatics tools to discover a gene coding for a putative polyester degrading enzyme (polyesterase). The gene was heterologously expressed, purified and biochemically characterized. Furthermore, its ability to degrade polyethylene terephthalate (PET) model substrates and synthetic plastics was assessed. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

237 KiB

Open AccessProceeding Paper

Production of Biofuels by 5-Hydroxymethylfurfural Etherification Using Ion-Exchange Resins as Solid Acid Catalysts

by Benjamín Torres Olea, Inmaculada Fúñez Nuñez, Cristina García Sancho, Juan Antonio Cecilia, Ramón Moreno Tost and Pedro Maireles Torres

Chem. Proc. 2020, 2(1), 34; https://doi.org/10.3390/ECCS2020-07587 - 9 Nov 2020

Viewed by 1444

Abstract

In this work, acidic ion-exchange resins with strong Brönsted sulphonic groups were assessed in the catalytic etherification of the platform molecule 5-(hydroxymethyl)furfural (HMF) to 5-(ethoxymethyl)furfural (EMF), a biofuel with an energy density close to that of gasoline (30 MJ/L) which also reduces emissions [...] Read more.

In this work, acidic ion-exchange resins with strong Brönsted sulphonic groups were assessed in the catalytic etherification of the platform molecule 5-(hydroxymethyl)furfural (HMF) to 5-(ethoxymethyl)furfural (EMF), a biofuel with an energy density close to that of gasoline (30 MJ/L) which also reduces emissions of NO_x and SO_x and solid particles respect to fossil-derived fuels. Catalytic performance was optimized modifying experimental parameters such as reaction time, temperature, and concentration of reagent employed. This process was carried out in batch reactors using ethanol 96% as solvent. Among different cation-exchange resins tested, Purolite CT275DR provided the fastest HMF conversion together with Purolite PD206, and the highest selectivity to EMF, achieving above 70% selectivity at 100 °C. Over time, strong acid sites favoured product hydrolysis opening the furan ring originating ethyl levulinate (EL) to the detriment of EMF selectivity. Purolite CT275DR was also utilised to realize the transformation from sugars directly to EMF in the same reaction medium, in a one-pot process, obtaining relevant results from fructose (37% HMF yield, 21% EMF yield after 5 h), but originating selectively ethylglucosides and ethylgalactosides in the presence of glucose and galactose, respectively, due to the absence of necessary Lewis acid sites to isomerize aldose and proceed with dehydration. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

750 KiB

Open AccessProceeding Paper

Capture and Methanation of CO₂ Using Dual-Function Materials (DFMs)

by Anastasios I. Tsiotsias, Nikolaos D. Charisiou, Ioannis V. Yentekakis and Maria A. Goula

Chem. Proc. 2020, 2(1), 35; https://doi.org/10.3390/ECCS2020-07567 - 9 Nov 2020

Cited by 7 | Viewed by 2582

Abstract

The conversion of CO₂, captured from flue gases, into synthetic natural gas (SNG) aims to create a closed carbon cycle, where excess H₂ produced from renewables is utilized to transform CO₂ released from existing conventional power plants into a [...] Read more.

The conversion of CO₂, captured from flue gases, into synthetic natural gas (SNG) aims to create a closed carbon cycle, where excess H₂ produced from renewables is utilized to transform CO₂ released from existing conventional power plants into a reliable and high energy density carrier, that is CH₄. In the last five years, extensive research effort has been dedicated to the synthesis and optimization of composite materials for the realization of this process. These materials, also known as dual-function materials or DFMs, typically consist of an alkaline metal oxide or carbonate phase, along with a Ru or Ni metallic phase supported on a high surface area carrier. The DFMs incorporate both sorptive and catalytic capabilities, capturing the CO₂ in the initial sorption step and then converting it into CH₄ upon H₂ inflow. The dispersion of the sorptive and catalytically active phases, the CO₂ affinity of the alkaline phase, the reducibility of the supported metals, and the selectivity towards CH₄ production are some of the parameters influencing their performance. Hereby, we aim to present the most recent works dedicated to the development and optimization of such dual-function materials to be used in the combined capture and methanation of CO₂. Full article

(This article belongs to the Proceedings of The 1st International Electronic Conference on Catalysis Sciences)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Chem. Proc., 2020, ECCS 2020

The 1st International Electronic Conference on Catalysis Sciences

Other

Further Information

Guidelines

MDPI Initiatives

Follow MDPI