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Articoli di riviste sul tema "Catalysts"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 25 luglio 2025

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1

Dagorne, Samuel. "Recent Developments on N-Heterocyclic Carbene Supported Zinc Complexes: Synthesis and Use in Catalysis." Synthesis 50, no. 18 (2018): 3662–70. http://dx.doi.org/10.1055/s-0037-1610088.

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The present contribution reviews the synthesis, reactivity, and use in catalysis of NHC–Zn complexes reported since 2013. NHC-stabilized Zn(II) species typically display enhanced stability relative to common organozinc species (such as Zn dialkyls), a feature of interest for the mediation of various chemical processes and the stabilization of reactive Zn-based species. Their use in catalysis is essentially dominated by reduction reactions of various unsaturated small molecules (including CO2), thus primarily involving Zn–H and Zn–alkyl derivatives as catalysts. Simple NHC adducts of Zn(II) dih

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2

Crawford, Jennifer, and Matthew Sigman. "Conformational Dynamics in Asymmetric Catalysis: Is Catalyst Flexibility a Design Element?" Synthesis 51, no. 05 (2019): 1021–36. http://dx.doi.org/10.1055/s-0037-1611636.

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Traditionally, highly selective low molecular weight catalysts have been designed to contain rigidifying structural elements. As a result, many proposed stereochemical models rely on steric repulsion for explaining the observed selectivity. Recently, as is the case for enzymatic systems, it has become apparent that some flexibility can be beneficial for imparting selectivity. Dynamic catalysts can reorganize to maximize attractive non-covalent interactions that stabilize the favored diastereomeric transition state, while minimizing repulsive non-covalent interactions for enhanced selectivity.

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Kaplunenko, Volodymyr, and Mykola Kosinov. "Electric field - induced catalysis. Laws of field catalysis." InterConf, no. 26(129) (October 18, 2022): 332–51. http://dx.doi.org/10.51582/interconf.19-20.10.2022.037.

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Abstract.The article explores a new type of catalysis - electric field catalysis. The laws of field catalysis are given. The characteristics of the electric field are determined, which set the values of the characteristics of the field catalysis. Field catalysis and field catalyst do not fit into the traditional definition of catalysis and catalyst, which may require a revision of the terminology of catalysis. The field is a more versatile catalyst compared to material catalysts, both in terms of its application to a wider range of chemical reactions, and in the ability to control the rate and

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4

Newman, R. A., J. A. Blazy, T. G. Fawcett, L. F. Whiting, and R. A. Stowe. "Use of the Dow-Developed DSC/XRD/MS in the Study of Several Model Copper-Based Catalyst Systems." Advances in X-ray Analysis 30 (1986): 493–502. http://dx.doi.org/10.1154/s0376030800021650.

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Due to the difficulty of analyzing materials at high temperatures and in reactive atmospheres, solid-state catalysts have often been developed with little knowledge of the true chemical behavior of the catalyst, except on a bulk scale. In the field of solid-state catalysis research, a great deal of time and effort is presently being spent to better characterize the chemical and physical properties which determine a particular catalyst‘s efficiency, lifetime, and selectivity. Recently, we have undertaken a study of model copper catalysts at The Dow Chemical Company in an effort to better unders

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5

Lomic, Gizela, Erne Kis, Goran Boskovic, and Radmila Marinkovic-Neducin. "Application of scanning electron microscopy in catalysis." Acta Periodica Technologica, no. 35 (2004): 67–77. http://dx.doi.org/10.2298/apt0435067l.

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A short survey of various information obtained by scanning electron microscopy (SEM) in the investigation of heterogeneous catalysts and nano-structured materials have been presented. The capabilities of SEM analysis and its application in testing catalysts in different fields of heterogeneous catalysis are illustrated. The results encompass the proper way of catalyst preparation, the mechanism of catalyst active sites formation catalysts changes and catalyst degradation during their application in different chemical processes. Presented SEM pictures have been taken on a SEM JOEL ISM 35 over 2

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6

Liu, Jingyue. "Advanced Electron Microscopy Characterization of Nanostructured Heterogeneous Catalysts." Microscopy and Microanalysis 10, no. 1 (2004): 55–76. http://dx.doi.org/10.1017/s1431927604040310.

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Heterogeneous catalysis is one of the oldest nanosciences. Although model catalysts can be designed, synthesized, and, to a certain degree, characterized, industrial heterogeneous catalysts are often chemically and physically complex systems that have been developed through many years of catalytic art, technology, and science. The preparation of commercial catalysts is generally not well controlled and is often based on accumulated experiences. Catalyst characterization is thus critical to developing new catalysts with better activity, selectivity, and/or stability. Advanced electron microscop

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7

Guerrero Fajardo, Carlos Alberto, Yvonne N’Guyen, Claire Courson, and Anne Cécile Roger. "Fe/SiO2 catalysts for the selective oxidation of methane to formaldehyde." Ingeniería e Investigación 26, no. 2 (2006): 37–44. http://dx.doi.org/10.15446/ing.investig.v26n2.14735.

