Deactivation Mechanism and Enhanced Durability of V₂O₅/TiO₂–SiO₂–MoO₃ Catalysts for NH₃−SCR in the Presence of SO₂

Abstract

V 2 O 5 /TiO 2-type catalysts are widely applied for selective catalytic NO reduction by NH 3 (NH 3-SCR), but enhanced sulfur tolerance and low-temperature activity are required. Herein, V 2 O 5 / TiO 2 À SiO 2 À MoO 3 (V/TSM) was demonstrated to have excellent catalytic activity and durability for NH 3-SCR in the presence of SO 2 at temperatures lower than 200°C. The deactivation mechanism and factors influencing SO 2 durability were investigated using catalytic durability tests, Fourier-transform infrared spectroscopy, and temperature-programmed desorption/ decomposition. Our results revealed that (NH 4) 2 S 2 O 3 and NH 4 HSO 4 form on catalyst surfaces by NH 3 À SO 2 À H 2 O reactions at low temperatures, resulting in catalyst deactivation via pore blockage. However, V/TSM was found to possess an increased number of active sites for decomposing deposited ammonium sulfate salts. The decomposition activity was related to the solid acidity, which enhanced SO 2 desorption and reactions between ammonium sulfate salts and NO. These findings will contribute to the development of catalysts with improved lifetimes for NH 3 À SCR.

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

“…Similar observation was reported for ZrO 2 supported catalysts modified with copper and iron [4] . On the other hand, ammonia can react with sulfur dioxide leading to accumulation of ammonium sulfate compounds, such as NH 4 HSO 4 (ammonium bisulfate) and (NH 4 ) 2 SO 4 (ammonium sulfate) which block the pores of catalyst [58] . Clogging of the pores can be directly correlated with deactivation of the NH 3 ‐SCR catalyst.…”

“…[4] On the other hand, ammonia can react with sulfur dioxide leading to accumulation of ammonium sulfate compounds, such as NH 4 HSO 4 (ammonium bisulfate) and (NH 4 ) 2 SO 4 (ammonium sulfate) which block the pores of catalyst. [58] Clogging of the pores can be directly correlated with deactivation of the NH 3 -SCR catalyst. A deep investigation on the effect of SO 2 is planned to be conducted in the future.…”

Rationally Designed Confined Structure Ce-Mn-TNTs Catalyst for Low-Temperature NH3-SCR Reaction with Superior Activity and H2O/SO2 Tolerance

“…The above peaks appeared in fresh Ce-Mn-TNT catalysts, which meant that fresh catalyst contains small amounts of H 2 O and undecomposed nitrates. When the catalysts were tested for SO 2 resistance, the peaks at 1406 and 3176 cm –1 belonged to NH 3 /NH 4 + binding to acidic sites, ,, while the peaks that appeared at 1000–1200 cm –1 belonged to sulfate species . When the reaction temperature was 280 °C, the Ce-Mn-TNT catalyst corresponded to a stronger signal peak for NH 4 + /NH 3 , implying that it possessed more surface acidic sites, which not only was conducive to the adsorption of NH 3 on the catalyst surface but also inhibited the adsorption of SO 2 to some extent.…”

“…When the catalysts were tested for SO 2 resistance, the peaks at 1406 and 3176 cm −1 belonged to NH 3 /NH 4 + binding to acidic sites, 1,44,45 while the peaks that appeared at 1000−1200 cm −1 belonged to sulfate species. 46 When the reaction temperature was 280 °C, the Ce-Mn-TNT catalyst corresponded to a stronger signal peak for NH 4 + /NH 3 , implying that it possessed more surface acidic sites, which not only was conducive to the adsorption of NH 3 on the catalyst surface but also inhibited the adsorption of SO 2 to some extent. This phenomenon explained the excellent anti-SO 2 performance of the Ce-Mn-TNT catalyst at 280 °C.…”

Influence of Calcination Temperature over Vanadium–Molybdenum Catalysts for the Selective Catalytic Reduction of NOx with NH3

“…To synthesize the V-based catalyst with higher SCR activity at a lower temperature, various oxide materials as promoters reported in previous research, such as transition metal oxides (WO 3 and MoO 3 ), , rare earth metals oxide (CeO 2 ), , and nonmetal oxides (SiO 2 ), can be activated with vanadium pentoxide. Wang et al studied that the incorporation of WO 3 into the V 2 O 5 /TiO 2 catalyst indeed enhances its Brønsted acid sites, which is crucial for improving its redox property at low temperatures.…”