CeO2-TiO2 catalyst prepared by physical mixing for NH3 selective catalytic reduction: Evidence about the migration of sulfates from TiO2 to CeO2 via simple calcination

Abstract

A mechanical mixture of CeO 2 and TiO 2 powder with a small amount of sulfate was applied for the selective catalytic reduction (SCR) of NO with NH 3 . After calcination at 500 o C, the mixed sample showed significantly enhanced activity and selectivity compared to the uncalcined one and, moreover, demonstrated even higher activity than the conventional V 2 O 5 /TiO 2 catalyst above 300 o C. Combined characterization results revealed that the main active sites were newly formed sulfate species on CeO 2 , the number of which increased with calcination. Temperatureresolved DRIFT spectra provided convincing evidence about the migration of sulfate species from TiO 2 to CeO 2 , as confirmed from the shift of ν(S=O) band as a result of the mechanical mixing and the subsequent calcination.

Suppressed Strong Metal–Support Interactions in Platinum on Sulfated Titania and Their Influence on the Oxidation of Carbon Monoxide

“…Commercial TiO 2 (DT‐51) contains 1.25 wt % sulfur (from elemental analysis), and it is designated as S‐TiO 2 in the present work. Sulfur‐free titania (TiO 2 ) was synthesized by a conventional sol–gel method in the optimized way to resemble the physical properties of S‐TiO 2 .…”

“…On the other hand, S‐TiO 2 shows a relatively large reduction band at 574 °C. The S species on the TiO 2 surface are known to cause a sharp reduction band at approximately 570 °C . Figure S6 b shows the reduction profiles of the Pt/TiO 2 and Pt/S‐TiO 2 catalysts.…”

Chemisorption of NH3 on Monomeric Vanadium Oxide Supported on Anatase TiO2: A Combined DRIFT and DFT Study

“…Supported vanadium oxide catalysts are known to have two kinds of acidic sites on the surface, Lewis acid sites and Brønsted acid sites . The standard SCR reaction usually occurs with the Eley–Rideal mechanism, which means that the NH 3 adsorbed on the acidic sites of catalysts can reduce gaseous NO molecule. , Hence, the site at which NH 3 molecules are adsorbed is an important factor in determining the activity or selectivity of the SCR reaction . In fact, it has been long controversial as to which NH 3 molecules are involved in the reaction more dominantly.…”