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Selective oxidation of methane to formaldehyde was analysed with iron catalysts supported on silica prepared by the sol-gel method, leading to obtaining a large support surface area facilitating high dispersion of iron on silica’s amorphous surface. Seven catalysts were prepared; one of them corresponded to the silica support and another five having an iron load 0.1-0.5% in weight. Catalyst 7 (0.5% Fe in weight) was prepared with neutral pH control and had the most homogeneous characteristics since it did not present isolated iron species, corroborated by SEM and TEM analysis. The highest BET

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8

Trigoura, Leslie, Yalan Xing, and Bhanu P. S. Chauhan. "Recyclable Catalysts for Alkyne Functionalization." Molecules 26, no. 12 (2021): 3525. http://dx.doi.org/10.3390/molecules26123525.

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In this review, we present an assessment of recent advances in alkyne functionalization reactions, classified according to different classes of recyclable catalysts. In this work, we have incorporated and reviewed the activity and selectivity of recyclable catalytic systems such as polysiloxane-encapsulated novel metal nanoparticle-based catalysts, silica–copper-supported nanocatalysts, graphitic carbon-supported nanocatalysts, metal organic framework (MOF) catalysts, porous organic framework (POP) catalysts, bio-material-supported catalysts, and metal/solvent free recyclable catalysts. In add

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9

Gai, P. L., K. Kourtakis, H. Dindi, and S. Ziemecki. "Novel Xerogel Catalyst Materials for Hydrogenation Reactions and the Role of Atomic Scale Interfaces." Microscopy and Microanalysis 5, S2 (1999): 704–5. http://dx.doi.org/10.1017/s1431927600016846.

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We are developing a new family of heterogeneous catalysts for hydrogenation catalysis. Catalyst synthesis is accomplished using colloidal polymerization chemistry which produce high surface area xerogel catalysts. These xerogels have been synthesized by one-step sol gel chemistry. These catalysts contain ruthenium and modifiers such as gold occluded or incorporated in a titanium oxide matrix. The materials, especially the modified systems exhibit favorable performance in microreactor evaluations for hydrogenation reactions and exhibit high activities. Nanostructural studies have revealed that

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10

Yap, Daryl Q. J., Raju Cheerlavancha, Renecia Lowe, Siyao Wang, and Luke Hunter. "Investigation of cis- and trans-4-Fluoroprolines as Enantioselective Catalysts in a Variety of Organic Transformations." Australian Journal of Chemistry 68, no. 1 (2015): 44. http://dx.doi.org/10.1071/ch14129.

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Stereoselective fluorination is known to rigidify the ring structure of l-proline, as a result of a combination of electrostatic and hyperconjugative effects associated with the C–F bond. This is a potential strategy for enhancing the enantioselectivity of proline-catalysed reactions. In this study, cis- and trans-4-fluoroprolines were investigated as catalysts in five different organic transformations, including examples of both enamine and iminium ion catalysis. Some significant differences in enantioselectivity were observed between the cis- and trans-isomers of the fluorinated catalysts, c

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11

Cottone, Grazia, Sergio Giuffrida, Stefano Bettati, et al. "More than a Confinement: “Soft” and “Hard” Enzyme Entrapment Modulates Biological Catalyst Function." Catalysts 9, no. 12 (2019): 1024. http://dx.doi.org/10.3390/catal9121024.

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Catalysis makes chemical and biochemical reactions kinetically accessible. From a technological point of view, organic, inorganic, and biochemical catalysis is relevant for several applications, from industrial synthesis to biomedical, material, and food sciences. A heterogeneous catalyst, i.e., a catalyst confined in a different phase with respect to the reagents’ phase, requires either its physical confinement in an immobilization matrix or its physical adsorption on a surface. In this review, we will focus on the immobilization of biological catalysts, i.e., enzymes, by comparing hard and s

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12

Wang, Ziyun, Hai-Feng Wang, and P. Hu. "Possibility of designing catalysts beyond the traditional volcano curve: a theoretical framework for multi-phase surfaces." Chemical Science 6, no. 10 (2015): 5703–11. http://dx.doi.org/10.1039/c5sc01732g.

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The current theory of catalyst activity in heterogeneous catalysis is mainly obtained from the study of catalysts with mono-phases, while most catalysts in real systems consist of multi-phases, the understanding of which is far short of chemists' expectation.

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Testa, Maria Luisa, and Valeria La Parola. "Sulfonic Acid-Functionalized Inorganic Materials as Efficient Catalysts in Various Applications: A Minireview." Catalysts 11, no. 10 (2021): 1143. http://dx.doi.org/10.3390/catal11101143.

