Enhanced Heck reaction on flower-like Co(Mg or Ni)Al layered double hydroxide supported ultrafine PdCo alloy nanocluster catalysts: the promotional effect of Co

2019 ◽  
Vol 48 (48) ◽  
pp. 17741-17751 ◽  
Author(s):  
Jin Li ◽  
Ying Song ◽  
Yajuan Wang ◽  
Hui Zhang
Keyword(s):  
Layered Double Hydroxide ◽  
Heck Reaction ◽  
Molar Ratio ◽  
Promotional Effect ◽  
Double Hydroxide

A series of PdCo alloy nanocluster (NC) catalysts x-PdCor/Co(Mg or Ni)Al-LDH (x: Pd loading, r: Co/Pd molar ratio) were synthesized by immobilizing ultrafine PdCor-PVP NCs on flower-like layered double hydroxide (LDH) supports.

scholarly journals Boron Removal Using Li-Al-OH Layered Double Hydroxide Prepared by One-Step Mechanochemical Approach

2018 ◽  
Author(s):  
Jingjing Tian ◽  
Jun Qu ◽  
Lei Wan ◽  
Qiwu Zhang ◽  
Huimin Gao
Keyword(s):  
Adsorption Capacity ◽  
Layered Double Hydroxide ◽  
Physical Adsorption ◽  
Molar Ratio ◽  
Mechanochemical Reaction ◽  
Boron Uptake ◽  
Dry Grinding ◽  
One Step ◽  
Double Hydroxide ◽  
Boron Adsorption

In this study, Li-Al-OH layered double hydroxide (LDH), which was prepared by solvent-free one-step mechanochemical reaction of LiOH and Al(OH)3, was applied to remove boron from aqueous solution. Dry-grinding for 3 h at a rotational speed of 500 rpm, Li/Al molar 1/2 was the optimum condition to prepare highly crystalline of Li-Al LDH phase with no evident impure phases. Two milling products with Li/Al molar ratio at 1/2 and 2/2 were evaluated for boron adsorption. The results confirmed that Li/Al molar ratio 2/2 sample showed high boron adsorption capacity due to the physical adsorption of Li-Al-OH LDH and chemical synergism of phase gel Al(OH)3. The adsorption isotherms, described by the Langmuir model, indicated maximum monolayer boron uptake capacity 45.45 mg/g, implying competitive adsorption capacity of the material in our experiment.

The Effect of Zinc to Aluminium Molar Ratio on the Physico-Chemical Properties of Zinc-Aluminium-3,4-Dichlorophenoxy Acetate Nanocomposite

2013 ◽  
Vol 756 ◽  
pp. 127-134
Author(s):  
Sheikh Ahmad Izaddin Sheikh Mohd Ghazali ◽  
Mohd Zobir Hussein ◽  
Siti Halimah Sarijo
Keyword(s):  
Layered Double Hydroxide ◽  
Mole Fraction ◽  
Self Assembly ◽  
Chemical Properties ◽  
Zinc Ion ◽  
Molar Ratio ◽  
Basal Spacing ◽  
Molar Ratios ◽  
Assembly Method ◽  
Double Hydroxide

Layered double hydroxide (LDH) hybrid materials of Zn-Al-layered double hydroxide-3,4-dichlorophenoxy acetate acidnanocomposites (ZADs) were prepared by direct self-assembly method. The pH of the solution was adjusted to 7.5 using 2M NaOH. Various Zn2+ to Al3+ molar ratios, R ranging from 1 to 6 were used with a fixed concentration of 3,4-D at 0.3 M. The Powder X-ray diffraction (PXRD) patterns showed the formation of well-ordered nanocomposite with the expansion of basal spacing from 8.9 Å in the Zinc-Aluminium-Layered Double Hydroxide (ZAL) to 18.7 - 22.1 Å in the resulting nanocomposites. The Fourier transform infrared (FTIR)spectra for the nanocomposites showed features for both ZAL and ZAD, showing the successful intercalation of the organic moiety into the LDH interlayer. The percentage loading of 3,4-dichlorophenoxy acetati acid(3,4-D) in LDH was found to be increased from 34.7-48.1 % (w/w), as the mole fraction of Al decreased from 0.44-0.15. This study shows that the mole fraction of zinc ion was replaced by aluminium ion in the LDH plays an important role in controlling the physic-chemical properties of the resulting material.

