An alternative to produce value added bio-based products from sugarcane bagasse

CLAUSER, N.; GUTIÉRREZ, S.; FELISSIA, F.; AREA M. C.; VALLEJOS M.E.

Concepción

Congreso; 3er Congreso Iberoamericano sobre Biorrefinerías (CIAB), 4to Congreso Latinoamericano sobre Biorrefinerías, y 2do Simposio Internacional sobre Materiales Lignocelulósicos; 2015

CIADEB-RIADICYP-PROVALOR-BIOREN- Centro de Biotecnología UdeC- Unidad de Desarrollo Tecnológico (UDT)- VTT

Small-sizedbiorefineries are not capital intensive and have lower transportation cost,lesser movements of liquid and solid streams, and lower heat transfer problemsthan high-sized ones. Xylitol production consists of the following stages:autohydrolysis of the hemicellulose of bagasse, concentration of spent liquor,acid post-hydrolysis, removal of inhibitors by adsorption, fermentation ofxylose to xylitol, and xylitol recovery by crystallization. A simplifiedkinetic model was developed for the extraction of xylose in the autohydrolysisprocess. Kinetic constantskhandk1were determined, and activation energies Eaand Ln(ko) for the kinetic reactions were calculated from the Arrhenius equations.Experimental data obtained by Vallejos et al., were used for the autohydrolysispretreatment step. Temperature and time for the maximum extraction of xylanswith minimal energy demand were determined with the model. The conditions andreactions for the other stages of the process were selected from updated bibliography.In addition, costs and benefits that could be obtained by exploiting theresidual solid feedstock were estimated. Sugarcane is so far the most efficientraw material for bioethanol production, involving four major unit operations:enzymatic hydrolysis, fermentation of sugars into ethanol, and ethanol recovery.Pellets production could be an interesting alternative for the hydrolysisresidue. In this work, the economics of xylitol production from hemicelluloses versusother alternatives was evaluated. Two alternatives for the use of the solid fractionwere proposed: (1) ethanol production or (2) pellets production. Figure 1 showsa simplified block flow diagram of the process to convert lignocellulosicmaterials into xylitol. Autohydrolysis treatment and evaporations are energy intensiveoperations because of high temperatures and large amounts of water involved.The most expensive equipments for the process would be the fermenter and thecrystallizer (approximately 19% of total capital investment). In this scenario,93.9 kg of xylitol could be obtained per ton of dry bagasse. The economic evaluationshowed long recovery periods. However, optimization of different steps, asliquid to solid ratio of pretreatment, evaporation, or fermentation, could representattractive and innovative alternatives to reduce the recovery periods ofcapital costs.