scholarly journals Excess soluble alkalis to prepare highly efficient MgO with relative low surface oxygen content applied in DMC synthesis

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ju Liu ◽  
Fei Chen ◽  
Wenbing Yang ◽  
Jianjun Guo ◽  
Guangwen Xu ◽  
...  
Keyword(s):  
Oxygen Content ◽  
Ethylene Carbonate ◽  
Sol Gel ◽  
Magnesium Carbonate ◽  
Bet Surface Area ◽  
Surface Oxygen ◽  
Characterization Methods ◽  
Basic Sites ◽  
Excellent Activity ◽  
Co Precipitation

AbstractThe activities of various MgO catalysts, which were prepared from different methods such as hydration synthesis, thermal decomposition, combustion, sol–gel and co-precipitation, were conducted in dimethyl carbonate (DMC) synthesis via transesterification of ethylene carbonate with methanol. MgO-P-Na2CO3-3.14 synthesized by the excess Na2CO3 precipitation compared the best catalytic activity and stability, which could be reused for seven times without obvious deactivation. The DMC yield was as high as 69.97% at 68 °C. The transesterification reaction could be separated into two steps, and the samples obtained by NaOH precipitant exhibited better ring-opening capability, while the catalysts acquired by Na2CO3 precipitant displayed superior transesterification ability. The structure-performance relationship was evaluated by multiple characterization methods. The results indicated that the as-synthesized catalyst derived from dried precursors with more crystalline magnesium carbonate was favorable for the promotion of DMC yield, and MgO-P-Na2CO3-3.14 with more Mg-O pairs, which were the active center for the transesterification of 2-hydroxyethyl methyl carbonate (HEMC) intermediate with methanol, resulted in more moderately basic sites left that was in accordance with the DMC yield variation. MgO-P-Na2CO3-3.14 with greater BET surface area and mesopore volume, relative low surface oxygen content and larger moderately basic sites amount compared the excellent activity in DMC synthesis.

scholarly journals Study the Effect on Activity of Alumina Supported CuO-CeO2-ZrO2 Catalysts Prepared by Four Methods for CO Oxidation

2014 ◽  
Vol 13 (2) ◽  
pp. 39
Author(s):  
Gaurav Rattan ◽  
R. Prasad
Keyword(s):  
Co Oxidation ◽  
Sol Gel ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Oxidation Of Co ◽  
Preparation Methods ◽  
Urea Nitrate ◽  
Fixed Weight ◽  
Excellent Activity ◽  
Co Precipitation

In the present study four catalysts, prepared by four different methods i.e. co- impregnation, citric acid sol-gel, urea nitrate combustion and urea gelation co- precipitation methods, have been used to study the effect of CO oxidation. The precursor Cu(NO3) 23H2O has been used as for the preparation of catalysts having the composition CuCe5.17Zr3.83Ox/-Al2O3(25wt%). Catalysts were calcined at 5000C and characterized by BET, XRD, TGA/DSC and SEM. A fixed weight (100 mg) of the catalyst was taken in a tubular fixed bed reactor at atmospheric pressure. 2.0% CO in air at a total feed rate of 60 ml/min was used in the reactor. The oxidation of CO to carbon dioxide was carried out at temperature ambient to 280oC. The preparation methods effect the catalytic activity of the catalysts as is discussed in the results. Excellent activity for CO oxidation is shown by the catalyst prepared by sol – gel method followed by co-impregnation, urea gelation and urea nitrate combustion methods. It exhibited the total conversion at 210oC. All the four catalysts prepared did not show any deactivation activity for 50 hours of continuous runs.

