Direct decomposition of N2O and the reduction of N2O with CH4 over Ga/H-ZSM-5 and Mo/Ga/H-ZSM-5 (Si/Al = 40) catalysts in a plug flow reactor under steady-state conditions as well as by temperature programmed surface reaction (TPSR) have been investigated. Ga ions were ion-exchanged from liquid phase while Mo was deposited onto the Ga/H-ZSM-5 sample using incipient wetness technique. The catalysts were characterized by means of XRF, XPS, TPR, CO chemisorption, TEM and EDS. The N2O forms redox centers in the Mo/Ga/H-ZSM-5 catalysts at elevated temperatures, which are extremely active in the reaction with CH4 already at around 373 K. Addition of Mo to the Ga/H-ZSM-5 decreased the T50 temperature in the N2O decomposition and reduction of N2O with CH4 from 819 to 787 K and from 755 to 646 K, respectively. The oxidation/reduction of the Mo/Ga/H-ZSM-5 sample is more favoured in the interaction with N2O/CH4 as compared to that using O2/H2 and the mechanism of the redox reactions might also be different. The reduction of N2O with CH4 cannot be described with the Mars-van Krevelen redox mechanism, but by the participation of CH4 via MoGa-OCH3 species in a complex oxygen transfer mechanism is proposed at which N2O does not directly reoxidise the reduced active centers.
- Complex oxygen transfer mechanism
- Direct decomposition
- Increasing activity
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