Selective Catalytic Reduction of NO_xwith Ammonia over Copper Ion Exchanged SAPO‐47 Zeolites in a Wide Temperature Range

Abstract

Copper‐exchanged H‐SAPO‐47 zeolites were synthesized by an aqueous solution ion exchange method and applied in the selective catalytic reduction of NO with NH3 (SCR). The microporous chabazite (CHA) structure of the catalysts was characterized and confirmed using synchrotron X‐ray diffraction and nitrogen adsorption–desorption experiments. The synthesized Cux‐SAPO‐47 catalysts exhibited excellent SCR activity and nearly 100 % N2 selectivity in a wide temperature range. The Cu0.1‐SAPO‐47 sample exhibited higher activity than the other samples below 250 °C. The weak Lewis acid sites originating from the introduction of Cu2+ were more active than the Brønsted acid sites of the zeolites framework at low temperature. Two types of isolated Cu2+ species with different coordination surroundings were found, namely, Cu2+ cations bonded with the six‐membered rings and those bonded in the CHA cages. The former species exhibited good stability and activity at high temperature, whereas the latter ones were more active at low temperature. The Cu0.1‐SAPO‐47 catalyst provided a considerable amount of isolated Cu2+ bonded in the CHA cages. These results indicated that active Lewis acid sites and isolated Cu2+ species are responsible for their excellent SCR activity.

Using Transient FTIR Spectroscopy to Probe Active Sites and Reaction Intermediates for Selective Catalytic Reduction of NO on Cu/SSZ-13 Catalysts

“…Steady-state SCR reaction tests were performed in a fixed-bed reaction system . First, 60 mg of the catalyst was pressed, crushed and sieved into 40–60 mesh sizes and placed inside a quartz tube with a 6 mm inner diameter.…”

“…Steady-state SCR reaction tests were performed in a fixedbed reaction system. 26 First, 60 mg of the catalyst was pressed, crushed and sieved into 40−60 mesh sizes and placed inside a quartz tube with a 6 mm inner diameter. The gaseous reactant mixture consisted of 500 ppm of NH 3 , 500 ppm of NO, 5% O 2 and balanced with N 2 .…”

Selective Catalytic Reduction of NOx with NH3 over Cu/SSZ-13: Elucidating Dynamics of Cu Active Sites with In Situ UV–Vis Spectroscopy and DFT Calculations

“…NO x and NH 3 conversions were calculated using formulas reported elsewhere. 40,41 2.3. Diffuse Reflectance UV−Vis Spectroscopy.…”

Advances in Catalytic Applications of Zeolite‐Supported Metal Catalysts

“…The Cu–SSZ‐13 exhibited nearly complete conversion of NO at reaction temperatures between 175 and 450 °C in the NH 3 ‐SCR reaction. Moreover, the silicoaluminophosphate zeolites with the same CHA topological structure as SSZ‐13, such as SAPO‐34, [ 199 ] SAPO‐44, [ 200 ] and SAPO‐47, [ 201 ] were also employed as popular supports to immobilize the Cu species for the NH 3 ‐SCR reaction and exhibited the good catalytic activity.…”