CN112442000B - An integrated reactor and method for preparing furfural and levulinic acid by graded agricultural and forestry waste biomass - Google Patents

Abstract

The invention discloses an integrated reactor and a method for preparing furfural and levulinic acid by using agricultural and forestry waste biomass in a grading manner. The integrated reactor comprises a reactor barrel, wherein a steam inlet spray pipe is arranged on the lower portion of the reactor barrel, a steam outlet regulating valve is arranged at the top of the reactor barrel, a mechanical stirring system is arranged on the reactor barrel and comprises a stirrer and a motor, the stirrer is arranged inside the reactor barrel, the motor drives the stirrer to rotate, and a biomass raw material inlet and an acid liquor replenishing inlet are formed in the top of the reactor barrel. The invention designs and develops a novel stripping-hydrolysis integrated depolymerization reactor based on the difference of depolymerization activation energy of cellulose and hemicellulose in biomass, provides a new thought of stepwise depolymerization and conversion of agriculture and forestry waste biomass, realizes the optimized matching of energy supply and substance conversion in the stepwise conversion process, and solves the problem of inconsistent requirements of hemicellulose stripping and cellulose hydrolysis conversion on process operation parameters.

Description

An integrated reaction of furfural and levulinic acid prepared by fractional production of agricultural and forestry waste biomass implements and methods

technical field

The invention relates to the technical field of biomass energy, in particular to an integrated reactor and method for preparing furfural and levulinic acid by graded agricultural and forestry waste biomass.

Background technique

my country is a big country in agriculture and forestry, and the stock of available biomass resources reaches 1 billion tons of standard coal per year. A large amount of discarded agricultural and forestry waste biomass has brought enormous environmental pressure every year. For example, the illegal and disorderly burning of a large number of agricultural and forestry wastes has been repeatedly banned, and the pollution caused by the concentrated burning of agricultural and forestry wastes under unfavorable weather conditions has intensified, leading to a sharp increase in smog. Therefore, the efficient treatment of agricultural and forestry waste biomass resources is one of the important contents of environmental governance.

Biomass is the only renewable carbon resource in nature with near-zero emission characteristics. The efficient utilization of biomass is one of the ideal ways to ensure the sustainable supply of clean energy. However, factors such as low efficiency and poor economy of the current biomass raw material conversion process limit the large-scale utilization of agricultural and forestry waste biomass. Recycling and high-value utilization of agricultural and forestry waste biomass has become a key technology in the field of environmental governance, and is of great significance to the country's major strategic needs such as improving the environment, meeting the supply of clean energy, and reducing dependence on foreign crude oil.

In the process of biomass utilization, efficient and directional depolymerization of biomass into platform compounds and chemicals is an extremely important step. For example, the Chinese invention patent ZL201610304296.5 proposes a new technology to prepare bio-aviation fuel by using lignocellulosic biomass through furfural and levulinic acid, which opens up a new way to synthesize hydrocarbon fuels from lignocellulosic raw materials. However, in the process of biomass depolymerization and conversion to furfural levulinic acid and other compounds, the traditional hydrothermal depolymerization technology still has the following bottlenecks that need to be broken through: (1) Because biomass raw materials are sensitive to heat, the traditional hydrothermal depolymerization technology There are many side reactions, the high selectivity of the target product is low, the product is complex, and the separation is difficult; (2) The biomass components are complex. Under the traditional "one-pot" hydrolysis process, it is difficult for different components to be separated under their respective optimal conditions. Under the depolymerization conversion, the target product yield is low, and the depolymerization efficiency is low; (3) high energy consumption and large steam consumption are not conducive to industrialization promotion.

