KR100376203B1 - A method of decomposing cellulose with sulfuric acid and various sulfate additives under sub- and supercritical water - Google Patents

Abstract

The present invention relates to continuous hydrolysis of cellulose slurry, and more particularly, to an apparatus and method for improving the yield of hydrolysis reaction to cellulose slurry using sulfuric acid or sulfate additives.

The present invention heats and pressurizes raw material water containing a small amount of sulfuric acid or sulfate to a subcritical water or supercritical water region in a heating unit, and then supplies the cellulose slurry supplied by the slurry pump to a reactor to hydrolyze the reaction. The reaction product exiting the reactor was first cooled by the cooling water supplied from the cooling water tank to terminate the reaction, followed by secondary cooling by a heat exchanger to completely terminate the reaction, and the reaction product was terminated by filtration. A series of devices and methods are provided that pass through a means to filter unreacted cellulose and obtain the filtrate from the product recovery tank.

Description

A method of decomposing cellulose with sulfuric acid and various sulfate additives under sub- and supercritical water}

The present invention relates to continuous hydrolysis of cellulose slurry, and more particularly, to an apparatus and method for improving the yield of hydrolysis reaction to cellulose slurry using sulfuric acid or sulfate additives.

Currently, a large amount of wastes contain many useful ingredients as chemical raw materials and energy sources, and a lot of research is being conducted to develop methods for using them. Among them, the treatment and efficient use of biomass wastes such as wood, bark and waste paper, which are emitted from agriculture, forestry, industry, and cities, have emerged as important issues. Biomass, which is drawing attention as a substitute for fossil fuels, is being disposed of in large quantities, and its utilization is very low compared to fossil fuels.

Biomass, the main ingredient of cellulose, is the most abundant substance on earth, and can be used as a raw material of high value-added synthetic polymer manufactured by liquid energy source or petrochemical industry. Even in Korea, the amount of sawdust generated in 1996 was 86.7 million tons and rice husks were 65 million tons. The effect can be obtained.

The conversion of biomass resources into liquid energy sources or high value-added materials consists of two processes: first hydrolysis of cellulose, a major component of biomass, into glucose or oligomer, followed by purification or fermentation. Among these processes, fermentation of glucose to be used as ethanol or as a food and feedstock is already developed and popularized. Therefore, a process of hydrolyzing biomass material and converting it into glucose is a core technology.

In general, there are three methods of recovering glucose or oligomer by decomposing cellulose.

(1) Acid catalyst hydrolysis method: The acid catalyst hydrolysis process is known as a conventional process with a long history. The reaction rate is slow and when operating at high temperature, corrosion of the device by acid and waste water treatment have been raised recently. It is not used.

(2) Enzymatic hydrolysis: Enzymatic hydrolysis process, which is being studied in earnest, also has problems in process efficiency and economic efficiency such as slow reaction rate, low activity of enzyme during long-term operation, and development of highly efficient strains There is no commercialization yet.

(3) Supercritical water hydrolysis method: Researches to develop the supercritical water reaction process by dramatically improving the hydrolysis reaction rate by physical treatment of converting water, which is the solvent which is most easily encountered, into the supercritical water area, It is actively progressing in developed countries. However, even in the case of hydrolysis using supercritical water, the reaction rate is very fast, but the disadvantage is that the yield of glucose in the product is as low as 20%.

It is therefore an object of the present invention to provide a series of apparatuses and methods for greatly improving the reaction rate in the hydrolysis method using supercritical water and improving the yield of the hydrolysis reaction.

The inventors of the present invention have repeatedly conducted various experiments to achieve the above object, and when a small amount of sulfuric acid or sulfate is added to the supercritical water, the decomposition rate of cellulose is increased and the yield of the product of hydrolysis is greatly improved. By confirming that, this invention was completed.

1 is a schematic configuration diagram of a reaction apparatus according to the present invention,

2 is a graph showing the yield of glucose according to residence time when 0.03 wt% of sulfuric acid is added under supercritical water conditions (400 ° C. and 30 MPa).

3 is a graph showing the yield of glucose according to residence time when 0.03 wt% of copper sulfate is added under supercritical water conditions (400 ° C., 30 MPa).

4 is a diagram showing the yield of glucose according to the concentration change of sulfuric acid when the residence time is 0.08 seconds in supercritical water conditions (400 ℃, 30MPa),

5 is a graph showing the yield of glucose according to residence time when 0.03 wt% is added under subcritical water conditions (360 ° C., 3030 MPa).

Explanation of symbols for major symbols in the drawings

1: raw material water tank, 2: high pressure pump,

3, 15: pressure gauge, 4: heating part,

8: reactor, 9: cellulose slurry,

10: slurry pump, 11: coolant pump

12: coolant tank, 13: heat exchanger,

14: filtration means, 16: pressure regulator

The present invention relates to a continuous hydrolysis reaction of cellulose, and more particularly, to an apparatus and a method for improving the yield of hydrolysis reaction to a cellulose slurry using sulfuric acid or sulfate additives.

