Study On The Effects Of Cellulose Structure Characteristics And Organic Phase On Biomass Acid Hydrolysis

During the last few decades, excessive consumption of fossil fuel has resulted in generation of high levels of pollution. Lignocellulosic biomass is considered as a promising alternative energy source due to its availability and renewability, and it has attracted extensive attention all around the world. The monosaccharides can be obtained from the hydrolysis of lignocellulosic biomass. On this basis, a sugar platform can be established to produce a variety of liquid fuels or other high-valued chemicals.The hydrolysis of biomass can be classified into two types, including acid hydrolysis and enzyme hydrolysis. Effective enzymatic conversion of lignocellulose into fermentable sugars is difficult because of high cellulose crystallinity and the presence of the complex structure of lignin and hemicellulose with cellulose. There are some obvious disadvantages using the processing of the dilute acid hydrolysis, but it is characterized by a high hydrolysis rate, conversion degree, and substrate adaptability, especially is considered to be the easiest way to realize industrialization production technology at present, many researchers have studied on it. Hemicellulose is relatively easy to be hydrolyzed using acids under current technologies. However, cellulose is difficult to be hydrolyzed to produce monosaccharides due to its high degree of polymerization and highly-ordered structure. The content of cellulose is the highest with approximately40%followed by hemicelluloses and lignin. The processing of efficient hydrolysis cellulose to produce glucose has important significance on the development of bioenergy products and high-value chemicals using biomass.Degree of polymerization (DP) and the crystalline plane are two important structure characteristics for cellulose hydrolysis. In order to explore how they affected cellulose hydrolysis, filter paper and microcrystalline cellulose (MCC) were treated with dilute hydrochloric acid to investigate the cellulose polymerization degree changing, a dynamic mathematical model about DP of cellulose changed with acid concentration, reaction temperature and reaction time was set up. The treated cellulose samples were hydrolyzed under the condition of140℃and30min for1.0wt%dilute hydrochloric acid hydrolysis with solid-liquid ratio1:40. The glucose yield was remarkably enhanced (Filter paper,9.2to14.3%; MCC,1.2to10.1%) as the change of cellulose DP and indices of crystal plane. Cotton linter was treated with sodium hydroxide with the purpose of changing its crystal plane. The glucose yield was increased from9.5to19.7%when treated with15%NaOH at50℃and30min. On the basis of experimental results, DP and crystal plane indices are two important features for sugar yield of cellulose acid hydrolysis.This article also used the diphasic system to hydrolyze biomass, except for the exploration on how degree of polymerization and crystalline plane affected cellulose acid hydrolysis. At the same time, we combined two-step hydrolysis with diphasic system to produce monosaccharide from corn stover. The first step was the hydrolysis of hemicellulose to produce xylose, and the second step was the hydrolysis of cellulose to produce glucose. After hydrolysis, the sugar concentration of water phase improved significantly, and it was convenient to the subsequent use of monosaccharides. What’s more, the efficiency of corn stover hydrolysis improved a lot using two-step acid hydrolysis, and the yield of monosaccharides also increased.