Ferrierite and Its Delaminated Forms Modified with Copper as Effective Catalysts for NH₃-SCO Process

Area of Science:

• Catalysis
• Materials Science
• Environmental Chemistry

Background:

• Zeolites, including ferrierites and their delaminated forms (ITQ-6), are versatile materials for catalysis.
• Incorporating aluminum (Al) or titanium (Ti) into zeolite frameworks influences their properties.
• Copper modification is a common strategy to enhance catalytic activity.

Purpose of the Study:

• To synthesize and characterize copper-modified ferrierite and ITQ-6 zeolites with Al or Ti.
• To evaluate the catalytic performance of these materials in the selective catalytic oxidation of ammonia to dinitrogen (NH3-SCO).
• To elucidate the role of different copper species in the catalytic process.

Main Methods:

• Synthesis of ferrierite and ITQ-6 zeolites with Al or Ti.
• Copper modification via ion-exchange.
• Characterization using ICP-OES, XRD, UV-Vis DRS, N2-sorption, NH3-TPD, and H2-TPR.
• Catalytic testing for NH3-SCO.

Main Results:

• Copper species were successfully introduced into Al- and Ti-containing ferrierites and ITQ-6.
• Aggregated copper oxide species on Ti-zeolites were active for ammonia oxidation to NO.
• Monomeric copper cations on Al-zeolites were active for selective reduction of NO by ammonia to dinitrogen.
• The internal-selective catalytic reduction (i-SCR) mechanism was proposed for ammonia oxidation.

Conclusions:

• The ratio of aggregated copper oxide species to monomeric copper cations is crucial for catalyst activity and selectivity in NH3-SCO.
• Cu/Al-ITQ-6 exhibited the best catalytic performance, likely due to an optimal balance of copper species.
• Understanding copper speciation is key to designing efficient catalysts for selective ammonia oxidation.