The Deactivation Mechanism of the Mo-Ce/Zr-PILC Catalyst Induced by Pb for the Selective Catalytic Reduction of NO with NH3.

Chenxi Li,Jin Cheng,Xinpeng Wang,Hongxing Dai,Fanwei Meng,Qing Ye

doi:10.3390/nano11102641

Chenxi Li, Jin Cheng + Show 4 more

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https://doi.org/10.3390/nano11102641

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Journal: Nanomaterials	Publication Date: Oct 7, 2021
Citations: 2	License type: CC BY 4.0

Affiliation: Beijing University of Technology

Abstract

As a heavy metal, Pb is one component in coal-fired flue gas and is widely considered to have a strong negative effect on catalyst activity in the selective catalytic reduction of NOx by NH3 (NH3-SCR). In this paper, we investigated the deactivation mechanism of the Mo-Ce/Zr-PILC catalyst induced by Pb in detail. We found that NO conversion over the 3Mo4Ce/Zr-PILC catalyst decreased greatly after the addition of Pb. The more severe deactivation induced by Pb was attributed to low surface area, lower amounts of chemisorbed oxygen species and surface Ce3+, and lower redox ability and surface acidity (especially a low number of Brønsted acid sites). Furthermore, the addition of Pb inhibited the formation of highly active intermediate nitrate species generated on the surface of the catalyst, hence decreasing the NH3-SCR activity.

Highlights

Nitrogen oxides (NOx ) are harmful to human health but are important precursors of secondary pollution [1,2,3]
It is reported that Mo modification could significantly promote the adsorption and activation of NH3 species, which is beneficial for improvement in NH3 -SCR activity [8]
It was found that these materials were the most promising SCR catalysts [9], among which the Mo-Ce/Zr-PILC catalysts exhibited outstanding NH3 -SCR activity

Summary

Introduction

Nitrogen oxides (NOx ) are harmful to human health but are important precursors of secondary pollution (e.g., photochemical smog, fine particles, and acid deposition) [1,2,3]. NH3 -SCR is an efficient and economical technology that has recently been used in the elimination of NOx from the exhausts of stationary and mobile sources. The V2 O5 −WO3 (MoO3 )/TiO2 catalysts are the most widely used catalyst systems in stationary sources [4]. These systems still have some inevitable practical defects, such as low N2 selectivity in the high-temperature range, high SO2 to SO3 conversion rates, and the strong biological toxicity of vanadium species [5]. It is urgent and necessary to develop a new SCR catalyst with low toxicity and high activity. Mo-Ce mixed-oxide catalysts have been extensively investigated. It was found that these materials were the most promising SCR catalysts [9], among which the Mo-Ce/Zr-PILC catalysts exhibited outstanding NH3 -SCR activity

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