NO Conversion with NH ₃ by Catalysts Derived from Ti-MWW Layered Zeolites with Tailored Porosity

Acid-treated Ti-MCM-22 zeolite and its micromesoporous derivatives, ITQ-2-A and MCM-36-A, were hydrothermally synthesized and then modified with copper cations by the ion-exchange method. The samples were characterized with respect to their physicochemical properties, including composition (ICP-OES), structure (XRD, STEM, UV–vis DRS), texture (low-temperature N2-sorption), surface acidity (NH3-TPD), and copper reducibility (H2-TPR). Cu-functionalized zeolites showed enhanced catalytic activity compared to commercial V2O5–TiO2 catalysts. They were found to be active and selective catalysts for the NH3–SCR process, operating effectively in the range of 200–325 °C. NH3–SCR activity strongly depended on the opening of the framework, indicating the micromesoporous structure as an important factor influencing improved NO conversion with ammonia. The formation of NO2, essential for the fast-SCR process, was identified as a crucial step in the reaction mechanism responsible for the low-temperature reduction of nitrogen(II) oxide with ammonia.