Fabrication of γ-MnO₂-Ce Pillared Montmorillonite for Low Temperature NH₃-SCR

Abstract

A series of γ-MnO2-Ce/MMT catalyst materials synthesized by homogeneous precipitation method was investigated for the selective catalytic reduction (SCR) of NOx with NH3. X-ray diffraction and specific surface areas were utilized for micro structure and layer spacing investigation. And NH3-TPD, Pyridoxine IR, H2-TPR and XPS were used to investigate Brønsted acid and Lewis acid, redox properties, atomic concentrations and element chemical state for as-prepared catalysts. The results showed that the γ-MnO2-Ce/MMT had superior NOx conversion compared to the bulk particles, among which 6 wt.% γ-MnO2-Ce/MMT displayed the best deNOx of 95.3% for the low temperature selective catalytic reduction of NOx with NH3 (NH3-SCR) under the GHSV of 25,000 h−1, therefore it is a promising catalyst for low temperature NH3-SCR.

Improved sulfur dioxide resistance of the Mn/Fe-PILC catalyst by the doping of ceria in the selective catalytic reduction of NO with NH3

“…Furthermore, Mn 2p 3/2 signal of each sample could be deconvoluted into three components at BE = 643.5−644.7, 641.7−642.9, and 640.5−641.7 eV, which were attributed to the surface Mn 4+ , Mn 3+ , and Mn 2+ species [27−29], respectively. As reported previously, the Mn 4+ species was more active for the lowtemperature SCR reaction [27]. The Mn 4+ /(Mn 2+ + Mn 3+ + Mn 4+ ) molar ratios on the sample surface were calculated, as listed in Table 2.…”

“…Ce 3d was tted into eight peaks (from 930 − 870 eV). The peaks labeled by v′, u′ can be assigned to Ce 3+ , and those marked by v, v″, v‴, u, u″, u‴ can be assigned to Ce 4+ [27].…”

Green Synthesized Montmorillonite/Carrageenan/Fe3O4 Nanocomposites for pH-Responsive Release of Protocatechuic Acid and Its Anticancer Activity

“…Besides, the intensity of MMT peak of MMT/CR/Fe 3 O 4 -NCs was reduced compared to pristine MMT. This might be due to the interrupted MMT flakes in the process of NCs fabrication, thus the adjacent flakes were connected permanently [33]. Furthermore, the presence of and (533) planes, respectively, for the face-centered cubic (fcc) Fe 3 O 4 lattice.…”

“…Besides, the intensity of MMT peak of MMT/CR/Fe 3 O 4 -NCs was reduced compared to pristine MMT. This might be due to the interrupted MMT flakes in the process of NCs fabrication, thus the adjacent flakes were connected permanently [ 33 ]. Furthermore, the presence of Fe 3 O 4 was confirmed without any impurity, such as hematite or maghemite, in which the diffraction peaks located at 2θ = 30.75°, 35.29°, 43.37°, 54.91°, 57.64°, 61.99°, 73.94°, corresponding to the (200), (311), (400), (422), (511), (440) and (533) planes, respectively, for the face-centered cubic (fcc) Fe 3 O 4 lattice.…”