Abstract: The phenomenon of the sharp increase of activity in reactions of deep oxidation found for the manganese oxide–alumina system calcined at 900–1000 ◦C was named as thermoactivation effect. This effect was shown to be associated with phase transformations in this system. Peculiarities of phase transformations in the MnOx /Al2O3 system after its calcination at 950 ◦C for 1–10 h were studied with XRD, TEM, XPS methods; the catalysts activity in deep oxidation of n-pentane was measured in a flow-circuit setup. It was found that a set of phase transformations occurred in the system, starting from the formation of the metastable nonstoichiometric manganese–alumina cubic spinel (after 1–2 h calcination) and nonequilibrium solid solution of Mn3+ ions in the structure of
-Al2O3 which decomposes producing high-temperature aluminas modified by manganese ions and particles of imperfect -Mn3O4 phase doped with aluminium ions. Increase of the calcination time to 10 h and more results in the formation of biphasic system composed of -Al2O3 and nanocrystalline -Mn3O4 modified by Al3+ ions. These transformations are associated with the maximum activity showed by catalysts calcined for 5–6 h in the reaction of n-pentane combustion.

Cite: Tsyrulnikov P.G. , Tsybulya S.V. , Kryukova G.N. , Boronin A.I. , Koscheev S.V. , Starostina T.G. , Bubnov A.V. , Kudrya E.N.
Phase Transformations in the Thermoactivated MnOx–Al2O3 Catalytic System
Journal of Molecular Catalysis A: Chemical. 2002. V.179. N1-2. P.213-220. DOI: 10.1016/S1381-1169(01)00327-2 WOS Scopus РИНЦ ANCAN OpenAlex

Dates:

Submitted:	Apr 19, 2001
Accepted:	Aug 17, 2001
Published online:	Jan 24, 2002
Published print:	Feb 18, 2002

Identifiers:

Web of science:	WOS:000173811100025
Scopus:	2-s2.0-0037127512
Elibrary:	13396198
Chemical Abstracts:	2002:93494
Chemical Abstracts (print):	136:343139
OpenAlex:	W1790522872

Citing:

DB	Citing
Web of science	28
Scopus	29
Elibrary	32
OpenAlex	27

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