Characterization and Hydroisomerization Performance of Mg‐Promoted, Pt/ZSM‐23‐Based Catalysts

Characterization and Hydroisomerization Performance of Mg‐Promoted, Pt/ZSM‐23‐Based Catalysts

The effect of Mg on the acidic and metal functions in Pt/ZSM‐23 catalysts has been studied, using both pure zeolite (Z) and preshaped ZSM‐23/Al2O3 composite (ZA) and varying the content and method of Mg loading. N2 physisorption, CO chemisorption, H2/O2 titration, XRD, TEM, TPR, and FTIR were employ...

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Bibliographic Details
Published in:European journal of inorganic chemistry Vol. 2022; no. 14
Main Authors: Bogomolova, Tatiana S., Lisitsyn, Alexander S., Ayupov, Artem B., Yu. Gerasimov, Evgeny, Klimov, Oleg V., Noskov, Alexander S., Yu. Smirnova, Marina
Format: Journal Article
Language:English
Published: Weinheim Wiley Subscription Services, Inc 17-05-2022
Subjects:
Aluminum oxide
Catalysts
Chemisorption
Dispersion
Heterogeneous catalysis
Hydroisomerization
Inorganic chemistry
Ion exchange
Isomerization
Magnesium
Phase composition
Platinum
Selectivity
Titration
Zeolites
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Summary:The effect of Mg on the acidic and metal functions in Pt/ZSM‐23 catalysts has been studied, using both pure zeolite (Z) and preshaped ZSM‐23/Al2O3 composite (ZA) and varying the content and method of Mg loading. N2 physisorption, CO chemisorption, H2/O2 titration, XRD, TEM, TPR, and FTIR were employed to characterize the phase composition, textural and acidic properties, platinum location and dispersion. The shaping procedure used left the acidity of the parent zeolite virtually intact, while Pt dispersion on the composite support was greatly increased. Despite the increased CPt/CH+ ratio, the Pt/ZA catalyst underperformed Pt/Z in the yield of branched isomers produced in n‐decane hydroconversion. Irrespective of the support, its impregnation with Mg allowed tuning the surface acidity and improving the isomerization selectivity above the level characteristic of unpromoted Pt/Z. However, the addition of Mg through ion‐exchange resulted in an opposite effect on the catalyst selectivity. Possible reasons of such a complex behavior are discussed. First systematic study of Pt(Mg)@ZSM‐23‐Al2O3 composite catalysts: Different routes of Mg addition into ZSM‐23 and ZSM‐23‐Al2O3, such as ion exchange and impregnation, were compared. Both routes improve the bifunctionality of the samples, but only impregnation provides better isoselectivity. The isomerization performance was discussed in terms of balance between metal and acid sites, their intimacy, and the ratio between external and total acidity.
ISSN:1434-1948
1099-0682
DOI:10.1002/ejic.202200085