The present invention provides a raw material water tank (1) containing raw water with a small amount of sulfuric acid or sulfate added thereto, a high pressure pump (2) for transferring the raw material water, and heating for raising the raw water to the required temperature and pressure. A raw material water supply part including a part 4; A cellulose slurry supply section including a slurry pump 10 for embedding the cellulose slurry 9 and supplying it to the raw material water; A hydrolysis reaction unit including a reactor (8) in which the raw material water and the cellulose cause a hydrolysis reaction; In order to terminate the hydrolysis reaction, the cooling water tank 12 for supplying the cooling water, the cooling water pump 11 for transferring the cooling water, and the reaction product in which the hydrolysis reaction is completed by the cooling water are again cooled by heat exchange. A hydrolysis reaction terminating unit including a heat exchanger 13 to be used; Filtration means (14) for filtering the unreacted cellulose from the reaction product from the heat exchanger (13), and a product recovery tank (17) for recovering the glucose component passed through the filtering means (14) Provide a series of devices. In this case, reference numerals 3 and 15 are pressure gauges, and 5, 6, and 7 are thermocouples.

In addition, the present invention, after heating and pressing the raw material water containing a small amount of sulfuric acid or sulfate in the subcritical water or supercritical water region in the heating section 4, the cellulose slurry (supplied by the slurry pump (10) ( 9) together with the reactor 8 to proceed with the hydrolysis reaction, the reaction product exiting the reactor 8 is first cooled by the cooling water supplied from the cooling water tank 12 to terminate the reaction, and then heat exchange Secondary cooling by means of a gas (13) to completely terminate the reaction, passing the reaction product after completion of the reaction through the filtration means (14) to filter out unreacted cellulose, and to obtain the filtrate from the product recovery tank (17). Provide a method.

In this invention, 0.01-0.1 wt% of sulfuric acid or sulfate is added to raw material water. The sulfate includes copper sulfate, iron sulfate, magnesium sulfate, and the like, and may be used together with sulfuric acid or alone. In the present invention, the sulfuric acid component performs a function as a catalyst, and when it is added at 0.01wt% or less with respect to the raw water, the reaction rate and reaction yield are lower, whereas when added at 0.1wt% or more, there is a problem of corrosion. Not only is not preferable because no further improvement in reaction yield is achieved.

In the present invention, the heating section 4 can heat and pressurize the raw material water to a subcritical water region of about 22 to 45 MPa at 330 ° C to 374 ° C. In this case, in the subcritical water region at a temperature lower than 330 ° C, the conversion rate and the reaction yield decrease, which is not preferable. On the other hand, in the heating section 4, the raw material water can be heated and pressurized from 374 ° C to 450 ° C to a supercritical water region of about 22 to 45 MPa. In this case, a rapid decomposition reaction proceeds at a temperature higher than 450 ° C. It is not preferable because the reaction yield of the hydrolyzate is lowered.

In the present invention, the heated and pressurized raw water is mixed with the cellulose slurry 9 supplied from the slurry pump 10 to enter the reactor 8. The cellulose slurry 9 is continuously supplied by the slurry pump 10 as a reactant, and a slurry having a uniform concentration with a stirrer is installed in the slurry pump 10 so that a constant concentration of slurry can be supplied. Is fed to the reactor (8). At this time, the slurry is mixed with the front of the supercritical water at the inlet of the reactor 8 at a constant flow rate ratio and then introduced into the reactor. As for the feed ratio of supercritical water and a slurry, about 2-4: 1 are preferable.

In the present invention, the mixture introduced into the reactor 8 undergoes a hydrolysis reaction in the following manner. ;

Cellulose + H ₂ O ⇒ glucose + fructose + oligomer

On the other hand, the supercritical water and the cellulose slurry perform hydrolysis while staying in the reactor 8 for 0.04 seconds to 2.5 seconds. At this time, the residence time (τ) in the reactor 8 can be calculated using the following equation. ;

Where ρ is the density of the mixture in the reactor, V is the volume of the reactor and F is the flow rate of the mixture. Therefore, since the residence time τ in the reactor 8 depends on the flow rate of the mixture when the density of the mixture and the volume of the reactor are constant, the reaction time τ can be adjusted by adjusting the flow rate.

In the present invention, after completion of the hydrolysis reaction in the reactor (8), the reactant coming out of the outlet is cooled by the cooling water supplied by the cooling water pump (11) to terminate the hydrolysis reaction, the supply amount of the cooling water is the raw water A flow rate of at least about the sum of the flow rates of the and cellulose slurry is suitable. In this step, the hydrolysis reaction is completed once, and the reaction product is sufficiently cooled through the heat exchanger (13).

In the present invention, the unreacted cellulose is removed while passing through the filtration means 14 in the reaction product in which the hydrolysis reaction is terminated. The filtrate from which the unreacted cellulose is removed by the filtration means 14 is recovered by the product recovery tank 17, and the internal pressure of the entire system is controlled by using the pressure regulators 3 and 16. At this time, the reaction product is in a solution state, and high performance liquid chromatography (HPLC) is used for analysis of the product, and the conversion rate of cellulose during the hydrolysis reaction is determined by the mass of unreacted cellulose present in the filtration means 14. It is easy to calculate by measuring.

