Influence of the addition of vanadium to Pt/TiO₂ catalyst on the selective catalytic oxidation of NH₃ to N₂
2019
Kim, Geo Jong | Kwon, Dong Wook | Shin, Jung Hun | Kim, Ki Wang | Hong, Sung Chang
In this work, the effect of the addition of vanadium to the Pt/TiO₂ catalyst on the selective catalytic oxidation (SCO) of NH₃ to N₂ was investigated. It was found that the addition of vanadium significantly enhanced catalytic activity at all tested temperatures. The Pt/V/TiO₂ catalyst exhibited the highest NH₃ conversion (∼100%) and NH₃ to N₂ conversion (∼81%) at 250°C. The physicochemical characteristics of the catalysts were investigated via Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), NH₃ temperature-programmed desorption (TPD), NH₃ temperature-programmed oxidation (TPO), and in situ Fourier-transform infrared (FTIR) spectroscopy. It was found that the addition of V to the catalyst enhanced the conversion of NH₃ as a result of the formation of new acid sites. The increase in the number of acid sites resulted in increased NH₃ to N₂ conversion via the internal selective catalytic reduction (i-SCR) mechanism. This mechanism involves the SCR of NOₓ, which are formed by the oxidation of NH₃. Based on experimental results and analyses of the catalysts modified by the addition of V, it was shown that there was a close relation between reaction selectivity and the surface oxygen species of the catalyst and N₂ yield. Furthermore, the addition of V increased the durability of SO₂ by inhibiting the formation of ammonium bisulfate (ABS).
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