scholarly journals Removal of Lead from Aqueous Solution by Adsorption using Magnesium Aluminium Hydrogenphosphate Layered Double Hydroxides

2014 ◽  
Vol 8 (1) ◽  
Author(s):  
Zaini Hamzah ◽  
Mohd Najif Ab Rahman ◽  
Yamin Yasin ◽  
Siti Mariam Sumari ◽  
Ahmad Saat
Keyword(s):  
Aqueous Solution ◽  
Layered Double Hydroxide ◽  
Molar Ratio ◽  
Maximum Adsorption Capacity ◽  
Lead Removal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
Double Hydroxide ◽  
Double Hydroxides

Layered double hydroxide with molar ratio of 4 (MAN 4) was synthesized by co-precipitation and followed by hydrothermal method. The compound was then later going through ion exchange with K2HPO4 for 48 hours to produce MgAlHPO4 (MAHP 4). The solid produced were characterized using X-ray diffraction (XRD) and Fourier Transform Infrared spectroscopy (FTIR). Adsorption of lead solution by MAHP 4 was carried out using batch experiment by mixing the lead solution and the solid of layered double hydroxide. The effects of various parameters such as contact time, pH, adsorbent dosage and initial concentration were investigated. The optimum pH for lead removal was found to be at pH of 5 and the optimum time of lead removal was found at 2 hours. The isotherm data was analysed using Langmuir and the correlation coefficient of 0.998 was obtained. The maximum adsorption capacity, Qo (mg/g) of 500 mg/g was also recorded from the Langmuir isotherm. The remaining lead solution was determined by using EDXRF (Energy Dispersive X-Ray Fluorescence spectrometry) model MiniPal 4 (PAN analytical). The results in this study indicate that MAHP 4 was an interesting adsorbent for removing lead from aqueous solution.

scholarly journals Synthesis and characterization of two-dimensional (2D) nanosheet zinc aluminum layered double hydroxide (Zn/Al LDH) via an alkali-free route

2021 ◽  
Vol 15 (1) ◽  
pp. 82
Author(s):  
Rabiatul Adawiyah Mohd Agus ◽  
Siti Khatijah Deraman ◽  
Nazrizawati A. Tajuddin
Keyword(s):  
Layered Double Hydroxide ◽  
Nitrate Solution ◽  
Zinc Nitrate ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Sem Image ◽  
Constant Ph ◽  
Xrd Patterns ◽  
Double Hydroxide

The effect of different molar ratios on the synthesis of zinc aluminium layered double hydroxide (Zn/Al LDH) via an alkali-free route was carried out in this research. This method was prepared by mixing zinc nitrate solution, aluminium nitrate solution, and ammonium carbonate solution at a constant pH of 8.5 with a spanning ratio of Zn to Al from 4:1, 3:1, and 2:1. The XRD patterns showed crystal nanostructure of Zn/Al LDHs was successfully formed. The lattice parameters (a and c) were slightly increased with the increasing of Zn/Al molar ratio. A larger hexagonal platelet is observed in the SEM image align with the high molar ratio of Zn/Al synthesized. The same trend has been observed in the FTIR spectra.   Keywords: Zn/Al LDH, alkali-free route, different molar ratio, XRD, SEM, FTIR

scholarly journals Zn-Al LAYERED DOUBLE HYDROXIDE AS HOST MATERIAL FOR SUNSCREEN COMPOUND OF p-AMINOBENZOIC ACID

2010 ◽  
Vol 7 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Roto Roto ◽  
Iqmal Tahir ◽  
Mustofa Mustofa
Keyword(s):  
Layered Double Hydroxide ◽  
Room Temperature ◽  
Interlayer Space ◽  
Uv Light ◽  
Structural Formula ◽  
Host Material ◽  
Molar Ratio ◽  
Aminobenzoic Acid ◽  
Protection Factor ◽  
Double Hydroxide

