scholarly journals The Effect of the ZrO2 Loading in SiO2@ZrO2-CaO Catalysts for Transesterification Reaction

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 221
Author(s):  
Daniela Salinas ◽  
Sichem Guerrero ◽  
Cristian H. Campos ◽  
Tatiana M. Bustamante ◽  
Gina Pecchi
Keyword(s):  
Sol Gel ◽  
Core Shell ◽  
Tem Analysis ◽  
Basic Sites ◽  
The Core ◽  
Surface Areas ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
The Fourier Transform ◽  
Sio2 Spheres

The effect of the ZrO2 loading was studied on spherical SiO2@ZrO2-CaO structures synthetized by a simple route that combines the Stöber and sol-gel methods. The texture of these materials was determined using SBET by N2 adsorption, where the increment in SiO2 spheres’ surface areas was reached with the incorporation of ZrO2. Combined the characterization techniques of using different alcoholic dissolutions of zirconium (VI) butoxide 0.04 M, 0.06 M, and 0.08 M, we obtained SiO2@ZrO2 materials with 5.7, 20.2, and 25.2 wt % of Zr. Transmission electron microscopy (TEM) analysis also uncovered the shape and reproducibility of the SiO2 spheres. The presence of Zr and Ca in the core–shell was also determined by TEM. X-ray diffraction (XRD) profiles showed that the c-ZrO2 phase changed in to m-ZrO2 by incorporating calcium, which was confirmed by Raman spectroscopy. The purity of the SiO2 spheres, as well as the presence of Zr and Ca in the core–shell, was assessed by the Fourier transform infrared (FTIR) method. CO2 temperature programmed desorption (TPD-CO2) measurements confirmed the increment in the amount of the basic sites and strength of these basic sites due to calcium incorporation. The catalyst reuse in FAME production from canola oil transesterification allowed confirmation that these calcium core@shell catalysts turn out to be actives and stables for this reaction.

Sub-Micrometer SiO2@ZnMoO4:Tb3+ Core-Shell Phosphors: Sol-Gel Synthesis and Characterization

2013 ◽  
Vol 800 ◽  
pp. 436-439
Author(s):  
Hu Yang ◽  
Xiao Bo Zhang ◽  
Juan Li ◽  
Yu Jun Lu
Keyword(s):  
Electron Microscopy ◽  
Sol Gel ◽  
Emission Spectra ◽  
Green Emission ◽  
Core Shell ◽  
Uniform Size ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Shell Particles ◽  
Sol Gel Synthesis

ZnMoO4:Tb3+ phosphor layers were grown on monodisperse SiO2 particles through a simple sol-gel method, resulting in the formation of core-shell structured SiO2@ZnMoO4:Tb3+ sub-microspheres. The resulting SiO2@ZnMoO4:Tb3+ core-shell particles were characterized by powder X-ray diffraction(XRD), field emission scanning electron microscopy(FESEM), transmission electron microscopy(TEM) and photoluminescence(PL). SEM and TEM analysis indicates that the obtained sub-microspheres have a uniform size distribution and obvious core-shell structure. SiO2@ZnMoO4:Tb3+ sub-microspheres show strong green emission under ultraviolet(275nm) illumination and the emission spectra are dominated by a 5D4→7F5 transition of Tb3+(543nm,green) from the ZnMoO4:Tb3+ shells. The optimum concentration for Tb3+ was determined to be 5 mol% of Zn2+ in ZnMoO4 host shells.

scholarly journals Synthesis of TiO2/SnO2 core shell nanocomposite via sol-gel method

2012 ◽  
Vol 05 ◽  
pp. 251-256 ◽  
Author(s):  
SORAIA KHOBY-SHENDY ◽  
MOHAMMAD REZA VAEZI ◽  
TORAJ EBADZADEH
Keyword(s):  
Sol Gel ◽  
Titanium Isopropoxide ◽  
Core Shell ◽  
Hydrothermal Processing ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
Transmission Electron ◽  
Diffraction Peaks ◽  
Hydrolysis Of

