scholarly journals Response to Comment on “High-surface-area corundum by mechanochemically induced phase transformation of boehmite”

Science ◽  
2020 ◽  
Vol 368 (6494) ◽  
pp. eabb0948
Author(s):  
Amol P. Amrute ◽  
Zbigniew Łodziana ◽  
Hannah Schreyer ◽  
Claudia Weidenthaler ◽  
Ferdi Schüth
Keyword(s):  
Phase Transformation ◽  
Surface Area ◽  
High Purity ◽  
High Surface ◽  
High Surface Area ◽  
Surface Areas

Li et al. commented that our report claims that methods reported thus far cannot enable the production of high-purity corundum with surface areas greater than 100 m2 g–1, and that our obtained material could be porous aggregates rather than nanoparticles. We disagree with both of these suggestions.

scholarly journals Comment on “High-surface-area corundum by mechanochemically induced phase transformation of boehmite”

Science ◽  
2020 ◽  
Vol 368 (6494) ◽  
pp. eabb0142 ◽  
Author(s):  
Jiangong Li ◽  
Sanxu Pu ◽  
Wenbin Cao ◽  
Lu Li ◽  
Ruiyun Guo
Keyword(s):  
Phase Transformation ◽  
Surface Area ◽  
High Purity ◽  
High Surface ◽  
High Surface Area ◽  
Surface Areas

Amrute et al. (Reports, 25 October 2019, p. 485) claimed that no methods were able to produce high-purity α-Al2O3 with surface areas greater than 100 m2 g–1, even though much higher surface areas up to 253 m2 g–1 have been reported. Moreover, the materials they obtained could be porous aggregates and may not be 13-nm nanoparticles, as claimed.

Preparation of CuCrO2 Powders with High Surface Areas

2014 ◽  
Vol 617 ◽  
pp. 187-190 ◽  
Author(s):  
Te Wei Chiu ◽  
Yi Wei Feng
Keyword(s):  
Nitric Acid ◽  
Surface Area ◽  
Chemical Treatment ◽  
High Surface ◽  
High Surface Area ◽  
Phase Evolution ◽  
Surface Areas ◽  
Pure Phase ◽  
Cu Ions

In this study, the effects of glycine-nitrate ratios and postcombustion chemical treatment on the phase evolution and surface area of CuCrO2powders were investigated. The pure phase of CuCrO2powders was obtained at a glycine-nitrate ratio of 1.2–1.4. When the glycine-nitrate ratio was higher than 1.9, the Cu ions were reduced to Cu(0) and the phase of Cu metal and Cr2O3were observed. However, when the glycine-nitrate ratio was lower than 1.1, the Cu ions were partially maintained as Cu(2+), and a bluish residue was observed. As-combusted CuCrO2powder with a high surface area (50 m2/g) was obtained at a glycine-nitrate ratio of 1.2. Furthermore, a high surface area (> 60 m2/g) was obtained by leaching as-combusted CuCrO2powder with diluted nitric acid.

Pyrolysis of Organosilicon Gels to Silicon Carbide

1986 ◽  
Vol 73 ◽  
Author(s):  
Joseph R. Fox ◽  
Douglas A. White ◽  
Susan M. Oleff ◽  
Robert D. Boyer ◽  
Phyllis A. Budinger
Keyword(s):  
Silicon Carbide ◽  
Surface Area ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Pyrolysis Products ◽  
Surface Areas ◽  
Physical Measurements

AbstractSol-gel precursors to silicon carbide have been prepared using trifunctional chloro and alkoxysilanes which contain both the silicon and carbon necessary for SiC formation. Crosslinked gels having the ideal formula [RSiO1 5].]n have been synthesized by a hydrolysis/condensation scheme for a series of saturated and unsaturated R groups. The starting gels have been characterized by a variety of elemental analysis, spectroscopic and physical measurements including IR. XRD. TGA.. surface area and pore volume. A particularly powerful method for characterizing these gels is the combination of 13C and 29 Si solid state NMR which can provide information about the degree of crosslinking as well as residual hydroxy/alkoxy content.The controlled pyrolysis of these gels has been used to prepare silicon carbide-containing ceramic products with surface areas in excess of 600m2/gm. The pyrolysis products are best described as a partially crystalline, partially amorphous mixture of β-SiC, silica and carbon. The effect of carbon chain length and the degree of unsaturation in the R group on the composition and surface area of the product has been determined. The origin of the high surface area of the pyrolysis products has been identified and its implications on potential uses of these materials is discussed.

