Selective Catalytic Reduction of NO_x with NH₃ on Cu-, Fe-, and Mn-Zeolites Prepared by Impregnation: Comparison of Activity and Hydrothermal Stability

Table 2

Physical characterization of catalysts.

Catalyst	Surface area (m^2·g^−1)	Total acidity (µmol of NH3·g^−1)		Metal/Si ratio^a (based on XPS)		Change (%)
		Fresh	HT	Fresh	HT
Cu-SSZ-13	549	1792	1580	0.0280	0.0292	4
Cu-BEA	523	1759	1186	0.0187	0.0300	38
Cu-ZSM-5	345	1671	1350	0.0189	0.0253	25
Fe-SSZ-13	585	1338	1098	0.0454	0.0491	8
Fe-BEA	518	1772	1195	0.0219	0.0231	5
Fe-ZSM-5	369	1519	1018	0.0247	0.0276	11
Mn-SSZ-13	577	1611	1358	0.0335	0.0488	31
Mn-BEA	528	1419	956	0.0242	0.0263	8
Mn-ZSM-5	355	1436	1065	0.0251	0.0298	16

^aCu/Si bulk composition is 0.032, Fe/Si bulk composition is 0.036, and Mn/Si bulk composition is 0.037.