(248ae) Integrated Biorefineries Using Ionic Liquids: Application to Macroalgae Feedstock

Fossil fuels are estimated to be exhausted in a few decades due to the increase in human population and living standards. A very important challenge is to find an environmentally friendly and sustainable new source of energy. Biofuels, energy from biomass is one of the most promising alternatives. Depending on the type of feedstock, biofuels have been classified as first generation (food crops), second generation or non-edible biomass (some crops, forest residues, animal fat, waste) and third generation biomass (microorganisms as microalgae). The importance of this alternative is reflected in the recent research projects funded by the European Commission like: Eurobioref (European Multilevel Integrated Biorefinery), Biocore (Biocommodity Refinery), Suprabio (Sustainable Products from Economic Processing of Biomass in highly Integrated Biorefineries) or Miracles (Multiproduct Integrated Biorefinery of Algae). One of the main outcomes of these projects is that future biorefineries must be highly integrated, flexible enough to allow the conversion of different feedstock (2nd and 3rd generation biomass) and multiproduct (biofuels, chemicals, polymers, energy, etc.)

One of the issues to be improved in biorefineries is the use of solvents, organic solvents are generally needed in different stages of the production process. These solvents are usually non-environmentally friendly, and its separation and recovery increase the overall cost significantly.

Ionic liquids are salts that are liquid at room temperature. Their properties make them a more environmentally friendly and less costly alternative to conventional species. Ionic liquids are usually used as substitutes of solvents but they can be also used as catalysts or catalyst supports among other uses. One of the main benefits of using ionic liquids, that makes them green solvents, is that they can be recovered almost completely.

In this work we present the process flowsheet of a whole multifeedstock / multiproduct integrated biorefinery. For each feedstock the different available processes are shown, for each process the routes to produce multiple products (chemicals like the antioxidant astaxanthin, polymers like PHB â??polyhydroxybutyrate-, specialty chemicals from levulinic acid and esters, biodiesel -mainly jet fuel-, bioethanol, etc.) and for each route some alternatives to achieve the desired product. Biorefinery integration is also depicted indicating what units can be used in several places of the plant. Finally, each operating unit that can use ionic liquids is marked commenting on the specific ionic liquids that are suitable for that unit and its benefits. Some examples of their use in the biorefinery: as solvents for lignocellulosic biomass, for the deconstruction of lignin, as catalysts in the transesterification reaction or in the enzymatic hydrolysis of sugars, as extraction agents of lipids from algae or other biomass, as entrainers in azeotropic distillation, etc.

To illustrate the potential of this approach we have selected a specific biomass, brown seaweed. This is the single lartest macroalgae resource and a very good candidate for energy processing. The carbohydrates present in these seaweed are mannitol, laminarin and alginates. Different products (biogas, bioethanol, value added chemicals like organic acids, etc) can be achieved depending on the carbohydrate used and the technology selected (anaerobic digestion, thermochemical conversion, hydrothermal liquefaction, fermentation, etc.).

Using this feedstock to analyse the benefits of each alternative a superstructure optimization as well as a simulation of the biorefinery is being developed. In this work we present the developed superstructure and the simulation of one of the routes remarking where the ionic liquids are used.

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