Combined IR spectroscopy and kinetic modeling of NOx storage and NO oxidation on Fe-BEA SCR catalysts

DRIFTS study of γFe2O3 nano‐catalyst for low‐temperature selective catalytic reduction of NOx with NH3

“…The band at 1194 cm −1 was attributed to an NO − species which could be transferred to nitrate in the presence of oxygen (Figure a). The weak band at 1398 cm −1 might be due to an intermediate product, such as a trans ‐N 2 O 2 2‐ species . The band near 1772 cm −1 was assigned to Fe 2+ ‐NO species, because the bands originating from (di)nitrosyls bonded to Fe 3+ are usually above 1805 cm −1 ; in addition, this band was not detected in the presence of oxygen (Figure a).…”

“…The band near 1772 cm −1 was assigned to Fe 2+ ‐NO species, because the bands originating from (di)nitrosyls bonded to Fe 3+ are usually above 1805 cm −1 ; in addition, this band was not detected in the presence of oxygen (Figure a). The new bands at 1602, 1575, and 1547 cm −1 raised during heating were assigned to the υ 3 high mode of bridging nitrate ((Fe‐O) 2 NO), bidentate nitrate (FeO 2 NO), and monodentate nitrate (FeONO 2 ) respectively, while the band at 1252 cm −1 was assigned to a υ 3 low mode of bidentate nitrate . In conclusion, the main adsorption products of NO at 30 °C were adsorbed NO 2 , monodentate nitrite, and NO − , which were desorbed or transformed to nitrate species during heating in the absence of oxygen.…”

“…A NO molecule could be adsorbed to the produced Fe 2+ sites to form Fe 2+ ‐NO species, giving rise to the band at 1772 cm −1 in Figure a. However, this band was not detected in the presence of oxygen (Figure a), because Fe 2+ was rapidly oxidized to Fe 3+ by oxygen (Reaction (4)), and the amount and effect of nitrosyls bonded to Fe 3+ (Fe 3+ ‐NO) were usually negligible . Reactions (7, 8, 4) combine to: …”

“…The weak band at 1398 cm À1 might be due to an intermediate product, such as a trans-N 2 O 2 2species. [32,36,38] The band near 1772 cm À1 was assigned to Fe 2þ -NO species, because the bands originating from (di)nitrosyls bonded to Fe 3þ are usually above 1805 cm À1 ; [38] in addition, this band was not detected in the presence of oxygen (Figure 9a). The new bands at 1602, 1575, and 1547 cm À1 raised during heating were assigned to the y 3 high mode of bridging nitrate ((Fe-O) 2 5 5NO), bidentate nitrate (Fe─O 2 ─NO), and monodentate nitrate (Fe─O─NO 2 ) respectively, while the band at 1252 cm À1 was assigned to a y 3 low mode of bidentate nitrate.…”

Synthesis, characterization and photocatalytic performance of W, N, S-tri-doped TiO2 under visible light irradiation

“…Several regulations have made global environmental pollution (air-soil-water) a serious problem [7][8][9][10][11], but, over the years, scientists have researched a solution to decrease or eliminate the impact of these kinds of pollution [12][13][14][15][16]. In this context, semiconducting photocatalysts have attracted interest for many potential applications in the air, water purification, and organic pollutant degradation [17][18][19].…”