A novel methodology for in situ redox active site titration of TiO 2 -supported vanadia during ethanol partial oxidation catalysis

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

“…It is known that samples with full theoretical monolayer coverage can inevitably have a small amount of crystalline V x O y clusters, which were not considered in DFT calculations. 44 In fact, it was also reported that V−O−V species exist even at extremely low surface coverages (<0.01 V/nm 2 ). 45 The purpose of this study is to investigate the acidic properties of monomeric V on TiO 2 surface so that the presence of crystalline V x O y could be avoided.…”

“…It can be thought that VO x /TiO 2 samples with monolayer coverage (7.5 V/nm 2 ) have oligomeric vanadia dominantly and even have a small amount of crystalline V x O y cluster. 44 The peak at 1596 cm −1 is probably attributed to Lewis−NH 3 of oligomeric vanadia species. The oligomeric vanadia with V−O−V group seem to have a different Lewis acidity compared to monomeric V species, which is beyond the scope of this paper.…”

Advanced Synthesis and Characterization of Vanadia/Titania Catalysts through a Molecular Approach

“…On the contrary, at low pH values (<5) and in the whole V concentration range studied, vanadium is mainly present in the form of the decamers (Figure 2 and Figure S1). The speciation is more complicated at the intermediate pH range (5)(6)(7)(8)(9). Vanadium is mainly distributed among the monomers, the dimers, and the quadramers, with much less contribution of the quintamers.…”

“…A comparison of Figure 8 with Figure 2f shows that the titania surface exhibits a preference for adsorbing monomers. In the intermediate pH region (6)(7)(8), Figure 2f shows that V is mainly in the form of quadramers in the solution. However, Figure 8 shows that at the same pH region, a significant portion of the deposited V is in the form of monomers.…”

“…More specifically, vanadia supported on titania catalysts is a very important material for many industrial processes, including those of environmental interest. It is worth mentioning dehydrogenation reactions [2][3][4][5], oxidation processes [6][7][8][9][10][11], water treatment through photocatalysis [12,13], and electrocatalysis [14]. However, the technology in which these catalysts are widely used is the selective catalytic reduction (SCR) of NO x , using mainly NH 3 as a reductant.…”