An FT-IR study of the adsorption of urea and ammonia over V2O5–MoO3–TiO2 SCR catalysts

A model V2O5–MoO3–TiO2 DeNOx catalyst has been prepared and briefly characterized. The adsorption of urea on it (and of ammonia for comparison) has also been investigated. It has been observed that urea can adsorb over the catalyst in an anionic form that can later decompose to isocyanate anions and ammonia and ammonium ion species. This mechanism suggests that the potential reactivity of the anionic form of urea and of isocyanate anions with VOCs, if they are present in the waste gas, possibly rise to polluting compounds must be taken into account for applications of the urea/DeNOx process.