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Journal articles on the topic 'Catalyst'
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1
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 selectivity. It is shown that a common donor-acceptor mechanism of catalysis is realized in heterogeneous and field catalysis. Generalized formulas are obtained, from which, as partial results, the laws of heterogeneous and field catalysis follow. New definitions of catalyst and field catalysis are given. The class of material catalysts has been expanded and supplemented with field catalysts.
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Ortega-Caballero, Fernando, and Mikael Bols. "Cyclodextrin derivatives with cyanohydrin and carboxylate groups as artificial glycosidases." Canadian Journal of Chemistry 84, no. 4 (April 1, 2006): 650–58. http://dx.doi.org/10.1139/v06-039.
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Two cyclodextrin derivatives (1 and 2) were prepared in an attempt to create glycosidase mimics with a general acid catalyst and a nucleophilic carboxylate group. The catalysts 1 and 2 were found to catalyse the hydrolysis of 4-nitrophenyl β-D-glucopyranoside at pH 8.0, but rapidly underwent decomposition with loss of hydrogen cyanide to convert the cyanohydrin to the corresponding aldehyde. The initial rate of the catalysis shows that the cyanohydrin group in these molecules functions as a good catalyst, but that the carboxylate has no positive effect. The decomposition product aldehydes display little or no catalysis. A mechanism for the decomposition is suggested.Key words: biomimicry, enzyme model, kinetics, intramolecular reaction.
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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 25 years of studies in the field of heterogeneous catalysis.
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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 prevention, wear resistance and anti-poisoning.
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Ma, Yubo, Zhixian Gao, Tao Yuan, and Tianfu Wang. "Kinetics of Dicyclopentadiene Hydroformylation over Rh–SiO2 Catalysts." Progress in Reaction Kinetics and Mechanism 42, no. 2 (May 2017): 191–99. http://dx.doi.org/10.3184/146867817x14821527549013.
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The hydroformylation of dicyclopentadiene (DCPD) to monoformyltricyclodecenes (MFTD) represents a key intermediate step in the conversion of the C5 fraction derived from the petrochemical process to value-added fine chemicals, for example, diformyltricyclodecanes and tricyclodecanedimethylol. Although both heterogeneous and homogeneous catalysts can catalyse this reaction, the heterogeneously catalysed pathway has received significantly less attention due to its lower catalytic activities. We demonstrate in this work that a low Rh loaded heterogeneous 0.1% Rh–SiO2 catalyst can present a similar performance relative to the homogeneous Rh(PPh3)Cl, a reference catalyst for this reaction. Furthermore, an extensive kinetic study of DCPD hydroformylation to MFTD using heterogeneous 0.1% Rh–SiO2 catalysts has been performed. A series of kinetic experiments was carried out over a broad range of conditions (temperature: 100–120 °C; pressure: 1.5–5 MPa; catalyst-to-reactant mass ratio: 0.02–0.05; PPh3 concentration: 5–12.5 g L−1). A kinetic analysis was carried out, indicating the activation energy for the reaction to be 84.7 kJ mol−1. DCPD conversion and MFTD yield could be optimised to be as high as 99% at 0.1% Rh loading, a DCPD/catalyst mass ratio of 25, a PPh3 concentration of 10 g L−1, a reaction time of 4 h and a reaction pressure of 4 MPa.
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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 (July 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 toluene diamine synthesis were analyzed by using the descriptor system of MIRA21. In this study, exploratory data analysis (EDA) has been used to understand the relationships between individual variables such as catalyst performance, reaction conditions, catalyst compositions, and sustainable parameters. The results will be applicable in catalyst design, and using machine learning tools will also be possible.
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Donatus Setyawan Purwo Handoko and Triyono. "Characterization of NI/Zeolite Catalyst Including Specific Surface Area, Acidity, Si/Al Ratio, Cation Content in Zeolite." Formosa Journal of Sustainable Research 2, no. 6 (June 30, 2023): 1457–70. http://dx.doi.org/10.55927/fjsr.v2i6.4396.
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Specific Surface Area, acidity, Si/Al ratio, and cation concentration in zeolite catalysts have all been studied in relation to Ni/zeolite catalysts. The zeolite was submerged in water for 24 hours, dried, and then calcined for 3 hours at 400 oC before being incubated for 2 hours to create the Ni/zeolite catalyst. then 24 hours of stirring soaking in 6 M HCl, followed by 3 hours of refluxing with 1 M NH4Cl and 2 hours of oxygen gas oxidation. The zeolite will subsequently be impregnated with Ni, oxidized for three hours, and reduced with hydrogen gas for two hours. Additionally, a Ni/zeolite catalyst was acquired. The catalyst's metal concentration was then determined by characterizing the Ni/zeolite mixture, Si/Al ratio, specific surface area, and acidity of the catalyst. The outcomes of the characterisation are as follows: Ca and Fe are the main metals present in the Ni/zeolite catalyst, with only trace amounts of Na, Mg, and other metals (5 mg/gram of catalyst) present. In the meantime, the catalyst's acidity was 0.24 mmol/gram catalyst acidity, its surface area was 2.18 m2/gram catalyst surface area, and its Si/Al catalyst ratio was 10.21
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Jin, Jia Min. "Catalysis Mechanism and Application of Carbon Gasification Reaction-A Comparison of Two Heterogeneous Catalysis Mechanisms." International Journal of Chemistry 14, no. 1 (April 14, 2022): 23. http://dx.doi.org/10.5539/ijc.v14n1p23.
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This article is a brief summary article of research. The results of the three times experiments are reviewed. two heterogeneous catalysis mechanisms are introduced, namely: Chemical Reaction Mode Cyclic Catalysis Mechanism-CRM and Electron Cyclic Donate-Accept Catalysis Mechanism-ECDAM or Electron Orbital Deformation-Recovery Cyclic Catalysis Mechanism -EODRM. Some difficulties encountered by CRM are listed. The author clearly points out that the CRM is not credible. This false theory has misled us for more than 100 years.
About ECDAM, the article also gives a brief description. The main point of ECDAM is that the catalysis phenomenon are physical rather than chemical phenomenon. The catalysts do not participate in chemical reactions. It's just contact, electron cyclic donate-accept or electron orbital deformation-recovery cycle. The theory contains three viewpoints:
1. There is a boundary between the catalyst and the poison.
2. The active of the catalyst or the degree of toxicity of the poison is closely related to ihe electronegative value of the catalyst or poison.
