Direct Synthesis of 3,5-Dinitropyrazole Catalyzed by Newly Sulfated Nanosolid Superacid TiO2/ SO

2011 ◽  
Vol 391-392 ◽  
pp. 1296-1301
Author(s):  
Li Min Xi ◽  
Xin Xin Zhang
Keyword(s):  
Direct Synthesis ◽  
Sol Gel ◽  
Acid Base ◽  
Direct Transformation ◽  
Acid Base Titration ◽  
Optimal Reaction Condition ◽  
Superacid Catalyst ◽  
Average Size ◽  
Optimal Reaction ◽  
Xrd And Tem

The newly sulfated nanosolid superacid TiO2/SO4 prepared by sol-gel method was broadly characterized by acid base titration, XRD and TEM, which identified that the superfine solid TiO2/SO4 showing good dispersibility with average size of 27 nm belongs to kind of crystalline nanoparticles. With the help of the catalyst TiO2/SO4, the optimal reaction condition for direct transformation of pyrazole and nitrosonitric acid into 3, 5-Dinitropyrazole was n (pyrazol)=0.10 mol, m (TiO2/SO4 )＝1.5g, V(n-octannol)＝90mL, and V(nitrosonitric acid)＝50mL. Moreover, the optimal yield of the catalytic reaction reached up to 59.4% when the reaction time is 7 hours. The nanosolid superacid catalyst is still of high activity after regenerating eight times by calcination at 600。C.

scholarly journals Efficient Catalytic Production of Biodiesel with Acid-Base Bifunctional Rod-Like Ca-B Oxides by the Sol-Gel Approach

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 83 ◽  
Author(s):  
Anping Wang ◽  
Hu Li ◽  
Heng Zhang ◽  
Hu Pan ◽  
Song Yang
Keyword(s):  
Renewable Resources ◽  
Sol Gel ◽  
Acid Value ◽  
Catalytic Performance ◽  
Acid Base ◽  
Reaction Conditions ◽  
One Pot ◽  
Catalytic Material ◽  
Acid And Base ◽  
Optimal Reaction

The search for acid-base bifunctional catalysts has become a hot topic in the preparation of biofuels from renewable resources. In the present work, a series of novel acid-base bifunctional metal-boron catalysts were successfully prepared by a sol-gel method and characterized by XRD, IR, SEM, TEM, TGA, BET, and TPD. Among those bifunctional solid materials, the Ca-B(700) catalyst had the highest density of both acid and base sites and showed excellent catalytic performance in the production of biodiesel from nonedible oils with high acid value. Under the optimal reaction conditions of 20/1 methanol/oil mole ratio and 4 wt % catalyst dosage at 105 °C for 2 h, a high biodiesel yield of 96.0% could be obtained from Jatropha curcas oil in one-pot. In addition, Ca-B(700) was also applicable to producing biodiesel from Firmiana platanifolia L.f. oil in a relatively low acid value, with an almost quantitative yield (98.5%) at 65 °C after 2 h. The Ca-B(700) catalyst had good stability and reusability, which is a promising acid-base bifunctional catalytic material for the preparation of biodiesel.

scholarly journals Optical ph sensing material prepared from doped sol-gel film for use in acid-base titration

2017 ◽  
Vol 18 (2) ◽  
Author(s):  
Musa Ahmad ◽  
T.W. Tan
Keyword(s):  
Sol Gel ◽  
Strong Acid ◽  
Thymol Blue ◽  
Bromophenol Blue ◽  
Ph Sensing ◽  
Acid Base ◽  
Strong Base ◽  
Sensing Material ◽  
Gel Film ◽  
Acid Base Titration

An optical pH sensing material has been prepared in this study by using sol-gel technique. Bromothymol blue, bromophenol blue and thymol blue were chosen in this study as acidbase indicators for strong acid-strong base, strong acid-weak base and weak acid-strong base titration, respectively. The results show that these indicators could be successfully entrapped inside the sol-gel film and still maintain its chemical behaviour as in solution. The entrapped acid-base indicators respond well to any pH changes and could be used to determine the end-point of the acid-base titration.

