Comparison between phosphine and NHC-modified Pd catalysts in the telomerization of butadiene with methanol - A kinetic study combined with model-based experimental analysis

Völkl L, Recker S, Niedermaier M, Kiermaier S, Strobel V, Maschmeyer D, Cole-Hamilton D, Marquardt W, Wasserscheid P, Haumann M (2015)

Publication Status: Published

Publication Type: Journal article

Publication year: 2015

Journal

Publisher: Elsevier

Book Volume: 329

Pages Range: 547-559

DOI: 10.1016/j.jcat.2015.06.004

Abstract

The telomerization of butadiene with methanol was investigated in the presence of different palladium catalysts modified either with triphenylphosphine (TPP) or 1,3-dimesityl-imidazol-2-ylidene (IMes) ligand. When pure butadiene was used as substrate, a moderate selectivity for the Pd-TPP catalyst toward the desired product 1-methoxy-2,7-octadiene (1-Mode) of around 87% was obtained, while the IMes carbene ligand almost exclusively formed 1-Mode with 97.5% selectivity. The selectivity remained unchanged when the pure butadiene feed was replaced by synthetic crack-C-4 (sCC(4)), a technical feed of 45 mol% butadiene and 55 mol% inerts (butenes and butanes). The TPP-modified catalyst showed a lower reaction rate, which was attributed to the expected dilution effect caused by the inerts. Surprisingly, the IMes-modified catalyst showed a higher rate with sCC(4) compared to the pure feed. By means of a model-based experimental analysis, kinetic rate equations could be derived. The kinetic modeling supports the assumption that the two catalyst systems follow different kinetic rate equations. For the Pd-TPP catalyst, the reaction kinetics were related to the Jolly mechanism. In contrast, the Jolly mechanism had to be adapted for the Pd-IMes catalyst as the impact of the base seems to differ strongly from that for the Pd-TPP catalyst. The Pd-IMes system was found to be zero order in butadiene at moderate to high butadiene concentrations and first order in base while the nucleophilicity of the base is influenced by the methanol amount resulting in a negative reaction order for methanol. (C) 2015 Elsevier Inc. All rights reserved.

Authors with CRIS profile

Involved external institutions

Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen Germany (DE) Evonik Degussa GmbH Germany (DE) University of St Andrews United Kingdom (GB)

How to cite

APA:

Völkl, L., Recker, S., Niedermaier, M., Kiermaier, S., Strobel, V., Maschmeyer, D.,... Haumann, M. (2015). Comparison between phosphine and NHC-modified Pd catalysts in the telomerization of butadiene with methanol - A kinetic study combined with model-based experimental analysis. Journal of Catalysis, 329, 547-559. https://doi.org/10.1016/j.jcat.2015.06.004

MLA:

Völkl, Lisa, et al. "Comparison between phosphine and NHC-modified Pd catalysts in the telomerization of butadiene with methanol - A kinetic study combined with model-based experimental analysis." Journal of Catalysis 329 (2015): 547-559.

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