scholarly journals Advances in Nanostructured Metal-Encapsulated Porous Organic-Polymer Composites for Catalyzed Organic Chemical Synthesis

Catalysts ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 492 ◽  
Author(s):  
Wilhemina Sebati ◽  
Suprakas Ray
Keyword(s):  
Binding Sites ◽  
Heterogeneous Catalysts ◽  
Acid Catalysis ◽  
High Surface ◽  
Organic Polymer ◽  
Organic Chemical ◽  
Characterization Methods ◽  
Catalytic Activities ◽  
Surface Areas ◽  
Nanostructured Metal

Porous organic polymers (POPs) are of growing research interest owing to their high surface areas, stabilities, controllable chemical configurations, and tunable pore volumes. The molecular nanoarchitecture of POP provides metal or metal oxide binding sites, which is promising for the development of advanced heterogeneous catalysts. This article highlights the development of numerous kinds of POPs and key achievements to date, including their functionalization and incorporation of nanoparticles into their framework structures, characterization methods that are predominantly in use for POP-based materials, and their applications as catalysts in several reactions. Scientists today are capable of preparing POP-based materials that show good selectivity, activity, durability, and recoverability, which can help overcome many of the current environmental and industrial problems. These POP-based materials exhibit enhanced catalytic activities for diverse reactions, including coupling, hydrogenation, and acid catalysis.

scholarly journals MOCVD of Field Emission Phosphors using a Liquid Delivery System

1997 ◽  
Vol 495 ◽  
Author(s):  
T. S. Moss ◽  
B. F. Espinoza ◽  
K. V. Salazar ◽  
R. C. Dye
Keyword(s):  
Thin Film ◽  
Field Emission ◽  
Delivery System ◽  
High Surface ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
X Ray ◽  
Surface Areas ◽  
Field Emission Displays ◽  
Liquid Delivery

ABSTRACTThin film phosphors for field emission displays show the potential to overcome the life-limiting problems that traditional powders face because of their high surface areas. By depositing a fully dense thin film, the surface area can be dramatically reduced, while the electrical and thermal conductivity is increased. Metal organic chemical vapor deposition offers the ability to deposit high quality, dense films that are crystalline-as-deposited and at temperatures low enough to allow for inexpensive glass. Deposition has been produced from mixtures of Y(tmhd)3, TEOS, Tb(tmhd)3, and O2 using a liquid delivery system. Coatings were shown to be composed of Y, Si, and Tb by x-ray fluorescence, but x-ray diffraction did not show any crystallinity. Excitation using radioluminescence produced a peak in the visible green at approximately 540 nm, indicative of the excitation of Tb3+. The morphology of the deposition was smooth, with surface features on the order of one micron and below. Some limited microcracking was also observed in the morphology because of the thermal expansion mismatch.

Synthesis of Mesoporous Tungsten Oxide/γ-Alumina and Surfactant-Capped Tungsten Oxide Nanoparticles and Their Catalytic Activities in Oxidative Cleavage of Oleic Acid

2016 ◽  
Vol 14 (4) ◽  
pp. 899-907 ◽  
Author(s):  
Amir Enferadi Kerenkan ◽  
Aimé Serge Ello ◽  
Bousselham Echchahed ◽  
Trong-On Do
Keyword(s):  
Tungsten Oxide ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Oxidative Cleavage ◽  
Type I ◽  
Type Ii ◽  
Catalytic Activities ◽  
Tungsten Oxide Nanoparticles ◽  
Catalytic Test

Abstract Unsaturated fatty acids can be converted into mono and dicarboxylic acids, which are applicably valuable materials, through oxidative cleavage reaction in the presence of a highly efficient catalyst/oxidant system. In this work, two types of advanced heterogeneous catalysts have been developed; (i) high surface area mesoporous tungsten oxide/γ-alumina mixed metal oxide, and (ii) surfactant-capped tungsten oxide nanoparticles. Various technique including N2 adsorption/desorption isotherms, XRD, SEM, EDS, TGA and catalytic test were used to monitor the physicochemical and catalytic properties of these materials. The characterization results revealed that type (i) materials exhibit high surface area and narrow particle size distribution, and the used surfactant could quantitatively enough cap the surface of type (ii) materials. The catalytic activities of these materials in the oxidative cleavage of oleic acid with H2O2 as oxidant were investigated. GC-MS was used to determine the produced amounts of desired products, azelaic and pelargonic acids. The catalytic test results showed more than 90 % conversion for type (ii) catalyst in 5 h reaction at 120 °C with acceptable production yields for azelaic and pelargonic acids. The significantly higher activity of this catalyst compared to type (i) arises from the interesting surface properties of tungsten oxides nanoparticles, which make them able to exploit the good features of homogeneous and heterogeneous catalysts.