Contents of the invention

The invention provides an integrated reactor and method for the graded preparation of furfural and levulinic acid from agricultural and forestry waste biomass. The invention designs and develops a new type of steam stripper based on the difference in depolymerization activation energy of cellulose and hemicellulose in biomass. - Hydrolysis integrated depolymerization reactor, put forward a new idea of step-by-step depolymerization and conversion of agricultural and forestry waste biomass, realize the optimal matching of energy supply and material conversion in the step-by-step conversion process, and solve the problem of hemicellulose stripping and cellulose The problem of inconsistent requirements for process operation parameters in hydrolysis conversion.

The object of the present invention is to propose an integrated reactor for the fractional preparation of furfural and levulinic acid from agricultural and forestry waste biomass. A steam outlet regulating valve, the reactor barrel is provided with a mechanical stirring system, the mechanical stirring system includes a stirrer arranged inside the reactor barrel and a motor that drives the stirrer to rotate, and the reactor barrel The top of the body is provided with a biomass raw material inlet and an acid liquid replenishment inlet, and a jacket auxiliary heating system is arranged outside the reactor cylinder, and the jacket auxiliary heating system includes a jacket arranged outside the reactor cylinder and a jacket steam inlet arranged on the jacket, and a jacket steam outlet is also arranged at the bottom of the jacket. When the stirrer rotates, the biomass raw material in the reactor can be stirred evenly in the radial direction and vertical direction.

The reactor proposed by the present invention is a stripping-hydrolysis integrated reactor. In the traditional furfural preparation technology, in order to ensure the stripping reaction time of raw materials, the aspect ratio (ratio of height and diameter) of the stripping tower is generally at 6 ~10, and the yield of the product can be increased by prolonging the stripping time, but the equipment investment and operation difficulty are increased. Biomass hydrolysis to prepare levulinic acid is generally carried out in a tank reactor. Since the raw materials are generally not pretreated, in order to increase the conversion efficiency, the yield of levulinic acid products is generally increased by stirring, increasing the liquid-solid ratio, and increasing the temperature. Rate. Combining the characteristics of the two traditional processes of steam stripping and hydrolysis, the present invention determines the preferred range of reactor height-to-diameter ratio, adopts a new type of agitator, and strengthens the heat and mass transfer in the process of biomass raw materials; Based on the difference in depolymerization temperature of hemicellulose and cellulose, a new method of decomposing and depolymerizing to prepare furfural and levulinic acid was proposed. In this new method, the biomass stripping process is equivalent to the pretreatment of biomass raw materials in the hydrolysis process, which realizes the coupling of biomass stripping and hydrolysis reactions, and improves the overall efficiency of the entire process technology.

Preferably, the ratio of the height of the reactor cylinder to the diameter of the cylinder is 3-5:1.

Preferably, the lower part of the reactor cylinder is provided with several steam inlet nozzles, and the steam inlet nozzles are evenly distributed around the cylinder. Further preferably, four steam inlet nozzles are uniformly arranged around the cylinder body in the lower part of the reactor cylinder. The uniform setting of the steam nozzle is to make the steam evenly enter the reactor and make it fully contact with the biomass raw material.

The bottom of the reactor cylinder is provided with a discharge quick-opening valve and a sampling port, and the top is provided with a temperature measuring port and a pressure measuring port. The temperature measuring port can measure the temperature in the reactor in real time through the thermocouple extending into the reactor, and the pressure measuring port can measure the pressure in the reactor in real time to ensure the smooth progress of the reaction.

Preferably, the material of the reactor cylinder and the agitator is an acid-resistant material, and the acid-resistant material is a Hastelloy material, a composite plate material lined with Hastelloy, enamel-lined steel, an inner liner Pressure and corrosion resistant material of PFA plastic or pressure and corrosion resistant material lined with PTFE.

