Kraft lignin reaction with paraformaldehyde
Author:
Paananen Hanna1, Pakkanen Tuula T.1
Affiliation:
1. Department of Chemistry , University of Eastern Finland , P.O. Box 111 , FI-80101 Joensuu , Finland
Abstract
Abstract
Lignin is the second most abundant biopolymer and will be an important source for carbon-containing compounds in the future. Based on their similar phenolic structures, lignin has great potential to become a valuable substitute for phenol in phenol-formaldehyde resin adhesives. To meet this aim, the sodium hydroxide (NaOH)-catalyzed reaction of kraft lignin with formaldehyde was studied by using paraformaldehyde (PFA) as a formaldehyde source. The advantage of using PFA, the solid polymer of formaldehyde, is the simple composition of the depolymerized solution. According to the results of differential scanning calorimetry (DSC), the lignin reaction was found to require a high NaOH concentration in order for the reaction with PFA to proceed at reasonably low temperatures compared to the curing temperature of phenol-formaldehyde resins (approximately 150°C). On the other hand, high alkalinity conditions are known to favor the disproportionation of formaldehyde to formic acid and methanol. Due to the moderate reactivity of lignin, the Cannizzaro reaction can compete with the methylolation reaction of lignin. Based on the results of 13C, 31P and 1H-13C heteronuclear single quantum correlation nuclear magnetic resonance (HSQC NMR), methylolation was found to be the main reaction occurring in the lignin-formaldehyde reaction.
Publisher
Walter de Gruyter GmbH
Reference49 articles.
1. Aminzadeh, S., Lauberts, M., Dobele, G., Ponomarenko, J., Mattsson, T., Lindström, M.E., Sevastyanova, O. (2018) Membrane filtration of kraft lignin: structural charactristics and antioxidant activity of the low-molecular-weight fraction. Ind. Crops Prod. 112:200–209. 2. Balakshin, M., Capanema, E. (2015) On the quantification of lignin hydroxyl groups with 31P and 13C NMR spectroscopy. J. Wood Chem. Technol. 35:220–237. 3. Bröll, D., Kaul, C., Krämer, A., Krammer, P., Richter, T., Jung, M., Vogel, H., Zehner, P. (1999) Chemistry in supercritical water. Angew. Chem. Int. Ed. 38:2998–3014. 4. Chakar, F.S., Ragauskas, A.J. (2004) Review of current and future softwood kraft lignin process chemistry. Ind. Crops Prod. 20:131–141. 5. Constant, S., Wienk, H.L.J., Frissen, A.E., de Peinder, P., Boelens, R., van Es, D.S., Grisel, R.J.H., Weckhuysen, B.M., Huijgen, W.J.J., Gosselink, R.J.A., Bruijnincx, P.C.A. (2016) New insights into the structure and composition of technical lignins: a comparative characterisation study. Green Chem. 18:2651–2665.
Cited by
6 articles.
订阅此论文施引文献
订阅此论文施引文献，注册后可以免费订阅5篇论文的施引文献，订阅后可以查看论文全部施引文献
|
|