14-06: Phosphoric acid-catalysed steam explosion of sugarcane biomass

One of the main objectives of the Canebiofuel project (http://www.canebiofuel.org), funded by the European Commission within the 7th Framework Programme, is to identify which sugarcane biomass fraction is most adequate for an enzyme-based conversion technology to second-generation fuel ethanol. Based on this, sugarcane bagasse and straw were harvested from a selected cultivar, characterized using a variety of analytical procedures and submitted to pretreatment methods such as auto-hydrolysis and acid-catalysed steam explosion.  Pretreatment was carried out with and without addition of phosphoric acid as catalyst under different temperatures, times and acid loadings using two adjacent 2³ factorial designs with three replicates at their center points. Both cane biomass were shown to be highly amenable to pretreatment and phosphoric acid catalysis resulted in a much better selectivity towards cane biomass carbohydrates (mostly hemicelluloses), yielding substrates that were highly accessible to enzymatic hydrolysis. The best conditions were shown to be 180ºC and 5-10min with a 9.5mg/g H₃PO₄ impregnation (dry basis) and these were valid for both cane biomass fractions. Hydrolyses were carried out in a rotisserie incubator with both unwashed and water-washed pretreated materials at 8wt% using 0.01mL/g (dry basis) of a new generation of fungal cellulases (Cellic CTec 2, Novozymes). Quadratic models were developed based on glucose release (measured by HPLC) and the resulting surface responses were useful to demonstrate the strong correlation that existed among pretreatment variables and experimental responses such as glucose recovery, total release of phenolic compounds and cellulose susceptibility to hydrolysis. Supported by: EU FP7 Programme, CAPES