Rational design of template-free MnOx-CeO2 hollow nanotube as de-NOx catalyst at low temperature

A Review of Low Temperature NH3-SCR for Removal of NOx

“…Their results demonstrate that the doping of Gd could restrains the transformation of MnO2 to Mn2O3 and the generation of MnSO4, obstructs the decrease in Lewis acid sites and the increase in Brønsted acid sites, and eases the competitive adsorption between the NO and SO2 and, thus, improves the resistance to SO2. Li et al [58] developed hollow MnOx-CeO2 binary nanotubes as efficient low-temperature NH3-SCR catalysts via an interfacial oxidation-reduction process using KMnO4 aqueous solution and Ce(OH)CO3 nanorod as both template and reducing agent without any other intermediate. They reported that the MnOx-CeO2 hollow nanotube catalyst with 3.75 g of Ce(OH)CO3 template (denoted it as MnOx-CeO2-B) exhibited outstanding performance with more than 96% NOx conversion in the temperature range of 100-180 °C.…”

“…Additionally, MnOx-CeO2-B catalyst showed an excellent resistance to H2O and SO2 ( Figure 4) and especially, the great SO2 tolerance was ascribed to the hierarchically porous and hollow structure that inhibits the deposition of ammonium sulfate species, and the doping of ceria that acts as an SO2 trap to limit sulfation of the main active phase. Li et al [58] developed hollow MnO x -CeO 2 binary nanotubes as efficient low-temperature NH 3 -SCR catalysts via an interfacial oxidation-reduction process using KMnO 4 aqueous solution and Ce(OH)CO 3 nanorod as both template and reducing agent without any other intermediate. They reported that the MnO x -CeO 2 hollow nanotube catalyst with 3.75 g of Ce(OH)CO 3 template (denoted it as MnO x -CeO 2 -B) exhibited outstanding performance with more than 96% NO x conversion in the temperature range of 100-180 • C. The best activity of the MnO x -CeO 2 -B catalyst was due to its ample number of surface Mn 4+ and O species, and hollow and porous structures that provide abundant Lewis acid sites and large surface area.…”

Preparation of Mesoporous Mn–Ce–Ti–O Aerogels by a One-Pot Sol–Gel Method for Selective Catalytic Reduction of NO with NH3

“…Materials 2020, 13, x FOR PEER REVIEW Figure 7b that the amount of the surface Brønsted acid sites of MCTO-x gradually decreased with the increase of calcination temperature, and the order was as follows: MCTO-400 (0.45 mmol·g −1 ) > MCTO-500 (0.29 mmol·g −1 ) > MCTO-600 (0.15 mmol·g −1 ) > MCTO-700 (0.14 mmol·g −1 ). With increases in the calcination temperature, the MCTO-600 exhibited the highest amount of adsorbed NH3 on Lewis acid sites (0.46 mmol·g −1 ), which had a stronger ability to adsorb and activate NH3 than Brønsted acid sites to facilitate the NH3-SCR process [2,45]. However, when the calcination temperature reached 700 °C, the amount of Lewis acid sites on the catalyst surface also began to decrease, which indicated that the higher calcination temperature led to the reduction of both the Brønsted and Lewis acid sites, causing weak NH3 adsorption and activation.…”

Mn−Co Mixed Oxide Nanosheets Vertically Anchored on H2Ti3O7 Nanowires: Full Exposure of Active Components Results in Significantly Enhanced Catalytic Performance

“…[9][10][11] So far,n umerous explorations have found that several transition metal oxides (TMOs) show great potential to lower the reaction temperature and broaden the operation temperature window, among which the manganese oxides (MnO x )r emarkably outperform the others in terms of the low-temperature de-NO x performance and have environmental benignc haracters. [14][15][16][17][18][19][20][21] In recent years, MnÀCo composite oxides have attracted considerable attention owing to their excellent de-NO x performances. [14][15][16][17][18][19][20][21] In recent years, MnÀCo composite oxides have attracted considerable attention owing to their excellent de-NO x performances.…”

“…[12,13] However,p ure MnO x catalysts still suffer from serious challenges owing to the low surfacearea, poor water tolerance and thermals tability.C onstructingM nO x -based composite oxidesb ym ixing with the other metal oxides is considered as an effective strategy to overcome these shortcomings.B ased on this, Mn-Ce,M n-Fe, and Mn-Tic omposite oxides have been developed for the SCR of NO x ,a nd remarkable achievements have been made. [14][15][16][17][18][19][20][21] In recent years, MnÀCo composite oxides have attracted considerable attention owing to their excellent de-NO x performances. Moreover,i ti sw ellk nown that the morphology and structure of catalysts play an important role in their catalytic performance in addition to the desirable compositions.…”