Study on Cu-Based Catalysts for Synthesis of Indole

2011 ◽  
Vol 295-297 ◽  
pp. 668-671 ◽  
Author(s):  
Jun De Xing ◽  
Xiao Fei Jia
Keyword(s):  
Grain Size ◽  
Ethylene Glycol ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Precipitation Method ◽  
Impregnation Method ◽  
Co Precipitation

A series of Cu-based catalysts for the synthesis of indole by the reaction of aniline and ethylene glycol were prepared and characterized by ICP-AES and XRD. The results indicated that the activity and stability of Cu/SiO2 catalyst was increased after adding Zn, Mn, Cr and Fe promoters. Mn promoter was favorable for the dispersion of Cu, Zn, Cr, Fe and enlarged the specific surface area of catalysts. It could be seen that the catalysts prepared by impregnation method had better stability and higher activity than the catalysts prepared by co-precipitation method. The catalysts with small grain size of Cu had higher activity than those with big grain size. Some catalysts showed excellent performances in this reaction.

Preparation and Characterization of the Typical Pt-NSR Catalyst

2011 ◽  
Vol 412 ◽  
pp. 365-369
Author(s):  
Yuan Feng Huang ◽  
Wei Jun Zhang ◽  
Li Shen ◽  
Jin Hu ◽  
Zhuo Heng Li ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Performance Testing ◽  
High Specific Surface Area ◽  
Impregnation Method ◽  
Temperature Programmed Reduction ◽  
Temperature Programmed ◽  
Co Precipitation

A series of Ba-Al-O NSR supports and Pt/Ba-Al-O NSR catalysts are prepared by co-precipitation and impregnation method in this work. The catalyst and the support are characterized by XRD, SEM, SBET performance testing. The structure and texture of the supports is observed and discussed. The results of SBET indicate that the supports possess relative high specific surface area (94~110 m2/g). Temperature programmed reduction is characterized by means of H2-TPR.

Influence of pH Value and Precipitant on Zn2SnO4 Formation via Co-Precipitation Method

2011 ◽  
Vol 291-294 ◽  
pp. 61-64
Author(s):  
Yu Shiang Wu ◽  
Min He Tsau
Keyword(s):  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ph Value ◽  
Particle Morphology ◽  
Nano Particles ◽  
Precipitation Method ◽  
Strong Base ◽  
Co Precipitation

Nanorod-shaped zinc stannate Zn2SnO4 (ZTO) with great photocatalytic activity was successfully synthesized via a co-precipitation method. In this paper, a strong base (NaOH) and a weak base (Na2CO3) are adopted as precipitants in order to form the precursor precipitate. The titration endpoints are fixed at pH6, pH8, and pH10 in order to adjust the solution precipitant quantity. Dependent variables above were not seen in other research before. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results show that the powders synthesized were ZTO nano-particles. Photocatalytic activity of the powders was measured utilizing a photocatalytic degradation reaction with methylene blue (MB) solution. The smallest particles were obtained by utilizing NaOH as a precipitant and adjusting pH to 6. Based on TEM images, the ZTO had nano-rod particle morphology. However, when precipitant Na2CO3 was utilized, particles agglomerated together, reducing specific surface area. Hence, the former sample shows better photocatalytic activity than the latter one. Consequently, powders titrated to pH6 by precipitant NaOH and calcined for 1 hour will form partly nano-rod particles with slight agglomeration, increasing the specific surface area of ZTO and bringing about the best photocatalytic characteristics.

Ultrathin γ-Al2O3 nanofibers with large specific surface area and their enhanced thermal stability by Si-doping

RSC Advances ◽  
2015 ◽  
Vol 5 (67) ◽  
pp. 54053-54058 ◽  
Author(s):  
Fang Hu ◽  
Xiang Wu ◽  
Yamin Wang ◽  
Xiaoyong Lai
Keyword(s):  
Thermal Stability ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Parallel Flow ◽  
Precipitation Method ◽  
Large Specific Surface Area ◽  
Si Doping ◽  
Co Precipitation

Ultrathin boehmite nanofibers were synthesized via a parallel flow co-precipitation method and then transformed into γ-Al2O3 nanofibers by calcination.

Facile Synthesis of CeO2/SnO2 N-N Heterostructure

2019 ◽  
Vol 891 ◽  
pp. 200-205 ◽  
Author(s):  
Pimpan Leangtanom ◽  
Nattharinee Charoenrat ◽  
Sukon Phanichphant ◽  
Viruntachar Kruefu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Average Particle Size ◽  
High Specific Surface Area ◽  
Element Composition ◽  
Precipitation Method ◽  
Average Particle ◽  
Tem Analysis ◽  
Co Precipitation

Cerium oxide and tin oxide nanocomposites (CeO2-SnO2 NCs) were successfully synthesized via a simple co-precipitation method. The structure and properties of the synthesized materials were characterized using several X-ray and electron-based techniques including XRD, FE-SEM, TEM, EDS and BET to unravel the structure, morphology, element composition and specific surface area. The XRD and BET results showed that the NCs have the characteristic crystalline structures of SnO2 and CeO2-SnO2 NCs, and high specific surface area (66.45 and 86.29 m2/g), respectively. Amorphous phase of CeO2 and SnO2 were not found in XRD patterns. EDS analysis confirms the absence of all element composition and the FE-SEM and TEM analysis observed as particles having the clear spherical morphologies with the average particle size of of SnO2 and CeO2-SnO2 NCs was about 13 and 10 nm, respectively.

