scholarly journals Ternary Hydrotalcites in the Multicomponent Synthesis of 4H-Pyrans

Catalysts ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 70 ◽  
Author(s):  
Eliana Nope ◽  
Ángel G. Sathicq ◽  
José J. Martínez ◽  
Hugo A. Rojas ◽  
Rafael Luque ◽  
...  
Keyword(s):  
Divalent Cations ◽  
Textural Properties ◽  
Precipitation Method ◽  
Ni Catalyst ◽  
X Ray Diffraction ◽  
Multicomponent Synthesis ◽  
Solvent Free Conditions ◽  
Xrd Patterns ◽  
Co Precipitation ◽  
Double Hydroxides

Lamellar double hydroxides (LDH) with double divalent cations were synthesized by the co-precipitation method and studied in the multicomponent synthesis of 4H-pyrans. The solids obtained were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), N2 adsorption isotherms, and thermogravimetric analysis (TGA). The XRD patterns confirmed the formation of LDHs in which the incorporation of Ni2+ or Co2+ improves their crystalline and textural properties. The results of catalytic activity showed that the synthesis of 4H-pyrans is favored in solvent-free conditions with the LDH–Ni catalyst, avoiding calcination processes. In addition, it was found that hydrotalcite with double divalent cations can conduct this reaction through multicomponent synthesis or by the Michael addition reaction, which can be performed by different types of basicity that depend on the composition of another divalent cation in the brucite layer or a calcination process.

Microstructure Characterization of Metal Mixed Oxides

MRS Advances ◽  
2017 ◽  
Vol 2 (64) ◽  
pp. 4025-4030 ◽  
Author(s):  
T. Kryshtab ◽  
H. A. Calderon ◽  
A. Kryvko
Keyword(s):  
Mixed Oxides ◽  
Profile Analysis ◽  
Atomic Resolution ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Reconstruction Procedure ◽  
Transmission Electron ◽  
Xrd Patterns ◽  
Co Precipitation

ABSTRACTThe microstructure of Ni-Mg-Al mixed oxides obtained by thermal decomposition of hydrotalcite-like compounds synthesized by a co-precipitation method has been studied by using X-ray diffraction (XRD) and atomic resolution transmission electron microscopy (TEM). XRD patterns revealed the formation of NixMg1-xO (x=0÷1), α-Al2O3 and traces of MgAl2O4 and NiAl2O4 phases. The peaks profile analysis indicated a small grain size, microdeformations and partial overlapping of peaks due to phases with different, but similar interplanar spacings. The microdeformations point out the presence of dislocations and the peaks shift associated with the presence of excess vacancies. The use of atomic resolution TEM made it possible to identify the phases, directly observe dislocations and demonstrate the vacancies excess. Atomic resolution TEM is achieved by applying an Exit Wave Reconstruction procedure with 40 low dose images taken at different defocus. The current results suggest that vacancies of metals are predominant in MgO (NiO) crystals and that vacancies of Oxygen are predominant in Al2O3 crystals.

Carboxymethylchitosan/Calcium Phosphate Hybrid Materials Prepared by an Innovative Auto-Catalytic Co-Precipitation Method

2005 ◽  
Vol 284-286 ◽  
pp. 701-704 ◽  
Author(s):  
S.A. Costa ◽  
J. Miguel Oliveira ◽  
Isabel B. Leonor ◽  
Rui L. Reis
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Precipitation Method ◽  
Porous Scaffolds ◽  
X Ray Diffraction ◽  
Polymer Precipitation ◽  
Acid Bath ◽  
The Fourier Transform ◽  
Xrd Patterns ◽  
Co Precipitation

In this study, it is shown that it is possible to prepare carboxymethyl-chitosan/Ca-P hybrids using an innovative “auto-catalytic” co-precipitation method, namely by using an acid and an oxidant bath. The X-ray diffraction (XRD) patterns evidenced the formation of crystalline calcium-phosphate precipitates when using an acid bath, while amorphous ones were obtained for those produced in the oxidant bath. The Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM/EDS) studies revealed that the extent of the polymer precipitation and formation of calcium-phosphates is directly dependent on the pH and composition of the baths. Furthermore, by conducting bioactivity tests in a simulated body fluid (SBF) followed by the SEM/EDS analysis it was possible to detect the formation of an apatite layer with a cauliflower-like morphology on the surface of hybrids prepared by the acid bath, after 7 days of immersion. These results are quite promising because they can allow for the production of bioactive and biodegradable 3D porous scaffolds to be used in bone tissue engineering applications.