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Acid catalysis is widely used in the chemical industry, and nowadays many efforts are being focused on replacing the more common homogeneous catalysts with heterogeneous ones in order to make greener the industrial processes. In this perspective, sulfonic solid acid materials represent a valid alternative to the homogenous mineral acid in several acid catalyzed reactions. In this minireview, an overview of the recent advances on the preparation, stability and application of these materials is reported. Special attention is addressed to the sustainability of the considered processes, starting f

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14

Qin, Helen. "Evaluation of Hydrogen-Oxygen Recombiner Catalysts Under Various Conditions for Nuclear and Non-Nuclear Hydrogen Safety." STEM Fellowship Journal 2, no. 1 (2016): 12–16. http://dx.doi.org/10.17975/sfj-2016-003.

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Hydrogen plays an important role in nuclear and non-nuclear safety, as the unsafe manipulation of hydrogen can lead to dangerous accidents. This concern has led the Hydrogen Isotopes Technology Branch at the Canadian Nuclear Laboratories to develop catalysts in order to aid in the recombination of hydrogen and oxygen. This research project evaluates catalysts with different compositions under various conditions (i.e. dry, humid) in a spinning basket reactor (SBR). Results suggest that catalysts with lower wetproof coating loading have higher activity levels after being exposed to water vapour

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Zhao, Xiaodan, and Lihao Liao. "Modern Organoselenium Catalysis: Opportunities and Challenges." Synlett 32, no. 13 (2021): 1262–68. http://dx.doi.org/10.1055/a-1506-5532.

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AbstractOrganoselenium catalysis has attracted increasing interest in recent years. This Cluster highlights recent key advances in this area regarding the functionalization of alkenes, alkynes, and arenes by electrophilic selenium catalysis, selenonium salt catalysis, selenium-based chalcogen-bonding catalysis, and Lewis basic selenium catalysis. These achievements might inspire and help future research.1 Introduction2 Electrophilic Selenium Catalysis3 Selenonium Salt Catalysis4 Selenium-Based Chalcogen-Bond Catalysis5 Lewis Basic Selenide Catalysis6 Conclusion

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16

Motokura, Ken, and Kyogo Maeda. "Recent Advances in Heterogeneous Ir Complex Catalysts for Aromatic C–H Borylation." Synthesis 53, no. 18 (2021): 3227–34. http://dx.doi.org/10.1055/a-1478-6118.

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AbstractAromatic C–H borylation catalyzed by an Ir complex is among the most powerful methods for activating inert bonds. The products, i.e., arylboronic acids and their esters, are usable chemicals for the Suzuki–Miyaura cross-coupling reaction, and significant effort has been directed toward the development of homogeneous catalysis chemistry. In this short review, we present a recent overview of current heterogeneous Ir-complex catalyst developments for aromatic C–H borylation. Not only have Ir complexes been immobilized on support surfaces with phosphine and bipyridine ligands, but Ir compl

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17

Mazaheri, Hoora, Hwai Chyuan Ong, Zeynab Amini, et al. "An Overview of Biodiesel Production via Calcium Oxide Based Catalysts: Current State and Perspective." Energies 14, no. 13 (2021): 3950. http://dx.doi.org/10.3390/en14133950.

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Biodiesel is a clean, renewable, liquid fuel that can be used in existing diesel engines without modification as pure or blend. Transesterification (the primary process for biodiesel generation) via heterogeneous catalysis using low-cost waste feedstocks for catalyst synthesis improves the economics of biodiesel production. Heterogeneous catalysts are preferred for the industrial generation of biodiesel due to their robustness and low costs due to the easy separation and relatively higher reusability. Calcium oxides found in abundance in nature, e.g., in seashells and eggshells, are promising

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18

Jurczak, Janusz, Maciej Majdecki, Patryk Niedbała, and Agata Tyszka-Gumkowska. "Assisted by Hydrogen-Bond Donors: Cinchona Quaternary Salts as Privileged Chiral Catalysts for Phase-Transfer Reactions." Synthesis 53, no. 16 (2021): 2777–86. http://dx.doi.org/10.1055/a-1472-7999.

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AbstractThis short review is devoted to asymmetric phase-transfer reactions that employ hybrid ammonium Cinchona catalysts supported by possessing hydrogen-bond donor groups. We present recent advances utilizing this type of catalyst in the field of biphasic reaction systems. The main emphasis is placed on the advantages of additional functional groups present in the structure of the catalyst, such as hydroxy, amide, (thio)urea or squaramide.1 Introduction2 Phase-Transfer Hybrid Cinchona Catalysts with a Free Hydroxy Group3 (Thio)urea Hybrid Cinchona Catalysts4 Hybrid Amide-Based Catalysts Bea

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19

Choudhury, Joyanta, and Shrivats Semwal. "Emergence of Stimuli-Controlled Switchable Bifunctional Catalysts." Synlett 29, no. 02 (2017): 141–47. http://dx.doi.org/10.1055/s-0036-1591741.

