Comprehensive analysis of sugarcane bagasse steam explosion using autocatalysis and dilute acid hydrolysis (H₃PO₄ and H₂SO₄) at equivalent combined severity factors

Steam explosion of sugarcane bagasse was carried out in the absence (autocatalysis) and presence of dilute phosphoric (H3PO4) and dilute sulfuric (H2SO4) as exogenous acid catalysts. Seven experiments were designed to operate at the same combined severity factor (CSF) of 0.76 ± 0.02: three autocatalytic steam explosion (steam-exploded bagasse, SEB), three with dilute H2SO4 (SEB/SA) and one with dilute H3PO4 (SEB/PA) that was used as reference. Steam treatment at the same CSF produced substrates with similar chemical compositions, rheological behaviors and glucose yields by enzymatic hydrolysis at 15% total solids (TS) using Cellic CTec3, except for two SEB/SA experiments that were carried out at lower temperatures and shorter times. SEB were the best substrates because they required the lowest power consumption for hydrolysis at 15% TS compared to SEB/SA and SEB/PA. Carbohydrates, aliphatic acids, furans and aromatic compounds were also characterized in pretreatment water-solubles by GC–MS and these varied considerably regardless of their equivalence in pretreatment CSF.