3. The active of catalyst is closely related to the chemical state of the catalyst
The selectivity of catalyst is also related to electronegative or energy level
According to ECDAM, the author considers that there are several problems worth studying in production and scientific research. such as: alumina is a poison in the Fe ammonia synthesis catalyst. The Cordierite (2MgO·2Al2O3·5SiO2) ceramic honeycomb support is also a poison in automotive exhaust purification catalyst. The Cordierite ceramic honeycomb is retardant in wall flow filter for diesel vehicles. Activated carbon is a poison in the Ruthenium catalyst for ammonia synthesis. Alumina and activated carbon all are a poison to noble metal catalysts, and so on.
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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 (June 2, 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 ions had significant effects on the catalytic activity of the catalyst. A certain proportion of Fe and Ti ions additionally enhanced the catalytic activity of the catalyst, with the catalyst-specific composition of Fe:Zr: Ti = 2:1: 1 showing optimal catalytic activity. A variety of substituents in the benzene ring, such as the electron-withdrawing group, the electron-donating group, large steric hindrance, and the position of the group on the benzene ring, had regular effects on the catalytic activity of the methyl benzoates. An increase in the catalyst activity occurred owing to the increases in the catalyst surface and the number of acid sites after the Fe ion was added. The catalytic activity remained unchanged after the facile recycling method was performed.
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Jankovič, Ľuboš, and Peter Komadel. "Catalytic Properties of a Heated Ammonium-Saturated Dioctahedral Smectite." Collection of Czechoslovak Chemical Communications 65, no. 9 (2000): 1527–36. http://dx.doi.org/10.1135/cccc20001527.
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A series of acid catalysts was prepared by heating of NH4-saturated montmorillonite at 200-600 °C for 24 h. Their catalytic activity was tested in acetylation of 3,4,5-trimethoxybenzaldehyde with acetic anhydride. This reaction is sufficiently sensitive to modification of the catalyst and thus suitable for testing catalytic activity of modified montmorillonites. Most of the prepared catalysts were able to catalyse the test reaction and produce diacetate in higher than 50% yields. The most active catalyst was obtained after heating at 300 °C. It was slightly less effective than commercially available acid-activated K10 catalyst.
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Pan, Dipika, and Jhuma Ganguly. "Assessment of Chitosan Based Catalyst and their Mode of Action." Current Organocatalysis 6, no. 2 (June 24, 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, nontoxicity, the lack of metal leaching possibility, inertness towards moisture and oxygen, easy handling and storage are the main advantages of organocatalysts. Traditional drawbacks associated with the metal-based heterogeneous catalysts, like longer reaction times during any synthesis, metal-leaching after every reaction and structural instability of the catalyst for prolonged recycling experiments are also very negligible for chitosan based catalysts. Besides, these catalysts can contribute more in catalysis due to their reusability and these special features increase their demand as the functionalized and profitable catalysts.Objective:The thorough description about the preparation of organocatalysts from chitosan and their uniqueness and novel activities in various famous reactions includes as the main aim of this review. Reusable and recycle nature of chitosan based organocatalysts gain the advantages over traditional and conventional catalyst which is further discussed over here.Methods and Discussions:In this article only those reactions are discussed where chitosan has been used both as support in heterogeneous catalysts or used as a catalyst itself without any co-catalyst for some reactions. Owing to its high biodegradability, nontoxicity, and antimicrobial properties, chitosan is widely-used as a green and sustainable polymeric catalyst in vast number of the reactions. Most of the preparations of catalyst have been achieved by exploring the complexation properties of chitosan with metal ions in heterogeneous molecular catalysis. Organocatalysis with chitosan is primarily discussed for carbon-carbon bond-forming reactions, carbon dioxide fixation through cyclo- addition reaction, condensation reaction and fine chemical synthesis reactions. Furthermore, its application as an enantioselective catalyst is also considered here for the chiral, helical organization of the chitosan skeleton. Moreover, another advantage of this polymeric catalyst is its easy recovery and reusability for several times under solvent-free conditions which is also explored in the current article.Conclusion:Important organocatalyzed reactions with either native chitosan or functionalized chitosan as catalysts have attracted great attention in the recent past. Also, chitosan has been widely used as a very promising support for the immobilization of catalytic metals for many reactions. In this review, various reactions have been discussed which show the potentiality of chitosan as catalyst or catalyst support.
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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 (January 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 this method, three efficient catalysts were prepared and CuO–Co3O4@SiO2 catalyst had the best catalytic performance. In a word, once it is applied in catalysts research, there will be a huge progress in catalysis and materials science fields.
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Otsuka, Yuta, Yuto Shimazaki, Hitoshi Nagaoka, Keiji Maruoka, and Takuya Hashimoto. "Scalable Synthesis of a Chiral Selenium π-Acid Catalyst and Its Use in Enantioselective Iminolactonization of β,γ-Unsaturated Amides." Synlett 30, no. 14 (June 28, 2019): 1679–82. http://dx.doi.org/10.1055/s-0039-1690109.
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Chiral selenium π-acid catalysis has for a long time been lagging behind other areas of asymmetric catalysis due to a lack of highly enantioselective catalysts. In this regard, we recently developed the first chiral selenium π-acid catalyst which performs the oxidative cyclization of β,γ-unsaturated carboxylic acids with high enantioselectivities. We report herein our improved synthesis of this chiral selenium catalyst, which allows access to a large quantity of the catalyst as the diselenide. In addition, the catalyst is tested in the oxidative cyclization of N-methoxy β,γ-unsaturated amides to give iminolactones with high enantioselectivities.
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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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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 understanding linked with improvements in spectroscopy, microscopy, theory, and catalyst performance testing. The following text includes a statement of recurrent themes in the discussion and examples of forefront science that evidences progress toward catalyst design.
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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 (September 18, 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 creates a need for highly selective catalysts. Synthetic control over the nanostructured environment of catalytic active sites could facilitate the creation of both more stable and selective catalysts. In this review, we discuss the use of metal oxide deposition as an emerging strategy that can be used to synthesize and/or modify heterogeneous catalysts to introduce tailored nanostructures. Several important applications are reviewed, including the synthesis of high surface area mesoporous metal oxides, the enhancement of catalyst stability, and the improvement of catalyst selectivity.
