CN104357588B - One kind surpasses/subcritical water CO2The method that hydrolysis sugarcane marrow prepares reduced sugar - Google Patents

Abstract

A method for preparing reducing sugar by hydrolyzing sugarcane pith with super/subcritical water- _CO2 , the steps are: (1) adding sugarcane pith and water into an autoclave, and filling it with _CO2 for reaction, controlling the temperature at 160-260°C, React under the conditions of pressure 1-8MPa and stirring speed 100-500r/min for 1-60min, then press filter the contents of the autoclave, take out the filtrate, which is reducing sugar, and leave the filter residue in the autoclave; (2) Step ( 1) Put water and _CO2 into the autoclave with filter residue to continue the reaction, control the temperature at 370-400°C, pressure 20-27MPa and stirring speed 100-500r/min for 0-5min, and then put the autoclave After the substance is cooled to room temperature, press filtration is performed, and the obtained filtrate is the reducing sugar. The method of the invention improves the yield of sugarcane pith hydrolysis, has no solvent pollution, and does not need complicated post-treatment procedures, and has fast reaction rate and high yield, and the yield of reducing sugar can reach more than 90%.

Description

A method for preparing reducing sugar by hydrolyzing cane pith with super/subcritical water-CO2

technical field

The invention belongs to the technical field of green chemistry and clean energy, and relates to a method for preparing reducing sugar by hydrolyzing sugarcane pith with super/subcritical water- _CO2 .

Background technique

Bagasse is a by-product of the sugar industry and is mainly used as a raw material for papermaking, but 30% to 40% of it is sugarcane pith (short fiber), which is mainly used for boiler combustion, and the utilization rate is very low. The main component of sugarcane pith is cellulose, and the core technology of converting cellulose into clean fuel is to use effective methods to hydrolyze cellulose into soluble reducing sugars such as glucose.

CN201310319341.0 discloses a pretreatment method for hydrochloric acid hydrolysis-cellulase ultrasonic enzymolysis of cellulose to prepare bioethanol, which is realized by the following steps: put the pulverized biomass in a reaction kettle, and use HCl solution at 30-100°C Soak for 2-120 hours, distill the reacted material under reduced pressure at 50-120°C, mix the residue with water and then distill it for 1-3 times, then adjust the residue to weak acidity with inorganic alkali, add cellulase and mix evenly, Enzymolysis at 40-60°C for 2-60 hours under the action of ultrasonic waves to obtain materials containing reducing sugars.

CN201210170770.1 discloses a process and equipment related to the preparation of reducing sugar by biological enzymatic hydrolysis. The equipment includes: an enzyme membrane reactor with a reaction liner for holding bagasse and cellulase buffer and completing the enzymatic hydrolysis reaction, And the water bath container used to provide a constant temperature water bath for the reaction liner, and the membrane module adapted to the reactor is used to separate the enzymolysis solution after the enzymolysis reaction to obtain reducing sugar and enzymolysis residue; the enzyme transfer device, It is used to fully contact the enzymolysis residue with new bagasse to carry out enzyme re-adsorption, and the new reaction material formed by the new bagasse after enzyme re-adsorption is transferred from the pipeline to the reaction liner of the enzyme membrane reactor to complete the enzymolysis reaction; and each Connecting pipes between units. The equipment enables the timely separation of reducing sugars in the preparation process, improves the efficiency of enzymatic hydrolysis, and re-adsorbs the enzyme of new substrates after enzymatic hydrolysis, realizes the recycling of enzymes, and reduces the cost of enzymatic hydrolysis.

CN200910072156.X discloses a method for making fermentable reducing sugar from biomass. After the selected biomass material is crushed and sieved into 60-mesh powder, it is placed in a beaker containing a certain concentration of organic acid and mixed evenly, and put into In a microwave oven, under the condition of microwave power of 400-700W, the irradiation treatment is carried out for 2-5 minutes, and the obtained product is suction-filtered and dried to constant weight. Then prepare the cellulase solution in the Erlenmeyer flask according to the solid-to-liquid ratio of 1:10-1:25, and pH 4-5, mix it with the biomass, and finally put the Erlenmeyer flask in a constant temperature water bath at 50-60°C for hydrolysis to obtain the reduced sugar

CN200910072867.7 discloses a method of using ionic liquids to treat cellulose biomass to produce fermentable reducing sugars. Different types of ionic liquids are synthesized, and the selected cellulose biomass is pulverized into powder and dissolved in ionic liquids at a certain solid-liquid ratio. In the liquid, react at 120-150° C. under normal pressure for 30-180 minutes. After the reaction, add deionized water to obtain regenerated cellulose, separate and dry to keep the weight. According to a certain solid-to-liquid ratio, prepare a cellulase solution at pH 4-5, mix it with regenerated cellulose, and place it in a constant temperature water bath at 50-60°C for enzymolysis; chemically analyze the reducing sugar content in the enzymolysis solution Quantitative analysis shows that the reducing sugar content can reach up to 42g/l.

