TY - JOUR
T1 - Quantification and classification of carbonyls in industrial humins and lignins by 19F NMR
AU - Constant, Sandra
AU - Lancefield, Christopher S.
AU - Weckhuysen, Bert M.
AU - Bruijnincx, Pieter C.A.
N1 - This project has been performed within the framework of the CatchBio program. The authors gratefully acknowledge the financial support of the Smart Mix Program of The Netherlands Ministry of Economic Affairs and The Netherlands Ministry of Education, Culture and Science.
PY - 2017/1/3
Y1 - 2017/1/3
N2 - Lignin and humins are both (by-)products of biorefining processes aimed at the valorization of lignocellulosic biomass. In order to improve the efficiency of such biorefineries and to develop new valorization pathways for these polymeric materials, detailed insight into their complex chemical structure and functional group distribution is required. Here, we report on the quantification and classification of the ketone and aldehyde carbonyl functional groups contained in these two polymers by 19F NMR. The known method of carbonyl derivatization with 4-(trifluoromethyl)phenylhydrazine to the corresponding hydrazone has been improved and simplified, allowing derivatization directly in an NMR tube, requiring no additional workup before quantification by 19F NMR. Furthermore, the scope of the method was assessed and expanded, with model compound studies, which included monomeric and dimeric compounds as well as synthetic polymers, showing that the carbonyl functions can indeed be reproducibly quantified. Using this model compound library, the carbonyl functional groups in two technical lignins (Indulin Kraft and Alcell) and, for the first time, an industrial humin could be quantified and classified. The industrial humin was found to contain 6.6 wt % of carbonyl functions, with aliphatic and conjugated carbonyls being detected. The relatively high abundance of such functional groups, which are amenable to further chemical modification, provides opportunities for the use of these humin byproducts in various applications, e.g., as materials after derivatization.
AB - Lignin and humins are both (by-)products of biorefining processes aimed at the valorization of lignocellulosic biomass. In order to improve the efficiency of such biorefineries and to develop new valorization pathways for these polymeric materials, detailed insight into their complex chemical structure and functional group distribution is required. Here, we report on the quantification and classification of the ketone and aldehyde carbonyl functional groups contained in these two polymers by 19F NMR. The known method of carbonyl derivatization with 4-(trifluoromethyl)phenylhydrazine to the corresponding hydrazone has been improved and simplified, allowing derivatization directly in an NMR tube, requiring no additional workup before quantification by 19F NMR. Furthermore, the scope of the method was assessed and expanded, with model compound studies, which included monomeric and dimeric compounds as well as synthetic polymers, showing that the carbonyl functions can indeed be reproducibly quantified. Using this model compound library, the carbonyl functional groups in two technical lignins (Indulin Kraft and Alcell) and, for the first time, an industrial humin could be quantified and classified. The industrial humin was found to contain 6.6 wt % of carbonyl functions, with aliphatic and conjugated carbonyls being detected. The relatively high abundance of such functional groups, which are amenable to further chemical modification, provides opportunities for the use of these humin byproducts in various applications, e.g., as materials after derivatization.
KW - Biomass
KW - Carbonyl quantification
KW - Functional group analysis
KW - Humin
KW - Lignin
U2 - 10.1021/acssuschemeng.6b02292
DO - 10.1021/acssuschemeng.6b02292
M3 - Article
AN - SCOPUS:85008440398
SN - 2168-0485
VL - 5
SP - 965
EP - 972
JO - ACS Sustainable Chemistry and Engineering
JF - ACS Sustainable Chemistry and Engineering
IS - 1
ER -