Acrylic polymer based on biorefinery solid waste and preparation method thereof

Abstract

The invention discloses an acrylic polymer based on biorefinery solid waste and a preparation method thereof, and belongs to the field of preparation of acrylic polymers. The invention relates to a preparation method of an acrylic polymer based on biorefinery solid waste. The preparation method comprises the following steps: a, hydrolyzing and fermenting cellulose biomass to obtain bio-based lactic acid; b, purifying the bio-based lactic acid; c, conveying the purified bio-based lactic acid, inert gas and water vapor into a fixed bed reactor, and performing multi-stage catalytic dehydration reaction under a micro-negative pressure condition to obtain acrylic acid reaction gas; d, separating and purifying the acrylic acid reaction gas to obtain purified acrylic acid; e, carrying out polymerization reaction on the purified acrylic acid to obtain an acrylic polymer; according to the method, side reactions can be reduced through introduction of water vapor and micro-negative pressure reaction, the yield of the acrylic polymer can be improved through segmented reaction and uniform distribution of gaseous lactic acid, meanwhile, reutilization of thermal resources is achieved, the preparation cost is reduced, and the benefits of production and preparation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of acrylic acid polymer preparation, and in particular to an acrylic acid polymer based on biorefining solid waste and a preparation method thereof. Background Art

[0002] Acrylic polymers are an important branch of the polymer industry due to their rich molecular design, excellent physical and chemical properties, and a wide range of applications. Due to their diverse chemical structures and adjustable properties, they are widely used in industry, daily chemicals, medical treatment, environmental protection and other fields. Acrylic polymers are a type of high molecular material produced by the polymerization reaction of acrylic acid or its derivatives (such as acrylates, acrylamide, etc.). The production of acrylic acid worldwide mainly undergoes the chlorohydrin method, cyanohydrin method, Reppe method, ketene method, acrylonitrile hydrolysis method and propylene two-step oxidation method.

[0003] In recent years, due to the continued high price of oil, the depletion of disposable energy, and the survival crisis brought about by environmental degradation, people's attention has once again focused on renewable resources. Among them, biomass resources have become a highlight with their efficient utilization through modern technology. Biomass is fermented to produce lactic acid and its derivatives, which are then dehydrated to produce acrylic acid or its derivatives. Lactic acid fermentation has the highest yield of product to substrate of all current industrial fermentation processes. Its main raw material is not only abundant corn starch, but also can use a large amount of cheaper solid waste such as cellulosic biomass (agricultural or forestry waste, such as straw, sugarcane bagasse, and sawdust) as the raw material for lactic acid production, which is low in cost. Therefore, the production process of producing acrylic acid by dehydrating lactic acid has obvious cost competitiveness and environmental benefits. However, the yield of acrylic acid polymers prepared by lactic acid-catalyzed dehydration is generally between 60% and 75% under laboratory conditions. However, in actual industrialization, due to raw material loss and purification steps, the total yield is generally 50% to 60%. Therefore, the yield of acrylic acid polymers in actual production is still not high, resulting in problems such as waste of raw materials, increased costs, and poor economic benefits in actual production. Therefore, how to improve the yield of acrylic acid polymers prepared by lactic acid-catalyzed dehydration is an urgent problem that technicians in this field need to solve. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of low yield when preparing acrylic acid polymer by lactic acid catalytic dehydration in the prior art, and to propose an acrylic acid polymer based on biorefining solid waste and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing acrylic acid polymers based on biorefining solid waste, using cellulosic biomass as raw material for lactic acid production, comprises the following steps: a. Producing bio-based lactic acid by hydrolysis and fermentation of cellulosic biomass; b. Purify the bio-based lactic acid and remove impurities; c. The purified bio-based lactic acid, inert gas, and water vapor are introduced into a fixed-bed reactor, and the bio-based lactic acid is gasified and then subjected to a multi-stage catalytic dehydration reaction under slightly negative pressure to obtain acrylic acid reaction gas; d. The acrylic acid reaction gas is separated and purified to obtain purified acrylic acid; e. performing a polymerization reaction on the purified acrylic acid to obtain an acrylic acid polymer.

[0006] In some embodiments, a segmented catalytic assembly and a segmented gasification assembly are provided in the fixed bed reactor. The segmented catalytic assembly includes a plurality of catalytic sections spaced apart along the direction of catalytic dehydration, for performing segmented catalytic dehydration of gaseous lactic acid. The segmented gasification assembly includes a plurality of heat exchange gasification sections spaced apart along the direction of catalytic dehydration, for heating and gasifying liquid lactic acid and transporting it to the fixed bed reactor, and the plurality of catalytic sections and the plurality of heat exchange gasification sections are cross-distributed.

