Monolith or Powder: Improper Sample Pretreatment May Mislead the Understanding of Industrial V 2 O 5 -WO 3 /TiO 2 Catalysts Operated in Stationary Resources.

Although various characterizations are widely applied to commercial V 2 O 5 -WO 3 /TiO 2 catalysts, the influence of the catalyst physical structure, i.e., monolith or powder, on the characterization results has not been investigated. Several important catalytic behaviors and phenomena were observed in this study using V 2 O 5 -WO 3 /TiO 2 monolithic catalysts employed for over 5000 h in various stationary flue gases, and many of the results were only observable on monolithic catalysts, such as depth-dependent distribution of external elements, penetration of As 2 O 3 , and the formation of Tl 2 O-TiO 2 p-n junctions. If the monolith is ground into powder states, it will alter or destroy the catalyst surface and remove important clues closely related to catalytic performance under working conditions. The redox and acidity properties of V 2 O 5 -WO 3 /TiO 2 obtained from powder samples may be significantly different from their true state under working conditions, resulting in a misperception of catalyst performance. Therefore, a cautious pretreatment should be taken into careful consideration when analyzing commercial honeycomb V 2 O 5 -WO 3 /TiO 2 catalysts.