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Effect of the Composition of Modified SO 4 2− /ZrO2 on Catalytic Properties in Reduction of NO by Hydrocarbons

“…On the other hand, in [13] using the same method it was shown that sulfated zirconium dioxide has superacid sites, evidence for which comes from the peak on the thermal desorption curve at 540°C. The results presented above are consistent with data we obtained previously in [2] showing that active oxide catalysts for the SCR process are bifunctional in nature, i.e., are characterized by the presence of an active metal and a certain acidity of the surface. In Fig.…”

“…Based on the intensity of the absorption bands, the concentration of Brönsted acid sites is higher for the unsulfated specimen. The absorption bands we observed (1625, 1595, 1450 cm -1 ) for both specimens, according to [2], characterize formation of sorption complexes of pyridine with electron-acceptor sites on the catalyst, i.e., formation of Lewis acid sites. The results obtained are consistent with the data in [14], in which diffuse reflection IR spectroscopy established that modification of the zirconium dioxide surface with sulfate groups leads to the appearance of a new type of Brönsted acid site.…”

“…We know that the activity of both zeolite and oxide catalysts in the SCR process correlates with the acidity of the surface [1,2]. Therefore as the object of our investigations we chose sulfated zirconium dioxide (SO 4 2− /ZrO 2 ) which, as a solid superacid, has attracted steady attention from researchers [3].…”

“…In this work, we have studied the effect of the synthesis conditions and the amount of sulfate ions on the catalytic properties of sulfated zirconium dioxide, modified by cobalt, iron, and manganese oxides, in selective catalytic reduction of NO by methane and a propane-butane mixture. We also studied the acid properties of the surface of the specimens by temperature programmed desorption of ammonia (TPDA) and IR spectroscopy (adsorption of pyridine) according to the techniques given in [2].…”

Two-stage Catalytic Reduction of NOx with Hydrocarbons

“…The appearance of this band is due to a linearly adsorbed NO species. 18 The 1628/1579 cm -1 pair appears together and grow with increasing temperature, but disappear at 350°C. These two bands are assigned to bridging and bidentate nitrates, respectively.…”