Abstract
The behaviour of a series of Ir‐based catalysts supported on SiO2, ZSM‐5 and γ‐Al2O3 with various Ir loadings prepared by impregnation method was conducted by temperature programmed reaction (TPR) technique. The result implies that NO is oxidized to NO2 while simultaneously being reduced to N2 or N2O in the NO reactions over iridium catalysts. The surface active phase over iridium catalysts that promote the NO reactions is IrO2. The catalytic activity increases with the increase of the Ir loading and support materials have a little effect on the catalytic activity. When the loading is less than 0.1%, the catalytic activity was found to be dependent on the nature of support materials and in order: Ir/ZSM‐5>Ir/γ‐Al2O3>Ir/SiO2. When the loading is higher than 0.1%, the catalytic activity for NO oxidation is in order: Ir/ZSM‐5>Ir/SiO2>Ir/γ ‐Al2O3, which is correlated with Ir dispersion on the surface of support materials and the catalytic activity for NO reduction is in sequence: Ir/γ ‐Al2O3>Ir/SiO2>Ir/ZSM‐5, which is attributed to the adsorbed‐dissociation of NO2. Compared to Pt/γ‐Al2O3, Ir/γ‐Al2O3 catalyst is more benefit for the NO reduction.
Highlights
With the increase concerns about energy crisis and global warming, more severe requirements about the emission of greenhouse gas CO2 and conservation of energy have been progressively brought forward
A series of temperature programmed reaction (TPR) and Temperature programmed desorption (TPD) experiments were carried out in order to give a research on the NO reactions over Ir-based catalysts in the presence of O2
The oxidation of NO to NO2 together with the reduction of NO2 to N2 through adsorption and decomposition were observed over Ir-based catalyst and IrO2 is the surface active phase in the NO reactions by XRD analysis
Summary
With the increase concerns about energy crisis and global warming, more severe requirements about the emission of greenhouse gas CO2 and conservation of energy have been progressively brought forward. NO Reactions Over Ir-Based Catalysts in the Presence of O2 S353 for the NO oxidation but Ir/γ-Al2O3 is more conducive to NO reduction.
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