Susana Peleteiro

Utilization of ionic liquids in lignocellulose biorefineries as agents for separation, derivatization, fractionation, or pretreatment.

Ionic liquids (ILs) can play multiple roles in lignocellulose biorefineries, including utilization as agents for the separation of selected compounds or as reaction media for processing lignocellulosic materials (LCM). Imidazolium-based ILs have been proposed for separating target components from LCM biorefinery streams, for example, the dehydration of ethanol-water mixtures or the extractive separation of biofuels (ethanol, butanol) or lactic acid from the respective fermentation broths. As in other industries, ILs are potentially suitable for removing volatile organic compounds or carbon dioxide from gaseous biorefinery effluents. On the other hand, cellulose dissolution in ILs allows homogeneous derivatization reactions to be carried out, opening new ways for product design or for improving the quality of the products. Imidazolium-based ILs are also suitable for processing native LCM, allowing the integral benefit of the feedstocks via separation of polysaccharides and lignin. Even strongly lignified materials can yield cellulose-enriched substrates highly susceptible to enzymatic hydrolysis upon ILs processing. Recent developments in enzymatic hydrolysis include the identification of ILs causing limited enzyme inhibition and the utilization of enzymes with improved performance in the presence of ILs.

Biorefinery of olive pruning using various processes.

Biorefinery developed involve separation of olive pruning into two parts: main (OPM) (stems>1cm diameter), and residual (OPR) (stems<1cm diameter, and leaves). OPM was submitted to hydrothermal treatment, separating: a liquid fraction (HL), rich in products of hemicelluloses decomposition, and other solid (HS), rich in cellulose and lignin. HS is subject to pulping, resulting: a liquid fraction (HPL), rich in lignin, and other solid (HPS), rich in cellulose. Up to 42% of the polysaccharides from OPM were recovered in HL as valuable compounds. HPS can be used for the bioethanol production by saccharification and fermentation, reaching a bioethanol conversion of 90.6% of the theoretical value. In addition, HPS obtained paper with lower strength properties than those of paper obtained from OPM pulp directly. OPR provided 18.70 MkJ/t heating values, 1094-2234°C flame temperature, and 45-53°C dew point temperature, with a cost of the unit of heat (3.20 €/MkJ) much lower than fossil fuels fluids.

Furfural production in biphasic media using an acidic ionic liquid as a catalyst

Ionic liquids are valuable tools for biorefineries. This study provides an experimental assessment on the utilization of an acidic ionic liquid (1-butyl-3-methylimidazolium hydrogen sulfate) as a catalyst for furfural production in water/solvent media. The substrates employed in experiments were commercial xylose (employed as a reference compound) or hemicellulosic saccharides obtained by hydrothermal processing of Eucalyptus globulus wood (which were employed as produced, after membrane concentration or after freeze-drying). A variety of reaction conditions (defined by temperature, reaction time and type of organic solvent) were considered. The possibility of recycling the catalyst was assessed in selected experiments.

Manufacture of furfural from xylan-containing biomass by acidic processing of hemicellulose-derived saccharides in biphasic media using microwave heating

Furfural was produced in biphasic media using a microwave-heated reactor. Diverse substrates were considered: xylose (considered as a reference compound) or hemicellulosic saccharides from Eucalyptus globulus wood or corncobs. Operation was carried out at 170°C for the desired reaction time in the presence of an acidic catalyst (sulfuric acid or HCl). The best furfural yields (67.8% and 72.5% from E. globulus wood and corncobs, respectively) were obtained operating for 10 min or 20 min with 1% or 0.5% HCl, respectively. These results were slightly lower than the ones obtained using xylose (a model substrate) under comparable reaction conditions, a fact ascribed to differences in the complexity of substrates and to the presence of contaminants.