[0007] In some embodiments, the catalytic units are respectively a first catalyst layer, a second catalyst layer and a third catalyst layer, and the catalysts in the first catalyst layer, the second catalyst layer and the third catalyst layer are all HZSM-5 molecular sieve or phosphate-supported catalyst.

[0008] In some embodiments, several of the heat exchange and gasification sections are respectively a first heat exchanger, a second heat exchanger and a third heat exchanger, the inlet of the first heat exchanger is the inlet of liquid lactic acid, and a first connecting pipe is connected between the outlet of the first heat exchanger and the inlet of the second heat exchanger, a second connecting pipe is connected between the outlet of the second heat exchanger and the inlet of the third heat exchanger, a third connecting pipe is connected between the outlet of the third heat exchanger and the air inlet of the fixed bed reactor, and a gaseous lactic acid distributor connected to the air inlet of the fixed bed reactor is provided inside the fixed bed reactor.

[0009] In some embodiments, a gas redistribution device is provided between the first heat exchanger and the second catalyst layer, and between the second heat exchanger and the third catalyst layer.

[0010] In some embodiments, the gas redistribution device includes a funnel-shaped collecting hood, a cylindrical distributing hood, and a frustum-shaped distributing plate arranged in the distributing hood. The large-diameter end of the collecting hood faces opposite to the direction of catalytic dehydration, and the small-diameter end is sealed and connected to one end of the distributing hood. The other end of the distributing hood is open and faces the direction of catalytic dehydration, and the inner diameter of the distributing hood is larger than the inner diameter of the small-diameter end of the collecting hood. The interior of the frustum-shaped distributing plate is hollow with openings at both ends and is coaxial with the distributing hood. There are several distributing plates, and the several distributing plates are distributed layer by layer from the inside to the outside and the diameter gradually increases. The taper of the several distributing plates from the inside to the outside gradually increases, and an annular distributing gap is formed between two adjacent distributing plates.

[0011] In some embodiments, heating jackets are provided on the outside of the fixed bed reactor at positions corresponding to the plurality of catalytic parts, and thermocouples are provided in the plurality of catalytic parts.

[0012] In some embodiments, the inert gas in step c is nitrogen or carbon dioxide, the volume ratio of water vapor to the gasified bio-based lactic acid feed is 5-10%, and the slightly negative pressure is 0.5-0.8 atm.

[0013] In some embodiments, the separation and purification in step d includes condensation recovery, distillation purification, and adsorption purification.

[0014] An acrylic acid polymer based on biorefining solid waste is prepared by the above method.

[0015] Compared with the prior art, the present invention provides an acrylic acid polymer based on biorefining solid waste and a preparation method thereof, which has the following beneficial effects.

[0016] 1. In the present invention, during the catalytic dehydration reaction, a certain amount of water vapor can inhibit the deposition of the carbon precursor by forming competitive adsorption, thereby reducing side reactions and playing a certain role in improving the yield of the acrylic acid polymer. In addition, the vacuum pump and the buffer tank can maintain a certain slight negative pressure in the fixed bed reactor, thereby further reducing side reactions, such as preventing decarboxylation to form acetic acid. At the same time, the vacuum pump can shorten the residence time of the product in the fixed bed reactor through the suction effect, thereby helping to control the reaction time and avoid overreaction.

[0017] 2. The present invention, through the coordination of the segmented gasification assembly and the segmented catalytic assembly, can not only directly cool the reacting gaseous lactic acid to a certain extent through the liquid lactic acid to prevent it from being overheated and coking, but the gaseous lactic acid can also heat the liquid lactic acid, so that the subsequently added liquid lactic acid can be heated and gasified while the lactic acid gas is cooled. Therefore, there is no need to arrange other special gasification equipment, the reuse of thermal resources is realized, the coupling of the reaction process is strengthened, and the preparation cost can be reduced to a certain extent, while the production efficiency is improved.

[0018] 3. The present invention, through the coordination of the segmented gasification assembly and the segmented catalytic assembly, can also achieve the purpose of segmented temperature control, thereby achieving the purpose of segmented catalytic dehydration of gaseous lactic acid. The low temperature in the front section promotes the adsorption and activation of lactic acid, and then as the temperature increases, the high temperature in the middle and back sections accelerates the dehydration reaction. By optimizing the heating form, the efficiency of the catalytic dehydration reaction can be improved to a certain extent, thereby having a positive effect on improving the yield and yield of acrylic acid polymerization.