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Khangarot, Rama Kanwar, Manisha Khandelwal, and Sumit Kumar Ray. "Syntheses and Applications of Singh’s Catalyst." Synthesis 52, no. 23 (August 19, 2020): 3577–82. http://dx.doi.org/10.1055/s-0040-1707235.
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Singh’s catalyst has emerged as one of the most promising and valuable catalysts in the field of asymmetric synthesis. Since its discovery, it has proven to be one of the best organocatalysts for asymmetric direct aldol reactions, and is equally efficient in aqueous and organic media. In this Short Review, we summarize reactions utilizing Singh’s catalyst under various conditions.1 Introduction2 Synthesis of Singh’s Catalyst3 Applications in Asymmetric Synthesis4 Conclusion
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Lukey, CA, MA Long, and JL Garnett. "Aromatic Hydrogen Isotope Exchange Reactions Catalyzed by Iridium Complexes in Aqueous Solution." Australian Journal of Chemistry 48, no. 1 (1995): 79. http://dx.doi.org/10.1071/ch9950079.
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Sodium hexachloroiridate (III) and sodium hexachloroiridate (IV) have been used as homogeneous catalysts for hydrogen isotope exchange between benzenoid compounds and water. The ideal solvent consisted of 50 mole % acetic acid/water, and the optimum temperature was found to be 160°C. Under these conditions the rate of incorporation of deuterium into benzene was significant (typically 15% D in 6 h), and reduction to iridium metal was minimized. The active catalytic species was identified as a solvated iridium(III) species, which is also postulated to be the active catalyst in solutions containing hexachloroiridate (IV). The kinetics of exchange in benzene catalysed by sodium hexachloroiridate (III) were elucidated, and found to be more complex than for the corresponding sodium tetrachloroplatinate (II) catalysed exchange, in that a two-term rate dependence was found for catalyst concentration and the reaction was inversely dependent on hydrogen ion concentration. The reaction was found to be independent of chloride ion concentration, this confirming that the active catalyst is a solvated species. Isotopic labelling in all compounds was confined to the aromatic ring, and most substituted benzenes exhibited deactivation of the ortho positions, indicating that a dissociative π-complex exchange mechanism was operating. This was confirmed by exchange into naphthalene, where it was found that labelling was predominantly in the β position. Facile exchange into nitrobenzene provided good evidence of homogeneous catalysis, and not catalysis by precipitated metal.
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Gamaliia, Vira, Artem Zabuga, and Gennadii Zabuga. "On the History of Developing Catalysis in Ukraine (1850s–1980s)." Acta Baltica Historiae et Philosophiae Scientiarum 11, no. 2 (December 15, 2023): 76–92. http://dx.doi.org/10.11590/abhps.2023.2.04.
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The article is dedicated to the history of developing highly effective catalysts in the leading scientific institutions of Ukraine and explores the prerequisites for developing theories in physical chemistry, in particular those related to kinetics and catalysis. It highlights the significance of scientific discoveries at the turn of the 19th and 20th century and their application by native scientists to advance theoretical development in the field of chemistry. Special attention is paid to the works of Lev Pisarzhevskii, focusing on his advancements in electronic chemistry and, in particular, the electronic theory of catalysis. The article also outlines current challenges in creating highly efficient catalysts for the chemical and light industry, emphasizing the importance of such indicators of catalysts as activity and selectivity. Drawing on historical, scientific and patent data, the study investigates the process of creating a highly efficient catalyst for obtaining acrylic acid from acrolein. This catalyst holds a great ractical importance for the production of various polymers in industrial conditions. It is shown that, as a result of research conducted by native scientists of the Institute of Physical Chemistry of the Academy of Sciences of the Ukrainian SSR and the Chemistry Department of Kyiv State University, the catalyst K-2-5 was developed. The catalyst has good indicators for the industrial production of acrylic acid from acrolein. The authors also highlight works studying the properties of the obtained catalyst, specifically its porous structure, which is an important factor in catalytic processes. They extensively focus on the kinetic indicators of catalytic reactions that occur when using this catalyst. The article also emphasizes the relevance of these developments for advancing research in catalysis and chemical industrial production.
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Nyembe, Sanele, Gebhu Ndlovu, Poslet Shumbula, Richard Harris, Nosipho Moloto, and Lucky Sikhwivhilu. "Laser Assisted Catalytic Growth of Silicon Nanowires Using Gold and Nickel Catalysts." Journal of Nanoscience and Nanotechnology 21, no. 10 (October 1, 2021): 5260–65. http://dx.doi.org/10.1166/jnn.2021.19448.
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Laser assisted synthesis of silicon nanowires (SiNWs) was successfully achieved through the use of gold and nickel as catalysts. The diameter of the resulting SiNWs was found to be dependent on that of the catalyst in the case of gold catalyst. The gold catalysed silicon nanowires were unevenly curved and branched owing to the high kinetic energy possessed by gold nanoparticles (AuNPs) at relatively high processing temperature. The use of nickel as catalyst resulted in the formation of several SiNWs on a single nickel catalyst crystallite due to interconnection of the nickel metal crystallites at processing temperature. The morphology of SiNWs catalysed by both nickel and gold was controlled by optimising the laser energy during ablation.
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Jia, Wenzhi, Xia Cai, Yong Zhang, Xiaohua Zuo, Juanjuan Yuan, Xinhua Liu, Zhirong Zhu, and Xiangyi Deng. "Catalytic Dehydrofluorination of Hydrofluoroalkanes to Fluorinated Olifein Over Ni/AlF3 Catalysts." MATEC Web of Conferences 238 (2018): 03004. http://dx.doi.org/10.1051/matecconf/201823803004.
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The hydrofluoric acid-resisting aluminum compounds (AlF3, AlPO4, AlN) supported with Ni catalyst were prepared by the wetness impregnation and tested for dehydrofluorination of hydrofluoroalkane to synthesize fluoroolefins. It is found that Ni/AlF3 catalyst has the best catalytic performance, CF3CFH2 conversion of 29.3% after the reaction at 430 °C for 30 h, CF2HCH3 conversion of 31.8% after the reaction at 250 °C for 30 h, respectively. Comparatively, dehydrofluorination temperature of CF3CFH2 is higher than CF2HCH3 over the aluminum compounds catalyst, and the activity of catalysts is related with Lewis acidity. For the aluminum compounds catalyst, addition of Ni had promoted the activity and stability of Lewis acidic catalysts, it is attributed to synergistic catalysis of Lewis acid sites and Ni.
