NO reduction with ethanol on MoO3/Al2O3 and CeO2-ZrO2-supported Pd catalysts

The reduction of NO with ethanol on MoO3/Al2O3 and CeO2-ZrO2-supported Pd catalysts was studied. The Pd/CeO2-ZrO2 sample showed higher activity for the conversion of NO and higher selectivity for N2 formation when compared to the Pd-MoO3/Al2O3 sample. The CO chemisorption results showed that the CeZr mixed oxide chemisorbed a higher amount of CO, and this is related to a higher reducibility capacity of this compound when compared to MoO3. Furthermore, TPD analysis of adsorbed NO and ethanol showed that the Pd/CeO2-ZrO2 catalyst has a higher ability of dissociating NO to N2 and of decomposition of ethanol with the formation of CO2. Also, TPSR experiments showed that on Pd-8Mo/Al2O3, ethanol competes with NO for adsorption sites on partially reduced molybdenum oxide. This was not the case for the Pd/Ce0.75Zr0.25O2 catalyst, where both NO and ethanol adsorb and decompose on the partially reduced mixed oxide surface. These facts are probably related to the better performance of this catalyst in relation to the Pd-MoO3/Al2O3 catalyst for the NO + ethanol reaction.