Preparation, Characterization and NO-CO Redox Reaction Studies over Palladium and Rhodium Oxides Supported on Manganese Dioxide

Abstract

The catalytic activity of PdO/MnO2 and Rh2O3/MnO2 is investigated for NO-CO redox reaction. Supported catalysts are prepared by wet impregnation method. Among the tested catalysts, PdO/MnO2 shows higher activity for this reaction. Active metal dispersion on MnO2 enhances the selectivity for N2 over N2O in this reaction. The XRD substantiate the formation of MnO2 monophasic phase. SEM images show the formation of elongated particles. TEM images indicate nano-size rod-like morphologies. An increase in the catalytic activity is observed on supported Pd and Rh oxides on MnO2. Temperature programmed desorption studies with NO and CO are undertaken to investigate the catalytic surface studies.

Effects of Ni modification on NO‐CO reaction with MnOx‐CuO/TiO2 catalysts

“…In situ FTIR of the NO‐CO reaction over Mn‐Cu/Ti and 0.05Ni‐Mn ­ ‐Cu/Ti was performed to understand the surface reaction situation. As shown in Figure , some reactant species of NO and CO, such as linear nitrate (1270 cm −1 ), bridged nitrate (1633 cm −1 ), weak adsorbed NO (1843 cm −1 , 1907 cm −1 ), and Cu + ‐CO or Cu + ‐(CO) 2 (2121 cm −1 ), were detected on the catalyst surface. Also, the intermediate product of N 2 O can be found at 2237 cm −1 and 2343 cm −1 .…”

“…Two desorption peaks around 112 and 187 °C were detected in these two catalysts, suggesting that there are two different types of active adsorption sites for CO on the catalyst surface. It has been reported that the peaks at lower and higher temperatures are due to the desorption of CO on Cu + and Mn 4+ , respectively. It should be noted that a TCD detector was used for CO‐TPD analysis; thus, the production of CO 2 cannot be ruled out.…”

“…As shown in Figure 7, some reactant species of NO and CO, such as linear nitrate (1270 cm À1 ), bridged nitrate (1633 cm À1 ), weak adsorbed NO (1843 cm À1 , 1907 cm À1 ), [18,44,45] and Cu þ -CO or Cu þ -(CO) 2 (2121 cm À1 ), [12,21,35,45] were detected on the catalyst surface. Also, the intermediate product of N 2 O can be found at 2237 cm À1 and 2343 cm À1 .…”