Fabrication and Characterization of Multi-Metal Catalytic Aerogels

Aerogels are low weight and density materials that also contain high surface area, porosity and thermally insulating properties because they are 90-99% air by volume. These properties give aerogels great potential as heterogeneous catalysts for applications in catalytic converters. Commercial catalytic converters currently use three-way catalysts based on precious metals (platinum, palladium, and rhodium) to oxidize hydrocarbons and carbon monoxide and reduce nitrous oxides, resulting in emission of water vapor, nitrogen gas and carbon dioxide instead of more harmful gases. The mining operations for these precious metals are expensive and thus aerogels are being studied as a potential replacement. In this work, Cerium-Copper-Silica (Ce-Cu-Si) and Cerium-Copper-Alumina (Ce-Cu-Al) aerogels were successfully synthesized through the sol-gel method. The aerogels were fabricated using Union College’s patented rapid supercritical extraction (RSCE) process. Three variations of each aerogel were made, varying the amount of copper and cerium salt impregnated into the gel. The molar ratios used were 75:25, 50:50 and 25:75 copper to cerium, respectively. The aerogels were characterized using IR spectroscopy, X-ray diffraction, SEM imaging, bulk density measurements and BET surface area measurements. The aerogels in this study were also subjected to catalytic characterization using the Union Catalytic Aerogel Testbed (UCAT) by flowing a mixture of propane, NO and CO gases over the aerogels and measuring their conversion. The Ce-Cu-Si and Ce-Cu-Al aerogels show promise as three-way catalysts.