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Polyoxometalate catalysts for biomass dissolution: understanding and design

  • Steven P. Kelley , Paula Berton , Andreas† Metlen and Robin D. Rogers EMAIL logo
Published/Copyright: May 31, 2018
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Abstract

The use of polyoxometalate catalysts for selective delignification of biomass presents a possible route toward using ionic liquids (ILs) to efficiently obtain high-molecular weight biopolymers from biomass. Rapid progress in this area will depend on recognizing and using the link with already well-developed inorganic chemistry in ILs pursued outside the field of biomass processing. Here, we use crystal structures determined from single crystal X-ray diffraction to better understand the behavior of [PV2Mo10O40]5-, a polyoxometalate catalyst known for its ability to promote selective delignification of biomass in the IL 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]). The crystal structure of [C2mim]5[PV2Mo10O40]·THF shows the formation of cationic shells around the anions which are likely representative of the interactions of this catalyst with [C2mim][OAc] itself. The reaction of NH4VO3 with [C2mim][OAc] is explored to better understand the chemistry of vanadium(V), which is critical to redox catalysis of [PV2Mo10O40]5-. This reaction gives crystals of [C2mim]4[V4O12], showing that this IL forms discrete metavanadates which are obtained from aqueous solutions in a specific pH range and indicating that the basicity of [OAc]- dominates the speciation of vanadium (V) in this IL.


†Current address: AMT1, Molenakkersstraat 51, 2910 Essen, Belgium


Acknowledgements

We would like to thank Dr. Mark Nieuwenhuyzen (Queen’s University Belfast) for structure refinement of [C2mim]5[PV2Mo10O40]·THF. This research was initiated at the Queen’s University Ionic Liquid Laboratory research center at Queen’s University Belfast and continued in the chemistry departments of The University of Alabama and McGill University. This research was undertaken, in part, thanks to funding from the Canada Excellence Research Chairs Program.

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Published Online: 2018-05-31

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