In summary, these methods for preparing reducing sugars from cellulose are mainly acid or enzymatic hydrolysis. The acid method can achieve a higher reaction rate with dilute sulfuric acid, which can significantly increase the hydrolysis rate of cellulose, but the acid is corrosive and harmful to the human body, and the reaction needs to be carried out in a corrosion-resistant reactor. High, and the reaction waste liquid pollutes the environment, and the post-processing steps are complicated. Enzymatic hydrolysis has the advantages of good selectivity, mild reaction conditions, environmental friendliness, and simple equipment, but the reaction cycle is too long, and the preparation and purification of cellulase is difficult and costly, and there is still a certain distance from large-scale industrial production. The method of ionic liquid treatment has the problems of difficult product separation and complicated follow-up treatment. In recent years, super/subcritical hydrothermal pretreatment of cellulose with water as solvent has become a research hotspot.

Contents of the invention

The present invention aims at the deficiencies of the above-mentioned technologies, and invents a method for preparing reducing sugar by hydrolyzing sugarcane pith with super/subcritical water- _CO2 , utilizing the coupling of super/subcritical water and _CO2 to hydrolyze sugarcane pith to prepare reducing sugar. The method is green and environment-friendly, the reaction cycle is short, the yield of reducing sugar is high, and the process flow is relatively simple.

For realizing the purpose of the present invention, the present invention provides following technical scheme:

A kind of super/subcritical water-CO _The method for preparing reducing sugar by hydrolyzing sugarcane pith, comprises the following steps:

(1) Add sugarcane pith and water to the autoclave, and fill it with CO ₂ as an auxiliary agent to react, control the temperature at 160~260℃, pressure 1~8MPa and stirring speed 100~500r/min for 1~60min , and then press-filter the contents of the autoclave, take out the filtrate, which is reducing sugar, and leave the filter residue in the autoclave;

(2) Put water and _CO2 into the autoclave with filter residue in step (1) as additives to continue the reaction in the autoclave, control the temperature at 370~400°C, pressure 20~27MPa and stirring speed 100~500r/min React under the same conditions for 3-5 minutes, then cool the contents of the autoclave to room temperature and perform pressure filtration, and the obtained filtrate is reducing sugar.

Wherein, the mass ratio of sugarcane pith added in step (1) to water is 1:20~1:100.

Wherein, the mass ratio of filter residue added in step (2) to water is 1:20-1:100.

Wherein, the water is distilled water or deionized water.

Compared with prior art, the beneficial effect of the present invention:

Using super/subcritical water- _CO2 combined with hydrolysis of sugarcane pith to prepare reducing sugar is equivalent to weak acid hydrolysis. Adding _CO2 during hydrolysis can increase the acidity of the system, further promote acid hydrolysis, and increase the yield of sugarcane pith hydrolysis, and There is no solvent pollution, and no complicated post-treatment process is required, and the reaction rate is fast and the yield is high, and the yield of reducing sugar can reach more than 90%. The raw material cane pith has been concentrated in the sugar factory during the sugar production process, so there is no need for collection and transportation costs; the cane pith has been crushed into fine particles during the sugar extraction process, and does not need to be crushed, and the production cost is far lower than Straw, corn cob and other raw materials. The use of waste cane pith in the production process of sucrose as raw material has important economic value and environmental protection significance for improving the reuse of cane pith.

detailed description

The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can implement according to the text of the description, and the protection scope of the present invention is not limited by the embodiments of the present invention. The autoclave used in the embodiment has a static seal magnetic stirring inside the kettle, and is inserted with an inlet and outlet pipe and a sampling pipe. In the embodiments, the subcritical water state reaction is called low temperature reaction, and the supercritical water state reaction is called high temperature reaction.

Example 1

Add sugarcane pith and distilled water to the autoclave at a mass ratio of 1:20, fill in 4MPa of _CO as an auxiliary agent for low-temperature reaction, control the reaction temperature at 210°C, reaction pressure 8MPa and stirring speed 500r/min for 30min; Then press filter the contents of the autoclave directly through the discharge pipe, and take out the filtrate, which is reducing sugar. The yield of the obtained reducing sugar is 26.6%. The filter residue is left in the autoclave as a high-temperature reaction raw material. 1: 60 Put water into the autoclave, fill it with 7MPa CO ₂ as an auxiliary agent for reaction, control the reaction temperature at 370°C, pressure 24MPa and stirring speed 500r/min for 3 minutes; cool the reaction product in the autoclave After reaching room temperature, pressure filtration was carried out, and the filtrate was a product containing reducing sugars. The yield of the obtained reducing sugars was 74.0%, and the total yield of reducing sugars hydrolyzed from cane pith was 80.9%.

