scholarly journals Palladium (II)–Salan Complexes as Catalysts for Suzuki–Miyaura C–C Cross-Coupling in Water and Air. Effect of the Various Bridging Units within the Diamine Moieties on the Catalytic Performance

Molecules ◽  
2020 ◽  
Vol 25 (17) ◽  
pp. 3993 ◽  
Author(s):  
Szilvia Bunda ◽  
Krisztina Voronova ◽  
Ágnes Kathó ◽  
Antal Udvardy ◽  
Ferenc Joó
Keyword(s):  
Specific Activity ◽  
Catalytic Performance ◽  
Water Soluble ◽  
Aryl Halides ◽  
X Ray Diffraction ◽  
Arylboronic Acid ◽  
X Ray ◽  
Highly Active ◽  
Air Effect

Water-soluble salan ligands were synthesized by hydrogenation and subsequent sulfonation of salens (N,N’-bis(slicylidene)ethylenediamine and analogues) with various bridging units (linkers) connecting the nitrogen atoms. Pd (II) complexes were obtained in reactions of sulfosalans and [PdCl4]2−. Characterization of the ligands and complexes included extensive X-ray diffraction studies, too. The Pd (II) complexes proved highly active catalysts of the Suzuki–Miyaura reaction of aryl halides and arylboronic acid derivatives at 80 °C in water and air. A comparative study of the Pd (II)–sulfosalan catalysts showed that the catalytic activity largely increased with increasing linker length and with increasing steric congestion around the N donor atoms of the ligands; the highest specific activity was 40,000 (mol substrate) (mol catalyst × h)−1. The substrate scope was explored with the use of the two most active catalysts, containing 1,4-butylene and 1,2-diphenylethylene linkers, respectively.

scholarly journals Preparation and Characterization of Rh/MgSNTs Catalyst for Hydroformylation of Vinyl Acetate: The Rh0 was Obtained by Calcination

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 215 ◽  
Author(s):  
Penghe Su ◽  
Ya Chen ◽  
Xiaotong Liu ◽  
Hongyuan Chuai ◽  
Hongchi Liu ◽  
...  
Keyword(s):  
Vinyl Acetate ◽  
Atomic Emission ◽  
Catalytic Performance ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Atomic Emission Spectrometer ◽  
Calcination Method

A simple and practical Rh-catalyzed hydroformylation of vinyl acetate has been synthesized via impregnation-calcination method using silicate nanotubes (MgSNTs) as the supporter. The Rh0 (zero valent state of rhodium) was obtained by calcination. The influence of calcination temperature on catalytic performance of the catalysts was investigated in detail. The catalysts were characterized in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectrometer (XPS), atomic emission spectrometer (ICP), and Brunauer–Emmett–Teller (BET) surface-area analyzers. The Rh/MgSNTs(a2) catalyst shows excellent catalytic activity, selectivity and superior cyclicity. The catalyst could be easily recovered by phase separation and was used up to four times.

scholarly journals Fe-Containing MOFs as Seeds for the Preparation of Highly Active Fe/Al-SBA-15 Catalysts in the NAlkylation of Aniline

Molecules ◽  
2019 ◽  
Vol 24 (15) ◽  
pp. 2695 ◽  
Author(s):  
Mhadmhan ◽  
Marquez-Medina ◽  
Romero ◽  
Reubroycharoen ◽  
Luque
Keyword(s):  
Photoelectron Spectroscopy ◽  
Inductively Coupled Plasma ◽  
Catalytic Performance ◽  
Alkylation Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Inductively Coupled ◽  
Highly Active ◽  
Milling Method ◽  
Plasma Mass Spectrometry

We have successfully incorporated iron species into mesoporous aluminosilicates (AlSBA15) using a simple mechanochemical milling method. The catalysts were characterized by nitrogen physisorption, inductively coupled plasma mass spectrometry (ICP-MS), pyridine (PY) and 2,6-dimethylpyridine (DMPY) pulse chromatography titration, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). The catalysts were tested in the N-alkylation reaction of aniline with benzyl alcohol for imine production. According to the results, the iron sources, acidity of catalyst and reaction conditions were important factors influencing the reaction. The catalyst showed excellent catalytic performance, achieving 97% of aniline conversion and 96% of imine selectivity under optimized conditions.

scholarly journals Immobilization of Am-241, Formed Under Plutonium Metal Conversion, Into Monazite-Type Ceramics

