Détermination de la cellulose, des hémicelluloses, de la lignine et des cendres dans diverses cultures lignocellulosiques dédiées à la production de bioéthanol de deuxième génération

Various green energy crops are available for the production of renewable energy vectors such as second generation bioethanol. The efficiency of the energy recovery potential of these lignocellulosic crops depends on the crop husbandry, their content of main components (cellulose, hemicelluloses, lignin, ash) and on the second generation bioethanol production process. The lignocellulosic crops investigated in this study are miscanthus (Miscanthus x giganteus J.M.Greef & Deuter ex Hodk. & Renvoize), switchgrass (Panicum virgatum L.), fescue (Festuca arundinacea Schreb.), fiber sorghum (Sorghum bicolor (L.) Moench), fiber corn (Zea mays L.), "cocksfoot-alfalfa" mixture (Dactylis glomerata L. - Medicago sativa L.), comfrey (Symphytum officinale L.), jerusalem artichoke (aerial part) (Helianthus tuberosus L.) and hemp (Cannabis sativa L.). The samples came from different energy crop trials and their content in cellulose, hemicelluloses and lignin was quantified using the Van Soest method. The ash content has also been quantified. The lignocellulosic crops with the best theoretical potential to produce second generation bioethanol based on their biochemical composition (with a yield of 100% for the hydrolysis and the fermentation of cellulose and hemicelluloses) are in decreasing order miscanthus, switchgrass, fescue, fiber sorghum, fiber corn and hemp. On one hand, these crops are composed of high amounts of cellulose and hemicelluloses and, on the other hand, the lignin and ash concentration are low. A principal component analysis showed that commeniloĩd monocotyledonous and dicotyledonous lignocellulosic crops formed two differentiated categories.