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Research on Pretreatment Technologies of Achnatherum Splendens for Fuel Ethanol

Author: NiTianRu
Tutor: Ren
School: Lanzhou Jiaotong University
Course: Environmental Science
Keywords: Fuel ethanol Pretreatment Lignin Hemicellulose removal rate Cellulose
CLC: TK6
Type: Master's thesis
Year: 2010
Downloads: 100
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Abstract

In recent years, growing energy consumption and serious environmental problems make people more and more interested in the use of alcohol as a transport fuel. Currently, the main raw material for the production of fuel ethanol in the world cereals such as corn, wheat, and so on. However, China and some countries, cereal production of fuel ethanol is not a sustainable approach. Lignocellulosic material is a potential raw material for the production of fuel ethanol, the lignocellulosic material has a cheap, renewable, resource-rich. Consist primarily of wood fiber raw materials for the production of fuel ethanol pretreatment, hydrolysis, fermentation, purification and liquid after to handle five steps. Preprocessing is a key step in the production of fuel ethanol. The purpose of the pretreatment of lignocellulosic material by removing the lignin and hemicellulose, reducing cellulose crystallinity, increased raw material porous to improve its enzymolysis. The present study, using Splendens as a raw material into fuel ethanol. The purpose of this study is the analysis of sodium hydroxide, ammonia, sulfuric acid and ammonia - sulfuric acid pretreatment on Splendens. Summarizes the sodium hydroxide, ammonia, sulfuric acid and ammonia - sulfuric pretreated solid lignin, hemicellulose and cellulose content. Discussed in a different dosage of sodium hydroxide, ammonia concentration, the concentration of sulfuric acid, liquid to solid ratio, reaction temperature and time under conditions, after pretreatment of solid lignin, hemicellulose and cellulose content variation. Further discussion of sodium hydroxide and ammonia pretreatment lignin removal rate variation and sulfuric acid and ammonia - sulfuric acid pretreatment of hemicellulose removal rate variation. In this study, were used sodium hydroxide, ammonia, sulfuric acid pretreatment Splendens. Sodium hydroxide pretreatment Achnatherum reaction, sodium hydroxide is used in an amount of 3-18% (based on the original dry matter), (v / w) of the liquid to solid ratio of 8:1-20:1, the reaction under the conditions of temperature range 60-100 ℃ processing the pulverized biomass 1.5h. The results show that the dosage of sodium hydroxide, liquid-solid ratio and reaction temperature the solid lignin after the pretreatment of the lignin and sodium hydroxide, the content of the hemicellulose and cellulose have a significant effect. When the sodium hydroxide used in an amount higher than 15% (based on the original dry matter), the dosage of sodium hydroxide on the removal rate of lignin is not significantly affected. When the liquid-solid ratio is less than 10:1 (v / w), it is difficult to make the reaction system was maintained homogeneous. When fixed dosage of sodium hydroxide, to improve the liquid-solid ratio (gt; 10:1), the lignin removal rate decreased. When the temperature is higher than 90 ° C, no significant effect of reaction temperature on the removal rate of lignin. The results showed that the optimum reaction conditions are as follows: The dosage of sodium hydroxide 15% (based on the original dry matter), liquid-solid ratio 10:1 (v / w), reaction temperature 90 ℃, reaction time 1.5h. In the preferred pretreatment conditions, the lignin is about 39%, the processed cellulose solids content is increased to 68.39%, and hemicellulose content is reduced to 19.86%. Ammonia soak method pretreatment Splendens, using 5-25wt% aqueous ammonia, and the pulverized biomass in the 45-85 ° C, the liquid to solid ratio of 12:1 (mass ratio) under the conditions of processing 12-72h. Ammonia concentration, reaction temperature and reaction time on the quality removal efficiency and ammonia after pretreatment solid lignin, hemicellulose and cellulose content has a significant effect. When the ammonia concentration is higher than 10wt%, no significant effect in the ammonia concentration of lignin. Under the conditions of 55 ℃, the removal rate of 26.55% compared to no significant different lignin removal rate of 26.31% and 65 ℃. Lignin removal rate decreased from 26.55% to 10.56% when the reaction temperature from 65 ℃ to 85 ℃. In the pretreatment of ammonia, when the reaction time is longer than 36h, the reaction time on the removal rate of lignin is not significantly affected. The results showed that the optimum reaction conditions are as follows: ammonia concentration of 10wt%, the reaction temperature is 