2001 ◽  
Author(s):  
A. S. Aloy ◽  
E. N. Kovarskaya ◽  
T. I. Koltsova ◽  
S. E. Samoylov ◽  
S. I. Rovnyi ◽  
...  
Keyword(s):  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Specific Activity ◽  
X Ray Diffraction ◽  
Cold Pressing ◽  
X Ray ◽  
Liquid Wastes ◽  
Plutonium Metal ◽  
Metallic Plutonium

Abstract Lanthanum orthophosphate with the monazite structure was proposed on examinations as a suitable matrix for immobilization of future americium-containing liquid wastes, which could be formed in conversion of metallic plutonium into oxide at PA “Mayak.” Specimens of monazite non-active ceramics were fabricated from LaPO4 powders obtained using a thin-film evaporator by either hot-pressing or cold-pressing and sintering at 900–1300 °C. According to electron microprobe analysis (EMPA), scanning electron microscopy (SEM), and X-ray diffraction (XRD), which were used for characterization of produced samples, all specimens did not contain any phase other than the monoclinic monazite phase. Ceramics having the specific activity of Am-241 2.13×107 Bq/g were prepared by only cold-pressing with subsequent sintering at 1300°C during 1 hour. The normalized leach rates of lanthanum and americium in distilled water at 90°C were less than 1.2×10−4 and 2.3 10−4 g/m2×day, respectively.

Synthesis and Photo-Catalytic Properties Characterization of Graphene/TiO2 Nanotube Composites

2013 ◽  
Vol 544 ◽  
pp. 21-24
Author(s):  
Cai Xia Li ◽  
Lin Zhang ◽  
Dan Yu Jiang ◽  
Qiang Li
Keyword(s):  
Catalytic Properties ◽  
Raw Materials ◽  
Catalytic Performance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Nanotube Composites ◽  
Degussa P25 ◽  
Concentrated Solution

Selecting graphene oxide (GO) and the Degussa P25 TiO2 (80% anatase and 20% rutile) as raw materials, the composites of graphene/TiO2 nano-tubes were simply and quickly prepared under the conditions of a concentrated solution of sodium hydroxide. The as-obtained composites’ phase structure was analyzed and characterized by powder X-ray diffraction (XRD), their morphologies were also observed and cross-confirmed under the Transmission Electron Microscopy (TEM). The measurements showed that the composites prepared in this work have a remarkable structure, and compared to the seperate TiO2 nano-tubes, the agglomeration of TiO2 nano-tubes covered on the surface of the graphene is apparently not so serious. In view of this, we preliminary tested the composites’ photo-catalytic performance with the visible light irradiation, and also made a comparison with TiO2 nano-tubes.

scholarly journals Synthesis, Characterization and Photocatalytic Activity of MoS2/ZnSe Heterostructures for the Degradation of Levofloxacin

Catalysts ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1380
Author(s):  
Effat Sitara ◽  
Muhammad Fahad Ehsan ◽  
Habib Nasir ◽  
Sadia Iram ◽  
Syeda Aqsa Batool Bukhari
Keyword(s):  
Visible Light ◽  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Reflectance Spectroscopy ◽  
New Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Degradation Activity ◽  
Antibiotic Degradation

Antibiotics have been extensively used over the last few decades. Due to their extensive usage and persistence in the environment, they are considered as emergent pollutants. It is, therefore, important to synthesize new materials for efficient antibiotic degradation. Herein, we report the MoS2/ZnSe heterostructures prepared by a simple ultrasonication method. Heterostructures were prepared with different ratios of MoS2 and ZnSe, i.e., 1:3, 1:1 and 3:1. Characterization of the heterostructures was done by UV-vis diffused reflectance spectroscopy (UV-vis-DRS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and photoluminescence (PL) techniques to understand the morphology and surface chemistry. The results show that an efficient interface was formed to harness the visible light and degrade levofloxacin, which was monitored by gradual decreases in the UV-vis absorbance signal of levofloxacin. Among the prepared heterostructures and their pure counter parts, MoS2/ZnSe 3:1 (3:1 MZ) showed a better degradation activity of 73.2% as compared to pure MoS2 (29%) and ZnSe (17.1%) in the presence of visible light in a time span of two hours. The reusability studies showed that the catalytic performance of 3:1 MZ did not decrease significantly after three cycles. Moreover, the morphology and the crystal structure also remained unchanged.

