Influences of Na+ co-cation on the structure and performance of Cu/SSZ-13 selective catalytic reduction catalysts

A series of Cu/H-SSZ-13 and Cu/Na-SSZ-13 catalysts are synthesized, degreened and hydrothermally aged for use in the standard NH3-SCR reaction. Surface area/pore volume and XRD analyses are used to probe the textural properties of the catalysts. H-2-TPR and EPR are used to quantitatively describe the various Cu species. NH3-SCR is carried out at a lower space velocity to probe the light-off behavior, and a higher space velocity to generate data for kinetic analysis. Na+ co-cation addition is found to promote turnover rates of isolated Cu-ions at low reaction temperatures. However, as Cu loadings increase, this promoting effect is compromised by decreases in Cu exchange capacity and hydrothermal stability of the Cu/Na-SSZ-13 catalysts.