A size-selective method for increasing the performance of Pt supported on tungstated zirconia catalysts for alkane isomerization: a combined experimental and theoretical DFT study

The trends in the development of acid catalysts for isomerization show that the diffusion and accessibility of products are more favored in mesoporous as compared to microporous materials. In this work, an easy metal alkoxide- and surfactant-free technique was developed to prepare mesoporous size-se...

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Bibliographic Details
Published in:New journal of chemistry 2021-06, Vol.45 (23), p.151-1523
Main Authors: Vera-Iturriaga, J, Madrigal-Carrillo, K. G, Hernández-Pichardo, M. L, Rodríguez, Juan I, Jiménez-Izal, E, Montoya de la Fuente, J. A
Format: Article
Language:English
Subjects:
Alkanes
Catalysts
Catalytic activity
Expulsion
Hydrogen peroxide
Isomerization
Isomers
Octane number
Selectivity
Tungsten
Zirconium dioxide
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Summary:The trends in the development of acid catalysts for isomerization show that the diffusion and accessibility of products are more favored in mesoporous as compared to microporous materials. In this work, an easy metal alkoxide- and surfactant-free technique was developed to prepare mesoporous size-selective Pt/WO 3 -ZrO 2 catalysts. A high-octane number blend was obtained in the n C 6 isomerization reaction with these catalysts. The use of H 2 O 2 produced an increase in the textural properties of the tungstated zirconia that generated a high expulsion of tungsten, significantly benefitting the development of Brønsted acid sites required in alkane isomerization reactions. Results show that these catalysts reached high conversion values (up to 85 mol%) and higher selectivity for bi-ramified isomers as compared to conventional tungstated zirconia (17 mol% for 2,2-dimethyl-butane and 13 mol% for 2,3-dimethyl-butane). The high catalytic activity is attributed to their improved mesoporous structure that allowed the formation of well-dispersed WO x clusters on the zirconia surface with an intermediate domain size. DFT calculations confirmed that intermediate WO x cluster sizes offer the best balance between the strength and number of Brønsted acid sites. A high-octane number blend was obtained with Pt/WO 3 -ZrO 2 catalysts, synthesized by an easy alkoxide-free method for the cluster size control.
ISSN:1144-0546
1369-9261
DOI:10.1039/d1nj01725j