Nanoparticles for Redox Catalysis: Three-Way-Catalyst for Automotive Exhausts
Lead Inventors: Siu-Wai Chan, Sc.D., Hongying Liang, Ph.D.Problem or Unmet Need:Three-way catalysis (TWC) is the main technology used to control emissions from gasoline engines. The catalyst uses an active coating incorporating metal oxides and combinations of precious metals (PM). However, there are a number of critical problems in this field. For example, low efficiency of catalysts is a major problem and defect density has been shown to be an important factor in catalytic activity; however, current methods to generate defects are expensive and difficult. Another challenging problem is phase separation of catalyst aging at high temperatures, characteristic to those prepared with commonly used methods. Moreover, any reduction of the usage of palladium will improve the cost-base of the present three way catalyst and possible diesel engine exhaust clean-up system. This technology presents a straightforward and more cost effective method to produce nanoparticles as redox catalysts for methanol reforming, water-gas shift and especially also three-way catalysis. It is an aqueous method to produce nanoparticle catalysts with metal ions or metal clusters in the oxide lattice. The metal ions and metal clusters strongly associated with surface cerium-oxygen have been found responsible for the activity. The co-precipitation method produces nanoparticle catalysts with a high defect density, which is an important characteristic of catalytically effective materials, especially for CO oxidation. Moreover, through the described room temperature reaction, very homogeneous, single phase samples have been obtained. The nanoparticles have been characterized by high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) to confirm extended defects and incorporation of palladium.
This technology provides a cost effective method using an aqueous medium and at a low temperature to prepare catalytic nanoparticles, which can reduce expenses of purchasing and disposing of organic solvents/reagents and of large energy input Current methods to generate defects in nanocrystals are expensive and difficult. This technology may be used to prepare nanoparticles with significant extended defects, under much more mild conditions with lower cost
These materials can be catalysts for methanol reforming, three-way catalysis and water-gas shift As redox catalysts, materials made from these nanoparticles may be incorporated in three-way catalytic converters for automobile exhausts The material may also be used in fuel cell powered electric cars These nanoparticles might also have usage in cold starting of automobile engine, lasers, hydrocarbon conversion reactors, and air filters for the conversion of carbon monoxide, and/or indoor volatile organic compounds
This technology presents a straightforward and more cost effective method to produce nanoparticles as redox catalysts for methanol reforming, water-gas shift and especially also three-way catalysis. It is an aqueous method to produce nanopartic...
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