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Title: Characterization of the Water-Soluble Fraction of Woody Biomass Pyrolysis Oils

Abstract

This paper reports a study of the chemical composition of the water soluble (WS) fraction obtained by cold water precipitation of two commercial wood pyrolysis oils (BTG and Amaron). The fraction studied accounts for between 50.3 and 51.3 wt. % of the oils. With the most common analytical techniques used today for the characterization of this fraction (KF titration, GC/MS, hydrolysable sugars and total carbohydrates), it is possible to quantify only between 45 and 50 wt. % of it. Our results confirm that most of the total carbohydrates (hydrolysable sugars and non-hydrolysable) are soluble in water. The ion chromatography hydrolysis method showed that between 11.6 and 17.3 wt. % of these oils were hydrolysable sugars. A small quantity of phenols detectable by GC/MS (between 2.5 and 3.9 wt. %) were identified. It is postulated that the unknown high molecular weight fraction (30-55 wt. %) is formed by highly dehydrated sugars rich in carbonyl groups and WS phenols. The overall content of carbonyl, carboxyl, hydroxyl and phenolic compounds in the WS fraction were quantified by titration, Folin-Ciocalteu, 31P-NMR and 1H-NMR. The WS fraction contains between 5.5 and 6.2 mmol/g of carbonyl groups, between 0.4 and 1.0 mmol/g of carboxylic acid groups,more » between 1.2 and 1.8 mmol/g phenolic -OH, and between 6.0 and 7.9 mmol/g of aliphatic alcohol groups. Translation into weight fractions of the WS was done by supposing surrogate structures for the water soluble phenols, carbonyl and carboxyl groups and we estimated the content of WS phenols (21-27 wt. %), carbonyl (5-14 wt.%), and carboxyl (0-4 wt.%). Together with the total carbohydrates (23-27 wt.%), this approach leads to > 90 wt. % of the WS material in the bio-oils being quantified. We speculate the larger portion of the difference between the total carbohydrates and hydrolysable sugars is the missing furanic fraction. Further refinement of the suggested methods and development of separation schemes to obtain and quantify sub-fractions with homogeneous composition (e.g. carbohydrates, high molecular weight WS phenols, furans, and dehydrated sugars) warrant further investigation.« less

Authors:
; ; ; ; ORCiD logo
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Bioenergy Technologies Office (EE-3B)
OSTI Identifier:
1356497
Report Number(s):
PNNL-SA-121870
Journal ID: ISSN 0887-0624
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Energy and Fuels; Journal Volume: 31; Journal Issue: 2
Country of Publication:
United States
Language:
English

Citation Formats

Stankovikj, Filip, McDonald, Armando G., Helms, Gregory L., Olarte, Mariefel V., and Garcia-Perez, Manuel. Characterization of the Water-Soluble Fraction of Woody Biomass Pyrolysis Oils. United States: N. p., 2017. Web. doi:10.1021/acs.energyfuels.6b02950.
Stankovikj, Filip, McDonald, Armando G., Helms, Gregory L., Olarte, Mariefel V., & Garcia-Perez, Manuel. Characterization of the Water-Soluble Fraction of Woody Biomass Pyrolysis Oils. United States. doi:10.1021/acs.energyfuels.6b02950.
Stankovikj, Filip, McDonald, Armando G., Helms, Gregory L., Olarte, Mariefel V., and Garcia-Perez, Manuel. Tue . "Characterization of the Water-Soluble Fraction of Woody Biomass Pyrolysis Oils". United States. doi:10.1021/acs.energyfuels.6b02950.
@article{osti_1356497,
title = {Characterization of the Water-Soluble Fraction of Woody Biomass Pyrolysis Oils},
author = {Stankovikj, Filip and McDonald, Armando G. and Helms, Gregory L. and Olarte, Mariefel V. and Garcia-Perez, Manuel},
abstractNote = {This paper reports a study of the chemical composition of the water soluble (WS) fraction obtained by cold water precipitation of two commercial wood pyrolysis oils (BTG and Amaron). The fraction studied accounts for between 50.3 and 51.3 wt. % of the oils. With the most common analytical techniques used today for the characterization of this fraction (KF titration, GC/MS, hydrolysable sugars and total carbohydrates), it is possible to quantify only between 45 and 50 wt. % of it. Our results confirm that most of the total carbohydrates (hydrolysable sugars and non-hydrolysable) are soluble in water. The ion chromatography hydrolysis method showed that between 11.6 and 17.3 wt. % of these oils were hydrolysable sugars. A small quantity of phenols detectable by GC/MS (between 2.5 and 3.9 wt. %) were identified. It is postulated that the unknown high molecular weight fraction (30-55 wt. %) is formed by highly dehydrated sugars rich in carbonyl groups and WS phenols. The overall content of carbonyl, carboxyl, hydroxyl and phenolic compounds in the WS fraction were quantified by titration, Folin-Ciocalteu, 31P-NMR and 1H-NMR. The WS fraction contains between 5.5 and 6.2 mmol/g of carbonyl groups, between 0.4 and 1.0 mmol/g of carboxylic acid groups, between 1.2 and 1.8 mmol/g phenolic -OH, and between 6.0 and 7.9 mmol/g of aliphatic alcohol groups. Translation into weight fractions of the WS was done by supposing surrogate structures for the water soluble phenols, carbonyl and carboxyl groups and we estimated the content of WS phenols (21-27 wt. %), carbonyl (5-14 wt.%), and carboxyl (0-4 wt.%). Together with the total carbohydrates (23-27 wt.%), this approach leads to > 90 wt. % of the WS material in the bio-oils being quantified. We speculate the larger portion of the difference between the total carbohydrates and hydrolysable sugars is the missing furanic fraction. Further refinement of the suggested methods and development of separation schemes to obtain and quantify sub-fractions with homogeneous composition (e.g. carbohydrates, high molecular weight WS phenols, furans, and dehydrated sugars) warrant further investigation.},
doi = {10.1021/acs.energyfuels.6b02950},
journal = {Energy and Fuels},
number = 2,
volume = 31,
place = {United States},
year = {Tue Jan 31 00:00:00 EST 2017},
month = {Tue Jan 31 00:00:00 EST 2017}
}