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Title: In-depth investigation on quantitative characterization of pyrolysis oil by 31P NMR

The characterization of different heteroatom functional groups by employing 31P NMR has been developed for almost 30 years. In this study, an in-depth investigation of this commonly used method has been accomplished for the analysis of pyrolysis oil. Several commonly used internal standards for 31P NMR have been examined by in situ monitoring. The results indicated that endo-N-hydroxy-5-norbornene-2,3-dicarboximide (NHND) is not stable after a long period of storage or experiment (>12 hours), but both cyclohexanol and triphenylphosphine oxide (TPPO) can be used as internal standards if a long experiment or storage is required. The pyrolysis oil has also been investigated by both short time (16 hours) in situ monitoring and long time (14 days) ex situ monitoring. The results showed that aliphatic OH, carboxylic acids and water contents are not very stable after 2 hours, and thus a short time of preparation, storage, and experiment need to be considered to ensure a precise quantitative measurement. The decomposition products are still unclear, but some preliminary investigations for different acids, (e.g. formic acid) have been accomplished. The results indicated that the aromatic carboxylic acids (benzoic acid and vanillic acid) are more stable than formic acid and acetic acid. Interestingly, the formic acidmore » will even decompose to some other compounds at the very beginning of the in situ monitoring test. Further characterization found that water is one of the major products for the decomposition of formic acid in the 31P NMR solution. Finally, as far as we know, this is the first report on such time-dependent changes when using 31P NMR to analyze the pyrolysis oil, and these results show that proper application of this method is essential to achieve reliable quantitative data.« less
Authors:
 [1] ;  [1]
  1. National Renewable Energy Lab. (NREL), Golden, CO (United States). National Bioenergy Center
Publication Date:
OSTI Identifier:
1239891
Report Number(s):
NREL/JA--5100-65452
Journal ID: ISSN 2046-2069; RSCACL
Grant/Contract Number:
AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
RSC Advances
Additional Journal Information:
Journal Volume: 6; Journal Issue: 21; Journal ID: ISSN 2046-2069
Publisher:
Royal Society of Chemistry
Research Org:
National Renewable Energy Laboratory (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; 09 BIOMASS FUELS NMR; 31P; pyrolysis; bio-oils; analytical; biofuels