Investigation of CO oxidation and NO reduction on three-way monolith catalysts with transient response techniques
| Autor: | Matti Härkönen, Veikko J. Pohjola, Juha Ahola, Marjo Luoma, Heikki Haario, Tapio Salmi, Teuvo Maunula |
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| Rok vydání: | 1997 |
| Předmět: |
Process Chemistry and Technology
Inorganic chemistry chemistry.chemical_element 02 engineering and technology engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology 7. Clean energy 01 natural sciences Catalysis 0104 chemical sciences Rhodium Reaction rate Adsorption chemistry 13. Climate action Reagent engineering Noble metal 0210 nano-technology Platinum Bimetallic strip General Environmental Science |
| Zdroj: | Applied Catalysis B: Environmental. 12:287-308 |
| ISSN: | 0926-3373 |
| DOI: | 10.1016/s0926-3373(96)00084-7 |
| Popis: | The kinetics of CO oxidation and NO reduction reactions over alumina and alumina-ceria supported Pt, Rh and bimetallic Pt/Rh catalysts coated on metallic monoliths were investigated using the step response technique at atmospheric pressure and at temperatures 30–350°C. The feed step change experiments from an inert flow to a flow of a reagent (O2, CO, NO and H2) showed that the ceria promoted catalysts had higher adsorption capacities, higher reaction rates and promoting effects by preventing the inhibitory effects of reactants, than the alumina supported noble metal catalysts. The effect of ceria was explained with adsorbate spillover from the noble metal sites to ceria. The step change experiments CO/O2 and O2/CO also revealed the enhancing effect of ceria. The step change experiments NO/H2 and H2/NO gave nitrogen as a main reduction product and N2O as a by-product. Preadsorption of NO on the catalyst surface decreased the catalyst activity in the reduction of NO with H2. The CO oxidation transients were modeled with a mechanism which consistent of CO and O2 adsorption and a surface reaction step. The NO reduction experiments with H2 revealed the role of N2O as a surface intermediate in the formation of N2. The formation of NN bonding was assumed to take place prior to, partly prior to or totally following to the NO bond breakage. High NO coverage favors N2O formation. Pt was shown to be more efficient than Rh for NO reduction by H2. |
| Databáze: | OpenAIRE |
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