Study On The Process And Mechanism Of High Boiling Solvent Pulping Of Bagasse

Solvent puping is available way that can separate fiber,lignin,sugars, and other components from raw materials to achieve cleaner production,.Ethanol and methanol as the representative of the lower aliphatic alcohol (boiling point less than 100℃) is the most common organic solvents of solvent pulping, due to these lower aliphatic alcohol solvent with a low boiling point, highly volatile and flammable properties, high pressure caused easily during ethanol pulping, high security requirements is needed for the process of pulping equipment and operation, otherwise the solvent recovery is very difficult. For this reason, 1,4 -butanediol is chose as solvent of pulping for this study, and explore the process and mechanism during HBS(1,4 - butanediol) pulping of bagasse , Research including: process conditions optimization of pulping and pulp washing , cooking reaction course, kinetics of deligniflcation and carbohydrate degradation. The results are as following:1,The HBS (1,4 - butanediol) pulping without acid catalyst showed that the temperature had greatest effect on cooking. The result of bagasse HBS pulping show that the appropriate conditions for the preparation of lignin and pulp: 1,4 - butanediol solvent concentration of 60 %, cooking temperature of 190℃, time at temperature of 90 min, liquid ratio of 1:6.2,The objectives of rearch were to investigate the effect of catalysts on HBS pulping,the results showed that: Catalyst (formic acid, acetic acid, citric acid) used in HBS pulping were able to increase the removal of lignin ,and reduce cooking temperatures and cooking time during HBS pulping, among them citric acid had the best obvious effects on the delignification ,however catalyst used in HBS pulping decrease the physical strength of the paper. The infrared analysis of the lignin showed that acid catalyst had little effect on the structure of lignin.3,HBS pulp washing research shows that the stage and solvent content of washing had greatest effect on pulp washing . After two stages of 1,4 -butanediol washing most of lignin adsorbed on the fiber surface were removed. SEM analysis of fiber surface showed that: the traditional washing used water in room temperature was not efficent for HBS pulp washing ,two stages of 1,4 -butanediol washing were able to remove lignin adsorbed on the fiber surface. Finally ,we can achieve the 1,4 - butanediol pulp washing appropriate conditions : washing solvent content greater than 60%, time at temperatue of 30 min, temperature of 80℃, liquid ratio of 1:6, washing stages of 2.4,Study of HBS cooking couse without catalyst show that pH of pulping system had great effect on delignification and carbohydrate degradation, reaction rate is fast at the previous stage and become slowly at later stage . The kinetics analysis of the cooking process showed that the delignification reaction follow two pseudo first-order kinetics,bulk and final phases., and the activation energy was 98.6 kJ/mol and 152.3kJ/mol ,respectively; The carbohydrate degradation of cooking process are all in the pseudo fist order ,the bulk an the residual phases activation energy were 117.4kJ/mol and 125.9kJ /mol, respectively.This paper study on the factor of cooking and washing duiring HBS pulping ,and optimize the appropriate conditions for the preparation of lignin and pulp ,and show reaction rules of physical chemistry, in order to provide the basic data for cleaner production of pulp and paper making and resource utilization of agricultural and forestry waste materials.