Memory effect of the CuZnAl-LDH derived catalyst precursor—In situ XRD studies

Authors: Paweł Kowalik, Marcin Konkol, Małgorzata Kondracka, Wiesław Próchniak, Robert Bicki, Paweł Wiercioch

Abstract:
Thermal decomposition of the CuZnAl-LDH catalyst precursor and the reverse structural transformations of the oxide forms upon addition of water have been investigated. The object of the studies was chosen in such a way thatits composition resembled that ofthe industrial methanol synthesis and low-temperature water gas shift catalysts precursors. The temperature ranges of the corresponding transformations have been assigned and the structural changes have been discussed. The CuZnAl-LDH catalyst precursor shows a distinct “memory effect” up to the temperatures of 400–600 ^◦C. The heat effect of the exothermic hydration process of the mixed oxides, (Cu,Zn)AlOx has been estimated and correlated with a degree of recovery of the material layered structure. Above 600 ^◦C irreversible structural transformations proceed, leading in consequence to the gradual decline of this effect. The recovery kinetics of the layered ordered structure has been determined based on the in situ XRD measurements and Avrami–Erofeev’s model.

Keywords:
CuZnAl catalyst precursor
Layered double hydroxides
Memory effect
Mixed metal oxides
XRD studies

Published in: Applied catalysis A: General  (Volumes 464–465, Pages 1-384, 15 August 2013)

Publisher: Elsevier  

ISSN Information: 0926-860X

Memory effect of the CuZnAl-LDH derived catalyst precursor—In situ XRD studies

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