Aerogels offer a potential alternative to noble metals that could reduce both the cost and environmental impact associated with catalytic converter production. The environmental impact of the production of aerogel catalysts could be further reduced by using a rapid supercritical extraction (RSCE) technique, which reduces the time and solvent waste associated with aerogel preparation. Alumina aerogels, which have shown activity in catalyzing exhaust processing reactions, were prepared using an epoxide-assisted gelation technique with RSCE processing in a contained mold in a hydraulic hot press. Samples were characterized by FTIR, XRD, SEM, EDX, nitrogen adsorption porosimetry and pycnometry. Solvent characterization by GC-MS headspace analysis shows that excess propylene oxide and chloropropanol products of an irreversible epoxide ring-opening reaction are present in the alumina gel following gelation, but can be removed via solvent exchange. Alumina aerogels with surface areas as high as 790 m2/g and bulk densities as low as 0.05 g/mL were prepared. Preliminary characterization of these aerogels, utilizing a catalytic test bed and a simulated emission gas blend, demonstrates that they have moderate ability for removal of hydrocarbons, carbon monoxide and nitrogen oxide.
Bibliographical noteFunding Information:
This material is based upon work supported by the National Science Foundation (NSF) under Grant Nos. CHE-0847901 and DMR-1206631 . The authors thank Michael E. Hagerman for helpful discussions, Justin E. Rodriguez for assistance with the catalytic test bed measurements, and the Union College Geology Department for use of the XRD instrument. SJJ and NJHD are grateful for summer funding from the Union College Summer Research Fellowship Program . Additional support of this project was provided through the Union College Faculty Research Fund , Student Research Grant and Presidential Green Grant programs. The SEM instrument was funded through grants from the National Science Foundation (NSF MRI 0619578 ) and New York State Assembly RESTORE-NY .
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- Alumina aerogels
- Catalytic aerogels
- Rapid supercritical extraction