The present invention also protects a method for the graded preparation of furfural and levulinic acid from agricultural and forestry waste biomass, which is realized through the above-mentioned integrated reactor for the graded preparation of furfural and levulinic acid from agricultural and forestry waste biomass, and the specific steps are: biomass raw materials Use dilute acid solution to evenly mix the acid and enter the cylinder through the raw material inlet of the biomass material. After sealing the feed inlet, turn on the motor to drive the agitator to rotate, inject saturated steam through the steam inlet nozzle, and adjust the steam outlet regulating valve to ensure 140 ℃-160℃ for steam extraction to prepare furfural; after the furfural stripping is completed, acid liquid is added from the acid liquid supply inlet, and saturated water steam is fed through the steam inlet nozzle, and the jacketed steam in the jacket auxiliary heating system Steam is fed into the inlet for auxiliary heating, and the temperature of the reactor is adjusted to 160°C-180°C through the steam outlet regulating valve to carry out hydrolysis to prepare levulinic acid.

The medium hemicellulose component of the biomass raw material proposed by the present invention is converted into furfural by steam stripping and depolymerization under relatively mild conditions (140°C-160°C), while the cellulose component is converted into furfural under the preferred condition of 160°C-180°C The hydrolysis is converted into levulinic acid, which realizes the step-by-step depolymerization and conversion of different components of biomass raw materials, and improves the yield of two target products at the same time. In addition, since the stripping of hemicellulose and the hydrolysis of cellulose are performed in series in the same reactor, the consumption of catalyst sulfuric acid and steam is saved, and the technical economy of hydrothermal depolymerization of biomass is greatly improved. Biomass raw materials include corn stalks, wheat stalks, cotton stalks, bagasse and wood chips.

Preferably, the dilute acid solution is a dilute sulfuric acid solution, the mass fraction of the dilute sulfuric acid solution is 5% to 15%, and the amount of sulfuric acid is 0.5% to 5% of the mass of the biomass raw material; The acid added to the liquid supplement inlet is sulfuric acid, the mass fraction of the sulfuric acid is 5%-15%, and the amount of sulfuric acid is 0.5%-1% of the mass of the biomass raw material.

Preferably, the stirring speed of the agitator is 5-20 rpm.

Preferably, the steam extraction time is 30-120 minutes; the hydrolysis time is 30-180 minutes.

Preferably, the pressure of the saturated water vapor is 1.2-1.5 MPa.

Compared with the prior art, the beneficial effect of the present invention is that efficient depolymerization of biomass is a key step in utilization of biomass. An extraction and hydrolysis integrated reactor and an application method thereof. The reactor combines the advantages of the stripping tower and the hydrolysis tank. It strips hemicellulose to produce furfural under relatively mild conditions, and then increases the temperature to hydrolyze the cellulose to prepare levulinic acid. The production of levulinic acid is realized in the same reactor. The hemicellulose and cellulose components in the material raw materials are converted into furfural and levulinic acid with high selectivity, which greatly reduces the steam consumption.

Description of drawings

Fig. 1 is the structural schematic diagram of the stripping-hydrolysis integration reactor of biomass fractionation preparation furfural and levulinic acid of the present invention;

Fig. 2 is a schematic diagram of the layout of the steam inlet nozzle in Fig. 1;

Description of reference signs: 1. Reactor cylinder; 2. Temperature measuring port; 3. Pressure measuring port; 4. Steam inlet nozzle; 4a, first steam inlet nozzle; 4b, second steam inlet nozzle; 4c , the third steam inlet nozzle; 4d, the fourth steam inlet nozzle; 5, the ribbon agitator; 6, the discharge quick-opening valve; 7, the sampling port; Inlet; 10. Biomass raw material inlet; 11. Mechanical stirring system; 12. Steam outlet regulating valve; 13. Acid liquid replenishment inlet; 14. Jacket auxiliary heating system.

detailed description

The following examples are to further illustrate the present invention, rather than limit the present invention. Unless otherwise specified, the equipment and reagents used in the present invention are conventional commercial products in the technical field.

