Examination of surface phenomena of V₂O₅loaded on new nanostructured TiO₂prepared by chemical vapor condensation for enhanced NH₃-based selective catalytic reduction (SCR) at low temperatures

Abstract

In this article, we describe the investigation and surface characterization of a chemical vapor condensation (CVC)-TiO2 support material used in a V2O5/TiO2 catalyst for enhanced selective catalytic reduction (SCR) activity and confirm the mechanism of surface reactions. On the basis of previous studies and comparison with a commercial TiO2 catalyst, we examine four fundamental questions: first, the reason for increased surface V(4+) ion concentrations; second, the origin of the increase in surface acid sites; third, a basis for synergistic influences on improvements in SCR activity; and fourth, a reason for improved catalytic activity at low reaction temperatures. In this study, we have cited the result of SCR with NH3 activity for removing NOx and analyzed data using the reported result and data from previous studies on V2O5/CVC-TiO2 for the SCR catalyst. In order to determine the properties of suitable CVC-TiO2 surfaces for efficient SCR catalysis at low temperatures, CVC-TiO2 specimens were prepared and characterized using techniques such as XRD, BET, HR-TEM, XPS, FT-IR, NH3-TPD, photoluminescence (PL) spectroscopy, H2-TPR, and cyclic voltammetry. The results obtained for the CVC-TiO2 materials were also compared with those of commercial TiO2.

Surface phenomenon of CeO2-added V2O5/TiO2 catalyst based chemical vapor condensation (CVC) for enhanced selective catalytic reduction at low temperatures

“…Liu et al [14] reported that Ti 3+ creates a free carrier (%electron) when oxidized to Ti 4+ . In addition, according to previous studies by Cha et al [13,16], the TiO 2 synthesized via CVC had a higher ratio of Ti 3+ ions and contained more free carriers, and had a clear effect on the oxide ion state of the loading material. We also thought that this was the reason for the higher ratio of Ce 3+ ions; CVC-TiO 2 has more free carriers on the material surface.…”

“…XPS Ti 2p spectra of pure TiO 2 catalysts. This figure was prepared by using XPS data from a previous paper by Cha et al [13] Figs. 5 and 6 show the XPS V 2p spectra of V 2 O 5 -CeO 2 /TiO 2 catalysts with only V 2 O 5 loaded on each TiO 2 support material (V 2 O 5 / TiO 2 ), respectively.…”

“…Previous studies [5,13,21] reported that oxygen species on surfaces and in lattices exposed to the surfaces of catalysts had positive effects on reduction capability with some metal oxide ions, such as titanium, vanadium, and cerium. The acidity and/or redox sites, such as Ce-OH (Ce 3+ , Ce 4+ , etc.)…”

“…and V-OH (V 4+ , V 5+ , etc. ), on the surface of the CVC-catalyst were generated from many acidic hydroxyls [20] when some material(s) were loaded onto the CVC-TiO 2 support material [13]. According to previous research [22,23], acid sites on the surfaces of SCR catalysts play a crucial role, such as to adsorb basic gas (NH 3 and/or ionized ammonia species) and as a surface reaction site, in the enhancement of catalytic activity in SCR with NH 3 .…”

One-step Synthesis of Ordered Pd@TiO2 Nanofibers Array Film as Outstanding NH3 Gas Sensor at Room Temperature

“…5b,c) compare with pure TiO 2 and apure TiO 2 (see Fig. S13), it can be observed that, besides the peak of Ti-O, its IR spectra displays additional features corresponding to two distinct NH 3 species: bands at 3340 and 1600 cm −1 , they are assigned to adsorb NH 3 on Lewis acid sites 53,54 .…”