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Wong, W.-Y., S. Lim, Y.-L. Pang, C.-H. Lim, F.-L. Pua, and G. Pua. "Response surface optimisation of biodiesel synthesis using biomass derived green heterogeneous catalyst." IOP Conference Series: Materials Science and Engineering 1257, no. 1 (October 1, 2022): 012010. http://dx.doi.org/10.1088/1757-899x/1257/1/012010.
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Abstract Although homogeneous alkali-catalysed transesterification is the typical process used in biodiesel production, it caused complications in downstream separation processes and an oversupply of glycerol as a by-product. The present work studied the synthesis of a novel sulfonated biomass-derived solid acid catalyst and its application in biodiesel production via interesterification of oleic acid. Solid acid catalysts were prepared by direct sulfonation via thermal treatment with concentrated sulfuric acid. The design of experiments was conducted via four-factors central composite design (CCD) coupled with response surface methodology (RSM) analysis. The parameters considered for optimisation included carbonisation and sulfonation temperatures, catalyst loading and reaction time, each varied at five levels. The maximum yield of fatty acid methyl ester (FAME) was obtained using optimum parameters as carbonisation temperature of 586 °C, sulfonation temperature of 110 °C, catalyst loading of 10.5 wt.% and reaction time of 7 h was 54.3 % based on the theoretical ester formation. A quadratic mathematical model in RSM was successfully established that can make effective predictions about the anticipated biodiesel yield. This study proved that the low-cost heterogeneous catalyst derived from biomass waste with a simple production route could catalyse the interesterification process under moderate process conditions.
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Utama, Panca Setia, Wahyu Bambang Widayatno, Muhammad Rizwan Azhar, Hussein Rasool Abid, Wenchao Peng, Oki Muraza, and Edy Saputra. "LaMnO3 Perovskite Activation of Peroxymonosulfate for Catalytic Palm Oil Mill Secondary Effluent Degradation." Journal of Applied Materials and Technology 2, no. 1 (November 12, 2020): 27–35. http://dx.doi.org/10.31258/jamt.2.1.27-35.
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The LaMnO3 perovskite catalyst was successfully synthesized using a simple solid-state reaction method. This catalyst is used to activate PMS in the organic content's degradation process in the secondary effluent palm oil mill (POMSE). The organic content in POMSE is equivalent to the COD value; thus the COD value is used as a parameter for the process's success. The catalyst performance test shows that the catalyst effectively reduces COD, and the waste meets the maximum threshold allowed by government regulations. The variables that affect the catalyst's effectiveness were the calcination temperature of the catalyst, catalyst loading, PMS concentration, and temperature. The temperature of calcination affects the perovskite crystal formation; the higher the temperature, the more active catalyst obtained. The catalyst loading and PMS concentration variables affect the degradation process of organic levels in POMSE; at low levels, the higher the catalyst loading and PMS concentrations will increase the effectiveness of the degradation process, but at certain levels, the addition of catalysts and PMS reduces the effectiveness of the process. LaMnO3-800oC catalyst presents the highest activity of 92.7% and met the allowable threshold of COD < 300 mg/L. The sequence for removal of COD among the three catalysts with an order of LaMnO3-800oC > LaMnO3-700oC > LaMnO3-600 oC. The pseudo-second-order kinetics equation fits the experimental data. The effect of temperature on the kinetics constant follows the Arrhenius equation. Furthermore, the catalyst obtained was stable, with no significant decrease in catalysts activity up to three runs.
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Gomes, Ruan, Denilson Costa, Roberto Junior, Milena Santos, Cristiane Rodella, Roger Fréty, Alessandra Beretta, and Soraia Brandão. "Dry Reforming of Methane over NiLa-Based Catalysts: Influence of Synthesis Method and Ba Addition on Catalytic Properties and Stability." Catalysts 9, no. 4 (March 30, 2019): 313. http://dx.doi.org/10.3390/catal9040313.
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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 becomes especially demanding when noble metal-free catalysts are targeted. In this work NiLa-based catalyst obtained from perovskite precursors La1−xBaxNiO3 (x = 0.0; 0.05; 0.1 and 0.2) and NiO/La2O3 were synthesized, characterized by in situ and operando XRD and tested in the dry reforming of methane. The characterization results showed that the addition of barium promoted BaCO3 segregation and changes in the catalyst structure. This partly affected the activity; however, the incorporation of Ba improved the catalyst resistance to deactivation process. The Ba-containing and Ba-free NiLa-based catalysts performed significantly better than NiO/La2O3 catalysts obtained by wet impregnation.
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Li, Yudong, Michael Hinshelwood, and Gottlieb S. Oehrlein. "Investigation of Ni catalyst activation during plasma-assisted methane oxidation." Journal of Physics D: Applied Physics 55, no. 15 (January 19, 2022): 155202. http://dx.doi.org/10.1088/1361-6463/ac4724.
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Abstract Atmospheric pressure plasma has shown promise in improving thermally activated catalytic reactions through a process termed plasma-catalysis synergy. In this work, we investigated atmospheric pressure plasma jet (APPJ)-assisted CH4 oxidation over a Ni/SiO2 .Al2O3 catalyst. Downstream gas-phase products from CH4 conversion were quantified by Fourier transform infrared spectroscopy. The catalyst near-surface region was characterized by in-situ diffuse reflectance infrared Fourier transform spectroscopy. The catalyst was observed to be activated at elevated temperature (500 °C) if it was exposed to the APPJ operated at large plasma power. ‘Catalyst activation’ signifies that the purely thermal conversion of CH4 using catalysts which had been pre-exposed to plasma became more intense and produced consistently CO product, even if the plasma was extinguished. Without the application of the APPJ to the Ni catalyst surface this was not observed at 500 °C. The study of different exposure conditions of the activated catalyst indicates that the reduction of the catalyst by the APPJ is likely the cause of the catalyst activation. We also observed a systematic shift of the vibrational frequency of adsorbed CO on Ni catalyst when plasma operating conditions and catalyst temperatures were varied and discussed possible explanations for the observed changes. This work provides insights into the plasma-catalyst interaction, especially catalyst modification in the plasma catalysis process, and potentially demonstrates the possibility of utilizing the surface CO as a local probe to understand the plasma-catalyst interaction and shed light on the complexity of plasma catalysis.