Zn-Al layered double hydroxide can be used as host material for UV active compound p-aminobenzoic acid (PABA), which is having capability to block UV light of sunlight. The formation of Zn-Al-PABA was best developed in which the nucleation process was done at room temperature and followed by hydrothermal treatment at 100 oC.   To make a better product, the molar ratio of Zn to Al to PABA was adjusted to 3:1:1. From the elemental analysis and the content of PABA, it was observed that the product has structural formula of Zn0,745Al0.254(OH)1.650(PABA)0.349. 0.684H2O. The particle size of the powder as estimated using SEM was in the range 100-200 nm. FTIR and XRD proved that the p-amino benzoate ion occupied the interlayer space. This material is expected to have high sun protection factor (SPF).   Keywords: layered double hydroxide, sunscreen, p-amino benzoic acid, nanoparticle

scholarly journals Hydrothermal Synthesis of Lanthanum-Doped MgAl-Layered Double Hydroxide/Graphene Oxide Hybrid and Its Application as Flame Retardant for Thermoplastic Polyurethane

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Yi Qian ◽  
Peng Qiao ◽  
Long Li ◽  
Haoyue Han ◽  
Haiming Zhang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Layered Double Hydroxide ◽  
Flame Retardancy ◽  
Thermoplastic Polyurethane ◽  
Smoke Suppression ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Cone Calorimeter Test ◽  
Double Hydroxide

A novel lanthanum-doped MgAl-layered double hydroxide/graphene oxide hybrid (La LDH/GO) with a La3+/Al3+ molar ratio of 0.05 was successfully synthesized by the hydrothermal method. The structure and morphology of as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). Then, La LDH/GO was added into thermoplastic polyurethane (TPU) to investigate its effect on flame retardancy, smoke suppression, and thermal stability of TPU composites. The cone calorimeter test (CCT) results indicated that the peak heat release rate (PHRR) and peak smoke production rate (PSPR) values of TPU with La LDH/GO decreased by 33.1% and 51% compared with neat TPU, respectively. Therefore, La LDH/GO can play a good role in flame retardancy and smoke suppression of TPU matrix during combustion. In the meantime, La LDH/GO could improve the char yield of TPU composites, which is attributed to the interaction between the physical barrier effect of GO and the catalytic effect of 0.05 La LDH.

scholarly journals Influence of Metallic Molar Ratio on the Electron Spin Resonance and Thermal Diffusivity of Zn–Al Layered Double Hydroxide

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Abdullah Ahmed Ali Ahmed ◽  
Zainal Abidin Talib ◽  
Mohd Zobir Hussein
Keyword(s):  
Electron Spin Resonance ◽  
Thermal Diffusivity ◽  
Layered Double Hydroxide ◽  
Electron Spin ◽  
Textural Properties ◽  
Esr Spectra ◽  
Magnetic Activity ◽  
Molar Ratio ◽  
Spin Resonance ◽  
Double Hydroxide

The coprecipitation method was used to prepare Zn–Al layered double hydroxide (Zn–Al–NO3-LDH) at pH 7.5 and different Zn2+/Al3+molar ratios of 2, 3, 4, 5, and 6. The elemental, structural, and textural properties of prepared samples were studied. The crystallinity of prepared LDH nanostructure decreases as Zn2+/Al3+molar ratio increases. The electron spin resonance (ESR) spectroscopy of different LDH samples showed new ESR spectra. These spectra were produced due to the presence of different phases with formed LDH such as ZnO phase and ZnAl2O4spinel. At low Zn2+/Al3+molar ratio, the ESR signals were produced from the presence of free nitrate anions in the LDH interlayer. Above Zn2+/Al3+= 2, the ESR signals were attributed to the existence of ZnO phase and ZnAl2O4spinel in the samples. Because the nuclear magnetic moment of67Zn is lower than27Al, the increasing in Zn2+/Al3+molar ratio causes a reduction of the magnetic activity of ZnAl2O4spinel. Thermal diffusivity versusin situtemperature showed nonlinear relation for different samples due to the changing in the water content of LDH as temperature increases. The dc conductivity of samples decreased as Zn2+/Al3+molar ratio.

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