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Can a single catalyst perform more than one ‘type’ of reaction? If we consider traditional design of catalysts, then the answer would probably be ‘no’. However, with the advancement of catalyst design concepts, chemists have been able to demonstrate the above task, thanks to ‘stimuli-switchable bifunctional catalysts’. Within the nascent research area of ‘artificial switchable catalysis’, this new type of system offers the potential to achieve complex functions which are otherwise difficult or impossible. This Synpacts article highlights the rise of these new-generation catalysts.1 Introductio

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20

Dadashi-Silab, Sajjad, and Krzysztof Matyjaszewski. "Iron Catalysts in Atom Transfer Radical Polymerization." Molecules 25, no. 7 (2020): 1648. http://dx.doi.org/10.3390/molecules25071648.

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Catalysts are essential for mediating a controlled polymerization in atom transfer radical polymerization (ATRP). Copper-based catalysts are widely explored in ATRP and are highly efficient, leading to well-controlled polymerization of a variety of functional monomers. In addition to copper, iron-based complexes offer new opportunities in ATRP catalysis to develop environmentally friendly, less toxic, inexpensive, and abundant catalytic systems. Despite the high efficiency of iron catalysts in controlling polymerization of various monomers including methacrylates and styrene, ATRP of acrylate-

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21

Wu, Jingyun. "Two-step synthesis and oxidizing power assessment of novel pyrylium." Theoretical and Natural Science 6, no. 1 (2023): 1–7. http://dx.doi.org/10.54254/2753-8818/6/20230107.

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Photoredox catalysis is a relatively new concept, and it involves the absorption of light for more productive use of lower energy radiation and to catalyze selective reactions. Traditionally, catalysts used for oxidation or reduction reactions were metal catalysts, such as iridium. However, these metal catalysts are not environmentally friendly and are expensive, prompting the use of organic catalysts. Pyrylium salt, an organic catalyst, can be used as a catalyst. However, the oxidizing ability of basic pyrylium is not that good and can still be improved. In this project, a pyrylium salt with

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22

Zhang, Meng. "A Novel Energy Band Match Method and a Highly Efficient CuO–Co3O4@SiO2 Catalyst for Dimethyl Carbonate Synthesis from CO2." Science of Advanced Materials 13, no. 1 (2021): 115–22. http://dx.doi.org/10.1166/sam.2021.3848.

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The present research on dimethyl carbonate (DMC) synthesis from CO2 was short of effective theoretical guidance and catalyst design was also blind. A kind of regular relationship was found from catalyst structure calculation and activity experiments. Therefore, a novel energy band matching method was proposed. After substantial verification experiments, it was proved to be correct. Whether one certain catalyst has catalytic activity can be judged predictably according to this novel method. Novel and efficient catalysts can be designed or selected on the basis of designer's wishes. Based on thi

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23

Su, Shu Hua, Shi Ye Feng, Yuan Fang Zhao, Qiang Lu, Wei Liang Cheng, and Chang Qing Dong. "Comparison of Three Types of NH₃-SCR Catalysts." Applied Mechanics and Materials 130-134 (October 2011): 418–21. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.418.

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The selective catalysis reduction (SCR) is one of the most promising technologies for NOx reduction at present. There are three types of NH3-SCR catalysts in the market, honeycomb catalyst, plate-types catalyst and corrugated catalyst. This paper firstly describes the preparation of the three types of catalysts, and then analyzes their performance. The analysis indicates the catalyst structure plays an important role on their performance. The honeycomb catalyst and plate-type catalyst are widely utilized in world’s coal power station, which should be due to their excellent capabilities of ash

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Pan, Dipika, and Jhuma Ganguly. "Assessment of Chitosan Based Catalyst and their Mode of Action." Current Organocatalysis 6, no. 2 (2019): 106–38. http://dx.doi.org/10.2174/2213337206666190327174103.

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Introduction:The popularity of chitosan is increasing among the researchers due to its environment friendly nature, high activity and easy approachability. Chitosan based catalysts are not only the most active and selective in catalytic reaction, but their “green” accessibility also makes them promising in organic catalysis. Chitosan is commonly extracted from chitin by alkaline deacetylation and it is the second abundant biopolymer in nature after cellulose. Chitosan based catalysts are advantageous by means of non-metallic activation as it involves small organic molecules. The robustness, no

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Lendzion-Bieluń, Zofia. "The effect of manganese on the structural and surface properties of nanocrystalline cobalt catalyst for ammonia synthesis." Open Chemistry 10, no. 2 (2012): 327–31. http://dx.doi.org/10.2478/s11532-011-0147-y.

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AbstractBased on the active surface model of the iron catalyst for ammonia synthesis, the assumptions which led to obtaining the cobalt catalyst for ammonia synthesis were described. The incorporation into the system small amounts of manganese, an element which binds oxygen stronger than cobalt, has influence the development of the catalyst’s specific surface area. The activity of manganese modified catalysts is higher than that of cobalt catalyst without manganese addition. The obtained catalysts were characterized with the following methods: ICP-OES, XRD, BET

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Jakab-Nácsa, Alexandra, Attila Garami, Béla Fiser, László Farkas, and Béla Viskolcz. "Towards Machine Learning in Heterogeneous Catalysis—A Case Study of 2,4-Dinitrotoluene Hydrogenation." International Journal of Molecular Sciences 24, no. 14 (2023): 11461. http://dx.doi.org/10.3390/ijms241411461.

