Effect of Wetting on the Nitrogen Adsorption—Desorption Isotherm of a Silica Aerogel

1950 ◽  
Vol 72 (9) ◽  
pp. 4289-4289 ◽  
Author(s):  
Marvin F. L. Johnson ◽  
Herman E. Ries
Keyword(s):  
Silica Aerogel ◽  
Nitrogen Adsorption ◽  
Desorption Isotherm ◽  
Adsorption Desorption

scholarly journals Catalytic Transfer of Fructose to 5-Hydroxymethylfurfural over Bimetal Oxide Catalysts

2019 ◽  
Vol 2019 ◽  
pp. 1-6
Author(s):  
Qiuyun Zhang ◽  
Xiaofang Liu ◽  
Tingting Yang ◽  
Quanlin Pu ◽  
Caiyan Yue ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Direct Conversion ◽  
Significant Loss ◽  
Desorption Isotherm ◽  
High Yield ◽  
Reaction Conditions ◽  
Strong Acidity ◽  
Adsorption Desorption

Direct conversion of fructose into 5-hydroxymethylfurfural (HMF) is achieved by using modified aluminum-molybdenum mixed oxide (S-AlMo) as solid acid catalysts. The synthesized catalyst was characterized by powder XRD, nitrogen adsorption-desorption isotherm, NH3-TPD, and SEM. As a result, the presence of strong acidity, mesostructures, and high surface area in the S-AlMo catalyst was confirmed by nitrogen adsorption-desorption isotherm and NH3-TPD studies. A study by optimizing the reaction conditions such as catalyst dosage, reaction temperature, and time has been performed. Under the optimal reaction conditions, HMF was obtained in a high yield of 49.8% by the dehydration of fructose. Moreover, the generality of the catalyst is also demonstrated by glucose and sucrose with moderate yields to HMF (24.9% from glucose; 27.6% from sucrose) again under mild conditions. After the reaction, the S-AlMo catalyst can be easily recovered and reused four times without significant loss of its catalytic activity.

Synthesis and Characterization of Zinc Phthalocyanine/Mesoporous Carbon Nitride Nanocomposites

2011 ◽  
Vol 364 ◽  
pp. 363-367 ◽  
Author(s):  
Shu Chin Lee ◽  
Hendrik O. Lintang ◽  
Yuliati Leny
Keyword(s):  
Visible Light ◽  
Mesoporous Carbon ◽  
Carbon Nitride ◽  
Broad Band ◽  
Nitrogen Adsorption ◽  
Desorption Isotherm ◽  
Zinc Phthalocyanine ◽  
Type Iv ◽  
Adsorption Desorption ◽  
Mesoporous Carbon Nitride

In this work, zinc phthalocyanine (ZnPc) was impregnated onto mesoporous carbon nitride (m-C3N4) to expand its absorption to longer wavelength. Nitrogen adsorption-desorption isotherm confirmed that the m-C3N4 showed type IV of adsorption-desorption isotherm. Transmission electron microscopy (TEM) revealed the presence of both nanosphere and nanoworm structure in the m-C3N4. Thermogravimetric analysis (TGA) showed that the synthesized m-C3N4 was thermally stable until 723 K. The presence of ZnPc on the m-C3N4 was confirmed from the X-ray diffraction (XRD) patterns and diffuse reflectance ultraviolet-visible (DR UV-Vis) spectra. The higher the amount of ZnPc loaded on m-C3N4, the higher the intensity of ZnPc peaks in the diffraction patterns. The successful impregnation of ZnPc onto the m-C3N4 was also supported by the color changing of the solids from yellow to blue, which can be seen as an additional broad band at 500-900 nm from the absorption spectra. Since the material gives visible light absorption, it is expected that the ZnPc/m-C3N4 would be a potential photocatalyst for reactions conducted under visible light irradiation.