The particles of TiO 2 core/ SnO 2 shell nanocomposite were prepared by hydrolysis of SnCl 4.5 H 2 O in the presence of titania nanoparticle after drying and calcinations treatments. TiO 2 particle were produced from titanium isopropoxide sol by hydrothermal processing. X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and transmission electron microscopy (TEM) were used to characterize the TiO 2/ SnO 2 core shell nanocomposites. The obtained results from XRD show that the SnO 2 nanoparticles coated on TiO 2 yields diffraction peaks correspond to the crystalline SnO 2 phase. Also, TEM results show that the nanocomposite particles have a spherical morphology and a narrow size distribution. The thickness of SnO 2 shell on the surface of TiO 2 particles were about 8 nm. Moreover, the results obtained from EDX analysis show that the core-shell structured nanocomposites have crystalline structure.

Preparation of GDC Nanopowders and GDC/YSZ Core-Shell Nanocomposites

2010 ◽  
Vol 434-435 ◽  
pp. 717-718
Author(s):  
Zuo Cai Huang ◽  
Bin Li ◽  
Wei Liu ◽  
Wei Pan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Sol Gel ◽  
Precipitation Method ◽  
Core Shell ◽  
The Core ◽  
Transmission Electron ◽  
Core Shell Structure ◽  
Co Precipitation

Nanocrystalline GDC as small as 5 nm was successfully synthesized via the co-precipitation method. GDC/YSZ core-shell nanocrystals, which were GDC nanocrystals overcoated by a thin YSZ layer, was successfully synthesized by the addition of GDC nanocrystals in the YSZ source solution using sol-gel method. The core-shell structure was supported by its high-resolution transmission electron microscopy results and the composition was investigated by EDX method.

scholarly journals The Influence Of NO/O2 On The NOx Storage Properties Over A Pt-Ba-Ce/γ-Al2O3 Catalyst

2019 ◽  
Vol 17 (1) ◽  
pp. 1459-1465
Author(s):  
Xuedong Feng ◽  
Jing Yi ◽  
Peng Luo
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
No Oxidation ◽  
Test Results ◽  
X Ray Diffraction ◽  
Storage Performance ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Physical And Chemical ◽  
Al2o3 Catalyst

AbstractWith the purpose of studying the influence of NO/O2 on the NOx storage activity, a Pt-Ba-Ce/γ-Al2O3 catalyst was synthesized by an acid-aided sol-gel method. The physical and chemical properties of the catalyst were characterized by X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) methods. The results showed that the composition of the catalyst was well-crystallized and the crystalline size of CeO2 (111) was about 5.7 nm. The mechanism of NO and NO2 storage and NOx temperature programmed desorption (NO-TPD) experiments were investigated to evaluate the NOx storage capacity of the catalyst. Pt-Ba-Ce/γ-Al2O3 catalyst presented the supreme NOx storage performance at 350℃, and the maximum value reached to 668.8 μmol / gcat. Compared with O2-free condition, NO oxidation to NO2 by O2 had a beneficial effect on the storage performance of NOx. NO-TPD test results showed that the NOx species stored on the catalyst surface still kept relatively stable even below 350℃.

Preparation of Poly(Vinylbenzyl Chloride)@Lead Sulfide (PVBC@PbS) Core-Shell Nanospheres and Adsorption of Phenol

2013 ◽  
Vol 704 ◽  
pp. 270-274 ◽  
Author(s):  
Jian Ye ◽  
Lan Ping Sun ◽  
Sheng Ping Gao
Keyword(s):  
Electron Microscopy ◽  
Lead Sulfide ◽  
Chemical Structure ◽  
Methyl Chloride ◽  
Core Shell ◽  
Subsequent Reaction ◽  
Chloride Lead ◽  
Transmission Electron ◽  
The Fourier Transform ◽  
Average Size