As shown in Figure 1 and Figure 2, the main structure of the steam stripping-hydrolysis integrated reactor for the fractional preparation of furfural and levulinic acid from agricultural and forestry waste biomass is as follows: it mainly includes a reactor cylinder 1 and a jacketed auxiliary heating system 14, and the reactor The lower part of the cylinder 1 is provided with a quick-opening valve 6 for discharging materials, a sampling port 7 for sampling during the reaction, and four steam inlet nozzles 4 are arranged on the side of the bottom of the reactor cylinder 1, and the first steam inlet nozzle 4a , the second steam inlet nozzle 4b, the third steam inlet nozzle 4c, and the fourth steam inlet nozzle 4d are evenly distributed along the circumference of the reactor cylinder 1, and the top of the reactor cylinder 1 is provided with a steam outlet regulating valve 12 for real-time measurement The temperature measurement port 2 for the temperature inside the reactor, the pressure measurement port 3 for real-time measurement of the pressure in the reactor, the biomass raw material inlet 10, the acid liquid supplement inlet 13, the reactor cylinder 1 is also provided with a mechanical stirring system 11, and the mechanical stirring The system 11 includes a motor and an agitator driven by the motor. In the present invention, the agitator is preferably a ribbon agitator 5 . The jacket auxiliary heating system 14 includes a jacket arranged outside the reactor cylinder 1 and a jacket steam inlet 9 arranged on the jacket, and a jacket steam outlet 8 is also arranged at the bottom of the jacket.

The height-to-diameter ratio of the cylinder body 1 of the integrated stripping-hydrolysis reactor is between 3:1 and 5:1. In the following examples, the reactor cylinder preferably has an aspect ratio of 4:1.

The reactor cylinder 1, the ribbon stirrer 5 and the pipe fittings in contact with the liquid are made of acid corrosion resistant materials, which include: Hastelloy material, composite plate material lined with Hastelloy, steel lined with enamel, inner Pressure-resistant material lined with PFA plastic and pressure-resistant material lined with polytetrafluoroethylene (PEFE). Sulfuric acid in the following examples is a sulfuric acid solution with a mass fraction of 8%.

Example 1

A method for graded preparation of furfural and levulinic acid from agricultural and forestry waste biomass, comprising the following steps: corn stalk raw material and dilute sulfuric acid solution are evenly mixed with acid, and then enter the reactor barrel 1 through the biomass raw material inlet 10 (the amount of sulfuric acid is corn stalk 1% of the straw mass), after sealing the feed inlet, feed 1.3MPa saturated water vapor, open the ribbon agitator 5, adjust the steam outlet regulating valve 12 to a temperature of 150°C inside the reactor, and carry out under this condition After steam extraction for 60 minutes, collect the stripping liquid, that is, the furfural-containing product liquid. After the furfural stripping is completed, add sulfuric acid from the acid liquid supplement inlet 13 (the sulfuric acid consumption is 1% of the corn stalk quality), and the rotating speed is 10rmp, and the jacket steam inlet 9 of the jacket auxiliary heating system 14 is passed into steam auxiliary heat, Raise the temperature and pressure of the reactor through the steam outlet regulating valve 12, and carry out hydrolysis to prepare levulinic acid when the temperature reaches 170° C., and the hydrolysis time is 120 minutes. The furfural yield and levulinic acid yield obtained in the test run are shown in Table 1.

Example 2-5

The operation method is the same as in Example 1, and the yield of furfural and the yield of levulinic acid are recorded in Table 1 by changing the stripping temperature, stripping time, hydrolysis temperature and hydrolysis time and other process conditions.

Table 1

It can be concluded from Table 1 that when the stripping temperature is ≥150°C, the hydrolysis temperature is ≥170°C, and the stripping time and hydrolysis time both reach 60 minutes, the yield of furfural and levulinic acid products is relatively high.

Example 6-9

The method for preparing furfural and levulinic acid by classification from agricultural and forestry waste biomass refers to Example 5. The stripping temperature is 150°C, the stripping time is 120min, the hydrolysis temperature is 180°C, and the hydrolysis time is 120min. The amount of sulfuric acid used for supplementing acid and the stirring rate, the yield of furfural and the yield of levulinic acid obtained are recorded in Table 2.