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Utilization of multivariate data analysis in catalysis research has extraordinary importance. The aim of the MIRA21 (MIskolc RAnking 21) model is to characterize heterogeneous catalysts with bias-free quantifiable data from 15 different variables to standardize catalyst characterization and provide an easy tool to compare, rank, and classify catalysts. The present work introduces and mathematically validates the MIRA21 model by identifying fundamentals affecting catalyst comparison and provides support for catalyst design. Literature data of 2,4-dinitrotoluene hydrogenation catalysts for tolue

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Du, Yuan-Peng, and Jeremy S. Luterbacher. "Designing Heterogeneous Catalysts for Renewable Catalysis Applications Using Metal Oxide Deposition." CHIMIA International Journal for Chemistry 73, no. 9 (2019): 698–706. http://dx.doi.org/10.2533/chimia.2019.698.

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Heterogeneous catalysis has long been a workhorse for the chemical industry and will likely play a key role in the emerging area of renewable chemistry. However, renewable molecule streams pose unique challenges for heterogeneous catalysis due to their high oxygen content, frequent low volatility and the near constant presence of water. These constraints can often lead to the need for catalyst operation in harsh liquid phase conditions, which has compounded traditional catalyst deactivation issues. Oxygenated molecules are also frequently more reactive than petroleum-derived molecules, which c

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Baráth, Eszter. "Selective Reduction of Carbonyl Compounds via (Asymmetric) Transfer Hydrogenation on Heterogeneous Catalysts." Synthesis 52, no. 04 (2020): 504–20. http://dx.doi.org/10.1055/s-0039-1691542.

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Based on the ever-increasing demand for optically pure compounds, the development of efficient methods to produce such products is very important. Homogeneous asymmetric catalysis occupies a prominent position in the ranking of chemical transformations, with transition metals coordinated to chiral ligands being applied extensively for this purpose. However, heterogeneous catalysts have the ability to further extend the field of asymmetric transformations, because of their beneficial properties such as high stability, ease of separation and regeneration, and the possibility to apply them in con

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Leitner, Walter. "Recent advances in catalyst immobilization using supercritical carbon dioxide." Pure and Applied Chemistry 76, no. 3 (2004): 635–44. http://dx.doi.org/10.1351/pac200476030635.

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Homogeneous organometallic catalysts have a great potential for the development of sustainable synthetic processes. There is, however, an urgent need for the development of new techniques to separate products and catalysts efficiently, allowing for recycling and reuse of the precious catalyst. The unique solvent properties of supercritical carbon dioxide offer new approaches for the immobilization of organometallic catalysts, many of which are suitable for efficient continuous-flow operation. Recent research in this field tries to combine the molecular nature of organometallic catalysts with t

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Liang, Yannan, Christopher Watson, Thomas Malinski, Justin Tepera, and David E. Bergbreiter. "Soluble polymer supports for homogeneous catalysis in flow reactions." Pure and Applied Chemistry 88, no. 10-11 (2016): 953–60. http://dx.doi.org/10.1515/pac-2016-0801.

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AbstractThe use of polyisobutylene and poly(4-dodecylstyrene) bound catalysts that contain transition metal or organocatalysts for cyclopropanation, ring-closing metathesis, and nucleophilic catalysis in flow chemistry schemes is described and compared with similar catalysts used in batch reactions. These Rh(II) carboxylate catalysts, N-heterocyclic carbene-ligated Ru(II) benzylidene catalysts, and analogs of 4-dimethylaminopyridine catalysts were used in reactions in heptane in flow and then separated in a gravity based liquid/liquid separation using a biphasic heptane/acetonitrile mixture. T

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Miceli, Mariachiara, Patrizia Frontera, Anastasia Macario, and Angela Malara. "Recovery/Reuse of Heterogeneous Supported Spent Catalysts." Catalysts 11, no. 5 (2021): 591. http://dx.doi.org/10.3390/catal11050591.

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The rapid separation and efficient recycling of catalysts after a catalytic reaction are considered important requirements along with the high catalytic performances. In this view, although heterogeneous catalysis is generally less efficient if compared to the homogeneous type, it is generally preferred since it benefits from the easy recovery of the catalyst. Recycling of heterogeneous catalysts using traditional methods of separation such as extraction, filtration, vacuum distillation, or centrifugation is tedious and time-consuming. They are uneconomic processes and, hence, they cannot be c

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Aceto, Domenico, Maria Carmen Bacariza, Arnaud Travert, Carlos Henriques, and Federico Azzolina-Jury. "Thermal and Plasma-Assisted CO2 Methanation over Ru/Zeolite: A Mechanistic Study Using In-Situ Operando FTIR." Catalysts 13, no. 3 (2023): 481. http://dx.doi.org/10.3390/catal13030481.

