Depolymerization of lignins and their applications for the preparation of polyols and rigid polyurethane foams: A review

Author

Nubla Mahmood, Zhongshun Yuan, John Schmidt and Xu, Chunbao (Charles)

Renewable and Sustainable Energy Reviews, 2016, vol. 60, issue C, pages 317-329

Abstract: Lignin, nature’s dominant aromatic polymer, is found in most terrestrial plants in the range of 15–40% dry weight and provides structural integrity. Kraft lignin (KL) is a major by-product of pulp & paper industry where, hydrolysis lignin (HL) is the solid residue left from the enzymatic hydrolysis of wood after the pretreatment processes in cellulosic ethanol plants. Currently, most of the lignin is burned to generate heat and electricity and remaining is considered as a low value material. Only 1% of the annually produced lignin is being commercialized for its application in the preparation of bio-chemicals and to limited extent for bio-materials. Although with much lower reactivity, even crude lignin (a natural polyol) can be directly incorporated into polyurethane (PU) foam formulation due to the presence of aliphatic and aromatic hydroxyl groups in its structure as the reactive sites. However, bio-replacement ratios are usually low ~20–30% and further increasing replacement ratios results in fragile and low strength foams. Lignin depolymerization with selective bond cleavage is still a major challenge for converting it into value-added precursors especially for its utilization in the preparation of rigid PU foams. Depolymerization of these macromolecules can result in the valuable products with high hydroxyl number/functionality and low molecular weights, which in turn will increase the percentage replacement of bio-based polyols in the PU foam formulations. The technical routes/technologies for the depolymerization of lignins and their effective utilization as polyols in PU foams are summarized in this review article. These include direct utilization of lignin as well as the incorporation of depolymerized lignins, with and without modification, at high replacement ratios in PU foams. The major emphasis was given on the effective utilization of low value lignin for high value applications. Some of the associated challenges for the production of materials from lignin are also discussed.

Keywords: Kraft lignin; Hydrolysis lignin; Depolymerization; Polyols; Rigid polyurethane foam (search for similar items in EconPapers)
Date: 2016
References: View references in EconPapers View complete reference list from CitEc
Citations Track citations by RSS feed

Downloads: (external link)
http://www.sciencedirect.com/science/article/pii/S1364032116000678
Full text for ScienceDirect subscribers only

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: http://EconPapers.repec.org/RePEc:eee:rensus:v:60:y:2016:i:c:p:317-329

Ordering information: This journal article can be ordered from
http://www.elsevier.com/wps/find/journaldescription.cws_home/600126/bibliographic
http://www.elsevier. ... 600126/bibliographic

Access Statistics for this article

Renewable and Sustainable Energy Reviews is currently edited by L. Kazmerski

More articles in Renewable and Sustainable Energy Reviews from Elsevier
Series data maintained by Dana Niculescu (repec@elsevier.com).

For further details log on website :
http://econpapers.repec.org/article/eeerensus/v_3a60_3ay_3a2016_3ai_3ac_3ap_3a317-329.htm