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Title: Lignin Depolymerization with Nitrate-Intercalated Hydrotalcite Catalysts

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 NO3– 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 NO3– anions are depleted, after which the activity can be restored by replenishing the NO3– 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.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States). National Bioenergy Center
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States). Hydrogen and Transportation Systems Center
  3. Shell Global Solutions, Inc., Houston, TX (United States). Shell Technology Center
  4. Shell Global Solutions, Inc., Amsterdam (Netherlands). Shell Technology Center
Publication Date:
OSTI Identifier:
1238322
Report Number(s):
NREL/JA-5100-65864
Journal ID: ISSN 2155-5435
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
ACS Catalysis
Additional Journal Information:
Journal Volume: 6; Journal Issue: 2; Journal ID: ISSN 2155-5435
Publisher:
American Chemical Society (ACS)
Research Org:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANAYLYTICAL CHEMISTRY; lignin valorization; lignin nitration; layered double hydroxide; catalyst recycle; catalyst regeneration