We have demonstrated the fabrication of novel poly(vinylbenzyl chloride)@lead sulfide (PVBC@PbS) core-shell nanospheres via the atom transfer reversible polymerization (ATRP) of lead dimethacrylate (Pb(MA)2) initiated from methyl chloride groups on surfaces of PVBC nanoparticles and subsequent reaction with ethanethioamide. The chemical structure of the PVBC@PbS nanospheres was confirmed by the fourier transform infrared (FTIR) spectroscopy, and the morphology of the nanospheres were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The average size of the nanospheres was determined to be about 100 nm. The PVBC@PbS nanospheres were able to absorb phenol in the solution, and the balanced adsorption capability of phenol to nanospheres could reach to 7.2 μg/mg.

Influence of Zr Additive on the Chemical Reduction Behaviour of MoO3 in Carbon Monoxide Atmosphere

2021 ◽  
Vol 317 ◽  
pp. 173-179
Author(s):  
Alinda Samsuri ◽  
Mohd Nor Latif ◽  
Norliza Dzakaria ◽  
Fairous Salleh ◽  
Maratun Ajina Abu Tahari ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Molybdenum Trioxide ◽  
Chemical Reduction ◽  
Reduction Process ◽  
Chemical Effect ◽  
Physical Analysis ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Reduction Behaviour ◽  
Temperature Programmed

Temperature-programmed reduction (TPR) was used to observe the chemical reduction behaviour of molybdenum trioxide (MoO3) and zirconia (Zr)-doped MoO3 catalyst by using carbon monoxide (CO) as the reductant. The characterisation of catalysts was performed by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) and transmission electron microscopy (TEM) analyses. The reduction performance were examined up to 700°C and reduction was continued for 60 min at 700°C in a stream of 20 vol. % CO in nitrogen. The TPR profile showed that the doped MoO­3 catalyst was slightly moved to a higher temperature (580°C) as compared to the undoped MoO3 catalyst, which began at around 550°C. The interaction between zirconia and molybdenum ions in doped MoO3 catalyst led to an increase in the reduction temperature. According to characterisation of the reduction products by using XRD, it revealed that the reduction behaviour of pure MoO3 to MoO2 by CO reductant involved two reduction stages with the formation of Mo4O11 as the intermediate product. Meanwhile, MoO3 catalyst doped with zirconia caused a delay in the reduction process and was proven by the presence of Mo4O11 species at the end of reactions. Physical analysis by using BET showed a slight increase in surface area of 3% Zr-MoO3 from 6.85 m2/g to 7.24 m2/g. As for TEM analysis, black tiny spots located around MoO3 particles revealed that the zirconia was successfully intercalated into MoO3 particles. This confirmed that formation of intermetallic between Zr-MoO3 catalyst will give new chemical and physical properties which has a remarkable chemical effect by disturbing the reduction progression of MoO3 catalyst.

The Preparation of Core/Shell Particles with Siloxane in the Shell

2005 ◽  
Vol 13 (7) ◽  
pp. 721-726
Author(s):  
Shunsheng Cao ◽  
Xiaobo Deng ◽  
Bailing Liu
Keyword(s):  
Dispersion Medium ◽  
Average Diameter ◽  
Butyl Methacrylate ◽  
Core Shell ◽  
The Core ◽  
Transmission Electron ◽  
Seeding Method ◽  
Emulsion Polymerisation ◽  
Shell Particles ◽  
Methacryloxypropyl Trimethoxysilane

Core-shell microspheres ranging in average diameter from 12.829 to 15.039 μm, with a poly butyl methacrylate (BMA) core, and a poly 3-(methacryloxypropyl)-trimethoxysilane (MATS) shell, were prepared with methanol as the dispersion medium, by a successive seeding method under kinetically controlled conditions. To date, although some of particles (PSi/PA) have been prepared by seeded emulsion polymerisation, only a few core/shell (PA/PSi) microspheres have been reported the literatures. To prepare core/shell (PA/PSi), the core was first synthesized by dispersion polymerisation and to form seeds; addition of MATS monomer was started after 90~95% conversion of the BMA. The reaction was prolonged for another 12 h to achieve complete consumption of MATS monomer. Microspheres; containing hydrophilic PBMA as the core and hydrophobic PMATS as the shell, were successfully formed through the free radical of surface in the core. The particles morphology and size distribution were examined using a Transmission electron microscope and a Malvern Master Sizer/E particle size analyser, respectively.

