Hydrothermal treatment and organosolv pulping of softwood assisted by carbon dioxide

IMLAUER VEDOYA, C.; FELISSIA, F.E.; VALLEJOS, M.E.; RAFFAELI N.; AREA, M.C.; DA SILVA CURVELO A.A.

Sao Paulo

Congreso; 51º Congresso Internacional de Celulose e Papel - X Congresso Iberoamericano de Pesquisa em Celulose e Papel; 2018

ABTCP

In the context of a biorefinery, the optimal use of the lignocellulosic biomass is of paramount importance to make it profitable. Fractionation strategies are deeply assessed over numerous raw materials to fulfill this requisite. Carbon dioxide at high pressure has been stated as a promising green solvent and its use in biomass fractionation has been studied. This work evaluates the effect of subcritical and supercritical CO2 in the hydrothermal treatment and the organosolv delignification, either as individual stages or as sequential processes, of pine sawdust, chips and milled chips. The main objective of hydrothermal treatment is to solubilize hemicelluloses, while in organosolv pulping the delignification of the material is pursued. The advantages of the incorporation of CO2 at high pressure to these conventional processes has been previously suggested in the literature. The hydrothermal and organosolv experiences were first performed according to simple factorial designs, followed by a set of extra experiments for further understanding of the pine behavior. The hydrothermal liquors and the final pulps were properly analyzed. The yield for hydrothermal experiences ranged from 76.2% to 99.2%. CO2 effect on yield and hemicelluloses removal is more noticeable at shorter periods of time and low (120°C) and mild temperatures (160°C), and it weakens as reaction time and temperature increase. The delignification rate during organosolv pulping ranged between 10.3% and 70.1%. For industrial sawdust, the presence of CO2 during organosolv pulping significantly affects delignification. The effect of hemicellulose removal prior to delignification varies depending on the raw material. A sequential combination of both hydrothermal treatment and organosolv pulping as a fractionation strategy impacts on the final composition of the pulps and on the extent of sugars loss.