scholarly journals Influence of Synthetic Approach of SiO2-ZrO2 Materials

2018 ◽  
Vol 5 (1) ◽  
pp. 34-40 ◽  
Author(s):  
Amit Kumar ◽  
Shailey Singhal ◽  
Shilpi Aggarwal ◽  
Rajendra Prasad Badoni ◽  
Amit Kumar Sharma
Keyword(s):  
Surface Area ◽  
Pore Volume ◽  
Mixed Oxides ◽  
Sol Gel ◽  
Bet Surface Area ◽  
Synthetic Approach ◽  
Total Acidity ◽  
Microwave Reactor ◽  
Co Precipitation ◽  
Standard Instrumentation

Abstract In the present manuscript, the effect of the synthetic route on the properties of SiO2-ZrO2 has been evaluated. Co-precipitation, sol-gel and microwave methods were adopted for synthesizing the structured oxide. The properties of the final products such as surface morphology, crystallinity, surface area, pore volume and size, particle size and total acidity were examined using standard instrumentation like Fe-SEM, XRD, BET and TPD. The results revealed that the mixed oxides were mesoporous in nature with a high BET surface area (315- 435m2/g). Among various methods, the microwave route achieved the highest surface area (433m2/g), pore volume (0.70cc/g) and pore size (6.50nm). The total acidity of the sample synthesized by the microwave reactor was also higher (0.296mmol/g) than that resulting from other methods. Results conclude that microwave method is a suitable choice for synthesizing the structured oxides with desirable properties.

Preparation of Y2Ti2O7 Nanocrystal by Sol-Gel Method and its Characterization

2010 ◽  
Vol 97-101 ◽  
pp. 2175-2179 ◽  
Author(s):  
Zhong Sheng Chen ◽  
Wei Ping Gong ◽  
Teng Fei Chen ◽  
Guo Xuan Xiong ◽  
Guo Lin Huang
Keyword(s):  
Citric Acid ◽  
Solid State ◽  
Sol Gel ◽  
Bet Surface Area ◽  
Tetrabutyl Titanate ◽  
Preparation Process ◽  
Excellent Activity ◽  
Dta Analysis ◽  
Ft Ir ◽  
Average Size

Y2Ti2O7 nanocrystals have been prepared at the calcining temperature of 700-900°C by using tetrabutyl titanate as starting materials and citric acid as chelator. The preparation process was monitored by XRD, FT-IR and TG-DTA analysis. Compared with traditional solid state reaction (SSR), the present used methods can prepare can Y2Ti2O7 nanocrystals at a relatively low temperature (750°C) and with shortened reaction time (dwelling time of 1 h). The morphology and averge size of as-prepared products were analysized by FESEM. Results showed that the as-prepared Y2Ti2O7 with good dispersibility and narrow size-distritution were all sphere-like; the average size was about 40-50 nm, Also, the obtained products had higher BET surface area (32 m2/g). These properties are very helpful for a photocatalytic catalyst to achieve excellent activity.

Studies on Adsorption Performance of Reactive Dye Remazol Navy RGB (RN-RGB) via Epoxide Functional Magnetic ?-Al2O3 Nanocomposite Particles

2017 ◽  
Vol 9 (4) ◽  
pp. 421-429
Author(s):  
S. S. Bristy ◽  
H. Ahmad
Keyword(s):  
Sol Gel ◽  
Reactive Dye ◽  
Al2o3 Nanoparticles ◽  
Silica Layer ◽  
Seeded Polymerization ◽  
Nanocomposite Particles ◽  
Adsorption Performance ◽  
Magnetite Fe3o4 ◽  
Co Precipitation

The nanocomposite particles named as ?-Al2O3/Fe3O4/SiO2/poly(glycidyl methacrylate) or ?-Al2O3/Fe3O4/SiO2/PGMA were prepared by multi-step process. At first, ?- Al2O3 nanoparticles were prepared by sol-gel method. Magnetite, Fe3O4, nanoparticles were then precipitated by in situ co-precipitation in presence of ?-Al2O3 particles, followed by incorporation of mesoporous silica layer using Stöber process. Finally, the surface of the ?-Al2O3/Fe3O4/SiO2 nanocomposite particles was modified by seeded polymerization of GMA using free radical polymerization. The surface modification, morphology and size distribution of the prepared nanocomposite particles were confirmed by FTIR, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The adsorption capacity of ?-Al2O3/Fe3O4/SiO2/PGMA nanocomposite particles was evaluated using remazol navy RGB (RN-RGB) as a model dye.

