Comparing oxidative and dilute acid wet explosion pretreatment of C ocksfoot grass at high dry matter concentration for cellulosic ethanol production

The choice of a suitable pretreatment method and the adjustment of the pretreatment parameters for efficient conversion of biomass are crucial for a successful biorefinery concept. In this study, cocksfoot grass, a suitable lignocellulosic biomass with a potential for large‐scale production was investigated for cellulosic ethanol production. The biomass raw materials were pretreated using wet explosion ( WE x) at 25% dry matter concentration with addition of oxygen or dilute sulfuric acid. The enzymatic hydrolysis of cellulose was significantly improved after pretreatment. The highest conversion into cellulose monomeric C 6 sugars was achieved for WE x condition AC ‐ E (180°C, 15 min, and 0.2% sulfuric acid). For that condition, the highest ethanol yield of 197 g/kg DM (97% of theoretical maximum value) was achieved for SSF process by S accharomyces cerevisiae . However, the highest concentration of hemicellulose C 5 sugars was found for WE x pretreatment condition O 2‐ A (160°C, 15 min, and 6 bar O 2 ) which means that the highest potential ethanol yield was found at this moderate pretreatment condition with oxygen added. Increasing the pretreatment temperature to 180–190°C with addition of oxygen or dilute sulfuric acid significantly degrades the solubilized hemicellulose sugars and thus, achieved the highest formation of by‐products.