Characterization of Highly Active Al2O3-TiO2 Supported Pt and Pd Catalysts for Hydrodechlorination of 1,2-Dichloroethane

2018 ◽  
Vol 17 (4) ◽  
Author(s):  
A. A. Granados-Fócil ◽  
S. Núñez-Correa ◽  
N. C. Martín-Guaregua ◽  
C. García-Mendoza ◽  
L. G. Woolfolk-Frías ◽  
...  
Keyword(s):  
Specific Activity ◽  
Supported Catalysts ◽  
Sol Gel ◽  
Atomic Ratio ◽  
X Ray Diffraction ◽  
Pd Catalysts ◽  
Transmission Microscopy ◽  
Highly Active ◽  
Temperature Programmed

Abstract Al2O3-TiO2 (AT) mixed oxide with atomic ratio Al/Ti = 25 and Al2O3 (A) supports were prepared by the sol-gel method and impregnated to obtain monometallic Pd and Pt (1 wt % of metal), and bimetallic PdPt (Pd/Pt = 4) catalysts. These catalysts were tested in the gas-phase hydrodechlorination of 1,2 dichloroethane. The materials were characterized by nitrogen physisorption, X-ray diffraction analysis (XRD), temperature-programmed reduction (TPR) and high-resolution transmission microscopy (HRTEM). AT support showed a BET area (422 m2/g), slightly higher than A(374 m2/g). The specific activity for the AT supported catalysts was higher than that for the A supported catalysts. The order of activity for the AT supported catalysts was as follows: Pd> PdPt> Pt and in terms of selectivity towards non-chlorinated compounds the order was PdPt> Pd> Pt. The differences in the activities and the selectivities can be explained by the presence of different species of Pd in the supported catalysts.

Photocatalytic Degradation of 2-chlorophenol under γ-Bi2MoO6/Graphene Oxide

MRS Advances ◽  
2019 ◽  
Vol 5 (11) ◽  
pp. 581-589 ◽  
Author(s):  
J. Rodríguez-López ◽  
R. Rangel ◽  
P. Bartolo-Pérez ◽  
J.J. Alvarado-Gil ◽  
J. L. Cervantes-López ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
Energy Gap ◽  
Physicochemical Characterization ◽  
Catalytic Performance ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
Bismuth Molybdate ◽  
X Ray

ABSTRACTThe present research was aimed to study the degradation of 2-Chlorophenol through the use of bismuth molybdate (γ-Bi2MoO6) structures supported on graphene oxide (GO) which is intended to control the recombination of charge carriers. γ-Bi2MoO6/GO systems were doped with nitrogen via chemical reaction, to reduce their energy gap, improving their photocatalytic activity. Structural and physicochemical characterization of the resulting catalysts were performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-Vis. The obtained compounds show good photo catalytic performance when using visible energy to degrade 2-Chlorophenol, obtaining 80% of degradation in 65 min.

Synthesis and Characterization of Modified Clays as Sorbents of Toluene and Xylene

2005 ◽  
Vol 498-499 ◽  
pp. 691-696 ◽  
Author(s):  
Marilda M.G. Ramos Vianna ◽  
Francisco Rolando Valenzuela-Díaz ◽  
Valquiria F.J. Kozievitch ◽  
Jo Dweck ◽  
Pedro M. Büchler
Keyword(s):  
Natural Waters ◽  
Waste Water Treatment ◽  
Permeable Reactive Barriers ◽  
Water Soluble ◽  
X Ray Diffraction ◽  
Ceramic Filters ◽  
X Ray ◽  
Benzene Toluene ◽  
Wyoming Bentonite

Benzene, toluene, ethylbenzene, and the xylenes (BTEX) are the major water-soluble constituents of gasoline that may contaminate soils and natural waters, which can be sorbed by organoclays. This study investigates the sorption of toluene and xylene by organoclays produced from Brazilian bentonite (SVC) and from Wyoming bentonite (SSA) with hexadecyltrimethylammonium (HDTMA), as well as by a commercial organoclay (SCo). The organoclays were characterized by X-Ray Diffraction, Differential Thermal Analysis, Thermogravimetry. Isothermal sorption were performed. The efficiencies of the organoclays on removing toluene increased in the order: SVC-HDTMA < SSA-HDTMA < SCo. The xylene sorption by SVC-HDTMA and SSA-HDTMA organoclays was about two times higher than by the SCo. These organoclays may be used as permeable reactive barriers or in ceramic filters for petroleum waste-water treatment systems.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

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