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Xu, Jun Qiang, Fang Guo, Jun Li, Xiu Zhi Ran, and Yan Tang. "Synthesis of the Cu/Flokite Catalysts and their Performances for Catalytic Wet Peroxide Oxidation of Phenol." Advanced Materials Research 560-561 (August 2012): 869–72. http://dx.doi.org/10.4028/www.scientific.net/amr.560-561.869.
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The supported Cu/Flokite catalysts were prepared by conventional incipient wetness impregnation. The catalysis oxidation degradation of phenol was carried out in heterogeneous catalyst and H2O2 process. The results indicated that the reaction system with catalyst and hydrogen peroxide was more benefit to degradation of phenol. When the phenol initial concentration was 100 mg/L, the phenol removal over the 2.5%Cu -2.5% Fe/Flokite catalyst could reach 96%. The peroxide catalytic oxidation process over the enhanced heterogeneous catalyst would be a novel technique for the treatment of phenol wastewater.
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Gupta, Raman, Monika Gupta, Satya Paul, and Rajive Gupta. "Silica-supported ZnCl2 — A highly active and reusable heterogeneous catalyst for the one-pot synthesis of dihydropyrimidinones–thiones." Canadian Journal of Chemistry 85, no. 3 (March 1, 2007): 197–201. http://dx.doi.org/10.1139/v07-018.
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A novel silica-supported zinc chloride catalyst was prepared and investigated for the Biginelli reaction. The key features of the catalyst include rapid reaction with 100% conversion of aldehyde, good catalyst recyclability, and high stability under the reaction conditions (passes hot filtration test successfully). A low catalyst loading (12 mol% of ZnCl2) was required to achieve a quantitative reaction. Other catalysts such as SiO2–AlCl2, SiO2–AlCl2–ZnCl2 were also prepared and their activity was compared with SiO2–ZnCl2 for the Biginelli reaction.Key words: silica gel, zinc chloride, Biginelli compounds, heterogeneous catalysis, reusability.
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Sankarshana, T., J. Soujanya, and A. Anil Kumar. "Triphase Catalysis Using Silica Gel as Support." International Journal of Chemical Reactor Engineering 11, no. 1 (July 4, 2013): 347–52. http://dx.doi.org/10.1515/ijcre-2013-0007.
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Abstract The oxidation reaction of 2-ethyl-1-hexanol with potassium permanganate in the presence and absence of silica-gel-supported phase-transfer catalyst (PTC) in triphasic conditions was studied. In a batch reactor, the performance of the solid-supported catalysts was compared with unsupported catalyst and without the catalyst. The effect of speed of agitation, catalyst concentration, potassium permanganate concentration and temperature on reaction rate was studied. The reaction is found to be in the kinetic regime. The rate of reaction with the catalyst immobilised on the silica gel was less compared to the catalyst without immobilisation. Triphase catalysis with supported PTCs has potential applications in the continuous quest for greener industrial practices.
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Zhuang, Huimin, Bili Chen, Wenjin Cai, Yanyan Xi, Tianxu Ye, Chuangye Wang, and Xufeng Lin. "UiO-66-supported Fe catalyst: a vapour deposition preparation method and its superior catalytic performance for removal of organic pollutants in water." Royal Society Open Science 6, no. 4 (April 2019): 182047. http://dx.doi.org/10.1098/rsos.182047.
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A vapour deposition (VD) method was established for preparation of the UiO-66-supported Fe (Fe/UiO-66) catalyst, which provided the first case of the metal-organic framework (MOF)-supported Fe catalyst prepared by using the vapour-based method. The Fe loading was around 7.0–8.5 wt% under the present preparation conditions. The crystal structure of UiO-66 was not obviously influenced by the Fe loading, while the surface area significantly decreased, implicating most of the Fe components resided in the pores on UiO-66. The results for the methyl orange (MO) removal tests showed that MO in aqueous solution can be removed by UiO-66 by adsorption, and in contrast, it can be oxidized by H 2 O 2 with the catalysis of Fe/UiO-66. Further catalytic tests showed that Fe/UiO-66 was rather effective to catalyse the oxidation of benzene derivatives like aniline in water in terms of chemical oxygen demand (COD) removal efficiency. The catalytic test results for Fe/UiO-66 were compared to those of Fe/Al 2 O 3 with the same Fe loading and to the catalysts reported in the literature. This paper provides a general strategy for VD preparation of MOF-supported Fe catalyst on the one hand, and new catalysts for removing organic pollutants from water, on the other hand.
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Hao, Panpan, Mingjiang Xie, Shanyong Chen, Muhong Li, Feifei Bi, Yu Zhang, Ming Lin, Xiangke Guo, Weiping Ding, and Xuefeng Guo. "Surrounded catalysts prepared by ion-exchange inverse loading." Science Advances 6, no. 20 (May 2020): eaay7031. http://dx.doi.org/10.1126/sciadv.aay7031.
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The supported catalyst featuring highly dispersed active phase on support is the most important kind of industrial catalyst. Extensive research has demonstrated the critical role (in catalysis) of the interfacial interaction/perimeter sites between the active phase and support. However, the supported catalyst prepared by traditional methods generally presents low interface density because of limit contact area. Here, an ion-exchange inverse loading (IEIL) method has been developed, in which the precursor of support is controllably deposited onto the precursor of active phase by ion-exchange reaction, leading to an active core surrounded (by support) catalyst with various structures. The unique surrounded structure presents not only high interface density and mutually changed interface but also high stability due to the physical isolation of active phase, revealing superior catalytic performances to the traditional supported catalysts, suggesting the great potential of this new surrounded catalyst as the upgrade of supported catalyst in heterogeneous catalysis.
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Liu, Jingyue. "Advanced Electron Microscopy Characterization of Nanostructured Heterogeneous Catalysts." Microscopy and Microanalysis 10, no. 1 (January 22, 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 microscopy, among many characterization techniques, can provide useful information for the fundamental understanding of heterogeneous catalysis and for guiding the development of industrial catalysts. In this article, we discuss the recent developments in applying advanced electron microscopy techniques to characterizing model and industrial heterogeneous catalysts. The importance of understanding the catalyst nanostructure and the challenges and opportunities of advanced electron microscopy in developing nanostructured catalysts are also discussed.
