(270f) Renewable Butadiene Production from Tetrahydrofuran over HZSM-5

Butadiene is an indispensable monomer to the production of synthetic rubber.¹ It is also used in other important copolymers with unique characteristics, such as styrene-butadiene rubber (SBR) and the impact-resistant ABS (acrylonitrile-butadiene-styrene) plastic. In the classic petrochemical approach butadience is recovered after separation of the C4 cut from naphtha crackers, where ethylene is the main product. However, the recent shale gas revolution increases reliance on non-conventional, shale-derived feeds for ethylene production, which leads to a shortage in C3/C4 olefins including butadiene.² Therefore, new, on-purpose butadiene production routes that are not coupled to ethylene production need to be developed.

In this work, we present a bio-based route to butadiene from tetrahydrofuran (THF), which can be produced by decarbonylation and reduction of biomass-derived furfural. The Brønsted-acidic zeolite HZSM-5 has shown good selectivity for THF dehydration to butadiene at low conversions, but the selectivity decreases at high conversions, due to byproducts such as formaldehyde and propene.³ In this paper, we present different decomposition pathways of THF on HZSM-5 using density functional theory (DFT) calculations, and elucidate reaction mechanisms for the formation of butadiene, formaldehyde and propene. . In addition, we develop a microkinetic model in order to identify key surface intermediates and the rate-limiting step and compare with experimentally obtained apparent activation energies and kinetics.

References:

1. Wagemann, K., Chemie Ingenieur Technik 2014, 86 (12), 2115-2134.

2. Bruijnincx, P. C. A.; Weckhuysen, B. M., Angewandte Chemie-International Edition 2013, 52 (46), 11980-11987.

3. Abdelrahman, O. A.; Park, D. S.; Vinter, K. P.; Spanjers, C. S.; Ren, L.; Cho, H. J.; Vlachos, D. G.; Fan, W.; Tsapatsis, M.; J., D. P., ACS Sustainable Chemistry and Engineering 2017, DOI: 10.1021/acssuschemeng.7b00745.