55 ° C, the reaction time 36h, liquid-solid ratio 12:1 (mass ratio). The best pretreatment conditions, the lignin removal rate of 26.58%, after processing the solid cellulose content increased to 64.20%, while the hemicellulose content is reduced to 23.63%. In the preferred pretreatment conditions, ammonia pretreatment of the lignin removal rate was significantly lower than the sodium hydroxide pretreatment lignin (39%). Sulfate pretreatment Achnatherum reaction, the use of 0.5-3% (w / v) sulfuric acid solution at 100 ℃, 8:1-20:1 (v / w) of the liquid to solid ratio, under the conditions of the pulverized biomass processing 12-72h . Concentration of sulfuric acid and liquid to solid ratio increased and prolonged reaction time have a significant effect on the removal of hemicellulose. Solid concentration of sulfuric acid and liquid to solid ratio increased and prolonged reaction time so pretreatment significantly reduced the hemicellulose content, cellulose and lignin content increased significantly. The study found that when the sulfuric acid concentration of 2% (v / w) close to the optimum level, because the time to a lower concentration of sulfuric acid to obtain a satisfactory pretreatment effect (hemicellulose removal rate of 78.87%). When liquid to solid ratio higher than 15:1 (v / w), the ratio of liquid to solid hemicellulose removal did not significantly affected. When the reaction time is longer than the 3h, the reaction time on the removal of hemicellulose no significant impact. The results showed that the optimal reaction conditions: sulfuric acid concentration of 2% (w / v), liquid-solid ratio 15:1 (v / w), reaction time 3h, the reaction temperature of 100 ° C. The best pretreatment conditions, hemicellulose rate of 92.57%, the treated solid in cellulose content increased to 66.79%. In the Splendens reaction of ammonia - sulfuric acid pretreatment, the ammonia soak method under the optimal reaction conditions pulverized biomass (10wt% ammonia, 55 ° C, the liquid-solid ratio 12:1,36 h), ammonia soak treatment substances and then with 0.5-2% (w / v) sulfuric acid solution treated in the liquid to solid ratio of 8:1-15:1 (v / w), 100 ℃ under conditions of 0.5-3h. Sulfuric acid pretreatment of the second stage, the increase in the concentration of sulfuric acid and the reaction time on the removal of hemicellulose has a significant impact; improvement of sulfuric acid concentration and the reaction time so that the solids sulfate after pretreatment hemicellulose content significantly reduced, cellulose and lignin content significantly increased; ratio of liquid to solid, solid hemicellulose removal and sulfuric acid pretreatment hemicellulose and lignin content did not significantly affect. In ammonia - sulfuric acid pretreatment of the second stage, when the sulfuric acid concentration is higher than 1.5% (w / v) of sulfuric acid concentration on the removal of hemicellulose no significant effect: when the liquid-solid ratio is higher than 8:1 (v / w), the liquid-solid ratio on the removal of hemicellulose no significant impact; when the reaction time is longer than 2h, the reaction time on the removal of hemicellulose no significant impact. Ammonia - sulfuric acid pretreatment optimal reaction conditions: the first stage, the ammonia concentration of 10 wt%, the reaction temperature is 55 ° C, reaction time 36h, liquid-solid ratio 12:1 (mass ratio); second stage, sulfuric acid concentration of 1.5%, liquid solid ratio of 8:1 (v / w), reaction time 2h, the reaction temperature is 100 ° C. In the preferred pretreatment conditions, the hemicellulose of the solids after treatment addition rate of 91.19% to 75.49%, cellulose content. Under mild reaction conditions, sodium hydroxide pretreatment can effectively remove the lignin. Ammonia pretreatment lignin is lower than expected, ammonia pretreatment can not remove Splendens contained lignin. Sulfuric acid pretreatment is suitable for the Splendens processing and optimal pretreatment conditions to obtain a satisfactory treatment effect (hemicellulose removal rate of 92.57%). Ammonia - sulfuric acid pretreatment can effectively remove the hemicellulose and the cellulose content of the solids after treatment was the highest in the four methods. Ammonia pretreatment, the first stage in addition to part of the hemicellulose, the fiber swelling the ammonia - of pretreatment Achnatherum sulfate reaction; ammonia pretreatment of the first stage of the second stage sulfuric acid compared with the use of sulfuric acid alone pretreatment Splendens preconditioning the concentration of the sulfuric acid solution and the liquid-solid ratio, reduced reaction time is shortened. The removal of lignin and hemicellulose can be improved Enzymolysis Achnatherum.

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