Ultradispersed Powdery Y2O3-Bi2O3-ZnO Composition with High Chemical Homogeneity for Fine-Grained Ceramics

2014 ◽  
Vol 87 ◽  
pp. 36-41
Author(s):  
Elena A. Trusova ◽  
Kirill V. Vokhmintcev ◽  
Aleksey N. Kirichenko
Keyword(s):  
Sol Gel ◽  
Particle Sizes ◽  
High Chemical ◽  
Chemical Homogeneity ◽  
Fine Grained ◽  
Gel Technique ◽  
Average Size ◽  
20 Nm ◽  
New Generation ◽  
Xrd And Tem

The technologically acceptable modified sol-gel technique was developed for obtaining the ultradispersed powdery composition Y2O3-Bi2O3-ZnO, which is promising new generation material for photocatalysts and solar cells. The solution for preparing a sintering composition with a high chemical homogeneity was proposed to provide using ultradispersed powders consisting of ZnO nanoparticles (40-70 nm), decorating with Bi2O3 and Y2O3 particles with average size of 4-20 nm. All synthesized powders were characterized by XRD and TEM methods. It was found that ZnO surface differently affects the dispersity of Bi2O3 and Y2O3 in the composites. TEM microphotographs show that the Bi2O3 particles uniformly distributed over ZnO surface. The Bi2O3 particle size on ZnO surface was 5-11 nm, which is significantly less than in the single powder of Bi2O3 (110-130 nm). However, in the case of Y2O3 similar effect was not observed, and average size of its crystallites was 5-12 nm, which agrees well with particle sizes in single powder.

Henderson Hasselbalch Relationship and Weak Acid Titration

2019 ◽  
Author(s):  
Marc Blétry
Keyword(s):  
Theoretical Framework ◽  
Weak Acid ◽  
Acid Base ◽  
Sensitive Technique ◽  
Chemistry Students ◽  
Advanced Students ◽  
Acid Titration ◽  
Acid Base Titration ◽  
Analytical Expressions

Henderson-Hasselbalch relation is generally the simplified theoretical framework used to introduce students to acid-base titration. However, it is not always valid and its limitations should be made clear to chemistry students. The appropriate parameter to evaluate its validity is K a /C 0 , in connection with Ostwald dilution law. For more advanced students, it is possible to deduce analytical expressions that always fit accurately acid-base titrations and allow an evaluation of Henderson Hasselbalch relation. Gran plot appears as a particularly sensitive technique to the breakdown of Henderson Hasselbalch relation.

scholarly journals Upconversion Luminescence of Silica–Calcia Nanoparticles Co-doped with Tm3+ and Yb3+ Ions

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 937
Author(s):  
Katarzyna Halubek-Gluchowska ◽  
Damian Szymański ◽  
Thi Ngoc Lam Tran ◽  
Maurizio Ferrari ◽  
Anna Lukowiak
Keyword(s):  
Energy Transfer ◽  
Near Infrared ◽  
Upconversion Luminescence ◽  
Sol Gel ◽  
Emission Spectra ◽  
Transmission Electron ◽  
Characteristic Emission ◽  
Diffraction Patterns ◽  
Size Of Particles ◽  
Average Size

Looking for upconverting biocompatible nanoparticles, we have prepared by the sol–gel method, silica–calcia glass nanopowders doped with different concentration of Tm3+ and Yb3+ ions (Tm3+ from 0.15 mol% up to 0.5 mol% and Yb3+ from 1 mol% up to 4 mol%) and characterized their structure, morphology, and optical properties. X-ray diffraction patterns indicated an amorphous phase of the silica-based glass with partial crystallization of samples with a higher content of lanthanides ions. Transmission electron microscopy images showed that the average size of particles decreased with increasing lanthanides content. The upconversion (UC) emission spectra and fluorescence lifetimes were registered under near infrared excitation (980 nm) at room temperature to study the energy transfer between Yb3+ and Tm3+ at various active ions concentrations. Characteristic emission bands of Tm3+ ions in the range of 350 nm to 850 nm were observed. To understand the mechanism of Yb3+–Tm3+ UC energy transfer in the SiO2–CaO powders, the kinetics of luminescence decays were studied.

