A. J. Ragauskas, C. K. Williams, B. H. Davison, G. Britovsek, J. Cairney et al., The Path Forward for Biofuels and Biomaterials. Science, issue.5760, pp.484-489, 2006.

R. El-hage, N. Brosse, L. Chrusciel, C. Sanchez, P. Sannigrahi et al., Characterization of milled wood lignin and ethanol organosolv lignin from miscanthus

, Polym. Degrad. Stab, vol.94, pp.1632-1638, 2009.

R. El-hage, L. Chrusciel, L. Desharnais, and N. Brosse, Effect of Autohydrolysis of Miscanthus x giganteus on Lignin Structure and Organosolv Delignification, Bioresour. Technol, vol.101, pp.9321-9329, 2010.

N. Jacquet, G. Maniet, C. Vanderghem, F. Delvigne, and A. Richel, Application of Steam Explosion as Pretreatment on Lignocellulosic Material: A Review, Ind. Eng. Chem. Res, vol.54, 2015.

M. Heitz, E. Capek-menard, P. G. Koeberle, J. Gagne, E. Chornet et al., Fractionation of Populus tremuloides at the pilot plant scale: optimization of steam pretreatment conditions using the STAKE II technology, Bioresour. Technol, vol.35, issue.1, pp.23-32, 1991.

L. A. Donaldson, K. K. Wong, and K. L. Mackie, Ultrastructure of steam-exploded wood, Wood Sci. Technol, vol.22, pp.103-114, 1988.

H. Chen and L. Liu, Unpolluted fractionation of wheat straw by steam explosion and ethanol extraction, Bioresour. Thechnol, vol.98, pp.666-676, 2007.

J. Li, G. Gellerstedt, and K. Toven, Steam explosion lignins; their extraction, structure and potential as feedstock for biodiesel and chemicals, Bioresour. Technol, vol.100, pp.2556-2561, 2009.

S. N. Sun, X. F. Cao, F. Xu, R. C. Sun, and G. L. Jones, Structural Features and Antioxidant Activities of Lignins from Steam-Exploded Bamboo (Phyllostachys pubescens), J. Agric. Food Chem, vol.62, pp.5939-5947, 2014.

T. M. Jarrell, C. L. Marcum, H. Sheng, B. C. Owen, C. J. O'lenick et al., Characterization of organosolv switchgrass lignin by using high 20 performance liquid chromatography/high resolution tandem mass spectrometry using hydroxide-doped negative-ion mode electrospray ionization, Green Chem, vol.16, issue.5, pp.2713-2727, 2014.

R. Martin-sampedro, E. A. Capanema, I. Hoeger, J. C. Villar, and O. J. Rojas, Lignin Changes after Steam Explosion and Laccase-Mediator Treatment of Eucalyptus Wood Chips

. Agric, Food Chem, vol.59, pp.8761-8769, 2011.

J. Li, G. Henriksson, and G. Gellerstedt, Lignin depolymerization/repolymerization and its critical role for delignification of aspen wood by steam explosion, Bioresource Technology, vol.98, pp.3061-3068, 2007.

T. Piellhop, J. Amgarten, and M. H. Studer, Rudolf von Rohr P. Pilot-scale steam explosion pretreatment with 2-naphthol to overcome high softwood recalcitrance, Biotechnology for Biofuels, vol.10, p.130, 2017.

H. Heikkinen, T. Elder, H. Maaheimo, S. Rovio, J. Rahikainen et al., Impact of Steam Explosion on the Wheat Straw Lignin Structure Studied by Solution-State Nuclear Magnetic Resonance and Density Functional Methods, J. Agric. Food Chem, vol.62, pp.10437-10444, 2014.