Formation of bismuth iron oxide based core–shell structures and their dielectric, ferroelectric and magnetic properties

2019 ◽  
Vol 7 (5) ◽  
pp. 1280-1291 ◽  
Author(s):  
Alaka Panda ◽  
R. Govindaraj ◽  
R. Mythili ◽  
G. Amarendra
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Magnetic Properties ◽  
Iron Oxide ◽  
Shell Structures ◽  
Core Shell ◽  
Bismuth Iron Oxide ◽  
The Core ◽  
Shell Nanostructures ◽  
Transmission Electron

Bismuth and iron oxides subjected to ball milling followed by controlled annealing treatments showed the formation of core–shell nanostructures with Bi2Fe4O9 as the core and a shell of BiFeO3 and Bi25FeO40 phases as deduced based on the analysis of transmission electron microscopy results.

Preparation and Characterization of Rare Earth Composite Catalytic Materials for Conversion of Exhaust from Natural Gas Automobiles

2013 ◽  
Vol 320 ◽  
pp. 413-418
Author(s):  
Yan Kun Yuan ◽  
Gang Xue ◽  
Sai Fei Wang ◽  
Xue Liang Zhang
Keyword(s):  
Rare Earth ◽  
Specific Surface ◽  
Sol Gel ◽  
Methane Combustion ◽  
Fluorite Structure ◽  
Perfect Crystal ◽  
Reduction Peak ◽  
Transmission Electron ◽  
Catalytic Material ◽  
Temperature Programmed

A series of rare-earth composite catalytic material LZ1,LZ2 and LZ3 that contains mixture of La0.9Sr0.1Co0.5Mn0.5O3and Ce0.7Zr0.3O2in different proportion (3:7, 5:5, 7:3) were prepared by a sol-gel method and characterized by X-ray diffraction (XRD), specific surface analysis (BET) , Transmission electron microscopy (TEM) and temperature programmed reduction (TPR). The results indicated that in LZ3, a perfect crystal structure of perovskite and a cubic fluorite structure were formed. Besides LZ3 presented scattered spherical granules with a particle size of about 30 nm and a specific surface area of 20.9870 m2/g. The temperature of reduction peak was lowest (490°C) and peak area was larger, so it had the best catalytic activity for methane combustion.

Influence of Various Reaction Parameters on the Process for Preparation of SiO2/TiO2 Core-Shell Particles

2015 ◽  
Vol 33 ◽  
pp. 27-37 ◽  
Author(s):  
Jhin Hong You ◽  
Yi Yin Kuo ◽  
Keh Ying Hsu
Keyword(s):  
Inorganic Compounds ◽  
Sol Gel ◽  
Chelating Agent ◽  
Condensation Process ◽  
Infrared Analysis ◽  
Ionic Surfactant ◽  
Core Shell ◽  
Reaction Parameters ◽  
The Core ◽  
Shell Particles

This study aims to describe the preparation and characterization of SiO2/TiO2 core-shell particles. In order to prepare the homogenous SiO2/TiO2 inorganic compounds by sol-gel process, SiO2 particles were used as the core, AcAc served as a chelating agent to chelate with TTIP (which was used as the precursor to TiO2), and PEG was added to stabilize the hydrolysis/condensation process. In addition, the ionic surfactant (SDS) and the nonionic surfactant (PVP) dispersed the core-shell particles. In order to improve the crystal structure, a high temperature was used to calcine the core-shell particles. The influence of various reaction parameters on the size, morphology and composition of the particles was also investigated. The properties of the particles were analyzed by electron microscopy, fourier transform infrared analysis, thermogravimetric analysis and powder X-ray diffraction.

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