Abstract: In this work, a series of the chromia/alumina catalysts with the same surface Cr concentration of 4.4 ± 0.2 at. Cr/nm2 and different K loadings (0-3.9 wt.%) has been investigated to evaluate the effect of K on the effective activation energy of isobutane dehydrogenation at 520-550 °C. The results of the study show that at K loadings up to 2.0 wt.%, K preferably interacts with alumina and modifies an average dispersion of Cr3+Ox species in the reduced catalysts, thus leading to a growth of conversion and selectivity, but the number of direct contacts of K with active sites is too low to affect the effective activation energy of dehydrogenation. When K loading is higher than 2.0 wt.%, the alumina capacity for K is reached and K interacts directly with Cr3+Ox species. This causes an enlargement of effective activation energy with K loading. One possible explanation relies on the formation of a new type of active sites in Cr3+-O(H)-K+ with modified energetics of the reaction pathway or even with other reaction pathway. Another explanation is that potassium ions, being in contact with active sites, induce strong chemisorption of water, which poisons active sites, especially at low temperatures of the reaction.

Cite: Nazimov D.A. , Klimov O.V. , Saiko A.V. , Trukhan S.N. , Glazneva T.S. , Prosvirin I.P. , Cherepanova S.V. , Noskov A.S.
Effect of the K Loading on Effective Activation Energy of Isobutane Dehydrogenation over Chromia/Alumina Catalysts
Catalysis Today. 2021. V.375. P.401-409. DOI: 10.1016/j.cattod.2020.03.005 WOS Scopus РИНЦ AN OpenAlex

Dates:

Submitted:	Nov 15, 2019
Accepted:	Mar 2, 2020
Published online:	Mar 3, 2020
Published print:	Sep 1, 2021

Identifiers:

Web of science:	WOS:000668234000007
Scopus:	2-s2.0-85081203426
Elibrary:	43256814
Chemical Abstracts:	2020:453437
OpenAlex:	W3010631946

Citing:

DB	Citing
Scopus	17
Elibrary	19
Web of science	18
OpenAlex	19

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