The combination of Cu(II) triethylenetetramine and N,N-dimethyl-3,5-dimethylpiperidinium as structure directing agents allowed the direct preparation of highly active and hydrothermally stable Cu-SAPO-18 for the selective catalytic reduction of NOx with NH3. The approach allows performing a one-pot synthesis avoiding intermediate calcination and ion exchange, while achieving complete framework Si isolation. Combination of physicochemical characterization techniques show that copper exists as extra-framework Cu2+, which have been identified as the specific active sites for the SCR of NOx. The selective presence of isolated Si species in the zeolitic framework introduces high hydrothermal stability.
Martínez-Franco, R., Moliner, M., & Corma, A. (2014). Direct synthesis design of Cu-SAPO-18, a very efficient catalyst for the SCR of NOx. Journal of Catalysis, 319, 36–43. https://doi.org/10.1016/j.jcat.2014.08.005