Oxidative Catalytic Decomposition of Toxic Gases Using Hydroxyapatite and Fluorhydroxyapatite

1994 ◽  
Vol 368 ◽  
Author(s):  
Timothy P. Palucka ◽  
Nicholas G. Eror ◽  
Thomas A. Mcnamara
Keyword(s):  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Catalytic Decomposition ◽  
Reaction Products ◽  
Fluorine Substitution ◽  
Dimethyl Methylphosphonate ◽  
Surface Areas ◽  
Percent Nitrogen ◽  
Protection Period

ABSTRACTAn oxidative catalytic route for the decomposition of nerve gases was investigated using hydroxyapatite (HA, chemical composition Ca10(PO4)6(OH)2) and its partially fluorinated analog fluorhydroxyapatite (FHA, Ca10(PO4)6Fx(OH)2−x). Samples were prepared with surface areas ranging from 34 to 238 m2/g to study surface area effects; 1.2 wt. % platinum was deposited on one substrate to investigate the effect of a transition metal on activity and selectivity. Reaction studies were performed using dimethyl methylphosphonate (DMMP), a nerve gas simulant, in a stream of 80 percent nitrogen and 20 percent oxygen at 573 K and atmospheric pressure. High surface area FHA samples showed an increase in the "protection period" (period of 100% conversion) with increasing fluorine substitution; such an increase was not seen for low surface area FHA samples. In the absence of platinum, the reaction products were methanol and dimethyl ether; with platinum, CO2 was also obtained.

Nitrogen and Water Sorption Properties of Ethyl-Substituted Silica Aerogels and Xerogels

1994 ◽  
Vol 371 ◽  
Author(s):  
Chunling Liu ◽  
Sridhar Komarneni
Keyword(s):  
Pore Structure ◽  
Surface Area ◽  
Water Sorption ◽  
Ph Value ◽  
High Surface ◽  
High Surface Area ◽  
Silica Aerogels ◽  
Modified Silica ◽  
Surface Areas ◽  
Water Sorption Properties

AbstractHigh surface area ethyltrimethoxysilane (ETMS) modified silica aerogels and xerogels were synthesized by cohydrolyzing the mixtures of ETMS and tetramethylorthosilicate (TMOS). The effects of ETMS content, pH value and solvent addition were investigated. The surface area, pore structure and hydrophobicity were studied using nitrogen and water sorption measurements. By ETMS modification of TMOS gels, high surface area, density and hydrophobicity were achieved. The 25 mole% ETMS-75 mole% TMOS was found to be the best composition for both aerogel and xerogel, which are hydrophobic and have surface areas of 1221 and 832 m2/g, respectively.

New ultrasonic assisted co-precipitation for high surface area oxide based nanostructured materials

2018 ◽  
Vol 3 (3) ◽  
pp. 244-250 ◽  
Author(s):  
Dereck N. F. Muche ◽  
Flavio L. Souza ◽  
Ricardo H. R. Castro
Keyword(s):  
Metal Oxide ◽  
Surface Area ◽  
Metal Oxide Nanoparticles ◽  
High Surface ◽  
High Surface Area ◽  
Oxide Nanoparticles ◽  
Specific Method ◽  
Surface Areas ◽  
Ultrasonic Assisted ◽  
Co Precipitation

A non-system specific method for the synthesis of metal oxide nanoparticles with high homogeneity, spherical morphology and high surface areas is proposed based on an aqueous precipitation.

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