Thermochemical Conversion of Lignin for Fuels and Chemicals: A Review

Abstract

Re´sume´-Conversion thermochimique de la lignine en carburants et produits chimiques : une revue -La lignine est une des composantes de la biomasse lignocellulosique potentiellement valorisable comme ressource renouvelable pour la production de carburants ou de produits chimiques. Apre`s se´paration de la matrice lignocellulosique, cette macromole´cule est de nos jours essentiellement utilise´e comme combustible dans l'industrie papetie`re. Outre cette filie`re papetie`re, la production d'e´thanol de seconde ge´ne´ration a`partir de la cellulose aura comme conse´quence la mise a`disponibilite´d'encore plus grandes quantite´s de lignine. De nouvelles applications pourront donc eˆtre propose´es pour l'utilisation de cette bio-ressource. Les diffe´rentes voies thermochimiques : pyrolyse, solvolyse, conversion hydrothermale et hydroconversion envisage´es pour la valorisation de la lignine sont de´crites dans cet article.Abstract -Thermochemical Conversion of Lignin for Fuels and Chemicals: A Review -Lignin is one of the biomass components potentially usable as renewable resource to produce fuels or chemicals. After separation from the lignocellulosic matrix, this macromolecule is nowadays essentially valorized by combustion in paper mills. If second generation ethanol is produced in the future from lignocellulosic biomass, some increasing reserves of lignin will be available in addition to the ones coming from the paper industry. The main thermochemical ways such as pyrolysis, solvolysis, hydrothermal conversion and hydroconversion considered for the valorization of the lignin are reviewed in this article.

Recent advances on the utilization of layered double hydroxides (LDHs) and related heterogeneous catalysts in a lignocellulosic-feedstock biorefinery scheme

“…Lignin is a rather complex three-dimensional amorphous polymer based on hydroxyl-phenylpropane units issued from three monomers: p-coumaryl, coniferyl and synapyl alcohols differently distributed depending on the vegetal source (softwood, hardwood or grass) 215,216 (Fig. 20a).…”

Theoretical kinetic study for methyl levulinate: oxidation by OH and CH3 radicals and further unimolecular decomposition pathways

“…The development of methods to process biomass components i.e. cellulose, hemicellulose, and lignin to chemical platforms with a focus on yields, cost, and possibility for adaptation to industrial scale is a challenging task that receives growing attention [2][3][4] . Among these platforms one finds, furfural and levulinic acid 2, 5, 6 part of the ten most interesting compounds that can be produced from biomass, according to the US Department of Energy 7 .…”

Lignin pyrolysis for profitable lignocellulosic biorefineries

“…in catalytic hydrogenation or conversion in supercritical fluids). For example, until now only the Japanese Noguchi process (catalytic hydrogenolysis of desulfonated lignin after lignin liquefaction by a treatment with phenol) and the American Lignol process (liquid phase catalytic hydroconversion) have been practised as the two main industrial processes to produce chemicals from lignin . Both processes were abandoned a long time ago for various reasons such as low yields, high lignin production costs, and high capital and/or operational costs.…”

“…Then, detailed physico‐chemical (including chemical reactivity) and biochemical (including biochemical reactivity) characterization is needed to assess the specific character of the lignin . Following a detailed characterization, preferred applications that match lignin's characteristics have to be found.…”