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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 (August 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 the materials contain dispersed catalyst clusters which are desirable microstructures for the catalysis since the majority of the atoms are exposed to catalysis and are potentially active sites.The composition and atomic structure of the xerogel catalysts containing ruthenium and other metals have been examined using our in-house developments of environmental high resolution electron microscopy (EHREM) the atomic scale [1-3] and low voltage high resolution SEM (LVSEM)[4] methods.
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Choudhury, Joyanta, and Shrivats Semwal. "Emergence of Stimuli-Controlled Switchable Bifunctional Catalysts." Synlett 29, no. 02 (December 19, 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 Introduction2 Key Advances3 Conclusion
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Shinde, Preeti S., Pradnya S. Suryawanshi, Kanchan K. Patil, Vedika M. Belekar, Sandeep A. Sankpal, Sagar D. Delekar, and Sushilkumar A. Jadhav. "A Brief Overview of Recent Progress in Porous Silica as Catalyst Supports." Journal of Composites Science 5, no. 3 (March 6, 2021): 75. http://dx.doi.org/10.3390/jcs5030075.
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Porous silica particles have shown applications in various technological fields including their use as catalyst supports in heterogeneous catalysis. The mesoporous silica particles have ordered porosity, high surface area, and good chemical stability. These interesting structural or textural properties make porous silica an attractive material for use as catalyst supports in various heterogeneous catalysis reactions. The colloidal nature of the porous silica particles is highly useful in catalytic applications as it guarantees better mass transfer properties and uniform distribution of the various metal or metal oxide nanocatalysts in solution. The catalysts show high activity, low degree of metal leaching, and ease in recycling when supported or immobilized on porous silica-based materials. In this overview, we have pointed out the importance of porous silica as catalyst supports. A variety of chemical reactions catalyzed by different catalysts loaded or embedded in porous silica supports are studied. The latest reports from the literature about the use of porous silica-based materials as catalyst supports are listed and analyzed. The new and continued trends are discussed with examples.
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Widiarti, Nuni, Ismi Arinal Haq, F. Widhi Mahatmanti, Harjito Harjito, Cepi Kurniawan, Surapto Suprapto, and Didik Prasetyoko. "Biodiesel Synthesis From Waste Cooking Oil Using CaO.SrO Catalyst By Transesterification Reaction In Batch Reactor." Jurnal Bahan Alam Terbarukan 7, no. 2 (December 20, 2018): 136–41. http://dx.doi.org/10.15294/jbat.v7i2.14925.
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CaO is a very good catalyst for oil transesterification reactions into biodiesel, but requires a reaction time of 2 hours to obtain equilibrium. The time of CaO catalysis reaction can be accelerated by modifying the CaO catalyst with SrO. Synthesis biodiesel of waste cooking oil has been successfully conducted by transesterification reaction that used batch reactor assisted by CaO.SrO catalyst. The aim of this study is to determine the characteristics and catalytic activity of catalyst in the transesterification reaction. Catalysts have been successfully synthesized by coprecipitation method with oil to methanol molar ratio of 1:1, and its calcined at 800oC for 3 hours. Catalyst was characterized by XRD to determine the crystallinity. The smaller catalyst crystallinity obtained as the decline in intensity and shifts diffraction angles of CaO modified SrO catalyst. Surface area of catalyst characterized by SAA, that allow surface area between CaO modified SrO by 10.217 m2/g. Transesterification reaction performed on variation time (30, 60, 90, 120, 150 minutes), and the catalysts amount (1, 2, 4, 6, 8% w/v). The optimum condition of catalytic activity in reaction for 2 hours and the catalyst amount is 1% w/v of reactants that produce yield of biodiesel is 96.4%.
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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, confirming that the ring pucker is important. However, no substantial improvements were observed relative to the parent catalyst, l-proline.
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Cottone, Grazia, Sergio Giuffrida, Stefano Bettati, Stefano Bruno, Barbara Campanini, Marialaura Marchetti, Stefania Abbruzzetti, et al. "More than a Confinement: “Soft” and “Hard” Enzyme Entrapment Modulates Biological Catalyst Function." Catalysts 9, no. 12 (December 4, 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 soft immobilization matrices and their effect on the modulation of the catalysts’ function. Indeed, unlike smaller molecules, the catalytic activity of protein catalysts depends on their structure, conformation, local environment, and dynamics, properties that can be strongly affected by the immobilization matrices, which, therefore, not only provide physical confinement, but also modulate catalysis.
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Li, Feng, and Hao Li. "Spatial compartmentalisation effects for multifunctionality catalysis: From dual sites to cascade reactions." Innovation & Technology Advances 2, no. 1 (March 12, 2024): 1–13. http://dx.doi.org/10.61187/ita.v2i1.54.
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Catalysis plays a key role in the production of fuels, industrial chemicals and the chemical transformation of fine chemicals. As society faces increasing environmental pollution and energy crises, tandem catalysis has attracted increasing attention as an outstanding model due to its sustainability and environmental friendliness. Compared with traditional stepwise synthesis methods, tandem catalysis not only can couple several different reactions together, but also does not require the separation of intermediates, which provides new ideas for improving reaction activity, regulating product selectivity and developing new methods for catalysis. In order to catalyse cascade reactions efficiently, it is crucial to design suitable multifunctional catalysts, which should contain at least two active sites and achieve spatial separation. Here, we introduce the realisation and application of spatial segregation of metal, acidic and basic sites with examples to provide further insight into the indispensable role of active site compartmentalisation effects in tandem catalysis. In addition, this study highlights the challenges and issues associated with such catalysts, emphasising the importance of effective catalyst enhancement and environmentally sustainable catalytic transformations. The results of the study are intended to provide guidance for the development of rational and efficient catalysts.
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Zhao, Yue Qing, Qian Yi Jia, Ying Hua Liang, Hong Xia Guo, Feng Feng Li, and Xin Hua Liu. "CuO-CoO-MnO/SiO2 Nanocomposite Aerogel as Catalysts Carrier and Its Cocatalysis Mechanism in the Synthesis of Diphenyl Carbonate." Advanced Materials Research 284-286 (July 2011): 707–10. http://dx.doi.org/10.4028/www.scientific.net/amr.284-286.707.
