Co-Products Strategies Based on Aqueous/Steam Treatments

All types of biomass can be considered as composed of 'chemical families' whose nature reflects the biology and biochemistry of each specific biomass. Carbohydrates, lignin and polyphenols, lipids and proteins are the major constitutive families which form into well organized ultrastructures. Extractives and inorganic salts are distributed through the matrix. Simple aqueous/steam treatments, whenproperly understood and applied, can progressively destructure the matrix and liberate specific biomass fractions. The result is known as fractionation. The selectivity of the fractionation, that is, the ability to separate one or more constitutive families from the others thus facilitating its subsequent processing and upgrading to marketable products, is essentially a function of how theaqueous/steam treatments are adapted to each of the biomass types. As well the compatibility of aqueous/steam treatments with benign chemicals and mild process conditions makes them attractive for the preparation of premium 'natural products'. This paper describes the principles of aqueous/steam treatments and the role of impregnation in ensuring uniform process conditions in the non-homogeneousmatrix. The technology and methods used to accomplish the progressive fractionation and recovery of key constitutive families will be presented and discussed based on results obtained with different types of biomass. Based mainly on our work, we will provide specific examples of commercially significant products that can be obtained by coupling the aqueous/steam approach with selectiveseparations and upgrading processes. By aiming at different end co-products, ranging from specific extractives and derivatives to oxychemicals, fibers, coloids and fuels the goal of implementing biomass mini-refineries can be technologically and economically met.