The Study On Steam-explosion Pretreatment Of Energy Grass

With the shortage of fossil fuels and the deterioration of environmental pollution,using biomass to convert Bio-ethanol can reduce the supply problem of coal and petroleum,promote the stable progress of the society.Pretreatment technology is the key to realize Lignocellulosic materials to produce Bio-ethanol.There are such problems as low efficiency,high cost and pollution in many pretreatment methods in practice.Steam explosion method is a pretreatment way of the combination of physical and chemical pretreatment,be less dosage of chemical reagents,be friendly to the environment.Steam explosion method is a kind of developing rapidly pretreatment technology in recent years.In this study,energy grass such as Panicum virgatum?Triarrhena sacchariflora?Miscanthus as raw materials were treated with steam explosion pretreatment.The effects of steam-explosion pretreatment on composition and enzymatic hydrolysis saccharification efficiency of solid residues The fiber structure of pretreated residues were studied with scanning electron microscopy(SEM),infrared spectroscopy(FT-IR)and X-ray diffraction spectrum methods.The primary conclusion were as follows:(1)In the raw material of Triarrhena sacchariflora,the content of cellulose was 48.32%,the content of hemicellulose was 24.68%,the content of lignin was 17.86%.In the raw material of Panicum virgatum,the content of cellulose was 37.10%,the content of hemicellulose was 32.10%,the content of lignin was 16.42%.In the raw material of Miscanthus,the content of cellulose was 36.21%,the content of hemicellulose was 29.20%,the content of lignin was 19.59%.Energy grass with high content of cellulose and hemicellulose as well as less lignin,were excellent lignocellulosic materials for the production of Bio-ethanol.(2)After Steam explosion pretreatment,the vast majority of hemicellulose in energy grass material was degraded and dissolved,a part of the lignin was destroyed,the comparative content of cellulose increased.After Steam explosion pretreatment,the content of extractive increased,the content of ash reduced.By scanning electron microscope observation,the fiber bundle were separated,and the fiber surface arised many cracks,the effective contact area of the fiber and the enzyme was increased after Steam explosion pretreatment.The comparative crystallinity of cellulose was increased,but the absolute crystallinity of cellulose was reduced.(3)The enzymatic hydrolysis saccharification efficiency of untreated Triarrhena saccharifloras was only 8.5%,the enzymatic hydrolysis saccharification efficiency was as high as 66.78%atl.79 MPa for 5.5 min.The enzymatic hydrolysis saccharification efficiency of Panicum virgatum raw material was 7.8%,the highest enzyme hydrolysis efficiency was 65.16%at1.76 MPa for 5.8 min.The enzymatic hydrolysis saccharification efficiency of Miscanthus raw material was 6.7%,the highest enzymatic hydrolysis saccharification efficiency was 63.36%atl.84 MPa for 5.4 min.By scanning electron microscope,the fiber surface of energy grass raw material degraded partly,the residual lignin deposited the fiber surface after enzymatic hydrolysis.After enzymatic hydrolysis,the fiber morphology of energy grass material which were treated with Steam explosion changed obviously,fiber bundle became shorter.The residual lignin came into being irregular granular material.After enzymatic hydrolysis,the cellulose relative crystallinity of energy grass raw material increased.The cellulose relative crystallinity of energy grass which were treated with Steam explosion reduced.