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CO2 methanation is an attractive reaction to convert CO2 into a widespread fuel such as methane, being the combination of catalysts and a dielectric barrier discharge (DBD) plasma responsible for synergistic effects on the catalyst’s performances. In this work, a Ru-based zeolite catalyst, 3Ru/CsUSY, was synthesized by incipient wetness impregnation and characterized by TGA, XRD, H2-TPR, N2 sorption and CO2-TPD. Catalysts were tested under thermal and plasma-assisted CO2 methanation conditions using in-situ operando FTIR, with the aim of comparing the mechanism under both types of catalysis. T

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BOUSBA, DALILA, CHAFIA SOBHI, AMNA ZOUAOUI, and SOUAD BOUASLA. "Synthesis of activated carbon sand their application in the synthesis of monometallic and bimetallic supported catalysts." Algerian Journal of Signals and Systems 5, no. 4 (2020): 190–96. http://dx.doi.org/10.51485/ajss.v5i4.116.

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Biomass-derived porous carbons are attractive materials for the synthesis of carbon-supported catalysts, carbonaceous catalysts are environmentally benign and could provide an important competitive advantage as compared to existing heterogeneous catalysts, however the surface properties of carbon materials and excellent physical and chemical properties are compatible with diverse catalysis reactions including organic transformations. Currently, activated carbons are one of well known carbonaceous materials for their catalytic properties and for use as support in heterogeneous catalysis. The su

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Chen, Huihui, Zhenhua Dong, and Jun Yue. "Advances in Microfluidic Synthesis of Solid Catalysts." Powders 1, no. 3 (2022): 155–83. http://dx.doi.org/10.3390/powders1030011.

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Heterogeneous catalysis plays a central role in the chemical and energy fields, owing to the high and tunable activities of solid catalysts that are essential to achieve the favorable reaction process efficiency, and their ease of recycle and reuse. Numerous research efforts have been focused on the synthesis of solid catalysts towards obtaining the desired structure, property and catalytic performance. The emergence and development of microfluidic reactor technology provide a new and attractive platform for the controllable synthesis of solid catalysts, primarily because of its superior mixin

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Patil, Siddappa A., Shivaputra A. Patil, and Renukadevi Patil. "Magnetic Nanoparticles Supported Carbene and Amine Based Metal Complexes in Catalysis." Journal of Nano Research 42 (July 2016): 112–35. http://dx.doi.org/10.4028/www.scientific.net/jnanor.42.112.

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Catalysis is one of the hottest research topics in chemistry. In recent years, metal complexes attracted great interest as catalysts towards various types of organic reactions. However, these catalysts, in most cases, suffer from the deficits during their recovery, recycling and the difficulty in separation of catalysts from the products. Therefore, the design and synthesis of recoverable and recyclable catalyst is very important aspect in catalysis. The aim of this review article is to highlight the speedy growth in the synthesis and catalytic applications of magnetic nanoparticles (Fe3O4, MN

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Clerici, Mario G. "Zeolites for Fine Chemical Production State of Art and Perspectives." Eurasian Chemico-Technological Journal 3, no. 4 (2017): 231. http://dx.doi.org/10.18321/ectj573.

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The paper analyses the role of catalysis and that of renewable resources in the frame of a sustainable development. The possible uses of natural feedstocks for chemical production and the application of catalytic<br />methods to their transformations are reviewed, with emphasis on carbohydrates and vegetable oils and on zeolite catalysts, respectively. The problems arising from the embedment of active sites on the catalyst<br />surface are discussed, with the aid of specific examples taken from oxidation and acid catalysed reactions.

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Shi, Chunjie, Xiaofeng Yu, Wei Wang, Haibing Wu, Ai Zhang, and Shengjin Liu. "The Activity and Cyclic Catalysis of Synthesized Iron-Supported Zr/Ti Solid Acid Catalysts in Methyl Benzoate Compounds." Catalysts 13, no. 6 (2023): 971. http://dx.doi.org/10.3390/catal13060971.

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The catalytic activity and cyclic catalysis of different methyl benzoates were studied by using a series of Lewis solid acid catalysts. The iron-supported zirconium/titanium solid acid catalysts were characterized using FTIR, SEM, XRD, and BET. The details of catalytic activity and cyclic catalysis verified that the catalyst catalyzed the reactions of 31 benzoic acids with different substituents and methanol. In addition, the mechanism was revealed according to the microstructure, acid strength, and specific surface area of the catalysts, and the yields of methyl benzoates by the GC-MS. Zr ion

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Tišler, Zdeněk, Pavla Vondrová, Kateřina Hrachovcová, et al. "Aldol Condensation of Cyclohexanone and Furfural in Fixed-Bed Reactor." Catalysts 9, no. 12 (2019): 1068. http://dx.doi.org/10.3390/catal9121068.

