Silica Aerogels Impregnated with Copper Nanoparticles: An Investigation of Three-Way Catalytic Ability

Automotive engines require three-way catalytic converters to reduce nitrogren oxides (NOx) and oxidize unburnt hydrocarbons (HCs) and carbon monoxide (CO) present in exhaust emissions. Current three-way catalytic converters use rare noble metals such as platinum, palladium and rhodium, which are wasteful and expensive to mine. Union College is investigating the use of aerogels as an alternative to these metals, due to the material’s high surface area, thermal stability and relatively low cost. We have found that copper-alumina aerogels will convert NOx, HCs and CO to less harmful emissions under conditions similar to those seen in automotive exhaust systems. These aerogels are formed by addition of dissolved copper salt to an alumina or silica wet gel and contain copper in its three oxidation states: Cu, Cu2O and CuO. This work aims to understand how the copper oxidation state affects catalytic aerogel properties by incorporating Cu, Cu2O , and CuO nanoparticles separately into silica aerogels. This will allow us to measure the individual contribution of each copper oxidation state to catalysis. The aerogels were successfully produced and show evidence of copper nanoparticles. Characterization methods include bulk density, surface area, X-ray diffraction patterns, scanning electron microscopy, and catalytic ability.