Characterization of Polystyrene (PS)/Organomodified Layered Double Hydroxide (OLDH) Nanocomposites Prepared by In Situ Polymerization

2011 ◽  
Vol 410 ◽  
pp. 164-167 ◽  
Author(s):  
Balakrushna Sahu ◽  
G. Pugazhenthi
Keyword(s):  
In Situ Polymerization ◽  
Sodium Dodecyl ◽  
Decomposition Temperature ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Stretching Vibration ◽  
Xrd Patterns ◽  
Co Precipitation ◽  
Double Hydroxide

PS/LDH nanocomposites were synthesized via in-situ polymerization technique using styrene monomer with toluene as a solvent. A series of LDHs (Mg-Al, Co-Al, Ni-Al, Cu-Al, Cu-Fe and Cu-Cr LDHs) was first prepared from their nitrate salts by co-precipitation method. The above prepared, pristine LDHs were organically modified using sodium dodecyl sulfate (SDS) to obtain organomodified LDHs (OLDH). Then, PS nanocomposites containing 5 wt.% OLDHs were prepared by in-situ polymerization method. The structural and thermal properties of LDHs and corresponding nanocomposites were characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA). The absence of OLDH peak (003) in the XRD patterns of PS/OLDH nanocomposite confirms the formation of exfoliated nanocomposites. The presence of sulfate groups in the modified LDHs is confirmed by FTIR analysis. The appearance of new peaks in the FTIR spectra in the region of 3400-3500 cm-1, 1670-1680 cm-1and 1200-1260 cm-1for O-H stretching, H-O-H vibration and stretching vibration of sulfate, respectively indicate the existence of LDHs in the PS/OLDH nanocomposites. The entire exfoliated PS/OLDH nanocomposites exhibit enhanced thermal stability relative to the pure PS. When 50% weight loss is selected as point of comparison, the decomposition temperature of nanocomposites is about 3-5oC higher than that of pure PS.

Behavior of Layered Double Hydroxides Having Different Divalent Transition Metal Groups

2014 ◽  
Vol 563 ◽  
pp. 94-101 ◽  
Author(s):  
Mazidah Mamat ◽  
Tei Tagg ◽  
Wan Mohd Khairul ◽  
Mohd Aidil Adhha Abdullah ◽  
Norhayati Mohd Tahir ◽  
...  
Keyword(s):  
Weight Loss ◽  
Transition Metal ◽  
Layered Double Hydroxides ◽  
Divalent Cations ◽  
Precipitation Method ◽  
Basal Spacing ◽  
Highest Weight ◽  
Ft Ir ◽  
Co Precipitation ◽  
Double Hydroxides

The layered double hydroxides (LDHs) with different divalent transition metal groups and nitrate as a counter anion were investigated. Three d-block divalent metals namely cobalt (Co), nickel (Ni) and copper (Cu) were selected. The cobalt/aluminium (CoAN)-, nickel/aluminium (NiAN)- and copper/aluminium (CuAN)-layered double hydroxides were successfully synthesized via co-precipitation method. All the obtained LDHs were characterized by PXRD, FT-IR, ICP-OES, CHNS and TGA/DTG analysis. Interestingly, behavior of the LDHs was dependent on the size of divalent cations. PXRD showed the basal spacing decrease in the order NiAN (0.88nm)> CuAN (0.87nm) > CoAN (0.74nm), and in a linear correlation with the increasing radii of the divalent cations. Similar trend is observed for the weight loss of LDHs, where NiAN has the highest weight loss (53%), followed by CuAN (43%) and CoAN (34%). Further elemental analysis showed the content of trivalent metal cations, nitrate anions and water molecules in the LDHs decrease with the increasing radii.

scholarly journals Mechanochemically synthesized LiAlOx catalyst for aqueous aldol condensation of furfural with acetone

