Abstract
A series of 9%CeOx–MnOx/TiO2–GO nanocomposites with different molar ratios of Ce/Mn were synthesized by the sol-gel and ultrasonic impregnation methods and characterized by field emission scanning electron microscope (FESEM), high resolution transmission electron microscopy (HRTEM), N2 adsorption (BET) analysis, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT–IR). The results showed that various valences of Ce and Mn oxides were uniformly distributed on the surface of TiO2–GO multilayered supports. The coexistence of various valences of Ce and Mn oxides can improve the redox performance of the catalyst. With the introduction of Ce, the amount of MnO2 and non-stoichiometric MnOx/Mn, the total oxygen and chemisorbed oxygen content, and the electron transfer ability of the catalyst increased significantly. When the molar ratio of Ce/Mn was 0.3, the catalysts exhibited high selective catalytic reduction activity (more than 99% at 180 °C) and N2 selectivity. The presence of hydrophilic groups on the surface of the GO was considered as the critical factor influencing the H2O resistance of the catalyst. Due to the pre-sulfuring process of GO, serious sulfation of the active component can be prevented, and the catalyst exhibited excellent SO2 resistance.
Highlights
Removal of the nitrogen oxides (NOx ) emitted from the combustion of fossil fuels has attracted much more attention worldwide because NOx can cause acid rain, photochemical smog, greenhouse effects, and damage to human health [1,2]
The results showed that the 9%MnOx /TiO2 –0.8%graphene oxide (GO) catalyst had the highest activity at low temperature [42]
0.4, the NOx conversion of 9%Ce–Mn/TiO2 –0.8%GO catalysts increased with the Ce/Mn ratio
Summary
Removal of the nitrogen oxides (NOx ) emitted from the combustion of fossil fuels has attracted much more attention worldwide because NOx can cause acid rain, photochemical smog, greenhouse effects, and damage to human health [1,2]. Low-temperature selective catalytic reduction (SCR) has been considered as a reasonable and effective strategy to decrease the NOx levels in gaseous emissions [3,4,5,6]. For their relatively high activities for low-temperature NH3 -SCR, Mn-based catalysts have attracted increasing attention. The selective catalytic reduction (SCR) activity of MnOx is not as high as expected, and the resistance of MnOx to SO2 and/or H2 O is relatively poor, so some other metal oxides are often added, such as CeOx [11], FeOx [12], NbOx [13], SnOx [14], and ZrOx [15]. The redox shift between Ce4+ and Ce3+ will result in the increase in the oxygen storage capability of MnOx and the oxygen migration speed, which
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