Insight into the synergism between MnO2 and acid sites over Mn-SiO2@TiO2 nano-cups for low-temperature selective catalytic reduction of NO with NH3

Siyi Zheng; Lei Song; Siyang Tang; Changjun Liu; Hairong Yue; Bin Liang

doi:10.1039/c7ra11868f

Insight into the synergism between MnO₂ and acid sites over Mn-SiO₂@TiO₂ nano-cups for low-temperature selective catalytic reduction of NO with NH₃

RSC Adv. 2018 Jan 9;8(4):1979-1986. doi: 10.1039/c7ra11868f. eCollection 2018 Jan 5.

Authors

Siyi Zheng¹, Lei Song¹, Siyang Tang¹, Changjun Liu^{1

2}, Hairong Yue¹, Bin Liang^{1

2}

Affiliations

¹ Multi-phases Mass Transfer and Reaction Engineering Laboratory, School of Chemical Engineering, Sichuan University Chengdu 610065 China hryue@scu.edu.cn +86 22 85997677 +86 22 85997677.
² Institute of New Energy and Low-Carbon Technology, Sichuan University Chengdu 610207 China.

Abstract

The rational synthesis of low-temperature catalysts with high catalytic activity and stability is highly desirable for the selective catalytic reduction of NO with NH₃. Here we synthesized a Mn-SiO₂/TiO₂ nano-cup catalyst via the coating of the mesoporous TiO₂ layers on SiO₂ spheres and subsequent inlay of MnO₂ nanoparticles in the narrow annulus. This catalyst exhibited superior catalytic SCR activities and stability for low-temperature selective catalytic reduction of NO with NH₃, with NO conversion of ∼100%, N₂ selectivity above 90% at a temperature ∼140 °C. The characterization results, such as BET, XRD, H₂-TPR, O₂/NH₃-TPD and XPS, indicated that this nano-cup structure catalyst possesses high concentration and dispersion of Mn⁴⁺ active species, strong chemisorbed O^- or O₂ ^2- species and highly stable MnO _X active components over the annular structures of the TiO₂ shell and SiO₂ sphere, and thus enhanced the low-temperature SCR performance.