The Origin of an Unexpected Increase in NH3–SCR Activity of Aged Cu-LTA Catalysts

We have recently reported an increase in low-temperature NH3–SCR activity of the copper-exchanged (Cu/Al = 0.50), high-silica (Si/Al = 23) LTA catalyst when it is hydrothermally aged at 1023–1173 K. Here we demonstrate that this unexpected phenomenon originates from the migration of Cu+ ions present...

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Published inACS catalysis Vol. 7; no. 10; pp. 6781 - 6785
Main Authors Ahn, Nak Ho, Ryu, Taekyung, Kang, Yonjoo, Kim, Hyojun, Shin, Jiho, Nam, In-Sik, Hong, Suk Bong
Format Journal Article
LanguageEnglish
Published American Chemical Society 06.10.2017
Subjects
copper cation migration
zeolites
heterogeneous catalysis
Cu-LTA
NH3−SCR
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Summary:We have recently reported an increase in low-temperature NH3–SCR activity of the copper-exchanged (Cu/Al = 0.50), high-silica (Si/Al = 23) LTA catalyst when it is hydrothermally aged at 1023–1173 K. Here we demonstrate that this unexpected phenomenon originates from the migration of Cu+ ions present inside the sod cages of Cu-LTA to the vacant single 6-rings which accompanies their oxidation to Cu2+ ions during (hydro)­thermal aging. Hence, the sod cages, which are inaccessible to almost all reactant species so as to be regarded as useless for zeolite catalysis, were found to serve as a “catalyst reservoir” during the course of nitrogen oxides (NO x ) reduction with NH3.
ISSN:2155-5435
2155-5435
DOI:10.1021/acscatal.7b02852