Preparation and Characterization of Silica Aerogels/Glass Wool Composites

2012 ◽  
Vol 534 ◽  
pp. 106-109 ◽  
Author(s):  
Jing Xiao Liu ◽  
Xiao Jie Wang ◽  
Fei Shi ◽  
Jia Yu Luo
Keyword(s):  
Thermal Conductivity ◽  
Silica Aerogel ◽  
Ambient Pressure ◽  
Measurement Instrument ◽  
Conductivity Measurement ◽  
Nitrogen Adsorption ◽  
Ambient Pressure Drying ◽  
Glass Wool ◽  
Silica Source ◽  
Adsorption Desorption

Using industrial water glass as silica source, silica aerogel/glass wool composite heat insulation materials were prepared through the gel moulding, surface modification and ambient pressure drying method. The microstructure and porous characteristics of the silica aerogel/glass wool composites were studied by scanning electron microscopy (SEM) and BET nitrogen adsorption-desorption method. The thermal conductivity of silica aerogel/glass wool composites was measured by the thermal conductivity measurement instrument. The results indicate that the as-prepared silica aerogel/glass wool composites exhibit strong hydrophobicity and excellent thermal insulation performance. The thermal conductivity of the obtained silica aerogel/glass wool composites is 1.1×10-2～2.0 W∙m-1∙K-1, and with the increasing of aerogels content, the thermal conductivity of the composites could be decreased further.

scholarly journals TEXTURAL AND MORPHOLOGICAL CHARACTERIZATION OF COPPER(II)-EXCHANGED ROMANIAN CALCIUM BENTONITE

2017 ◽  
Vol 20 (3) ◽  
Author(s):  
ANA-MARIA GEORGESCU ◽  
GHEORGHE BRABIE ◽  
ILEANA DENISA NISTOR ◽  
CLAUDE PENOT ◽  
FRANÇOISE NARDOU
Keyword(s):  
Ion Exchange ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Nitrogen Adsorption ◽  
Desorption Isotherm ◽  
Scanning Electron Micrographs ◽  
Adsorption Desorption ◽  
Calcium Bentonite ◽  
Scanning Electron

<p>Romanian calcium bentonite was modified by copper(II) ion-exchange, by varying the copper precursors (chloride, sulphate) and synthesis parameters (pH, temperature, time). The quantification of the Cu(II) ions was carried out by atomic absorption spectrophotometer. The modified bentonites were characterized by textural analysis (specific surface area by the Brunauer-Emmett-Teller method (BET) and by nitrogen adsorption/desorption isotherm), structural composition (X-ray diffraction (XRD)) and morphological analysis (scanning electron microscopy (SEM)). Analysis of the nitrogen adsorption/desorption isotherm shows that ion exchanged bentonites, not only contain mesopores, but micropores in larger quantities too. The values of the specific surface area increased by about 20 m<sup>2</sup>/g compared with raw bentonite, but the interlamellar distance values do not vary substantially. Scanning electron micrographs were acquired to demonstrate changes in the texture of the clay before and after ion exchange.</p>

scholarly journals Pore Modification and Phosphorus Doping Effect on Phosphoric Acid-Activated Fe-N-C for Alkaline Oxygen Reduction Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1519
Author(s):  
Jong Gyeong Kim ◽  
Sunghoon Han ◽  
Chanho Pak
Keyword(s):  
Phosphoric Acid ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Electronic States ◽  
Nitrogen Adsorption ◽  
Reduction Reaction ◽  
Phosphorus Doping ◽  
X Ray ◽  
Precious Metal Catalysts ◽  
Adsorption Desorption

The price and scarcity of platinum has driven up the demand for non-precious metal catalysts such as Fe-N-C. In this study, the effects of phosphoric acid (PA) activation and phosphorus doping were investigated using Fe-N-C catalysts prepared using SBA-15 as a sacrificial template. The physical and structural changes caused by the addition of PA were analyzed by nitrogen adsorption/desorption and X-ray diffraction. Analysis of the electronic states of Fe, N, and P were conducted by X-ray photoelectron spectroscopy. The amount and size of micropores varied depending on the PA content, with changes in pore structure observed using 0.066 g of PA. The electronic states of Fe and N did not change significantly after treatment with PA, and P was mainly found in states bonded to oxygen or carbon. When 0.135 g of PA was introduced per 1 g of silica, a catalytic activity which was increased slightly by 10 mV at −3 mA/cm2 was observed. A change in Fe-N-C stability was also observed through the introduction of PA.