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Aldol condensation reaction is usually catalysed using homogeneous catalysts. However, the heterogeneous catalysis offers interesting advantages and the possibility of cleaner biofuels production. Nowadays, one of the most used kinds of heterogeneous catalysts are hydrotalcites, which belong to a group of layered double hydroxides. This paper describes the aldol condensation of cyclohexanone (CH) and furfural (F) using Mg/Al mixed oxides and rehydrated mixed oxides in order to compare the catalyst activity after calcination and rehydration, as well as the possibility of its regeneration. The c

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Zhao, Da, Roland Petzold, Jiyao Yan, Dieter Muri, and Tobias Ritter. "Tritiation of aryl thianthrenium salts with a molecular palladium catalyst." Nature 600, no. 7889 (2021): 444–49. http://dx.doi.org/10.1038/s41586-021-04007-y.

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AbstractTritium labelling is a critical tool for investigating the pharmacokinetic and pharmacodynamic properties of drugs, autoradiography, receptor binding and receptor occupancy studies1. Tritium gas is the preferred source of tritium for the preparation of labelled molecules because it is available in high isotopic purity2. The introduction of tritium labels from tritium gas is commonly achieved by heterogeneous transition-metal-catalysed tritiation of aryl (pseudo)halides. However, heterogeneous catalysts such as palladium supported on carbon operate through a reaction mechanism that also

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Pacultová, Bílková, Klegova, et al. "Co-Mn-Al Mixed Oxides Promoted by K for Direct NO Decomposition: Effect of Preparation Parameters." Catalysts 9, no. 7 (2019): 593. http://dx.doi.org/10.3390/catal9070593.

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Abstract (sommario):

Fundamental research on direct NO decomposition is still needed for the design of a sufficiently active, stable and selective catalyst. Co-based mixed oxides promoted by alkali metals are promising catalysts for direct NO decomposition, but which parameters play the key role in NO decomposition over mixed oxide catalysts? How do applied preparation conditions affect the obtained catalyst’s properties?

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Rasaq, Waheed A., Charles Odilichukwu R. Okpala, Chinenye Adaobi Igwegbe, and Andrzej Białowiec. "Catalyst-Enhancing Hydrothermal Carbonization of Biomass for Hydrochar and Liquid Fuel Production—A Review." Materials 17, no. 11 (2024): 2579. http://dx.doi.org/10.3390/ma17112579.

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Abstract (sommario):

The research impact of catalysts on the hydrothermal carbonization (HTC) process remains an ongoing debate, especially regarding the quest to enhance biomass conversion into fuels and chemicals, which requires diverse catalysts to optimize bio-oil utilization. Comprehensive insights and standardized analytical methodologies are crucial for understanding HTC’s potential benefits in terms of biomass conversion stages. This review seeks to understand how catalysts enhance the HTC of biomass for liquid fuel and hydrochar production, drawing from the following key sections: (a) catalyst types appli

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Bergbreiter, David E., Andrew Kippenberger, and Zhenqi Zhong. "Catalysis with palladium colloids supported in poly(acrylic acid)-grafted polyethylene and polystyrene." Canadian Journal of Chemistry 84, no. 10 (2006): 1343–50. http://dx.doi.org/10.1139/v06-076.

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Abstract (sommario):

Grafts of poly(acrylic acid) on polyethylene powder (PE-g-PAA) or polystyrene (PS-g-PAA) can be used to support Pd(0) crystallites that function like a homogeneous Pd(0) catalyst in some reactions. These Pd–PE-g-PAA catalysts were active in allylic substitution reactions in the presence of added phosphine ligand. A catalyst analogous to the Pd–PE-g-PAA powder catalyst on polystyrene (Pd–PS-g-PAA) was similarly active for allylic substitution and could also be used in Heck reactions at 80–100 °C in N,N-dimethylacetamide (DMA). Analysis of the product solutions for Pd leachate and a correlation

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Imrich, Biehler, Maichle-Mössmer, and Ziegler. "Carbohydrate-Based Chiral Iodoarene Catalysts: A Survey through the Development of an Improved Catalyst Design." Molecules 24, no. 21 (2019): 3883. http://dx.doi.org/10.3390/molecules24213883.

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Abstract (sommario):

Iodoarene catalysts can be applied in versatile reactions, for instance in the construction of complex chiral molecules via dearomatization of simple aromatic compounds. Recently, we reported the synthesis of the first carbohydrate-based chiral iodoarene catalysts and their application in asymmetric catalysis. Here we describe the synthesis of some new and improved catalysts. An account on how we got to the improved catalyst design, as well as the X-ray structure of one of the carbohydrate-based iodoarenes, is given.

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Zhang, Yujun, Hui Teng, Junpeng Chen, et al. "Application of Palladium Single Atoms in C−C Coupling Reactions of Pharmaceutical Synthesis." Advances in Computer and Engineering Technology Research 1, no. 1 (2023): 192. http://dx.doi.org/10.61935/acetr.1.1.2023.p192.

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Abstract (sommario):

Designing highly active and structurally well-defined catalysts while reducing the amount of catalyst has become a key issue in heterogeneous catalytic reactions. In this study, palladium single-atom catalysts were prepared for efficient catalysis in the Suzuki cross-coupling reaction of iodobenzene and phenylboronic acid, which was prepared by one-step high-temperature pyrolysis. The palladium single-atom catalysts have high activity as well as stability in Suzuki cross-coupling reactions and have great potential in catalyzing organic reactions.