Co-Precipitation Processing of Nanosized (Y,Gd)2O3: Eu Powder and Its Enhanced X-Ray Excited Luminescence

2005 ◽  
Vol 492-493 ◽  
pp. 101-108 ◽  
Author(s):  
Ying Shi ◽  
Ji Yang Chen ◽  
Jian Lin Shi
Keyword(s):  
Grain Size ◽  
Phase Transformation ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Luminescence Intensity ◽  
X Ray ◽  
Ft Ir ◽  
Co Precipitation ◽  
Excited Luminescence

Preparation of nanosized (Y,Gd)2O3:Eu powders by co-precipitation processing is reported. Phase transformation during calcination was studied by means of DTA-TG FT-IR, SEM and XRD in detail. It was found that the morphologies and X-ray excited luminescence of (Y,Gd)2O3:Eu powders were greatly influenced by the precipitants used. The (Y,Gd)2O3:Eu powder resulted from the complex precipitants of NH3•H2O and NH4HCO3 possessed best microstructural features with grain size of about 30nm and specific surface area of 38m2/g after being calcined at 8500C for 2hr, showing a much finer grain and less agglomeration than those from other two precipitation processing. It was demonstrated that nanosized (Y,Gd)2O3:Eu powder from complex precipitant exhibited much higher luminescence intensity at 611nm under excitation of X-ray (70Kev). which might be attributed to less degree of agglomeration among primary grains, decreasing the probability of non-radiation relaxation.

Synthesis of Novel Core-Shell Structured Hydroxyapatite/Meso-Silica for Removal of Methylene Blue from Aqueous Solutions

2012 ◽  
Vol 463-464 ◽  
pp. 543-547 ◽  
Author(s):  
Cheng Feng Li ◽  
Xiao Lu Ge ◽  
Shu Guang Liu ◽  
Fei Yu Liu
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Core Shell ◽  
Adsorption Desorption

Core-shell structured hydroxyapatite (HA)/meso-silica was prepared and used as absorbance of methylene blue (MB). HA/meso-silica was synthesized in three steps: preparation of nano-sized HA by wet precipitation method, coating of dense silica and deposition of meso-silica shell on HA. As-received samples were characterized by Fourier transformed infare spectra, small angle X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. A wormhole framework mesostructure was found for HA/meso-silica. The specific surface area and pore volume were 128 m2•g-1 and 0.36 cm3•g-1, respectively. From the adsorption isotherm, HA/meso-silica with the great specific surface area exhibited a prominent adsorption capacity of MB (134.0 mg/g) in comparison with bare HA (0 mg/g). This study might shed light on surface modification of conventional low-cost adsorbents for removal of organic pollutants from aqueous solutions.

scholarly journals Synthesis of Spherical Silica by Sol-Gel Method and Its Application as Catalyst Support

2011 ◽  
Vol 10 (2) ◽  
pp. 25
Author(s):  
Anirut Leksomboon ◽  
Bunjerd Jongsomjit
Keyword(s):  
Particle Size ◽  
Ethylene Glycol ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Weight Ratio ◽  
Gel Method ◽  
Sol Gel Method ◽  
Spherical Silica

In this present study, the spherical silica support was synthesized from tetraethyloxysilane (TEOS), water, sodium hydroxide, ethylene glycol and n-dodecyltrimethyl ammonium bromide (C12TMABr). The particle size was controlled by variation of the ethylene glycol co-solvent weight ratio of a sol-gel method preparation in the range of 0.10 to 0.50. In addition, the particle size apparently increases with high weight ratio of co-solvent, but the particle size distribution was broader. The standard deviation of particle diameter is large when the co-solvent weight ratio is more than 0.35 and less than 0.15. However, the specific surface area was similar for all weight ratios ranging from 1000 to 1300 m2/g. The synthesized silica was spherical and has high specific surface area. The cobalt was impregnated onto the obtained silica to produce the cobalt catalyst used for CO2 hydrogenation.</

scholarly journals The referential grain size and effective porosity in the Kozeny–Carman model

2016 ◽  
Author(s):  
K. Urumović ◽  
K. Urumović Sr.
Keyword(s):  
Grain Size ◽  
Hydraulic Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Effective Porosity ◽  
Critical Conditions ◽  
Saturated Porous Media ◽  
New Developments ◽  
Mean Grain Size