Effect of Carbon Pre-Treatment on Pd Dispersion in Synthesis of Pd/C Catalyst

2014 ◽  
Vol 804 ◽  
pp. 149-152 ◽  
Author(s):  
Ji Sun Kim ◽  
Jae Ho Baek ◽  
Myung Hwan Kim ◽  
Seong Soo Hong ◽  
Man Sig Lee
Keyword(s):  
Surface Area ◽  
Nitrogen Adsorption ◽  
Area Ratio ◽  
High Dispersion ◽  
Co Chemisorption ◽  
Pd Dispersion ◽  
Before And After ◽  
Pre Treatment ◽  
Treated Carbon ◽  
Adsorption Desorption

In this study, we confirmed effect of carbon pre-treatment on Pd dispersion in synthesis of Pd/C catalyst. Physical characteristics on the surface of before and after pre-treated carbon were analyzed by nitrogen adsorption-desorption analysis. The dispersion and size of Pd particles were analyzed by XRD, FE-TEM and CO-chemisorption. After pre-treatment, surface area of carbon were decreased. And mesopore area ratio were increased with decreasing micropore area ratio. In the case of pre-treated carbon, we confirmed high dispersion of Pd particles.

Texture Evaluation of Sol-Gel Derived Mesoporous Bioactive Glass

2013 ◽  
Vol 284-287 ◽  
pp. 230-234
Author(s):  
Yu Jen Chou ◽  
Chi Jen Shih ◽  
Shao Ju Shih
Keyword(s):  
Surface Area ◽  
Calcination Temperature ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Nitrogen Adsorption ◽  
Bioactive Glasses ◽  
Transmission Electron ◽  
Sol Gel Process ◽  
Adsorption Desorption

Recent years mesoporous bioactive glasses (MBGs) have become important biomaterials because of their high surface area and the superior bioactivity. Various studies have reported that when MBGs implanted in a human body, hydroxyl apatite layers, constituting the main inorganic components of human bones, will form on the MBG surfaces to increase the bioactivity. Therefore, MBGs have been widely applied in the fields of tissue regeneration and drug delivery. The sol-gel process has replaced the conventional glasses process for MBG synthesis because of the advantages of low contamination, chemical flexibility and lower calcination temperature. In the sol-gel process, several types of surfactants were mixed with MBG precursor solutions to generate micelle structures. Afterwards, these micelles decompose to form porous structures after calcination. Although calcination is significant for contamination, crystalline and surface area in MBG, to the best of the authors’ knowledge, only few systematic studies related to calcination were reported. This study correlated the calcination parameters and the microstructure of MBGs. Microstructure evaluation was characterized by transmission electron microscopy and nitrogen adsorption/desorption. The experimental results show that the surface area and the pore size of MBGs decreased with the increasing of the calcination temperature, and decreased dramatically at 800°C due to the formation of crystalline phases.

scholarly journals Ball-milling effect on Indonesian natural bentonite for manganese removal from acid mine drainage

2018 ◽  
Vol 156 ◽  
pp. 03046 ◽  
Author(s):  
Widyawanto Prastistho ◽  
Winarto Kurniawan ◽  
Hirofumi Hinode
Keyword(s):  
Particle Size ◽  
Acid Mine Drainage ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Mine Drainage ◽  
Nitrogen Adsorption ◽  
Exchange Capacity ◽  
Manganese Removal ◽  
Acid Mine ◽  
Adsorption Desorption

The influences of mechanical milling on Indonesian Natural Bentonite (INB) characteristics and manganese (Mn) removal from acid mine drainage (AMD) were investigated. The INB characteristics were observed by scanning electron microscope (SEM), X-ray diffraction (XRD), nitrogen adsorption-desorption for specific surface area (SSA) and microporosity measurement, cation exchange capacity (CEC) and particle size distribution (PSD) analyzer. Four minutes milling with frequency 20 Hz on INB caused morphological change which showed more crumbled and destructed particle, lost the (001) peak but still retained the (100) peak that indicated delamination of montmorillonite mineral without breaking the tetrahedral-octahedral-tetrahedral (T-O-T) structure, rose the CEC from 28.49 meq/100g to 35.51 meq/100g, increase in the SSA from 60.63 m2/g to 104.88 m2/g, significant increase in microporosity which described in the t plots and decrease in the mean particle size distribution peak from 49.28 μm to 38.84 μm. The effect of contact time and effect of adsorbent dosage on Mn sorption was studied. Both unmilled and milled samples reached equilibrium at 24 hours and the pH rose from 4 to 7 in first 30 minutes. The Mn removal percentage increased significantly after milling. Using Langmuir isotherm, the maximum adsorbed metals (qmax) also increased from 0.570 to 4.219 mg/g.

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