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
L. N. Stepanova ◽  
R. M. Mironenko ◽  
O. B. Belskaya ◽  
V. A. Likholobov
Keyword(s):  
Mixed Oxide ◽  
Aldol Condensation ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Centripetal Acceleration ◽  
Oh Groups ◽  
Short Period ◽  
Temperature Programmed ◽  
Co Precipitation ◽  
Double Hydroxides

AbstractIn the present study, the mechanochemical method is proposed for synthesis of LiAl-layered double hydroxides (LDHs). This method is eco-friendly and allows obtaining LiAl-LDH under relatively mild conditions (centripetal acceleration of milling bodies 300 m s-2) and in a short period of time (15 minutes). The structures of as-prepared LiAl-LDH, LiAl-mixed oxide (calcined LDH) and “activated” LiAl-LDH obtained after rehydration of the corresponding mixed oxide were confirmed by X-ray diffraction. The basicity of LiAlOx was measured by temperature-programmed desorption of CO2 and double isotherm technique. According to data obtained, LiAl-mixed oxide has a significant higher carbon dioxide adsorption capacity compared to MgAlmixed oxides prepared by conventional co-precipitation method. This indicates a large amount of basic surface sites with different strength (strong, medium and weak) for Li-containing systems. The formation of “activated” LiAl-LDH having Bronsted basic sites (OH groups in the interlayer space) provides an increased catalytic activity of LiAlOx in the reaction of aqueous-phase aldol condensation between furfural and acetone.

scholarly journals Structural Analysis using X-Ray Diffraction and FTIR Spectroscopic Studies on Mn2+ Substituted CaWO4 Materials Synthesized by Coprecipitation Method

2019 ◽  
Vol 32 (1) ◽  
pp. 49-52
Author(s):  
M. Jaganadha Rao ◽  
K.S.R. Murthy ◽  
Ch. Ravi Shankar Kumar ◽  
Anjali Jha ◽  
G.S.V.R.K. Choudary ◽  
...  
Keyword(s):  
Crystallite Size ◽  
Point Group ◽  
Size Composition ◽  
Spectroscopic Studies ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Xrd Patterns ◽  
Co Precipitation ◽  
Synthesis Of Materials

Present day technology requires synthesis of materials with low energy consumption, free mercury pollution and its reliability. A novel material with control of crystallite size, composition and simple for white light relies in synthesis of materials. The present focus of article attributes series of manganese doped Ca1-xMnxWO4 luminescent materials with co-precipitation method. Reported studies attempts with change in structure of calcium tungstate (CaWO4) are observed with dopants like Eu3+, Eu2+, Tb3+, etc. However the effect of Mn2+ on structural properties of CaWO4 are quite interesting. The synthesized samples were characterized with X-ray diffraction for lattice parameters, crystallite size and FTIR studies for bonding mechanism of O-W-O stretching and W-O-W bridge bond. Rietveld profile refinement of XRD patterns using MAUD program Ca1-xMnxWO4 revealed the Scheelite type structure with C4h point group and I41/a space group. Characterization studies reveal that doping of Mn2+ doping upto 0.1 in place of Ca2+ will not change the phase of Scheelite structure.

scholarly journals Dielectric properties of Bi-substituted LDHs synthesized by co-precipitation and sol-gel methods

2019 ◽  
Vol 37 (2) ◽  
pp. 190-195 ◽  
Author(s):  
Denis Sokol ◽  
Maksim Ivanov ◽  
Andrei N. Salak ◽  
Robertas Grigalaitis ◽  
Juras Banys ◽  
...  
Keyword(s):  
Sol Gel ◽  
Xrd Analysis ◽  
Precipitation Method ◽  
Complexing Agent ◽  
Mixed Metal Oxides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
Double Hydroxides ◽  
Gel Processing

AbstractMagnesium-aluminum-bismuth layered double hydroxides (Mg3Al1−xBix; LDHs) were prepared using both coprecipitation and sol-gel methods. For the preparation of Mg/Al/Bi LDH by the co-precipitation method, the appropriate amounts of dissolved starting materials (Al(NO3)3 · 9H2O, Mg(NO3)2 · 6H2O and Bi(NO3)3 · 5H2O) were mixed with a solution of NaHCO3:NaOH. In the sol-gel processing, the precursor Mg–Al–Bi–O gels were synthesized using the same starting materials and ethylene glycol as complexing agent. The mixed-metal oxides obtained by subsequent heating of Mg–Al–Bi–O gels at 650 °C were reconstructed to Mg3Al1−xBix LDHs in water at 80 °C. All the synthesized products were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and dielectric measurements.

