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Abstract: The methane oxidation reaction was studied as a function of temperature for a gas mixture representative of a combined heat power (CHP) within a dielectric barrier discharge (DBD) reactor. The effect of energy deposition was studied, with energy deposition ranging from 36 to 58JL−1, to maintain a low NO x formation at high temperature. In the current study, we also investigated the combined process of a dielectric barrier discharge and γ-alumina noble metal catalysts such as platinum and palladium. In order to separate the catalytic effects from the plasma activation, the work included both purely catalytic and plasma activation processes using a complete CHP mixture with 4% of water in the feed. It was found that the presence of water leads to increase the methane conversion in purely plasma activation processes. Moreover, a higher efficiency for methane oxidation in CHP conditions was observed with the plasma–Pd(X)/Al2O3 systems. [Copyright &y& Elsevier]

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: In order to improve a “Three Function Catalysts Model”, the present paper deals with alumina based catalysts containing cobalt and palladium for the NO reduction by methane. The deNO x temperature window was estimated by adsorption and subsequent desorption of NO in lean conditions. Two NO x desorption peaks were detected for both catalysts. For Pd(0.63)Co(0.58)/Al2O3, the two desorption peaks appeared at 205 and 423°C, whereas for Pd(0.14)Co(0.57)/Al2O3, the maxima desorption temperature peaks were at 205 and 487°C. In addition, NO oxidation was also studied to evaluate the catalyst first function. It was found that, the oxidation begins on Co–Pd/Al2O3 around 250°C. On Pd(0.63)Co(0.58)/Al2O3, 8% of deNO x were found in the range of the second NO x desorption peak temperature (410°C). During TPSR, C x H y O z species such as formaldehyde were detected. These oxygenate species are the reactive intermediate for deNO x by methane. [Copyright &y& Elsevier]