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CuO-CoO-MnO/SiO2 nanocomposite aerogel as catalysts carrier was prepared via sol-gel process and CO2supercritical drying (SCD) technique. Catalyst supported by the nanocomposite aerogel was prepared via impregnation method. The catalyst was used for the synthesis of diphenyl carbonate (DPC), and the yield of DPC in mass is up to 26.31%. The catalysis system of PdCl2/Co(OAc)2-Cu(OAc)2-Mn(OAc)2/TBAB/H2BQ is favorable to the synthesis of DPC. PdCl2, acetates of transition metals and H2BQ were the key catalyst, inorganic cocatalyst and organic cocatalyst, respectively. TBAB was the surface active agent of Pd0and stabilizer of Pd2+in the catalysis system.
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Clerici, Mario G. "Zeolites for Fine Chemical Production State of Art and Perspectives." Eurasian Chemico-Technological Journal 3, no. 4 (July 10, 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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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 (December 15, 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 results in the reduction of other functional groups that are prominently featured in pharmaceuticals3. Homogeneous palladium catalysts can react chemoselectively with aryl (pseudo)halides but have not been used for hydrogenolysis reactions because, after required oxidative addition, they cannot split dihydrogen4. Here we report a homogenous hydrogenolysis reaction with a well defined, molecular palladium catalyst. We show how the thianthrene leaving group—which can be introduced selectively into pharmaceuticals by late-stage C–H functionalization5—differs in its coordinating ability to relevant palladium(II) catalysts from conventional leaving groups to enable the previously unrealized catalysis with dihydrogen. This distinct reactivity combined with the chemoselectivity of a well defined molecular palladium catalyst enables the tritiation of small-molecule pharmaceuticals that contain functionality that may otherwise not be tolerated by heterogeneous catalysts. The tritiation reaction does not require an inert atmosphere or dry conditions and is therefore practical and robust to execute, and could have an immediate impact in the discovery and development of pharmaceuticals.
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Xu, Jun Qiang, Fang Guo, Shu Shu Zou, and Xue Jun Quan. "Optimization of the Catalytic Wet Peroxide Oxidation of Phenol over the Fe/NH4Y Catalyst." Materials Science Forum 694 (July 2011): 640–44. http://dx.doi.org/10.4028/www.scientific.net/msf.694.640.
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The heterogeneous NH4Y zeolite-supported iron catalysts were prepared by incipient wetness impregnation. The catalysis oxidation degradation of phenol was carried over the heterogeneous catalyst in the peroxide catalytic oxidation process. Compared with the homogeneous Fenton process, the Fe/ NH4Y-acid catalyst can effectively degrade contaminants with high catalytic activity and easy catalyst separation from the solution. The phenol removal efficiency could reach 96% in the optimum experimental conditions. These process conditions were as follows: iron content is 5%, reaction time was 60 min, reaction temperature was 70 oC, the catalyst dosage was 1g/L, the H2O2 concentration was 1.65g/L.
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Guo, Fang, Jun Qiang Xu, and Jun Li. "Kinetics Studies for Catalytic Oxidation of Methyl Orange over the Heterogeneous Fe/Beta Catalysts." Advanced Materials Research 807-809 (September 2013): 361–64. http://dx.doi.org/10.4028/www.scientific.net/amr.807-809.361.
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The Fe/Beta catalysts were prepared by conventional incipient wetness impregnation. The catalysis oxidation degradation of methyl orange was carried out in catalyst and H2O2 process. The results indicated that the catalyst and hydrogen peroxide were more benefit to degradation of methyl orange. The reaction condition was optimized. The optimum reaction process was as follow: iron amount of catalyst was 1.25%, the catalyst dosage and H2O2 concentration was 1 mg/L and 1.5 mg/L, and reaction temperature was 70 °C. The apparent activation energy (65 KJ/mol) was obtained according to the arrhenius formula, which was benefit to study the reaction mechanism.
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Trigoura, Leslie, Yalan Xing, and Bhanu P. S. Chauhan. "Recyclable Catalysts for Alkyne Functionalization." Molecules 26, no. 12 (June 9, 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 addition, several alkyne functionalization reactions have been elucidated to demonstrate the success and efficiency of recyclable catalysts. In addition, this review also provides the fundamental knowledge required for utilization of green catalysts, which can combine the advantageous features of both homogeneous (catalyst modulation) and heterogeneous (catalyst recycling) catalysis.
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Liu, Chongfei, Xuetao Wang, Lili Xing, Xingxing Cheng, Xingyu Zhang, Haojie Li, and Mengjie Liu. "Effect of Zr Modification on NH3-SCR Reaction Performance of Cu-Ce/SAPO-34 Catalysts." Applied Sciences 13, no. 8 (April 10, 2023): 4763. http://dx.doi.org/10.3390/app13084763.
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Molecular sieve catalysts containing transition metals have been attracting attention for their potential applications in various fields, including environmental and industrial catalysis. A Cu-Ce-Zr/SAPO-34 series of molecular sieve catalysts were prepared by the impregnation method, and the effect of Zr introduction on the selective catalytic reduction of NO by Cu-Ce/SAPO-34 molecular sieve catalysts was explored. Through various characterization methods, the physical and chemical properties of the catalysts were analyzed, and the denitration mechanism of the molecular sieve catalyst was discussed. This study found that the total acid content of the acid sites on the catalyst surface decreased with the introduction of Zr, leading to a decrease in the denitration efficiency of the catalyst. At 350–400 °C, the denitration efficiency of the 4Cu-4Ce-4Zr/SAPO-34 catalyst was over 80%, and at 400–500 °C, it was over 99%. Moreover, excessive metal Zr could destroy its CHA structure and decrease the denitration efficiency of the catalyst. This study analyzed the reaction mechanism of NH3-SCR of Zr-modified polymetallic zeolites and the effect of Zr modification on the NH3-SCR reaction results. This study contributes to the understanding of the performance of molecular sieve catalysts containing transition metals. Reliable conclusions were obtained, which offer data support for future research in the field of NH3-SCR.
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Shera Farisya, Mohamad Rasid, Ramli Irmawati, Ishak Nor Shafizah, Yun Hin Taufiq-Yap, Ernee Noryana Muhamad, Siew Ling Lee, and Nurrulhidayah Salamun. "Assessment on the Effect of Sulfuric Acid Concentration on Physicochemical Properties of Sulfated-Titania Catalyst and Glycerol Acetylation Performance." Catalysts 11, no. 12 (December 17, 2021): 1542. http://dx.doi.org/10.3390/catal11121542.