scholarly journals Commercial Cokes and Graphites as Anode Materials for Lithium - Ion Cells

1997 ◽  
Vol 496 ◽  
Author(s):  
David J. Derwin ◽  
Kim Kinoshita ◽  
Tri D. Tran ◽  
Peter Zaleski
Keyword(s):  
Electron Microscopy ◽  
Ethylene Carbonate ◽  
Average Particle Size ◽  
Chemical Properties ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Bet Surface Area ◽  
Average Particle ◽  
Electrochemical Characteristics ◽  
Wide Range

AbstractSeveral types of carbonaceous materials from Superior Graphite Co. were investigated for lithium ion intercalation. These commercially available cokes, graphitized cokes and graphites have a wide range of physical and chemical properties. The coke materials were investigated in propylene carbonate based electrolytes and the graphitic materials were studied in ethylene carbonate / dimethyl solutions to prevent exfoliation. The reversible capacities of disordered cokes are below 230 mAh / g and those for many highly ordered synthetic (artificial) and natural graphites approached 372 mAh / g (LiC6). The irreversible capacity losses vary between 15 to as much as 200 % of reversible capacities for various types of carbon. Heat treated cokes with the average particle size of 10 microns showed marked improvements in reversible capacity for lithium intercalation. The electrochemical characteristics are correlated with data obtained from scanning electron microscopy (SEM), high resolution transmission electron microscopy (TAM), X - ray diffraction (XRD) and BET surface area analysis. The electrochemical performance, availability, cost and manufacturability of these commercial carbons will be discussed.

scholarly journals Magnetite-Silica Core/Shell Nanostructures: From Surface Functionalization towards Biomedical Applications—A Review

2021 ◽  
Vol 11 (22) ◽  
pp. 11075
Author(s):  
Angela Spoială ◽  
Cornelia-Ioana Ilie ◽  
Luminița Narcisa Crăciun ◽  
Denisa Ficai ◽  
Anton Ficai ◽  
...  
Keyword(s):  
Magnetite Nanoparticles ◽  
Biomedical Applications ◽  
Sol Gel ◽  
Magnetic Nanomaterials ◽  
Core Shell ◽  
Synthesis Methods ◽  
Shell Nanostructures ◽  
Silica Core ◽  
Magnetic Resonance Imaging Mri ◽  
Co Precipitation

The interconnection of nanotechnology and medicine could lead to improved materials, offering a better quality of life and new opportunities for biomedical applications, moving from research to clinical applications. Magnetite nanoparticles are interesting magnetic nanomaterials because of the property-depending methods chosen for their synthesis. Magnetite nanoparticles can be coated with various materials, resulting in “core/shell” magnetic structures with tunable properties. To synthesize promising materials with promising implications for biomedical applications, the researchers functionalized magnetite nanoparticles with silica and, thanks to the presence of silanol groups, the functionality, biocompatibility, and hydrophilicity were improved. This review highlights the most important synthesis methods for silica-coated with magnetite nanoparticles. From the presented methods, the most used was the Stöber method; there are also other syntheses presented in the review, such as co-precipitation, sol-gel, thermal decomposition, and the hydrothermal method. The second part of the review presents the main applications of magnetite-silica core/shell nanostructures. Magnetite-silica core/shell nanostructures have promising biomedical applications in magnetic resonance imaging (MRI) as a contrast agent, hyperthermia, drug delivery systems, and selective cancer therapy but also in developing magnetic micro devices.

