Abstract
A series of CeOx catalysts supported by commercial porous cordierite ceramics (CPCC) and synthesized porous cordierite ceramics (SPCC) from fly ash were prepared for selective catalytic reduction of NOx with ammonia (NH3-SCR). A greater than 90% NOx conversion rate was achieved by the SPCC supported catalyst at 250–300 °C when the concentration of loading precursor was 0.6 mol/L (denoted as 0.6Ce/SPCC), which is more advantageous than the CPCC supported ones. The EDS mapping results reveal the existence of evenly distributed impurities on the surface of SPCC, which hence might be able to provide more attachment sites for CeOx particles. Further measurements with temperature programmed reduction by hydrogen (H2-TPR) demonstrate more reducible species on the surface of 0.6Ce/SPCC, thus giving rise to better NH3-SCR performance at a low-temperature range. The X-ray photoelectron spectroscopy (XPS) analyses reveal that the Ce atom ratio is higher in 0.6Ce/SPCC, indicating that a higher concentration of catalytic active sites could be found on the surface of 0.6Ce/SPCC. The in situ diffused reflectance infrared fourier transform spectroscopy (DRIFTS) results indicate that the SCR reactions over 0.6Ce/SPCC follow both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. Hence, the SPCC might be a promising candidate to provide support for NH3-SCR catalysts, which also provide a valuable approach to recycling the fly ash.
Highlights
Nitrogen oxides (NOx ) are major air pollutants in ambient air, contributing to the formation of secondary inorganic aerosols, increasing nitrate/sulfate ratios in precipitation and leading to climate forcing effects [1]
It is obvious that the prepared commercial porous cordierite ceramics (CPCC) catalysts exhibit preferable NOx conversion ratios at a high temperature range
(>300 ◦ C), and efficiencies greater than 90% are yielded at 300–350 ◦ C for the 0.4Ce/CPCC, 0.6Ce/CPCC, and 0.8Ce/CPCC samples
Summary
Nitrogen oxides (NOx ) are major air pollutants in ambient air, contributing to the formation of secondary inorganic aerosols, increasing nitrate/sulfate ratios in precipitation and leading to climate forcing effects [1]. It is still a major challenge to purify the NOx from waste gas effectively [2]. NH3 -SCR has been widely acknowledged as the most efficient method for flue gas denitration in thermal power plants, while an SCR catalyst with high performance and stability is regarded as the core of the SCR technology [3,4,5]. V2 O5 -WO3 /TiO2 and V2 O5 -MoO3 /TiO2 are commercial catalysts that are widely used in treating NOx from large scale stationary and mobile sources [6,7]. These commercial catalysts can only show high catalytic efficiency in a narrow temperature window of.
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