Acid–base sensor based on sol–gel encapsulation of bromothymol blue in silica: application for milk spoilage detection

2021 ◽  
Author(s):  
Mariele K. Stocker ◽  
Murilo L. Sanson ◽  
Arthur A. Bernardes ◽  
Antonio Marchi Netto ◽  
Rodrigo Brambilla
Keyword(s):  
Sol Gel ◽  
Bromothymol Blue ◽  
Acid Base

scholarly journals Room Temperature Syntheses of ZnO and Their Structures

Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 733
Author(s):  
Domenica Donia ◽  
Elvira Maria Bauer ◽  
Mauro Missori ◽  
Ludovica Roselli ◽  
Daniele Cecchetti ◽  
...  
Keyword(s):  
Room Temperature ◽  
Direct Synthesis ◽  
Threshold Value ◽  
Rietveld Analysis ◽  
Synthesis Temperature ◽  
Density Variation ◽  
Controlled Synthesis ◽  
Sem Images ◽  
Aqueous Solvent ◽  
Average Size

ZnO has many technological applications which largely depend on its properties, which can be tuned by controlled synthesis. Ideally, the most convenient ZnO synthesis is carried out at room temperature in an aqueous solvent. However, the correct temperature values are often loosely defined. In the current paper, we performed the synthesis of ZnO in an aqueous solvent by varying the reaction and drying temperatures by 10 °C steps, and we monitored the synthesis products primarily by XRD). We found out that a simple direct synthesis of ZnO, without additional surfactant, pumping, or freezing, required both a reaction (TP) and a drying (TD) temperature of 40 °C. Higher temperatures also afforded ZnO, but lowering any of the TP or TD below the threshold value resulted either in the achievement of Zn(OH)2 or a mixture of Zn(OH)2/ZnO. A more detailed Rietveld analysis of the ZnO samples revealed a density variation of about 4% (5.44 to 5.68 gcm−3) with the synthesis temperature, and an increase of the nanoparticles’ average size, which was also verified by SEM images. The average size of the ZnO synthesized at TP = TD = 40 °C was 42 nm, as estimated by XRD, and 53 ± 10 nm, as estimated by SEM. For higher synthesis temperatures, they vary between 76 nm and 71 nm (XRD estimate) or 65 ± 12 nm and 69 ± 11 nm (SEM estimate) for TP =50 °C, TD = 40 °C, or TP = TD = 60 °C, respectively. At TP = TD = 30 °C, micrometric structures aggregated in foils are obtained, which segregate nanoparticles of ZnO if TD is raised to 40 °C. The optical properties of ZnO obtained by UV-Vis reflectance spectroscopy indicate a red shift of the band gap by ~0.1 eV.

A Convenient Method for Preparing Well-Dispersed Er2Zr2O7 Nanocrystals

2010 ◽  
Vol 123-125 ◽  
pp. 611-614 ◽  
Author(s):  
Yu Ping Tong ◽  
Rui Zhu Zhang ◽  
Shun Bo Zhao ◽  
Chang Yong Li
Keyword(s):  
Particle Size ◽  
Combustion Synthesis ◽  
Crystal Size ◽  
Lattice Distortion ◽  
Combustion Method ◽  
Treatment Temperature ◽  
Synthesis Process ◽  
Thermal Treatment Temperature ◽  
Average Size ◽  
Xrd And Tem

Well-dispersed fluorite Er2Zr2O7 nanocrystals have been successfully prepared by a convenient salt-assistant combustion method. The effects of calcinations temperature and salt category on the characteristics of the products were investigated by XRD and TEM. The thermal treatment temperature has an important effect on crystal size and lattice distortion of the nanocrystals. The experiment showed that the introduction of salt in the combustion synthesis process resulted in the formation of well-dispersed Er2Zr2O7 nanocrystals. The average size was 30 nm and was in agreement with the XRD result, which indicated that the nanocrystals were uniform in particle size distribution. Moreover, the possible formation process in the salt-assisted combustion synthesis was also analyzed.

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