A. O. Yoan, Y. Xue, and M. J. Kiki, Gabon Wood Industry and Chinese Companies Activities, vol.05, pp.1-15, 2018.

N. S. Nguema, Présentation du Secteur Forestier au Gabon:Rapport sur l'évolution de la mise en oeuvre de la politique du Gouvernement dans les secteurs Forêts

. Aquatculture, Rapport sur l'évolution de la mise en oeuvre de la politique du Gouvernement dans les secteurs Forêts,Pêches et Aquatculture, Aires protégées et Formation, 2009.

, eur+Forestier+au+Gabon/eb4427e5-f61c-4b09-83c3-6ab5bcfa14b4?

R. Safou-tchiama, S. N. Obame, N. Brosse, P. Soulounganga, and T. A. Barhe, Investigating the potential of Aucoumea klaineana Pierre sapwood and heartwood wastes to produce cellulosic ethanol, African Journal of Biotechnology, vol.15, issue.46, pp.2587-2595, 2016.

R. Safou-tchiama, P. Soulounganga, P. S. Engozogho-anris, A. Bikoro-bi-athomo, T. Barhé et al., Understanding the natural durability of some African tropical heartwoods toward Pycnoporus sanguineus and Antrodia sp.: lignin structure and cellulose morphology control, Journal of the Indian Academy of Wood Sciences, vol.15, issue.2, pp.162-171, 2018.

R. P. Overend and E. Chornet, Fractionation of lignocellulosics by steam-aqueous pretreatments, Phil Trans R Soc Lond A, vol.321, pp.523-536, 1987.

A. Granata and D. S. Argyropoulos, 2-chloro-4,4,5,5-tetramethyl-1,3,2-dioxaphospholane, a reagent for the accurate determination of the uncondensed and condensed phenolic moieties in lignins, J Agric Food Chem, vol.43, pp.1538-1544, 1995.

H. Guo, B. Zhang, Z. Qi, C. Li, J. Ji et al.,

, ChemSusChem, vol.10, pp.523-532, 2017.

X. Wang, Y. Guo, J. Zhou, and G. Sun, Structural changes of poplar wood lignin after supercritical pretreatment using carbon dioxide and ethanol -water as co-solvents, RCS Adv, vol.7, pp.8314-8322, 2017.

T. Auxenfans, D. Cronier, B. Chabbert, and G. Paes, Understanding the structural and chemical changes of plant biomass following steam explosion pretreatment, Biotechnology for Biofuels, vol.10, pp.36-37, 2017.
URL : https://hal.archives-ouvertes.fr/hal-01602522

U. Westermark, B. Samuelsson, and K. Lundquist, Homolytic cleavage of ?-ether-bond in phenolic beta-O-4 structures in wood lignin and in guaiacylglyrerol-?-guaiacyl ether, Res. Chem. Intermed, vol.21, issue.3-5, pp.343-352, 1995.

M. Tanahashi, Characterization and degradation mechanisms of wood components by steam explosion and utilization of exploded wood, vol.77, pp.49-117, 1990.

, Table 2 Assignments of 13 C/ 1 H cross signals in HSQC NMR spectra ?C/?H(ppm)

, C?/H? in resinol substructure (B)

, C?/H? in phenyl coumaran substructure (C)

, C?/H? in ?-O-4 linkage (A)

, C?/H? in phenyl coumaran substructure (C)

, C?/H? in resinol substructure (B)

, C?/H? in ?-O-4 linkage (A)

, C?/H? in ?-O-4 linkage from guaiacyl units (A)

, C?/H? in ?-O-4 linkage from syringyl units (A)

, C?/H? in resinol substructure (B)

, C?/H ? in phenyl coumaran substructure (C)

, C2,6/H2,6 in syringyle units (S)

, C2,6/H2,6 condensed in syringyl units (S)

, C2,6/H2,6 in oxydised syringyl units (S')

, C2/H2 in oxydised guaiacyl units

, C2/H2 in Ferulate (FA)

, C?/H? in ferulate (FA)

, C2,6/H2, vol.6, pp.p-hydroxyphenyl

, C2,6/H2,6 in p-hydroxybenzoate units, p.2