Effects of calcination temperature on physicochemical property and activity of CuSO₄/TiO₂ ammonia-selective catalytic reduction catalysts

CuSO₄/TiO₂ catalysts with high catalytic activity and excellent resistant to SO₂ and H₂O, were thought to be promising catalysts used in Selective catalytic reduction of nitrogen oxides by NH₃. The performance of catalysts is largely affected by calcination temperature. Here, effects of calcination temperature on physicochemical property and catalytic activity of CuSO₄/TiO₂ catalysts were investigated in depth. Catalyst samples calcined at different temperatures were prepared first and then physicochemical properties of the catalyst were characterized by N₂ adsorption-desorption, X-ray diffraction, thermogravimetric analysis, Raman spectra, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption of NH₃, temperature-programmed reduction of H₂ and in situ diffuse reflectance infrared Fourier transform spectroscopy. Results revealed that high calcination temperature had three main effects on the catalyst. First, sintering and anatase transform into rutile with increase of calcination temperature, causing a decrement of specific surface area. Second, decomposition of CuSO₄ under higher calcination temperature, resulting in disappears of Brønsted acid sites (S-OH), which had an adverse effect on surface acidity. Third, CuO from the decomposition of CuSO₄ changed surface reducibility of the catalyst and favored the process of NH₃ oxidation to nitrogen oxides (NO_x). Thus, catalytic activity of the catalyst calcined under high temperatures (≥600°C) decreased largely.