Direct synthesis design of Cu-SAPO-18, a very efficient catalyst for the SCR of NOx

•Specific cyclic ammonium cations allow the direct synthesis of Cu-SAPO-18 catalysts.•Complete framework Si isolation can be achieved for Cu-SAPO-18 materials.•Cu-SAPO-18 shows high catalytic activity and hydrothermal stability for SCR of NOx.

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.

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