Hereinafter, the most preferred embodiment of the present invention will be described in detail with specific numerical values. However, the preferred embodiment of the present invention is only one example presented to practice the present invention, it is obvious that the scope of the present invention is not limited by the embodiments presented herein.

<< Example 1 >>

The raw material water which added 0.03 wt% sulfuric acid and copper sulfate to raw material water was sent to the heating part 4 using the high pressure pump 2, and it was made into the supercritical water state of 400 degreeC and 30 MPa there. On the other hand, after fully stirring for 30 minutes or more using the stirrer in a slurry apparatus, the cellulose slurry was supplied to the reactor 8. At this time, the reactor 8 was supplied with supercritical water at a flow rate of 19.6 ml / min and a cellulose slurry at a flow rate of 8.4 ml / min, respectively, which were directly mixed in the reactor 8 to undergo a hydrolysis reaction. It is preferable that the concentration of the cellulose slurry after mixing with the supercritical water in the reactor 8 is 3 wt%. The reactor (8) was made of a stainless tube to have a volume of 0.115 cm ³ , and a heating tape was installed outside the reactor to fine tune the temperature in the reactor (8).

In order to stop the reaction of the effluent from the reactor 8 rapidly, a cooling water at room temperature was supplied at the end of the reactor. The cooling water was supplied at a flow rate of 13.05 ml / min using the cooling water pump 11, and then secondly, the temperature of the reactant was lowered to room temperature through the double tube heat exchanger 13. The unreacted cellulose in the effluent passed through the reactor was recovered from the metal filter 14 having pores of 0.5 μm, and the reaction product passed through the filter was collected after passing through the pressure regulating valve 16. The conversion rate was calculated by measuring the weight of the recovered unreacted cellulose, and liquid chromatography was used to analyze the product. As a result of the reaction, the conversion was found to be 99% or more.

<< Example 2 >>

In Example 1, it was carried out in the same manner as in Example 1 except that the condition of the heating unit 4 was carried out in a subcritical water state of 360 ℃, 30MPa. As a result of the reaction, the conversion was found to be 90%.

As described above, in the present invention, instead of the conventional method using pure subcritical water or supercritical water only, a small amount of sulfuric acid and sulfate catalysts were added to the supercritical water as a reaction medium to rapidly decompose cellulose in a very short time. In addition, by significantly improving the yield of glucose up to 50wt% or more it can be usefully used as a petrochemical raw material.

Therefore, the present invention is expected to make a great contribution in the treatment of biomass waste.

In the above description of the continuous decomposition method of the cellulose according to the present invention by way of examples, which is described only the most preferred embodiment of the present invention, of course, the present invention is not limited thereto. In addition, anyone of ordinary skill in the art will be able to make various modifications and imitations according to the description of the present specification, but it will be apparent that this is also outside the scope of the present invention.

Claims (6)

Raw material tank (1) containing raw material water to which sulfuric acid or sulfate is added in small amounts, a high pressure pump (2) for transferring the raw material water, and a heating unit (4) for raising the raw material water to the required temperature and pressure. Raw water supply unit including; A cellulose slurry supply section including a slurry pump 10 for embedding the cellulose slurry 9 and supplying it to the raw material water; A hydrolysis reaction unit including a reactor (8) in which the raw material water and the cellulose cause a hydrolysis reaction; In order to terminate the hydrolysis reaction, the cooling water tank 12 for supplying the cooling water, the cooling water pump 11 for transferring the cooling water, and the reaction product in which the hydrolysis reaction is completed by the cooling water are again cooled by heat exchange. A hydrolysis reaction terminating unit including a heat exchanger 13 to be used; Reaction consisting of a filtration means 14 for filtering unreacted cellulose from the reaction product from the heat exchanger 13 and a product recovery tank 17 for recovering the glucose component passed through the filtration means 14. A continuous decomposition device of cellulose comprising a product recovery unit. The raw material water containing a small amount of sulfuric acid or sulfate is heated and pressurized in the subcritical water or supercritical water region in the heating section 4, and then the reactor together with the cellulose slurry 9 supplied by the slurry pump 10 described above. (8) was supplied to advance the hydrolysis reaction, and the reaction product exiting the reactor (8) was first cooled by the cooling water supplied from the cooling water tank (12) to terminate the reaction, and then to the heat exchanger (13). Cellulose, characterized in that the reaction is completed by secondary cooling to complete the reaction, the reaction product is terminated through the filtering means 14 to filter the unreacted cellulose, the filtrate is obtained from the product recovery tank 17 Continuous hydrolysis method. The method of claim 2, The sulfur or sulfates may be used alone or in combination, and they are used by 0.01 to 0.1wt%. The method of claim 2, Said subcritical water region is a temperature of 330 degreeC-374 degreeC, and the pressure of 22-45 Mpa. The method of claim 2, The supercritical water region is characterized in that the temperature of 374 ℃ to 450 ℃ and 22-45 MPa pressure. The method of claim 2, The residence time of the reactants in the reactor (8) is characterized in that from 0.04 seconds to 2.5 seconds.