scholarly journals SYNTHESIS OF ZnO-Аg NANOPARTICLES BY SOL-GEL METHOD

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Savka Janković ◽  
Dragana Milisavić ◽  
Tanja Okolić ◽  
Dijana Jelić
Keyword(s):  
Zno Nanoparticles ◽  
Wide Spectrum ◽  
Sol Gel ◽  
Synthesis Method ◽  
Material Surface ◽  
Characterization Methods ◽  
Gel Method ◽  
X Ray ◽  
Sol Gel Method ◽  
Doped Zno

Zinc oxide is a highly applicable semiconductor material. Wide applica-tion of this nanomaterial is connected to wide spectrum of energy band gap, high bond en-ergy, great thermal conductivity, but also with its non-toxicity, antibacterial activity, bio-compatibility and biodegradability characteristics. The aim of this paper is synthesis and characterization of silver doped ZnO nanoparticles (ZnO:Ag NP) using sol-gel method. Ob-tained samples of silver doped ZnO nanoparticles were characterized by following tech-niques: Fourier-transform infrared spectroscopy (FTIR), UV/VIS spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spec-troscopy (EDX). Efficiency of provided synthesis method was examined by FTIR spectros-copy. XRD determined the purity and crystallinity, and wurtzite structure of synthesized material. Surface morphology and the effect of doping were examined using SEM and EDX characterization methods. Results showed better conductivity after doping ZnO nanoparti-cles with silver. SEM micrographs showed ZnO:Ag NP in the form of nanorods with a par-ticle average size of 6 nm.

scholarly journals Synthesis of Brushite from Phophogypsum Industrial Waste

2021 ◽  
Vol 12 (5) ◽  
pp. 6580-6588
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Industrial Waste ◽  
Sol Gel ◽  
Dicalcium Phosphate Dihydrate ◽  
X Ray Diffraction ◽  
Characterization Methods ◽  
X Ray ◽  
Phosphate Dihydrate ◽  
Scanning Electron

Dicalcium phosphate dihydrate (DCPD) nanoparticles, also known as brushite, are considered an important bioceramic compound. In this study, brushite was prepared from Moroccan phosphogypsum (PG) using a new sol-gel method. A two-step technique undergoes the synthesis of brushite, the preparation of anhydrite from PG followed by adding phosphoric acid in the presence of sodium hydroxide. The morphology, the chemical composition, and the crystallites size were obtained using Scanning Electron Microscopy (SEM-EDAX), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR), respectively. According to the Debye-Scherrer equation, these characterization methods indicated that the synthesized brushite was highly pure according to the Ca/P ratio of 1.14 and an average crystallites size estimated at 66 nm. These results proved that the brushite was successfully synthesized from Moroccan phosphogypsum.

scholarly journals A novel green nonaqueous sol-gel process for preparation of partially stabilized zirconia nanopowder

2017 ◽  
Vol 11 (3) ◽  
pp. 220-224 ◽  
Author(s):  
Guo Feng ◽  
Weihui Jiang ◽  
Jianmin Liu ◽  
Quan Zhang ◽  
Qian Wu ◽  
...  
Keyword(s):  
Bending Strength ◽  
Sol Gel ◽  
Sintered Sample ◽  
Zirconium Oxychloride ◽  
Bet Surface Area ◽  
Nanometer Scale ◽  
Stabilized Zirconia ◽  
Zirconia Powder ◽  
Sol Gel Process ◽  
Sintering Behaviour

A novel green nonaqueous sol-gel process was developed to prepare 3mol% Y2O3-doped ZrO2 nanopowder from zirconium oxychloride and without need for washing of the obtained particles. It was shown that highly dispersive nanometer-scale zirconia powder with the particle size of 15-25 nm and BET surface area of 41.2m2/g can be prepared. The sintering behaviour was also investigated. Density of the translucent body sintered at 1400?C is 98.7 ? 0.3% of its theoretical density and the surface and cross section areas are dense without holes or other defects. The bending strength of the sintered sample is 928 ? 64MPa.

Sign in / Sign up

Export Citation Format

Share Document