Abstract. In this paper, the results of permeability and specific surface area analyses as functions of granulometric composition of various sediments (from silty clays to very well-graded gravels) are presented. The effective porosity and the referential grain size are presented as fundamental granulometric parameters expressing an effect of the forces operating on fluid movement through the saturated porous media. This paper suggests procedures for calculating referential grain size and determining effective (flow) porosity, which result in parameters that reliably determine the specific surface area and permeability. These procedures ensure the successful application of the Kozeny–Carman model up to the limits of validity of Darcy’s law. The value of effective porosity in the referential mean grain size function was calibrated within the range of 1.5 μm to 6.0 mm. The reliability of the parameters applied in the KC model was confirmed by a very high correlation between the predicted and tested hydraulic conductivity values (R2=0.99 for sandy and gravelly materials; R2=0.70 for clayey-silty materials). The group representation of hydraulic conductivity (ranging from 10–12 m/s up to 10–2 m/s) presents a coefficient of correlation of R2=0.97 for a total of 175 samples of various deposits. These results present new developments in the research of the effective porosity, the permeability and the specific surface area distributions of porous materials. This is important because these three parameters are critical conditions for successful groundwater flow modeling and contaminant transport. Additionally, from a practical viewpoint, it is very important to identify these parameters swiftly and very accurately.

Preparation of Nanosize Anatase TiO2 Powders by Hydrothermal Synthesis

2007 ◽  
Vol 336-338 ◽  
pp. 2017-2020 ◽  
Author(s):  
Fan Yong Ran ◽  
Wen Bin Cao ◽  
Yan Hong Li ◽  
Xiao Ning Zhang
Keyword(s):  
Grain Size ◽  
Hydrothermal Synthesis ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Reaction Temperature ◽  
Reaction System ◽  
Anatase Tio2 ◽  
Holding Time ◽  
Precursor Concentration

Nanosize anatase TiO2 powders have been synthesized by hydrothermal synthesis by using technical grade TiOSO4 as precursor and urea as precipitating agent. The initial pressure of the reaction system was set at 6 MPa. Stirring speed was fixed at 300r/min. The reaction system reacted at the temperature ranged from 110 to 150°C for holding 2hrs to 8hrs and the concentration of the precursor was ranged from 0.25M to1.5M. XRD patterns show that the synthesized powders are in the form of anatase phase. Calculated grain size is ranged from 6.7 to 8.9nm by Scherrer method from the line broadening of the (101) diffraction peak of anatase. The specific surface area of the powders synthesized under different conditions is ranged from 124 to 240m2/g. The grain size of the powders increases with the increase of the reaction temperature, holding time and precursor concentration, respectively. The specific surface area decreases with the increase of reaction temperature and holding time, and does not obviously change with the change of precursor concentration when the concentration of the precursor is less than 1M. However, when the concentration is higher than 1M, the specific surface area will decrease quickly with the increase of the precursor concentration. XRD and DSC-TG analysis shows that the synthesized anatase TiO2 will begin to transform to rutile TiO2 at about 840°C. When heated to 1000°C for holding 1h, the anatase powders will transform to rutile completely.

scholarly journals Retrieval of Snow Properties from the Sentinel-3 Ocean and Land Colour Instrument

2019 ◽  
Vol 11 (19) ◽  
pp. 2280 ◽  
Author(s):  
Alexander Kokhanovsky ◽  
Maxim Lamare ◽  
Olaf Danne ◽  
Carsten Brockmann ◽  
Marie Dumont ◽  
...  
Keyword(s):  
Grain Size ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Environmental Changes ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
The Arctic ◽  
Observation Data ◽  
Snow Properties

The Sentinel Application Platform (SNAP) architecture facilitates Earth Observation data processing. In this work, we present results from a new Snow Processor for SNAP. We also describe physical principles behind the developed snow property retrieval technique based on the analysis of Ocean and Land Colour Instrument (OLCI) onboard Sentinel-3A/B measurements over clean and polluted snow fields. Using OLCI spectral reflectance measurements in the range 400–1020 nm, we derived important snow properties such as spectral and broadband albedo, snow specific surface area, snow extent and grain size on a spatial grid of 300 m. The algorithm also incorporated cloud screening and atmospheric correction procedures over snow surfaces. We present validation results using ground measurements from Antarctica, the Greenland ice sheet and the French Alps. We find the spectral albedo retrieved with accuracy of better than 3% on average, making our retrievals sufficient for a variety of applications. Broadband albedo is retrieved with the average accuracy of about 5% over snow. Therefore, the uncertainties of satellite retrievals are close to experimental errors of ground measurements. The retrieved surface grain size shows good agreement with ground observations. Snow specific surface area observations are also consistent with our OLCI retrievals. We present snow albedo and grain size mapping over the inland ice sheet of Greenland for areas including dry snow, melted/melting snow and impurity rich bare ice. The algorithm can be applied to OLCI Sentinel-3 measurements providing an opportunity for creation of long-term snow property records essential for climate monitoring and data assimilation studies—especially in the Arctic region, where we face rapid environmental changes including reduction of snow/ice extent and, therefore, planetary albedo.

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