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In this research, a solid acid catalyst was synthesized to catalyse glycerol acetylation into acetins. The sulphated-titania catalysts were prepared via the wet impregnation method at different sulfuric acid concentrations (5%, 10%, 15%, and 20%) and denoted as 5SA, 10SA, 15SA, and 20SA, respectively. The synthesized catalysts were characterized using FTIR, XRD, TGA, BET, NH3-TPD, XRF, and SEM-EDX. The synthesized catalysts were tested on glycerol acetylation reaction at conditions: 0.5 g catalyst loading, 100–120 °C temperature, 1:6 glycerol/acetic acid molar ratios, and 2–4 h reaction time. The final product obtained was analysed using GC-FID. An increment in sulfuric acid concentration reduces the surface area, pore volume, and particles size. However, the increment has increased the number of active sites (Lewis acid) and strong acid strength. 15SA catalyst exhibited excellent glycerol conversion (>90%) and the highest selectivity of triacetin (42%). Besides sufficient surface area (1.9 m2 g−1) and good porosity structure, the great performance of the 15SA catalyst was attributed to its high acid site density (342.6 µmol g−1) and the high active site of metal oxide (95%).
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Amrutkar, Rakesh D., Shivam S. Bhalerao, Akanksha S. Bhoir, Rina H. Bhusare, Samiksha S. Bodhare, and Jagruti N. Borse. "Role of catalyst in organic synthesis." Current Trends in Pharmacy and Pharmaceutical Chemistry 4, no. 3 (August 15, 2022): 115–19. http://dx.doi.org/10.18231/j.ctppc.2022.019.
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Catalyst is a common word that comes across while studying chemistry especially while learning about chemical reactions. While some of the chemical reactions occur quickly, some take a long time and require extra materials or effort. In Chemistry, catalysts are defined as those substances which alter the rate of reaction by changing the path of reaction. Most of the time a catalyst is used to speed up or increase the rate of the reaction. However, if we go to a deeper level, catalysts are used to break or rebuild the chemical bonds between the atoms which are present in the molecules of different elements or compounds. In essence, catalysts encourage molecules to react and make the whole reaction process easier and efficient. The present review focuses on history, types and role of catalysis in organic reaction.
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Utama, Herti, Simparmin Br Ginting, Dwi Derti Sulistiowati, and Ria Putri Hermiyati. "The Effect Catalyst Natural Zeolite of Lampung On The Synthesis Of α-Terpineol From Turpentine." INSIST 2, no. 2 (January 25, 2019): 89. http://dx.doi.org/10.23960/ins.v2i2.87.
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The major component of turpentine is α-pinene. Alpha pinene can be hydrated using an acid catalyst to produce α-terpineol. It can be used as a perfume, anti -insect, and disinfectants. The using of heterogeneous catalysts as natural zeolite can be a new alternative to replacehomogeneous catalysts. The purpose of this study was to determine the effect of zeolite catalysts and the reaction time which resulting the highest conversion on hydration reactions of turpentine to α-terpineol. Parameters were the effect of catalyst concentration of (5%, 10% and 15%) and the reaction time (60 minutes, 120 minutes and 180 minutes). The turpentine, aquadest and isopropyl alcohol were reacted in the three neck flask at the temperature of 70°C. The result of this study showed that the best condition the hydration of turpentine α-terpineol was achieced at 15% catalyst concentration and the reaction time of 180 minutes. The convertion was obtained to be 4.875%.Keywords— Turpentine, Hydration, Alpha terpineol, Catalys,Natural Zeolite.
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Holzwarth, Arnold, and Wilhelm F. Maier. "Catalytic Phenomena in Combinatorial Libraries of Heterogeneous Catalysts." Platinum Metals Review 44, no. 1 (January 1, 2000): 16–21. http://dx.doi.org/10.1595/003214000x4411621.
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Combinatorial catalysis is becoming a significant method for investigating the activities of large numbers of potential catalysts. A very important prerequisite for making use of combinatorial catalysis research is a reliable, fast and efficient technique for monitoring the catalytic activities. Emissivity-corrected infrared thermography, which monitors the heat changes resulting from the heat of reaction on catalyst surfaces, is such a technique. In this article we describe emissivity-corrected infrared thermography and demonstrate its performance, over time, in monitoring the catalytic activities of catalyst libraries. It is shown that not only can static relative activity be displayed, but also that catalyst-specific time-dependent properties, such as activation and deactivation phenomena can be demonstrated.
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Latos, Piotr, Anna Wolny, and Anna Chrobok. "Supported Ionic Liquid Phase Catalysts Dedicated for Continuous Flow Synthesis." Materials 16, no. 5 (March 5, 2023): 2106. http://dx.doi.org/10.3390/ma16052106.
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Heterogeneous catalysis, although known for over a century, is constantly improved and plays a key role in solving the present problems in chemical technology. Thanks to the development of modern materials engineering, solid supports for catalytic phases having a highly developed surface are available. Recently, continuous-flow synthesis started to be a key technology in the synthesis of high added value chemicals. These processes are more efficient, sustainable, safer and cheaper to operate. The most promising is the use of heterogeneous catalyst with column-type fixed-bed reactors. The advantages of the use of heterogeneous catalyst in continuous flow reactors are the physical separation of product and catalyst, as well as the reduction in inactivation and loss of the catalyst. However, the state-of-the-art use of heterogeneous catalysts in flow systems compared to homogenous ones remains still open. The lifetime of heterogeneous catalysts remains a significant hurdle to realise sustainable flow synthesis. The goal of this review article was to present a state of knowledge concerning the application of Supported Ionic Liquid Phase (SILP) catalysts dedicated for continuous flow synthesis.
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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 (October 1, 2006): 1343–50. http://dx.doi.org/10.1139/v06-076.
Full textAbstract:
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 of the Pd leaching with product formation in the allylic substitution chemistry for both types of catalysts suggests that the active catalysts in these reactions are leached from the support. In the case of the allylic substitution reaction, external triphenylphosphine and substrate together are required for the chemistry and Pd leaching.Key words: catalysis, palladium, allylic substitution, grafted polystyrene, supported catalysts.