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The Experiment Research Of Cellulose Hydrolysis By Extremely-Low Sulfuric Acid

Posted on:2012-12-21Degree:MasterType:Thesis
Country:ChinaCandidate:L F YangFull Text:PDF
GTID:2272330368958477Subject:Chemical Engineering and Technology
Abstract/Summary:PDF Full Text Request
Although research of biomass ethanol producing technology has done for many years, but there still be many problems to be solved. Pretreatment and saccharification technology of biomass materials is one of the most important step of biomass ethanol. utilization of cellulose is the core task of industries, ultra-low acid refers to acid concentration below 0.2%, hydrolysis by using ultra-low acid can reduce environmental pressure of acidic solution, can reduce the alkali substances needed, can protect the equipment from corrupting, can reduce the fermentable sugars’ degradation in acidic medium solution. To get hydrolysis solution of high sugar content, this paper has done a series of experiments.Response surface method was used to optimize cellulose hydrolysis by extremely-low acid, experiments were carried out according central composite design (CCD) of four factors (temperature, time, acid concentration and liquid-to-solid ratio (L/S). Then, further study has done.The results show that extremely-low-acid hydrolysis of cellulose of the optimum conditions are reaction temperature 205℃, liquid to solid ratio 15.72,0.15% acid concentration, reaction time 33min, pressure 3MPa, speed 500rpm.To research the cocatalyst effect of metal salt in cellulose hydrolysis by extremely-low acid, Choosing 7 different kinds of metal salts:K2SO4、MgSO4、Na2SO4、A12(SO4)3、CuSO4、FeSO4、Fe2(SO4)3 in 3 different concentration as cocatalysts. Then, the results reveal that the cocatalyst effects of K2SO4 is better.. By the experimental results and literatures, we choose K2SO4 as representative metal salt inferring the mechanism of metal salt in cellulose hydrolysis by extremely-low acid, making a theoretical guidance for the subsequent research work.A pseudo-homogenous consecutive first-order reaction kinetic modeling lodged by Saeman could describe the hydrolysis process correctly, which means the hydrolysis of extremely low acid and metal salt still follow the model of cellulose→reducing sugar such as glucose→egradation products such as 5-HMF in the macroscopic. After adding metal salt, hydro lyzed can base narrowing. Ea2 value is greater than Eal, shows that temperature rises, accelerating sugar decomposition rate. It is not suitable for high temperature response.
Keywords/Search Tags:ultra-low acid, cellulose, reducing sugar, hydrolysis, metal salt
PDF Full Text Request
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