scholarly journals Fabrication of 12CaO·7Al2O3 powders with high specific surface area by sol–gel and ball-milling method

2011 ◽  
Vol 119 (1390) ◽  
pp. 460-463 ◽  
Author(s):  
Kotaro OZAWA ◽  
Naonori SAKAMOTO ◽  
Naoki WAKIYA ◽  
Hisao SUZUKI
Keyword(s):  
Specific Surface ◽  
Ball Milling ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
High Specific Surface Area ◽  
Milling Method

Preparation and Characterization of Phloroglucinol-Resorcinol-Formaldehyde Carbon Aerogels

2013 ◽  
Vol 423-426 ◽  
pp. 523-527
Author(s):  
Xuan Liu ◽  
Zhen Fa Liu ◽  
Hao Lin Fu ◽  
Rui He ◽  
Li Hui Zhang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
High Specific Surface Area ◽  
Carbon Aerogels ◽  
Resorcinol Formaldehyde ◽  
Sol Gel Process ◽  
Solvent Replacement ◽  
Organic Aerogels

Phloroglucinol-resorcinol-formaldehyde organic aerogels (PRF) were prepared using phloroglucinol, resorcinol and formaldehyde in a sol-gel process, solvent replacement and drying at room temperature. The phloroglucinol-resorcinol-formaldehyde carbon aerogels (CPRF) were prepared by charring the PRF at high temperature under the aegis of helium flow. The microstructure of CPRF was characterized by infrared spectroscopy, specific surface area analyzer and scanning electron microscopy. The results showed that the CPRF had continuous network structure and high specific surface area.

Preparation and Characterization of Ultralow Density Silica Aerogels by Acetonitrile Supercritical Drying

2012 ◽  
Vol 519 ◽  
pp. 83-86 ◽  
Author(s):  
Guang Wu Liu ◽  
Xing Yuan Ni ◽  
Bin Zhou ◽  
Qiu Jie Yu
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Silica Aerogel ◽  
Sol Gel ◽  
Supercritical Drying ◽  
Silica Aerogels ◽  
High Specific Surface Area ◽  
Molar Ratio ◽  
Sol Gel Process

This paper deals with the synthesis of ultralow density silica aerogels using tetramethyl orthosilicate (TMOS) as the precursor via sol-gel process followed by supercritical drying using acetonitrile solvent extraction. Ultralow density silica aerogels with 6 mg/cc of density was made for the molar ratio by this method. The microstructure and morphology of the ultralow density silica aerogels was characterized by the specific surface area, SBET, SEM, and the pore size distribution techniques. The results show that the ultralow density silica aerogel has the high specific surface area of 812m2/g. Thermal conductivities at desired temperatures were analyzed by the transient plane heat source method. Thermal conductivity coefficients of silica aerogel monoliths changed from 0.024 to 0.043W/ (m K) as temperature increased to 400°C, revealed an excellent heat insulation effect during thermal process.

Novel Al2O3–SiO2composite aerogels with high specific surface area at elevated temperatures with different alumina/silica molar ratios prepared by a non-alkoxide sol–gel method

RSC Advances ◽  
2016 ◽  
Vol 6 (7) ◽  
pp. 5611-5620 ◽  
Author(s):  
Xiaodong Wu ◽  
Gaofeng Shao ◽  
Xiaodong Shen ◽  
Sheng Cui ◽  
Ling Wang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Elevated Temperatures ◽  
Inorganic Salt ◽  
Sol Gel ◽  
High Specific Surface Area ◽  
Gel Method ◽  
Molar Ratios ◽  
Composite Aerogels

We have developed a new sol–gel route to synthesise Al2O3–SiO2composite aerogels with different alumina/silica (Al/Si) molar ratios using an inexpensive inorganic salt.

Synthesis and Structural Characterization of SiO2-Al2O3 Xerogels

2007 ◽  
Vol 336-338 ◽  
pp. 2286-2289
Author(s):  
Fei He ◽  
Xiao Dong He ◽  
Yao Li
Keyword(s):  
Structural Change ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Mesoporous Structure ◽  
Supercritical Drying ◽  
High Specific Surface Area ◽  
Molar Ratio

Low-density xSiO2-(1-x)Al2O3 xerogels with x=0.9, 0.8, 0.7, 0.6 (mole fractions) were prepared by sol-gel and non-supercritical drying. Silica alkogels, which were the framework of binary composite materials, formed from tetraethyl orthosilicate (TEOS) by hydrolytic condensation with a molar ratio of TEOS: H2O: alcohol: hydrochloric acid: ammonia =1: 4: 10: 7.5×10-4: 0.0375. Aluminum hydroxide derived from Al(NO3)3·9H2O and NH4OH acting in the alcohol solution under the condition of catalyst. After filtrating and washing, the precipitation was mixed into silica sols to form SiO2-Al2O3 mixed oxide gels with different silicon and aluminum molar ratio. The structural change and crystallization of the binary xerogels were investigated after heat treatment at 600 for 2 h by the means of X-ray diffraction. Nitrogen adsorption experiment was performed to estimate specific surface area, porous volume and pore size distribution. The structural change of xerogels was observed by FT-IR spectroscopy. The resulting mixed xerogels possess of mesoporous structure which is characteristic of cylindrical pores, high specific surface area of 596-863 m2/g and a relatively narrow pore distribution of 2.8-30 nm. Al2O3 is introduced into the SiO2 phase and some of Al-O-Si bonds form.

