Issue 11, 2022

Single Mo atoms paired with neighbouring Ti atoms catalytically decompose ammonium bisulfate formed in low-temperature SCR

Abstract

Selective catalytic reduction (SCR) of NOx with NH3 has been widely used for NOx emission control, but commercial catalysts inevitably suffer severe deactivation in SO2-containing stack gases at low temperatures because the ammonium bisulfate (NH4HSO4, ABS) formed in SCR blocks the surface active sites. We resolve this issue by developing a TiO2-supported single-atom Mo catalyst (Mo1/TiO2) that decomposes ABS at ∼225 °C, far lower than the dew point of ABS (∼260 °C). Single Mo atoms paired with the neighboring surface Ti atoms function as Mo–Ti acid–base dual sites, which respectively adsorb the NH4+ and HSO4 of ABS. After the oxidation of NH4+ by surface lattice oxygen on the Mo sites, electrons left behind on the dual sites are localized around the Fermi level, which allows them to transfer to the adsorbed HSO4 on the Ti sites, thus releasing SO2 at low temperatures. The Mo1/TiO2 catalyst with Mo–Ti acid–base dual sites enables the decomposition of ABS at low temperatures, and thus this work provides a way to effectively control NOx emission particularly from industrial boilers.

Graphical abstract: Single Mo atoms paired with neighbouring Ti atoms catalytically decompose ammonium bisulfate formed in low-temperature SCR

Supplementary files

Article information

Article type
Paper
Submitted
25 Sept. 2021
Accepted
31 Okt. 2021
First published
01 Nov. 2021

J. Mater. Chem. A, 2022,10, 6065-6072

Single Mo atoms paired with neighbouring Ti atoms catalytically decompose ammonium bisulfate formed in low-temperature SCR

J. Chen, X. Fang, Z. Ren, W. Qu, X. Hu, Z. Ma, L. Chen, X. Liu, Y. Chen and X. Tang, J. Mater. Chem. A, 2022, 10, 6065 DOI: 10.1039/D1TA08269H

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