Search

Abstract: The aim of the present work is to study the selective reduction of NO x from natural gas sources using unburned methane or hydrogen as reducing agents. The results suggest that the NO x are reduced by H2 at low temperature, when methane is not activated and at higher temperature the methane is then the main reducing agent. Similar results are obtained for alumina supported palladium and alumina supported cobald-palladium catalysts at low temperature in presence of hydrogen suggesting that the active phase for the reaction NO/H2 is the palladium. However, at high temperature the higher activity is obtained on bimetallic catalyst. The presence of cobalt enhances the catalytic activity. This result suggests that cobalt and palladium both in cationic form are the active sites when the reducing agent is the methane. [Copyright &y& Elsevier]

Abstract: The aim of the present work is to study the selective reduction of NO x from natural gas sources. The unburned methane can be used as reductant. Another reductant such as hydrogen can be created in situ, using a microreformer. The results suggest that the NO x are reduced by H2 at low temperature, when methane is not activated and at higher temperature the methane is then the main reductant. However, the catalytic behaviour depends on the metal precursor and the catalyst treatment. The most prominent result is obtained on the palladium catalyst prepared from Pd(NH3)4(NO3)2 precursor. Comparing the reduction and the calcination step in the course of catalyst preparation, one can conclude that calcination lead to the higher activity in deNO x , since reduced catalysts are oxidized during the deNO x process. [Copyright &y& Elsevier]

Abstract: Pd/Al2O3 was tested for the selective reduction of NO and simultaneous oxidation of methane by NO and O2 from reverse spillover on alumina supported palladium. The results of CH4/Ar and CH4/NO/Ar experiments clearly demonstrated the two sources of surface oxygen species able to oxidize the methane. When oxygen from the reverse spillover is totally consumed, the reaction NO/CH4 is stoichiometric, all oxygen come from the NO dissociation. The role of methane is similar to CO in TWC since methane removes the oxygen, from NO dissociation on the cationic sites of Pd atoms, and permits the reaction to proceed further. [Copyright &y& Elsevier]