Example 2:

Add sugarcane pith and deionized water to the autoclave at a mass ratio of 1:60, fill in 2MPa _CO2 as an auxiliary agent for low-temperature reaction, and control the reaction temperature at 260°C, reaction pressure 5MPa and stirring speed 300r/min. 60min; then directly through the discharge pipe, the material in the autoclave is press-filtered, and the filtrate is taken out, which is reducing sugar, and the resulting reducing sugar yield is 23.7%, and the filter residue is left in the autoclave as a high-temperature reaction raw material Ionized water is added into the autoclave according to the mass ratio of 1:20, filled with 7MPa CO ₂ as an auxiliary agent for reaction, and the reaction temperature is controlled at 390°C, the pressure is 26MPa and the stirring speed is 300r/min. The reaction is 5min; After the reaction product in the kettle was cooled to room temperature, pressure filtration was performed. The filtrate was a product containing reducing sugar. The yield of reducing sugar obtained was 75.4%, and the total yield of reducing sugar hydrolyzed from cane pith was 81.2%.

Example 3:

Add sugarcane pith and deionized water to the autoclave at a mass ratio of 1: 100, and control the reaction temperature to react for 40 minutes under the conditions of 160°C, reaction pressure 1MPa and stirring speed 100r/min; The substance is subjected to pressure filtration, and the filtrate is taken out, which is reducing sugar. The yield of the resulting reducing sugar is 20.7%. The filter residue is left in the autoclave as a high-temperature reaction raw material, and water is added to the autoclave according to the mass ratio of filter residue and distilled water at 1:100. , filled with 7MPa of _CO2 as an auxiliary agent to react, control the reaction temperature at 400°C, pressure of 27MPa and stirring speed of 100r/min for 5min; press filter the product in the kettle, the filtrate is the product containing reducing sugar, The resulting reducing sugar yield was 76.0%, and the total yield of reducing sugar by hydrolysis of cane pith was 81.0%.

Example 4:

With reference to the operating method of Example 3, the following parameters were changed respectively: the ratio of sugarcane pith to water, the reaction temperature, the reaction pressure, the reaction time, and the stirring speed to prepare the reducing sugar reaction to obtain the data in Table 1.

Table 1

In Table 1, the solid-to-liquid ratio is the mass ratio of bagasse to deionized water, and the yield is the resulting reducing sugar yield, and the sum of the reducing sugar yields after the reactions in each step is the final reducing sugar yield of the method. As can be seen from the table, the method of the present invention uses carbon dioxide as an auxiliary agent, and the reducing sugar prepared by hydrolyzing sugarcane pith in super/subcritical water has a very high yield, and the total yield is as high as more than 90%.

Using super/subcritical water- _CO2 combined with hydrolysis of sugarcane pith to prepare reducing sugar is equivalent to weak acid hydrolysis. Adding _CO2 during hydrolysis can increase the acidity of the system, further promote acid hydrolysis, and increase the yield of sugarcane pith hydrolysis without Solvent pollution, no complicated post-treatment process, fast reaction rate, high yield, reducing sugar yield can reach more than 90%. The raw material cane pith has been concentrated in the sugar factory during the sugar production process, so there is no need for collection and transportation costs; the cane pith has been crushed into fine particles during the sugar extraction process, and does not need to be crushed, and the production cost is far lower than Straw, corn cob and other raw materials. The waste cane pith in the production process of sucrose is used as raw material, which has important economic value and environmental protection significance for improving the reuse of cane pith. Moreover, in the process from low temperature reaction to high temperature reaction, there is no need to cool down, and the autoclave can be directly used The discharge pipe removes the reducing sugar from the autoclave, so that no further heating is required for high-temperature reactions, which greatly reduces energy consumption.

Claims (2)

1. a kind of super/subcritical water-CO _The method that hydrolysis cane pith prepares reducing sugar, is characterized in that, comprises following operation steps: (1) Add sugarcane pith and water to the autoclave, and fill it with CO ₂ to react, control the temperature at 190-200°C, pressure 7-8MPa and stirring speed 100-500r/min for 1-60min, then put The material in the autoclave is press-filtered, and the filtrate is taken out, which is reducing sugar, and the filter residue is left in the autoclave; the mass ratio of the added sugarcane pith to water is 1:20~1:60; (2) Add water and _CO2 to the autoclave with filter residue in step (1) to continue the reaction, control the temperature at 375~380°C, pressure 20~27MPa and stirring speed 100~500r/min for 3~5min, Then cool the contents of the autoclave to room temperature and perform pressure filtration, and the obtained filtrate is reducing sugar; the mass ratio of the added filter residue to water is 1:50. 2. according to the described super/subcritical water-CO of claim ₁ The method for preparing reducing sugar by hydrolyzing cane pith, is characterized in that: described water is distilled water or deionized water.