Effect of Sulfur on Mn/Ti Catalysts Prepared Using Chemical Vapor Condensation (CVC) for Low-Temperature NO Reduction

Abstract

Mn/Ti catalysts prepared through impregnation of manganese acetate and a manganese nitrate precursor via the chemical vapor condensation (CVC) method were investigated in this study to assess NH3-selective catalytic reduction (SCR) activity. Manganese (Mn) loaded on a synthesized TiO2 catalyst showed good low-temperature NO reduction activity and better resistance to sulfur poisoning in presence of SO2. Mn loaded on synthesized TiO2 prepared from manganese acetate precursor especially exhibited a high NO conversion of 98.4% at 150 °C. Moreover, it presented high NO conversions within the entire operating temperature window in comparison with other catalysts, which may be attributed to smaller particle size, scattered amorphous Mn over the catalyst surface, higher dispersion, and an abundant Mn2O3 phase. X-ray photoelectron spectroscopy (XPS) analysis of the spent catalyst following the SCR reaction in presence of SO2 verified that the formation of sulfated titanium and manganese sulfate was significantly inhibited, and that the deposition concentration of ammonium sulfate on active sites was low owing to impregnation of Mn acetate onto synthesized TiO2. FT-IR analysis indicated that the catalyst also contained larger quantities of N–H bonds in NH3, synchronizing with Lewis acid sites on its surface.

Characteristics of Manganese Supported on Hydrous Titanium Oxide Catalysts for the Selective Catalytic Reduction of NOx with Ammonia

“…In our experiment, the catalysts that emitted a large amount of nitrous oxide in the SCR reaction also released a lot of nitrous oxide in ammonia oxidation. This trend is also found in other research [12], which implies that ammonia activation in the catalyst surface is a key factor to determine the selectivity of nitrous oxide. Kapteijn et al attributed the nitrous oxide formation in pure manganese oxide to an oxidative abstraction of hydrogens from ammonia.…”

Silicotungstic acid modified Ce‐Fe‐Ox catalyst for selective catalytic reduction of NOx with NH3: Effect of the amount of HSiW

“…As for Fe atoms, the characteristic peaks were centered at 710.8 eV (Fe 2p 3/2 ) and 724.5 eV (Fe 2p 1/2 ), respectively. The Fe 2p 3/2 peak centered at 710.5 eV assigned to the oxidation state Fe 2+ and Fe 3+ centered at 712.2 eV . Besides, there was a satellite peak was detected at 719.0 eV, which was assigned to the existence of Fe 2 O 3.…”

Sulfur and Water Resistance of Mn-Based Catalysts for Low-Temperature Selective Catalytic Reduction of NOx: A Review

“…As shown in Figure 24, the NO conversion decreased to 60% and it recovered to almost the original level when the SO 2 supply was shut off. Park et al [83] prepared Mn/Ti catalysts via chemical vapor condensation (CVC) method and claimed that this Mn/Ti not only showed higher activity at low temperature but also exhibited better tolerance to water and sulfur. Only a small NO conversion decrease from 70 to 58% was found under 200 ppm of SO 2 in 250 min at 100 • C. Liu et al [46] prepared an Mn-Ce-Ti catalyst using the hydrothermal method, and the NO x conversion over the Mn 0.2 Ce 0.1 Ti 0.7 O x catalyst under H 2 O and SO 2 was further investigated at 200 • C. As shown in Figure 25, the introduction of H 2 O and SO 2 induced a slight decrease in NO x conversion.…”

“…As shown in Figure 24, the NO conversion decreased to 60% and it recovered to almost the original level when the SO2 supply was shut off. Park et al [83] prepared Mn/Ti catalysts via chemical vapor condensation (CVC) method and claimed that this Mn/Ti not only showed higher activity at low temperature but also exhibited better tolerance to water and sulfur. Only a small NO conversion decrease from 70 to 58% was found under 200 ppm of SO2 in 250 min at 100 °C.…”