scholarly journals Preparing Silica Aerogel Monoliths via a Rapid Supercritical Extraction Method

10.3791/51421 ◽  
2014 ◽  
Author(s):  
Mary K. Carroll ◽  
Ann M. Anderson ◽  
Caroline A. Gorka
Keyword(s):  
Silica Aerogel ◽  
Extraction Method ◽  
Supercritical Extraction ◽  
Rapid Supercritical Extraction

Synthesis and Characterization of Copper-Nanoparticle-Containing Silica Aerogel Prepared via Rapid Supercritical Extraction for Applications in Three-Way Catalysis

MRS Advances ◽  
2017 ◽  
Vol 2 (57) ◽  
pp. 3485-3490 ◽  
Author(s):  
Ann M. Anderson ◽  
Elizabeth A. Donlon ◽  
Adam A. Forti ◽  
Vinicius P. Silva ◽  
Bradford A. Bruno ◽  
...  
Keyword(s):  
Silica Aerogel ◽  
Silica Aerogels ◽  
Supercritical Extraction ◽  
X Ray Diffraction ◽  
Initial Oxidation ◽  
Catalytically Active ◽  
Show Evidence ◽  
Rapid Supercritical Extraction ◽  
Three Way Catalysis

ABSTRACTCopper-alumina and copper-silica aerogels formed by impregnation of a copper(II) salt into an alumina or silica wet gel before supercritical extraction have been found to contain copper in multiple oxidation states: Cu0, Cu+1 and Cu+2. These aerogels are effective at catalyzing the reduction of NO and the oxidation of HCs and CO under conditions similar to those found in automotive three way catalysts. In this work we have developed a preparation method incorporating Cu0, Cu+1 and Cu+2 nanoparticles directly into silica aerogels. Nanoparticles in the form of (a) Cu0 nanorods (100 nm diameter, 10-20 μm length); (b) Cu+1 nanoparticles (350 nm diameter); and (c) Cu+2 nanoparticles (25-55 nm diameter) were added (0.5-15% by weight) to separate precursor mixtures consisting of tetramethyl orthosilicate, methanol, water and ammonia. These precursor mixtures were then processed using a rapid supercritical extraction (RSCE) method to form aerogels. The resulting aerogels show evidence of nanoparticles dispersed throughout the silica aerogel structure. Addition of Cu+1 and Cu+2 nanoparticles decreases the surface area of the aerogels significantly. X-Ray diffraction shows that regardless of initial oxidation state of the nanoparticles, crystalline Cu0 is detected after RSCE processing to 290 °C. Following heat treatment at 700 °C, crystalline Cu+2 is detected. The copper containing silica aerogels are found to be catalytically active with light-off temperatures (50% conversion) for NO and CO at 400 °C in three-way catalytic applications.

scholarly journals Epoxide-assisted alumina aerogels by rapid supercritical extraction

2015 ◽  
Vol 426 ◽  
pp. 141-149 ◽  
Author(s):  
Stephen J. Juhl ◽  
Nicholas J.H. Dunn ◽  
Mary K. Carroll ◽  
Ann M. Anderson ◽  
Bradford A. Bruno ◽  
...  
Keyword(s):  
Supercritical Extraction ◽  
Alumina Aerogels ◽  
Rapid Supercritical Extraction

Hydrophobic silica aerogels prepared via rapid supercritical extraction

2009 ◽  
Vol 53 (2) ◽  
pp. 199-207 ◽  
Author(s):  
Ann M. Anderson ◽  
Mary K. Carroll ◽  
Emily C. Green ◽  
Jason T. Melville ◽  
Michael S. Bono
Keyword(s):  
Silica Aerogels ◽  
Supercritical Extraction ◽  
Hydrophobic Silica ◽  
Rapid Supercritical Extraction

scholarly journals Fabrication and Testing of Catalytic Aerogels Prepared Via Rapid Supercritical Extraction

10.3791/57075 ◽  
2018 ◽  
Author(s):  
Ann M Anderson ◽  
Bradford A Bruno ◽  
Elizabeth A Donlon ◽  
Luisa F Posada ◽  
Mary K Carroll
Keyword(s):  
Supercritical Extraction ◽  
Rapid Supercritical Extraction
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