Table 2

The amount of sulfuric acid mixed with acid for the first time Furfural yield (%) Supplementary acid sulfuric acid dosage Stirring rate (rmp) Levulinic acid yield (%) Example 5 1% 11.2 1% 10 15.5 Example 6 1% 11.2 1% 5 14.6 Example 7 1% 11.2 1% 20 15.5 Example 8 0.5% 4.9 1% 10 13.0 Example 9 5% 11.9 0.5% 10 15.8

The amount of sulfuric acid used in Table 2 is expressed as a percentage of straw raw materials.

Drawn from Table 2, when the amount of sulfuric acid mixed with acid for the first time and the amount of supplemented sulfuric acid reached 1%, the yield of furfural and levulinic acid was higher. When the amount of sulfuric acid is small, the reaction of biomass raw materials is insufficient, resulting in low yields of target products furfural and levulinic acid.

Example 10

The method for preparing furfural and levulinic acid by graded agricultural and forestry waste biomass refers to Example 5. The amount of sulfuric acid mixed with acid for the first time is 2% of the straw mass, the stripping temperature is 150°C, and the stripping time is 120min. The amount of steam consumed, furfural yield The yields are shown in Table 3.

Example 11

Currently, the furfural in the industry adopts the direct stripping process, and the stripping reactor does not have a stirring device. For comparison, with reference to Example 10, the amount of sulfuric acid mixed with acid for the first time is 2% of the straw quality, the stripping temperature is 150°C, the stripping time is 120min, the stirrer is not opened (no stirring), and the same amount of steam is consumed as in Example 10 The yield of the furfural yield when is as shown in table 3.

Example 12

The method for preparing furfural and levulinic acid by classification of agricultural and forestry waste biomass refers to Example 5. The amount of sulfuric acid mixed with acid for the first time is 2% of the straw mass, and the hydrolysis is directly carried out without stripping. The hydrolysis temperature is 180° C. and the hydrolysis time is 120 minutes. The amount of steam consumed, the yield of furfural, and the yield of levulinic acid are shown in Table 3. For ease of comparison, the yield of total steam consumed in Example 5, furfural yield, and levulinic acid is also recorded in Table 3.

table 3

The amount of sulfuric acid used in the table is expressed as a percentage of straw raw materials, and the total steam consumption is the amount of steam consumed per ton of straw raw materials.

From the data in Table 3, 1 ton of corn stalk raw material can be used to produce 112kg furfural and 155kg levulinic acid using the method of the present invention, and the steam consumption is only 7 tons; The amount of furfural and levulinic acid requires 2 tons of corn stalks as raw material and 11.5 tons of steam consumption. The integrated reactor and method for preparing furfural and levulinic acid by gradually depolymerizing hemicellulose and cellulose in biomass raw materials proposed by the present invention save nearly 40% of steam.

Example 13

In the stripping-hydrolysis integrated reactor with an aspect ratio of 8:1, referring to the method of Example 5, the amount of sulfuric acid mixed with acid for the first time is 1% of the straw mass, the stripping temperature is 150°C, and the stripping time is 120min , the amount of sulfuric acid for supplementing acid was 1% of the straw mass, the hydrolysis temperature was 180°C, the hydrolysis time was 120min, and the yields of furfural and levulinic acid were 11.7% and 10.3%, respectively. Compared with Example 5, the yield of levulinic acid decreased significantly. The reason for the analysis was that the aspect ratio was too large, and the raw materials in the upper part of the reactor were not fully submerged by high-temperature liquid water, which affected the hydrolysis efficiency.

