Feng He

Performance regulation of Mn/TiO2 catalysts by surfactants for the selective catalytic reduction of NO with NH3 at low temperatures

A series of Mn/TiO2 catalysts were prepared using different dosage of cetyl trimethyl ammonium bromide (CTAB) and polyethylene glycol (PEG) 600 as surfactants by sol–gel method. When CTAB/Ti and PEG/Ti were 0.075 and 0.13, the morphology of the catalysts exhibited nano rod and regular sphere structure, respectively, and the activity was also the highest. The superior SCR activity of NC(0.075)-Mn/TiO2 and NP(0.13)-Mn/TiO2 catalysts was mainly due to the larger surface area and stronger reduction ability. In addition, it was found that the SCR activity of the catalysts with PEG600 as surfactants was generally higher than that of CTAB as surfactants, which may be due to its advantages in specific surface area, crystallinity, acidity, surface ion and chemisorbed oxygen concentration, and reducibility.

NH3-SCR Performance and Applicability of Mn-Based Spinels over TiO2 Catalyst

A series of Mn-based spinels over TiO2 catalysts have been prepared with the impregnation method. Catalysts were comprehensively characterized using XRD, FESEM, H2-TPR, and the activity evaluation of NH3-SCR, while long-time stability tests and the effect of H2O on NH3-SCR were also investigated. Meanwhile, K poisoning effect was studied by preparing K-doped catalysts (K-Mn/TiO2, K-Cu-Mn/TiO2, K-Mg-Mn/TiO2 and K-Co-Mn/TiO2). According to the characterizations, Cu-Mn/TiO2, Mg-Mn/TiO2 and Co-Mn/TiO2 catalysts exhibited superior low-temperature SCR activity, stability, K resistance and H2O resistance due to the formation of spinels (MgMn2O4, CoMn2O4, CuMn2O4).

NH 3 -SCR Activity of MnOx/CeO 2 Catalyst at Low Temperature

In this paper, CeO2 was synthesized and used as carrier, meanwhile, MnOx was supported by different methods. The NH3-SCR activity of MnOx/CeO2 at low temperature has also been studied. The results show that the performance of the MnOX/CeO2 catalyst prepared by hydrothermal deposition method (MC-h) can reach up to 80% at 180 ℃, while the impregnation method (MC-i) is only 70% at 180 ℃. Testing results indicate that the catalysts synthesized by the hydrothermal deposition method have larger specific surface area and higher reducibility, and manganese oxide existed in the form of nanorods is more favorable for the contact between the active component and the reactive gas. All of these are beneficial to the SCR reaction.

Effect of Calcination Temperature on the SCR Activity of Fe–S/TiO 2 Catalysts

A series of Fe–S/TiO2 catalysts were prepared at different calcination temperatures by impregnation method and its performance of selective catalytic reduction (SCR) of NO with NH3 was investigated at temperatures ranging from 200 to 400 °C. Fe–S/TiO2-300 °C catalyst showed the highest activity, the NO conversion reaching over 80% in the range of 280–400 °C. With the help of XRD, H2-TPR and NH3-TPD, the structures and properties of catalysts were characterized. With the increase of calcination temperature, the Fe(OH)SO4 content in the catalyst decreased gradually. In addition, When the calcination temperature was below 400 °C, the main crystal phase in the catalyst is Fe(OH)SO4 and FeSO4. However, when it was 500 °C, the crystal phase of the active material became Fe2(SO4)3 and FeSO4. What’s more, the reduction ability of several catalysts showed no much difference, but the surface acidity was quite different, as the acidity of the Fe–S/TiO2-300 °C catalyst was the strongest.