scholarly journals Catalytic activities of heterogeneous catalysts obtained by copolymerization of metal-containing 2-(acetoacetoxy)ethyl methacrylate

2018 ◽  
Vol 16 (1) ◽  
pp. 520-534 ◽  
Author(s):  
Giuseppe Romanazzi ◽  
Piero Mastrorilli ◽  
Mario Latronico ◽  
Matilda Mali ◽  
Angelo Nacci ◽  
...  
Keyword(s):  
Heterogeneous Catalysts ◽  
High Efficiency ◽  
Organic Polymer ◽  
Metal Leaching ◽  
Metal Catalyst ◽  
Catalytic Activities ◽  
Ethyl Methacrylate ◽  
Heterogenous Catalyst ◽  
Multiple Cycles ◽  
Excellent Selectivity

AbstractAmong the synthetic strategies commonly used for supporting a metal complex onto an organic polymer in order to obtain an heterogenous catalyst, a valid choice is to synthesize a metal containing monomer (MCM), which can subsequently be subjected to polymerization with suitable comonomers and crosslinkers, achieving a supported transition metal catalyst as a metal-containing polymer (MCP). In this context, during the last two decades, we explored the use of 2-(acetoacetoxy)ethyl methacrylate (HAAEMA) as a ligand to prepare several MCMs for the relevant MCPs. In this review we summarize and discuss our developments in the studies of the catalytic activity of these “hybrid” catalysts. These catalysts have demonstrated high efficiency and/or excellent selectivity in several kinds of chemical reactions and very often they could be recovered and reused in multiple cycles maintaining their activity and selectivity without suffering from appreciable metal leaching.

Heteropoly Compounds: Efficient Superacid Catalysts

1994 ◽  
Vol 368 ◽  
Author(s):  
Makoto Misono ◽  
Toshio Okuhara
Keyword(s):  
Acid Catalysis ◽  
Tertiary Structure ◽  
High Surface ◽  
Surface Concentration ◽  
Acid Sites ◽  
Heteropoly Compounds ◽  
Catalytic Activities ◽  
High Surface Concentration ◽  
Superacid Catalysts ◽  
Constituent Elements

ABSTRACTOur recent studies on the acidity and acid catalysis of heteropoly compounds are described, together with a brief introduction of the background. High catalytic activities were observed due to the combination of their superacidity, pseudoliquid behavior, acid-base bifunctionality and/or high surface concentration of proton. It was also shown how the acid strength and the number of acid sites as well as their tertiary structure were controlled by the constituent elements (heteroand addenda-atoms and counter cations), and how those properties were correlated with the catalytic activities

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

A Highly Crystalline Anthracene-Based MOF-74 Series Featuring Electrical Conductivity and Luminescence

2019 ◽  
Author(s):  
Patricia Scheurle ◽  
Andre Mähringer ◽  
Andreas Jakowetz ◽  
Pouya Hosseini ◽  
Alexander Richter ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Metal Ions ◽  
Light Emission ◽  
Block Design ◽  
High Surface ◽  
Visible Spectrum ◽  
Building Blocks ◽  
Divalent Metal Ions ◽  
Conductivity Enhancement ◽  
Surface Areas

Recently, a small group of metal-organic frameworks (MOFs) has been discovered featuring substantial charge transport properties and electrical conductivity, hence promising to broaden the scope of potential MOF applications in fields such as batteries, fuel cells and supercapacitors. In combination with light emission, electroactive MOFs are intriguing candidates for chemical sensing and optoelectronic applications. Here, we incorporated anthracene-based building blocks into the MOF-74 topology with five different divalent metal ions, that is, Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, resulting in a series of highly crystalline MOFs, coined ANMOF-74(M). This series of MOFs features substantial photoluminescence, with ANMOF-74(Zn) emitting across the whole visible spectrum. The materials moreover combine this photoluminescence with high surface areas and electrical conductivity. Compared to the original MOF-74 materials constructed from 2,5-dihydroxy terephthalic acid and the same metal ions Zn2+, Mg2+, Ni2+, Co2+ and Mn2+, we observed a conductivity enhancement of up to six orders of magnitude. Our results point towards the importance of building block design and the careful choice of the embedded MOF topology for obtaining materials with desired properties such as photoluminescence and electrical conductivity.