Synthesis and sintering of Ca0.5Sr0.5Zr4P6O24 powders by the decomposition/combustion of Ca-, Sr-, nitrate-ammonium dihydrogen phosphate-urea mixtures

1994 ◽  
Vol 9 (9) ◽  
pp. 2398-2403 ◽  
Author(s):  
Chang S. Hong ◽  
P. Ravindranathan ◽  
Dinesh K. Agrawal ◽  
Rustum Roy
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sintered Density ◽  
Sol Gel ◽  
Combustion Method ◽  
High Specific Surface Area ◽  
Dihydrogen Phosphate ◽  
Ammonium Dihydrogen Phosphate ◽  
Batch Weight

Ca0.5Sr0.5Zr4P6O24 (CSZP) powders were prepared by the decomposition/combustion method using Ca(NO3)2 · 4H2O, Sr(NO3)2, ZrO(NO3)2 · xH2O, NH4H2PO4, urea, and NH4NO3 as starting materials. The homogenized slurries of the mixture were heated at 500 °C for 5 min to obtain CSZP powders. The as-synthesized powders were amorphous and crystallized after heating 800 °C for 2 h. The specific surface area of the powder was varied with the batch weight of starting materials or the amount of urea and ammonium nitrate. Powders with high specific surface area (150 m2/g) could be produced by this method. The sinterability of the powders was comparable to that of sol-gel derived powders. The sintered density of the compacts was 99% of theoretical after firing in air at 1350 °C for 6 h.

scholarly journals A Study on the Effect of Different Ball Milling Methods on the NH3-SCR Activity of Aluminum-Laden Bayan Obo Tailings

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 568
Author(s):  
Xinrui Bai ◽  
Jiawei Lin ◽  
Zedong Chen ◽  
Limin Hou ◽  
Wenfei Wu
Keyword(s):  
Specific Surface ◽  
Ball Milling ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Conversion Rate ◽  
Nh3 Scr ◽  
Milling Method ◽  
Bayan Obo ◽  
Active Substances

Rich in Fe, Ce, Mn, Si and other elements which have good catalytic activity, Bayan Obo rare-earth tailings are naturally advantaged as the carrier of denitrification catalysts. In this paper, pseudo boehmite (γ-Al2O3) was mixed with Bayan Obo tailings using different ball milling methods for modification to prepare NH3-SCR catalysts. The effect of different mixing methods on the SCR denitrification activity at a low temperature was investigated and the prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), temperature programed desorption (NH3-TPD), temperature programed reduction (H2-TPR) and other means. The conversion rate of NOx at 250–350 °C was above 80% and the highest conversion rate of NOx of 90% was achieved at 300 °C. SEM and XRD revealed that the tailings modified by pseudo boehmite (γ-Al2O3) using the ordinary ball milling method have loose structure and good dispersion of active substances, and specific surface area (BET) analysis shows that the tailings have the maximum specific surface area and pore volume. However, over grinding and secondary spheronization were observed in the tailings modified by pseudo boehmite (γ-Al2O3) using high energy ball milling method, leading to the decrease of specific surface area and pore volume, poor dispersion of active substances, and ultimately low denitrification rate.

Rapid preparation process, structure and thermal stability of lanthanum doped alumina aerogels with a high specific surface area

RSC Advances ◽  
2016 ◽  
Vol 6 (31) ◽  
pp. 26271-26279 ◽  
Author(s):  
Jingfeng Yang ◽  
Qihua Wang ◽  
Tingmei Wang ◽  
Yongmin Liang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Supercritical Drying ◽  
High Specific Surface Area ◽  
Rapid Preparation ◽  
Alumina Aerogels ◽  
Process Structure ◽  
Thermal Stability Of

In this study, we developed a new and rapid preparation method of alumina aerogels based on the sol–gel method and supercritical drying technique and prepared alumina aerogels with high specific surface area.

Novel 0D-nanocarbon-silica ceramic composites: sol–gel synthesis and high-temperature evolution

2020 ◽  
Vol 49 (21) ◽  
pp. 7144-7154 ◽  
Author(s):  
Alexander Ott ◽  
Simone Rogg ◽  
Stefan Lauterbach ◽  
Hans-Joachim Kleebe ◽  
Christian Hess ◽  
...  
Keyword(s):  
High Temperature ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sol Gel ◽  
Ceramic Composites ◽  
High Specific Surface Area ◽  
Gel Method ◽  
Sol Gel Synthesis ◽  
Silica Ceramic

Novel mesoporous, high specific surface area (up to 562 m2 g−1) 0D-nanocarbon-based silicon-containing ceramic composites were produced by a straightforward sol–gel method followed by polymer-to-ceramic transformation.

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