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Deng, Jianghai, and Qiuyun Zhou. "The Semi-Closed Molten Salt-Assisted One-Step Synthesis of N-P-Fe Tridoped Porous Carbon Nanotubes for an Efficient Oxygen Reduction Reaction." Catalysts 13, no. 5 (2023): 824. http://dx.doi.org/10.3390/catal13050824.

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Transition metal and heteroatom co-doped carbon nanomaterials (TM-H-C) are considered to be the most promising candidates to replace the expensive platinum-based catalysts for oxygen reduction reactions (ORR). Herein, we report a semi-closed molten salt-assisted one-step strategy for fabricating N-P-Fe-tridoped porous carbon nanotube (CNT) catalysts by using the evaporation of ZnCl2 and the catalysis of iron ions to control the heteroatoms doping process and CNT formation. The resultant densely packed porous CNT structure imparts final catalysts with an enhanced mass transfer ability for elect

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Hu, Changsong, Chengwu Qiu, Wenli Zhang, et al. "Insights into the Role of Pt Promoter in Co/TiO2 Catalysts for CO Hydrogenation." Catalysts 14, no. 12 (2024): 922. https://doi.org/10.3390/catal14120922.

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Abstract (sommario):

Platinum is widely used as a reduction promoter in transition metal heterogeneous catalysts, while its effects on the catalyst’s properties and CO hydrogenation behavior remain unclear. In this study, an improvement in the reducibility of platinum-promoted catalysts is observed. Notably, platinum suppresses the aggregation of cobalt nanoparticles (CoNPs) during catalyst preparation, as evidenced by STEM/TEM and XRD analyses, which reveal the presence of smaller CoNPs and weakened cobalt diffraction in platinum-promoted catalysts. In addition, platinum also promotes the formation of more active

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Takabatake, Moe, and Ken Motokura. "Montmorillonite-based heterogeneous catalysts for efficient organic reactions." Nano Express 3, no. 1 (2022): 014004. http://dx.doi.org/10.1088/2632-959x/ac5ac3.

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Abstract In this review, we give a brief overview of recently developed montmorillonite-based heterogeneous catalysts used for efficient organic reactions. Cation-exchanged montmorillonite catalysts, metal catalysts supported on montmorillonite, and an interlayer design used for selective catalysis are introduced and discussed. In traditional syntheses, homogeneous acids and metal salts were used as catalysts, but the difficulty in separation of catalysts from products was a bottleneck when considering industrialization. The use of solid heterogeneous catalysts is one of the major solutions to

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Gomes, Ruan, Denilson Costa, Roberto Junior, et al. "Dry Reforming of Methane over NiLa-Based Catalysts: Influence of Synthesis Method and Ba Addition on Catalytic Properties and Stability." Catalysts 9, no. 4 (2019): 313. http://dx.doi.org/10.3390/catal9040313.

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Abstract (sommario):

CO2 reforming of CH4 to produce CO and H2 is a traditional challenge in catalysis. This area is still very active because of the potentials offered by the combined utilization of two green-house gases. The development of active, stable, and economical catalysts remains a key factor for the exploitation of natural gas (NG) with captured CO2 and biogas to produce chemicals or fuels via syngas. The major issue associated with the dry reforming process is catalyst deactivation by carbon deposition. The development of suitable catalyst formulations is one strategy for the mitigation of coking which

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Li, Gui Hua, and An Feng Wang. "Oxidative Esterification of Methacrolein to Methyl Methacrylate over La Doped Catalyst." Advanced Materials Research 512-515 (May 2012): 2390–93. http://dx.doi.org/10.4028/www.scientific.net/amr.512-515.2390.

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Abstract (sommario):

In this present work, rare earth elements La was added to catalysts for the oxidative esterification of methacrolein (MAL) to methyl methacrylate(MMA). Catalysts were characterized by means of BET techniques. Effects of La proportion, material liquid pH and catalyst amount on catalytic performance were investigated. The results indicated that the addation of La in appropriate proportion could improve the catalyst’s activity. 1.0% was found to be the optimum La additional amount. Under the condition of reation temperature 323K, w%(catalyst) 3.6%, proportion of La in the catalyst 1%, pH of mater

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Gates, Bruce C. "Concluding remarks: progress toward the design of solid catalysts." Faraday Discussions 188 (2016): 591–602. http://dx.doi.org/10.1039/c6fd00134c.

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Abstract (sommario):

The 2016 Faraday Discussion on the topic “Designing New Heterogeneous Catalysts” brought together a group of scientists and engineers to address forefront topics in catalysis and the challenge of catalyst design—which is daunting because of the intrinsic non-uniformity of the surfaces of catalytic materials. “Catalyst design” has taken on a pragmatic meaning which implies the discovery of new and better catalysts on the basis of fundamental understanding of the catalyst structure and performance. The presentations and discussion at the meeting illustrate the rapid progress in this understandin

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