Phosphorus Containing Porous Organic Polymers: Synthetic Techniques and Applications in Organic Synthesis and Catalysis

2021 ◽  
Author(s):  
Pramod Kumar ◽  
Animesh Das ◽  
Biplab Maji
Keyword(s):  
Organic Synthesis ◽  
Homogeneous Catalysis ◽  
Heterogeneous Catalysts ◽  
Organic Polymer ◽  
Organic Polymers ◽  
Porous Organic Polymers ◽  
Porous Organic Polymer ◽  
Phosphorus Containing

The phosphorous-containing porous organic polymer is a trending material for the synthesis of heterogeneous catalysts. Decades of investigations have established phosphines as versatile ligands in homogeneous catalysis. Recently, phosphine-based heterogeneous...

scholarly journals Mitigating the Agglomeration of Nanofiller in a Mixed Matrix Membrane by Incorporating an Interface Agent

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 328
Author(s):  
Manh-Tuan Vu ◽  
Gloria M. Monsalve-Bravo ◽  
Rijia Lin ◽  
Mengran Li ◽  
Suresh K. Bhatia ◽  
...  
Keyword(s):  
Gas Separation ◽  
Polymer Matrix ◽  
Ion Beam ◽  
High Surface ◽  
Mixed Matrix Membrane ◽  
Mechanical And Thermal Properties ◽  
Separation Membranes ◽  
Surface Areas ◽  
Separation Membrane ◽  
Focus Ion Beam

Nanodiamonds (ND) have recently emerged as excellent candidates for various applications including membrane technology due to their nanoscale size, non-toxic nature, excellent mechanical and thermal properties, high surface areas and tuneable surface structures with functional groups. However, their non-porous structure and strong tendency to aggregate are hindering their potential in gas separation membrane applications. To overcome those issues, this study proposes an efficient approach by decorating the ND surface with polyethyleneimine (PEI) before embedding it into the polymer matrix to fabricate MMMs for CO2/N2 separation. Acting as both interfacial binder and gas carrier agent, the PEI layer enhances the polymer/filler interfacial interaction, minimising the agglomeration of ND in the polymer matrix, which is evidenced by the focus ion beam scanning electron microscopy (FIB-SEM). The incorporation of PEI into the membrane matrix effectively improves the CO2/N2 selectivity compared to the pristine polymer membranes. The improvement in CO2/N2 selectivity is also modelled by calculating the interfacial permeabilities with the Felske model using the gas permeabilities in the MMM. This study proposes a simple and effective modification method to address both the interface and gas selectivity in the application of nanoscale and non-porous fillers in gas separation membranes.

scholarly journals A simple one-step electrochemical deposition of bioinspired nanocomposite for the non-enzymatic detection of dopamine

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Vijayaraj Kathiresan ◽  
Dinakaran Thirumalai ◽  
Thenmozhi Rajarathinam ◽  
Miri Yeom ◽  
Jaewon Lee ◽  
...  
Keyword(s):  
Electrochemical Deposition ◽  
Electrochemical Impedance ◽  
High Surface ◽  
Electrochemical Characteristics ◽  
Surface Areas ◽  
Electrochemically Reduced Graphene Oxide ◽  
Sensitivity And Selectivity ◽  
Controlled Deposition ◽  
Enzymatic Detection ◽  
Walled Carbon Nanotubes

AbstractA simple and cost-effective electrochemical synthesis of carbon-based nanomaterials for electrochemical biosensor is of great challenge these days. Our study describes a single-step electrochemical deposition strategy to prepare a nanocomposite of electrochemically reduced graphene oxide (ErGO), multi-walled carbon nanotubes (MWCNTs), and polypyrrole (PPy) in an aqueous solution of pH 7.0 for dopamine (DA) detection. The ErGO/MWCNTs/PPy nanocomposites show enhanced electrochemical performance due to the strong π–π* stacking interactions among ErGO, MWCNTs, and PPy. The efficient interaction of the nanocomposites is confirmed by evaluating its physical and electrochemical characteristics using field-emission scanning electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and amperometry. The deposited nanocomposites are highly stable on the substrates and possess high surface areas, which is vital to improve the sensitivity and selectivity for DA detection. The controlled deposition of the ErGO/MWCNTs/PPy nanocomposites can provide enhanced electrochemical detection of DA. The sensor demonstrates a short time response within 2 s and is a highly sensitive approach for DA detection with a dynamic linear range of 25–1000 nM (R2 = 0.999). The detection limit is estimated to be 2.3 nM, and the sensor sensitivity is calculated to be 8.96 μA μM−1 cm−2, with no distinct responses observed for other biological molecules.

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