The promotion effect of manganese on Cu/SAPO for selective catalytic reduction of NO_x with NH₃

Abstract

The activity and hydrothermal stability of Cu/SAPO and xMn-2Cu/SAPO for low-temperature selective catalytic reduction of NO x with ammonia were investigated. An ion-exchanged method was employed to synthesize xMn-2Cu/SAPO, which was characterized by N 2 adsorption, ICP-AES, X-ray diffraction (XRD), NH 3 -temperature programmed desorption (NH 3 -TPD), NO oxidation, X-ray photoelectron spectrum (XPS), UV-vis, H 2 -temperature programmed reduction (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectra (DRIFTS). 2Mn-2Cu/SAPO and 4Mn-2Cu/SAPO showed the best SCR activity, in that at 150 C NO conversion reached 76% and N 2 selectivity was above 95% for the samples.NO oxidation results showed that the 2Mn-2Cu/SAPO had the best NO oxidation activity and the BET surface area decreased as manganese loading increased. XRD results showed that the metal species was well dispersed. NH 3 -TPD showed that the acid sites have no significant influence on the SCR activity of xMn-2Cu/SAPO. H 2 -TPR patterns showed good redox capacity for xMn-2Cu/SAPO. UV-vis and H 2 -TPR showed that the ratio of Mn 4+ to Mn 3+ increased as manganese loading increased. XPS spectra showed a significant amount of Mn 3+ and Mn 4+ species on the surface and addition of manganese increased the ratio of Cu 2+ . The promotion effect of manganese to 2Cu/SAPO comes from the generation of Mn 3+ and Mn 4+ species. Deduced from the DRIFTS spectra, the Elay-Rideal mechanism was effective on 4Mn-2Cu/SAPO.

Effect of CaCO3on catalytic activity of Fe–Ce/Ti catalysts for NH3-SCR reaction

“…For this purpose, many catalysts containing metal oxides have been found to possess high catalytic activity for SCR reaction including Fe, Ce, Mn, and Cu based catalysts. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] Based on our previous study, we found the Fe-Ce/Ti catalysts could exhibit high catalytic activity for the NH 3 -SCR reaction. However, there are several components in the real ue gases including K, Ca, CO 2, and SO 2 , which will lead to the physical or chemical deactivation of catalysts and thus restrict the industrial application of catalysts.…”

Investigation of Mn Promotion on HKUST‐1 Metal‐Organic Frameworks for Low‐Temperature Selective Catalytic Reduction of NO with NH3

“…Our results, in terms of Mn content, agree well with those previously reported for Cu-SAPO-34 catalysts with 4 wt.% of Mn loading, or Cu-SSZ-13 catalysts, where the most promising catalysts have been ascribed to Mn content of 3 and 5 wt.% (depending on the temperature). [41,54,55] Despite small activity differences between HKUST-1-Mn2.5 and HKUST-1-Mn3.75 samples, we selected the latter to examine its resistance in the presence of H 2 O and SO 2 (separately).…”

“…The following activity ranking can be observed: Mn3.75>Mn2.5>Mn5.0>Mn7.5>Mn10.0>support. In the existing literature, manganese was found to promote zeolite‐based catalysts in SCR of NOx with NH 3 , e. g. in Cu‐SAPO‐34 catalysts or Cu‐SSZ‐13 [41,54,55] . The beneficial effect of manganese on Cu‐SAPO‐34 and Mn@Cu 2 (BTC) 2 catalysts has been attributed to the generation of Mn 3+ and Mn 4+ species, or the presence of Mn 3 O 4 , whereas the impregnated MnO x species markedly improved the redox ability of Cu‐SSZ‐13 catalysts.…”

Pd Nanoparticles Decorated on ZnO/Fe3O4 Cores and Doped with Mn2+ and Mn3+ for Catalytic C–C Coupling, Nitroaromatics Reduction, and the Oxidation of Alcohols and Hydrocarbons

“…However, the comparative analysis of high-resolution Mn 2p spectra of fresh and reused Mn 3+ -Pd@ l -dopa-ZnO/Fe 3 O 4 showed interesting results (Figure A). The Mn 2p region of the fresh catalyst [Figure A­(a)] was resolved into two peaks namely Mn 2p 3/2 and Mn 2p 1/2 at binding energies of 642.2 and 654.2 eV, respectively, which could be rationally assigned to an oxidation state of +3. − The peak observed at 655.8 eV corresponds to the Zn L 2 MM Auger peak . Mn 2p spectra of reused Mn 3+ -Pd@ l -dopa-ZnO/Fe 3 O 4 [Figure A­(b)] revealed the presence of two additional peaks at 640.9 and 652.8 eV, corresponding to 2p 3/2 and 2p 1/2 peaks of Mn 2+ , as compared to that of the fresh catalyst where no such peaks have been observed. − , Furthermore, the satellite peak at 645.8 eV is a characteristic feature of Mn 2+ ions. , This confirms the transformation of some of the Mn 3+ ions of Mn 3+ -Pd@ l -dopa-ZnO/Fe 3 O 4 into Mn 2+ ions during C–C coupling.…”

“…55 Mn 2p spectra of reused Mn 3+ -Pd@L-dopa-ZnO/Fe 3 O 4 [Figure 5A(b)] revealed the presence of two additional peaks at 640.9 and 652.8 eV, corresponding to 2p 3/2 and 2p 1/2 peaks of Mn 2+ , as compared to that of the fresh catalyst where no such peaks have been observed. [51][52][53][54]56 Furthermore, the satellite peak at 645.8 eV is a characteristic feature of Mn 2+ ions. 51,56 This confirms the transformation of some of the Mn 3+ ions of Mn 3+ -Pd@L-dopa-ZnO/Fe 3 O 4 into Mn 2+ ions during C−C coupling.…”