The above are only preferred implementations of the present invention, and it should be noted that the above preferred implementations should not be regarded as limiting the present invention, and the scope of protection of the present invention should be based on the scope defined in the claims. For those skilled in the art, without departing from the spirit and scope of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims (9)

1. An integrated reactor for preparing furfural and levulinic acid by classification of agricultural and forestry waste biomass is characterized in that it includes a reactor cylinder, the bottom of the reactor cylinder is provided with a steam inlet nozzle, and the top is provided with a steam inlet nozzle. An outlet regulating valve, the reactor cylinder is provided with a mechanical stirring system, the mechanical stirring system includes an agitator arranged inside the reactor cylinder and a motor that drives the agitator to rotate, and the reactor cylinder The top is provided with a biomass raw material inlet and an acid liquid replenishment inlet, and a jacketed auxiliary heating system is arranged outside the reactor cylinder, and the jacket auxiliary heating system includes a jacket arranged outside the reactor cylinder and The jacket steam inlet is arranged on the jacket, the jacket steam outlet is also arranged at the bottom of the jacket, and the ratio of the height of the reactor cylinder to the diameter of the reactor cylinder is 3-5:1. 2. the integrated reactor for preparing furfural and levulinic acid according to the classification of agricultural and forestry waste biomass according to claim 1, is characterized in that, the lower part of the cylinder body of the reactor is provided with several steam inlet nozzles, and the steam inlet nozzle The tubes are evenly distributed around the cylinder. 3. the integrated reactor for preparing furfural and levulinic acid according to the classification of agricultural and forestry waste biomass according to claim 1, is characterized in that, the bottom of the cylinder body of the reactor is provided with a quick-opening valve and a sampling port, and the top is A temperature measuring port and a pressure measuring port are provided. 4. the integrated reactor for preparing furfural and levulinic acid according to the classification of agricultural and forestry waste biomass according to claim 1, is characterized in that, the material of described reactor barrel and agitator is acid corrosion resistant material, and described The acid corrosion-resistant material is Hastelloy material, Hastelloy-lined composite plate material, enamel-lined steel, PFA plastic-lined pressure-resistant material or PTFE-lined pressure-resistant material. 5. A method for preparing furfural and levulinic acid by classification of agricultural and forestry waste biomass is characterized in that, the integrated reactor for preparing furfural and levulinic acid by the classification of agricultural and forestry waste biomass according to claim 1 is realized, and the specific steps It is: the biomass raw material is evenly mixed with dilute acid solution, and then enters the reactor cylinder through the biomass material raw material inlet. After the feed inlet is sealed, the motor is turned on to drive the agitator to rotate. Steam outlet regulating valve, steam extraction at 140°C-160°C to prepare furfural; after furfural stripping is completed, acid liquid is added from the acid liquid replenishment inlet, and saturated water vapor is fed through the steam inlet nozzle. The steam inlet of the jacket of the heat system is fed with steam for auxiliary heating, and the temperature of the reactor is adjusted to 160°C-180°C through the steam outlet regulating valve for hydrolysis to prepare levulinic acid. 6. the method for preparing furfural and levulinic acid according to the classification of agricultural and forestry waste biomass according to claim 5, is characterized in that, described dilute acid solution is dilute sulfuric acid solution, and the massfraction of described dilute sulfuric acid solution is 5% ～15%, the consumption of sulfuric acid is 0.5%～5% of biomass raw material quality; The acid added from the acid liquid supplement inlet is sulfuric acid, the mass fraction of described sulfuric acid is 5～15%, and the sulfuric acid consumption is 0.5% to 1% of the quality of biomass raw materials. 7. The method for fractionally preparing furfural and levulinic acid from agricultural and forestry waste biomass according to claim 5, characterized in that, the stirring rate of the agitator is 5-20 rpm. 8. The method for preparing furfural and levulinic acid by fractional production of agricultural and forestry waste biomass according to claim 5, characterized in that, the steam extraction time is 30-120 minutes; the hydrolysis time is 30-180 minutes. 9 . The method for fractionally preparing furfural and levulinic acid from agricultural and forestry waste biomass according to claim 5 , wherein the pressure of the saturated water vapor is 1.2-1.5 MPa.

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