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Renewable 1,3-butadiene (1,3-BD, C4H6) was synthesized from the tandem decyclization and dehydration of biomass-derived tetrahydrofuran (THF) on weak Brønsted acid zeolite catalysts. 1,3-BD is a highly solicited monomer for the synthesis of rubbers and elastomers. Selective conversion of THF to 1,3-BD was recently measured on phosphorus-modified siliceous zeolites (P-zeosils) at both high and low space velocities, albeit with low per-site catalytic activity. In this work, we combined kinetic analyses and QM/MM calculations to evaluate the interaction of THF with the various Brønsted acid sites (BAS) of Boric (B), Phosphoric (P), and Sulfuric (S) acid modified silicalite-1 catalysts toward a dehydra-decyclization pathway to form 1,3-BD. Detailed kinetic measurements revealed that all three catalysts exhibited high selectivity to 1,3-BD ca. 64–96% in the order of S-MFI > P-MFI > B-MFI at a given temperature (360 °C). Notably, the S-MFI maintained a selectivity >90% for all evaluated process conditions. The computational results suggested that the nature of the Brønsted acid sites and the adsorption energetics (relative THF-acid site interaction energies) are distinct in each catalyst. Additionally, the protonation of THF can be improved with the addition of a water molecule acting as a proton shuttle, particularly in S-MFI. Overall, S-containing zeosils exhibited the ability to control reaction pathways and product distribution in dehydra-decyclization chemistry optimization within microporous zeolites, providing another alternative weak-acid catalytic material.
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Catalytic dehydration of levoglucosan to levoglucosenone using Brønsted solid acid catalysts in tetrahydrofuran
We studied the production of levoglucosenone (LGO) via levoglucosan (LGA) dehydration using Brønsted solid acid catalysts in tetrahydrofuran (THF). The use of propylsulfonic acid functionalized silica catalysts increased the production of LGO by a factor of two compared to the use of homogeneous acid catalysts. We obtained LGO selectivities of up to 59% at 100% LGA conversion using solid Brønsted acid catalysts. Water produced during the reaction promotes the solvation of the acid proton reducing the activity and the LGO production. Using solid acid catalysts functionalized with propylsulfonic acid reduces this effect. The hydrophilicity of the catalyst surface seems to have an effect on reducing the interaction of water with the acid site, improving the catalyst stability.
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- Award ID(s):
- 1632824
- PAR ID:
- 10182017
- Date Published:
- Journal Name:
- Green Chemistry
- Volume:
- 21
- Issue:
- 18
- ISSN:
- 1463-9262
- Page Range / eLocation ID:
- 4988 to 4999
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/C9GC01526D
