Selective catalytic reduction of NOx with ammonia over novel Cu ion‐exchanged SAPO‐47 zeolites in a wide temperature range

Yani Zhang; Yue Peng; Chizhong Wang; Kezhi Li; Shuai Liu; Xiansheng Li; Jianjun Chen; Junhua Li

Index: 10.1002/cctc.201800169

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Abstract

Copper exchanged H‐SAPO‐47 zeolites were synthesized by 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 characterzied 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 originated from the introduction of Cu2+ were more active than Brønsted acid sites of zeolites framework at low temperature. Two types of isolated Cu2+ species with differernt coordination surroundings (Cu2+ cations bonded with six‐ring or CHA cages) were found. The former species exhibited good stability and high temperature activity; whereas the later ones were more active at relatively low temperature.The Cu0.1‐SAPO‐47 catalyst provided considerable isolated Cu2+ bonded in the CHA cages. These results indicated that active Lewis acid sites and isolated Cu2+ species were responsible for their excellent SCR activity.