Lignocellulosic biomass: a sustainable platform for the production of bio-based chemicals and polymers

In pursuit of more sustainable and competitive biorefineries, the effective valorisation of lignin is key. An alluring opportunity is the exploitation of lignin as a resource for chemicals. Three technological biorefinery aspects will determine the realisation of a successful lignin-to-chemicals valorisation chain, namely (i) lignocellulose fractionation, (ii) lignin depolymerisation, and (iii) upgrading towards targeted chemicals. This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations. To navigate the reader through the overwhelming collection of literature on each topic, distinct strategies/topics were delineated and summarised in comprehensive overview figures. Upon closer inspection, conceptual principles arise that rationalise the success of certain methodologies, and more importantly, can guide future research to further expand the portfolio of promising technologies. When targeting chemicals, a key objective during the fractionation and depolymerisation stage is to minimise lignin condensation (i.e. formation of resistive carbon–carbon linkages). During fractionation, this can be achieved by either (i) preserving the (native) lignin structure or (ii) by tolerating depolymerisation of the lignin polymer but preventing condensation through chemical quenching or physical removal of reactive intermediates. The latter strategy is also commonly applied in the lignin depolymerisation stage, while an alternative approach is to augment the relative rate of depolymerisation vs. condensation by enhancing the reactivity of the lignin structure towards depolymerisation. Finally, because depolymerised lignins often consist of a complex mixture of various compounds, upgrading of the raw product mixture through convergent transformations embodies a promising approach to decrease the complexity. This particular upgrading approach is termed funneling, and includes both chemocatalytic and biological strategies.

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Chemicals from lignin: an interplay of lignocellulose fractionation, depolymerisation, and upgrading

The demand for petroleum dependent chemicals and materials has been increasing despite the dwindling of their fossil resources. As the dead-end of petroleum based industry has started to appear, today's modern society has to implement alternative energy and valuable chemical resources immediately. Owing to the importance of lignocellulosic biomass being the most abundant and bio-renewable biomass on earth, this critical review provides insights into the potential of lignocellulosic biomass as an alternative platform to fossil resources. In this context, over 200 value-added compounds, which can be derived from lignocellulosic biomass by various treatment methods, are presented with their references. Lignocellulosic biomass based polymers and their commercial importance are also reported mainly in the frame of these compounds. This review article aims to draw the map of lignocellulosic biomass derived chemicals and their synthetic polymers, and to reveal the scope of this map in today's modern chemical and polymer industry.

Lignin is one of the main components of plant cell wall and it is a natural phenolic polymer with high molecular weight, complex composition and structure. Lignin biosynthesis extensively contributes to plant growth, tissue/organ development, lodging resistance and the responses to a variety of biotic and abiotic stresses. In the present review, we systematically introduce the biosynthesis of lignin and its regulation by genetic modification and summarize the main biological functions of lignin in plants and their applications. We hope this review will give an in-depth understanding of the important roles of lignin biosynthesis in various plants’ biological processes and provide a theoretical basis for the genetic improvement of lignin content and composition in energy plants and crops.

https://www.mdpi.com/1422-0067/19/2/335/pdf

Lignins: Biosynthesis and Biological Functions in Plants

https://pubs.rsc.org/en/content/articlepdf/2016/gc/c5gc03043a

New insights into the structure and composition of technical lignins: a comparative characterisation study

https://pubs.rsc.org/en/content/articlepdf/2014/gc/c3gc42184h

Biobased furandicarboxylic acids (FDCAs): effects of isomeric substitution on polyester synthesis and properties

Membrane separation and characterisation of lignin and its derived products obtained by a mild ethanol organosolv treatment of rice straw

Condensation products having adhesive properties are obtained by reaction of a polyamine with at least two equivalents of an oligosaccharide or a derivative thereof. Examples of the oligosaccharide include glucose, lactose, lactobionic acid and gluconic acid. Examples of the polyamine include diethylene triamine and triethylene tetraamine. The reaction may be a direct amination of the oligosaccharide, with the formation of a glycosylamine and optional N-acylation, or a reductive amination of the oligosaccharide, a glycitylamine being obtained, or alternatively an amidation of an glyconic acid. The condensation products can be used for gluing, for example, paper, cardboard, wood, plastic or glass at low or high temperature.

Sugar amines and sugar amides and use as glues

Diesters of dianhydroglycitols can be prepared by esterification of dianhydroglycitols, anhydroglycitols and/or glycitols with alkylcarboxylic or arylcarboxylic acids in the presence of an acid catalyst, the acid catalyst being a macroporous acid ion exchange resin. If glycitols or monoanhydroglycitols are used as the starting material, the reaction temperature is initially of the order of 120° C. and after the dehydration is approximately 140° C.

Augustinus Emmanuel Frissen

Papers

New insights into the structure and composition of technical lignins: a comparative characterisation study

Biobased furandicarboxylic acids (FDCAs): effects of isomeric substitution on polyester synthesis and properties

Membrane separation and characterisation of lignin and its derived products obtained by a mild ethanol organosolv treatment of rice straw

Sugar amines and sugar amides and use as glues

Synthesis of anhydroglycitol esters of improved colour