Processing of Miscanthus sinensis toproduce sugars or cellulose pulp

Abstract

Eight genotypes of Miscanthus sinensis were provided by WPR with differences in composition and digestibility. The eight genotypes showed significant differences in chemical composition. A correlation between glucose and lignin content and digestibility could be present. Fermentable sugars The 8 genotypes were subjected to a two-stage process to produce fermentable sugars. The first stage consisted of an acid treatment at elevated pressure and temperature, the second stage of an enzymatic hydrolysis. Clear differences in the amount of fermentable sugars obtained were found. The genotype with the highest digestibility (074, lowest amount of cellulose and lignin) also resulted in the highest amount of fermentable sugars. Correlation between the digestibility and fermentable sugar yield of the other genotypes was less clear. Two genotypes (017 and 074) were also subjected to three other pulping processes as first stage (acid super heated steam (SHS), alkaline SHS and alkaline pulping at 120 °C), followed by a second stage of enzymatic hydrolysis. Similar results were obtained: the genotype with the highest digestibility (074, lowest amount of cellulose and lignin) also resulted in the highest amount of glucose. Release of xylose was similar. Overall, glucose release was limited, xylose release was moderate for the alkaline treated pulps. Cellulose pulp Another part of the study was the conversion of two genotypes (017 and 074) to cellulose pulp by four different methods: prehydrolysis followed by organosolv, acid super heated steam (SHS, alkaline SHS and alkaline pulping at 120 °C. The cellulose pulps were used to make hand sheets. The glucose content (cellulose) after treatment was increased from 38% to 60% for Miscanthus 017 and from 30% to 59% for Miscanthus 074. After acid and SHS treatment still a high percentage of lignin (AIL) was present in the product. After alkaline treatment a high amount of xylose (hemicellulose) was still present. For the production of a cellulose pulp, the alkaline 50L treatment of both Miscanthus genotypes was most promising as this treatment resulted in samples with the highest cellulose content, around 60 wt%. However, more purification steps are required to obtain a pure cellulose product. Based on the composition of the starting material Miscanthus 017 is more interesting due to a higher initial cellulose content. Hand sheets The fibre properties of cellulose pulps and the mechanical-and physical properties of hand sheets were analysed. The cellulose-enriched samples were disintegrated, mechanically beaten and handsheets were prepared. The properties of these handsheets were determined to provide insight in the morphology of the pulps after chemical treatment, and on the performance for application in paper products. Results showed that the acid-SHS treatment was less effective in breaking down the fibre bundles of the Miscanthus biomass into fibres compared to the alkaline treatments. The acid treated cellulose pulp was not fully disintegrated into fibres, resulting in a high bul...