Mn−Co Mixed Oxide Nanosheets Vertically Anchored on H2Ti3O7 Nanowires: Full Exposure of Active Components Results in Significantly Enhanced Catalytic Performance. Issue 13 (7th May 2018)

• Record Type: Journal Article
• Authors: Shi, Jian‐Wen; Fan, Zhaoyang; Gao, Chen; Gao, Ge; Wang, Baorui; Wang, Yao; He, Chi; Niu, Chunming
• Is Part Of: ChemCatChem. Volume 10:Issue 13(2018)
• Page Start: 2833
• Page End: 2844
• Publication Date: 2018-05-07
• Subjects: low-temperature catalysis -- manganese oxides -- nitrogen oxides -- reaction mechanism -- selective catalytic reduction; Catalysis -- Periodicals; 541.39505
• DOI: 10.1002/cctc.201800227
• Languages: English
• ISSNs: 1867-3880

Abstract

Abstract: The full exposure of active ingredients plays an important role in the enhancement of catalytic performance. In this work, a series of novel catalysts, Mn−Co mixed oxide nanosheets with ultrathin thickness (about 3.5 nm) and different Mn/Co ratios (0.52, 0.69, and 1.52) vertically anchored on a support (H2 Ti3 O7 nanowires), are rationally developed. This unique structure not only fully exposes the active ingredients of the Mn−Co mixed oxides, but also is very favorable for the diffusion and transfer of gas molecules through the space between these standing nanosheets. As expected, the developed catalysts (MnO x ‐CoO y /H2 Ti3 O7, MnCoTi), especially MnCoTi‐2 with the Mn/Co molar ratio of 0.69, present excellent low‐temperature selective catalytic reduction (SCR) performance, high N2 selectivity, superior water tolerance and stability. The relative turnover frequency (TOF) value over MnCoTi‐2 at 100 °C is as high as 9.25×10 −4 s −1 under the gas hourly space velocity (GHSV) of 200 000 h −1, which is rarely reported among Mn‐Ti, Mn−Co, and Mn−Co‐Ti mixed oxide catalysts. The results of in situ diffuse reflectance infrared Fourier transform spectroscopy suggest that the coordinated NH3, NH4 + ions, adsorbed NO2, and bidentate nitrate are the reactive species and the Eley–Rideal and Langmuir–Hinshelwood mechanisms can be simultaneously involved on the surface of the MnCoTi‐2 at a relatively low temperature (90 °C). Abstract : Full exposure : A series of Mn−Co mixed oxide ultrathin nanosheets, with different Mn/Co ratios, vertically anchored on a support (H2 Ti3 O7 nanowires) is rationally developed. The unique structure not only fully exposes the active ingredients of the Mn−Co mixed oxides, but also is very favorable for the diffusion and transfer of gas molecules through the space between these standing nanosheets, leading to excellent low‐temperature selective catalytic reduction performance, high N2 selectivity, superior water tolerance, and stability.