Lignin Depolymerization with Nitrate-Intercalated Hydrotalcite Catalysts

Kruger, Jacob S.; Cleveland, Nicholas S.; Zhang, Shuting; Katahira, Rui; Black, Brenna A.; Chupka, Gina M.; Lammens, Tijs; Hamilton, Phillip G.; Biddy, Mary J.; Beckham, Gregg T.

doi:10.1021/acscatal.5b02062

DOE OSTI · 1238322

Lignin Depolymerization with Nitrate-Intercalated Hydrotalcite Catalysts

Kruger, Jacob S.·Cleveland, Nicholas S.·Zhang, Shuting·Katahira, Rui·Black, Brenna A.·Chupka, Gina M.·Lammens, Tijs·Hamilton, Phillip G.·Biddy, Mary J.·Beckham, Gregg T.

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Abstract

Hydrotalcites (HTCs) exhibit multiple adjustable parameters to tune catalytic activity, including interlayer anion composition, metal hydroxide layer composition, and catalyst preparation methods. Here in this paper, we report the influence of several of these parameters on β-O-4 bond scission in a lignin model dimer, 2-phenoxy-1-phenethanol (PE), to yield phenol and acetophenone. We find that the presence of both basic and NO 3 – anions in the interlayer increases the catalyst activity by 2–3-fold. In contrast, other anions or transition metals do not enhance catalytic activity in comparison to blank HTC. The catalyst is not active for C–C bond cleavage on lignin model dimers and has no effect on dimers without an α-OH group. Most importantly, the catalyst is highly active in the depolymerization of two process-relevant lignin substrates, producing a significant amount of low-molecular-weight aromatic species. The catalyst can be recycled until the NO 3 – anions are depleted, after which the activity can be restored by replenishing the NO 3 – reservoir and regenerating the hydrated HTC structure. These results demonstrate a route to selective lignin depolymerization in a heterogeneous system with an inexpensive, earth-abundant, commercially relevant, and easily regenerated catalyst.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY catalyst recycle catalyst regeneration layered double hydroxide lignin nitration lignin valorization

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Kruger, Jacob S., Cleveland, Nicholas S., Zhang, Shuting, Katahira, Rui, Black, Brenna A., Chupka, Gina M., Lammens, Tijs, Hamilton, Phillip G., Biddy, Mary J., Beckham, Gregg T.. 2016-01-13. Lignin Depolymerization with Nitrate-Intercalated Hydrotalcite Catalysts. https://doi.org/10.1021/acscatal.5b02062

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