scholarly journals X-RD, TEM, Magnetic Studies on NixZn1-xFe2O4 (Where x= 0.2, 0.4, 0.5, 0.6 and 0.8) Nano Scale Particles by Chemical Co-Precipitation Method

2015 ◽  
Vol 60 ◽  
pp. 20-24
Author(s):  
B. Suryanarayana ◽  
V. Raghavendra ◽  
K. Chandra Mouli
Keyword(s):  
Average Particle Size ◽  
Lattice Parameter ◽  
Precipitation Method ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
Zinc Nanoparticles ◽  
X Ray ◽  
Xrd Patterns ◽  
Co Precipitation

Nickel zinc nanoparticles NixZn1-xFe2O4 (where x= 0.2, 0.4, 0.5, 0.6 and 0.8) by Chemical Co-Precipitation method. The samples were characterised by X-ray diffraction (XRD), TEM, VSM .The powders of XRD patterns confirm a single spinel crystalline phase with cubic structure formation with no indication of any other secondary or unidentified phase. The lattice parameter changed from 8.336 Å to 8.382 Å. The average particle size ranged 20 to 80 nm was observed by TEM.

scholarly journals Removal of Iron(II) Using Intercalated Ca/Al Layered Double Hydroxides with [α-SiW12O40]4-

2019 ◽  
Vol 14 (2) ◽  
pp. 260 ◽  
Author(s):  
Tarmizi Taher ◽  
Mikha Meilinda Christina ◽  
Muhammad Said ◽  
Nurlisa Hidayati ◽  
Ferlinahayati Ferlinahayati ◽  
...  
Keyword(s):  
Adsorption Process ◽  
Layer Structure ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Co Precipitation ◽  
Double Hydroxide ◽  
Double Hydroxides ◽  
Synthesized Materials

Ca/Al layered double hydroxide (LDH) was successfully synthesized by co-precipitation method at pH 11 under room temperature condition then followed by calcination at 800 oC. The synthesized Ca/Al LDH was further intercalated with Keggin ion [α-SiW12O40]4- in order to prepare the intercalated form of Ca/Al LDH. The synthesized materials were characterized by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) and used as an adsorbent for iron(II) removal from the aqueous medium. The adsorption performance was investigated by studying the kinetics and thermodynamic properties of the adsorption process. The results showed that pristine Ca/Al LDH exhibited diffraction peak at 2θ about 20o which corresponds to the layer structure of the LDH material. For the intercalated Ca/Al LDH, the diffraction observed at 2θ around 30-40o indicated that the [α-SiW12O40]4- was successfully intercalated into the interlayer space of Ca/Al LDH. Furthermore, the intercalated Ca/Al LDH showed higher adsorption capacity toward iron(II) than the pristine form of Ca/Al LDH. Copyright © 2019 BCREC Group. All rights reserved 

Magnetically recyclable silica-coated magnetite-molybdate nanocatalyst and its applications in N-formylation reactions under solvent-free conditions-

2022 ◽  
Vol 19 ◽  
Author(s):  
Runjhun Tandon ◽  
Shripad Patil ◽  
Nitin Tandon ◽  
Pushpendra Kumar
Keyword(s):  
Catalytic Activity ◽  
Solvent Free ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Solvent Free Conditions ◽  
Ft Ir ◽  
Co Precipitation ◽  
Coated Nanoparticle ◽  
Scanning Electron

Abstract: A novel magnetite silica-coated nanoparticle-supported molybdate nanocatalyst has been prepared successfully by a simple co-precipitation method. Prepared nanocatalyst has been characterized by different techniques like Fourier Transmission Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscope (FE-SEM) and Energy Dispersive X-ray Spectroscopy (EDX). Further, the catalytic activity of the nanocatalyst was explored for N-formylation reactions under solvent-free conditions. Interestingly, the catalyst could be reused for 10 cycles and only 2 mol % of the catalyst was sufficient to catalyze the N-formylation reaction at 700C under solvent-free conditions.

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