[0019] 4. The present invention, through the provision of a gas redistribution device, can redistribute the unevenly distributed lactic acid gas flow in the catalytic dehydration reaction, so that the lactic acid gas flow can pass through each catalyst layer evenly, avoiding excessive concentration or excessive dispersion of the lactic acid gas flow in a certain place within the catalyst layer, thereby ensuring that the lactic acid contacts the catalyst evenly in the gaseous state, and thereby making the catalytic dehydration reaction more uniform and efficient, which undoubtedly also helps to improve the yield of acrylic acid polymer.

[0020] Other advantages, objects and features of the present invention will be described in part in the following description; and in part will be apparent to those skilled in the art based on an examination of the following; or may be taught from the practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the process flow of the present invention.

[0022] Figure 2 This is a schematic diagram of the planar structure of the fixed bed reactor.

[0023] Figure 3 This is a schematic diagram of the cross-sectional structure of the fixed bed reactor.

[0024] Figure 4 This is a schematic cross-sectional view of the gas redistribution device.

[0025] Figure 5 This is a schematic diagram of the three-dimensional structure of the gas redistribution device when viewed from above.

[0026] In the picture: 10. Distillation tower; 20. Fixed-bed reactor; 201. First catalyst layer; 202. Second catalyst layer; 203. Third catalyst layer; 204. First heat exchanger; 205. Second heat exchanger; 206. Third heat exchanger; 207. First connecting pipe; 208. Second connecting pipe; 209. Third connecting pipe; 210. Gas redistribution device; 2101. Collecting hood; 2102. Distributing hood; 2103. Distributing plate; 211. Gaseous lactic acid distributor; 212. Feed pipe; 213. Discharge pipe; 214. Inert gas inlet pipe; 215. Steam inlet pipe; 216. Heating jacket; 217. Thermocouple; 30. Condenser; 40. Buffer tank; 50. Vacuum pump; 60. Vacuum distillation tower; 70. Adsorption column; 80. Polymerization reactor; 90. Metering pump; 100. Recovery pipe. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0028] Reference Figure 1 A method for preparing acrylic acid polymers based on biorefining solid waste, using cellulosic biomass as raw material for lactic acid production, comprises the following steps: a. Producing bio-based lactic acid by hydrolysis and fermentation of cellulosic biomass; b. Purify the bio-based lactic acid and remove impurities; c. The purified bio-based lactic acid, inert gas and water vapor are introduced into a fixed bed reactor 20, and the bio-based lactic acid is gasified and subjected to a multi-stage catalytic dehydration reaction under slightly negative pressure conditions at a reaction temperature of 200-300 ° C to obtain acrylic acid reaction gas; d. The acrylic acid reaction gas is separated and purified to obtain purified acrylic acid; e. The purified acrylic acid is polymerized in a polymerization reaction vessel 80 with stirring and temperature control. During the reaction, the temperature is controlled between 60-90 ° C and continuous stirring is performed to ensure uniform heat transfer. At the same time, potassium persulfate initiator is added to the polymerization vessel 80. Under its action, acrylic acid undergoes free radical polymerization in aqueous solution or bulk to obtain an acrylic acid polymer.

[0029] In step b, a distillation tower 10 is used to purify the bio-based lactic acid to remove impurities such as inorganic salts and water. The purification and impurity removal steps can ensure the subsequent reaction efficiency; The introduction of an inert gas in step c can reduce the partial pressure of lactic acid and the probability of intermolecular collisions. The inert gas is nitrogen or carbon dioxide. By introducing water vapor at a feed volume ratio of 5-10% to the gasified bio-based lactic acid, the deposition of the carbon precursor can be suppressed by forming competitive adsorption, thereby reducing side reactions and playing a certain role in improving the yield of the acrylic acid polymer.

[0030] Furthermore, by sequentially providing a buffer tank 40 and a vacuum pump 50 between the condenser 30 and the vacuum distillation tower 60, the vacuum pump 50 can evacuate the fixed bed reactor 20 during the reaction, thereby generating a slight negative pressure in the fixed bed reactor 20. At the same time, the buffer tank 40 can maintain the slight negative pressure at 0.5-0.8 atm, thereby further reducing side reactions, such as preventing decarboxylation to produce acetic acid, and shortening the product residence time. The separation and purification in step d includes condensation recovery, distillation purification and adsorption purification, and is carried out in sequence through the condenser 30, the vacuum distillation tower 60 and the adsorption column 70. In the condenser 30, the reaction gas is condensed and separated into liquid acrylic acid and unreacted lactic acid, and then the unreacted lactic acid is discharged and recovered. The liquid acrylic acid is then separated into acrylic acid and low-boiling point impurities such as water and acetic acid by the vacuum distillation tower 60. Finally, the residual impurities are adsorbed by the adsorption column 70 to achieve the purification of acrylic acid.

[0031] Reference Figure 2 and 3 The fixed bed reactor 20 is provided with a segmented catalytic assembly and a segmented gasification assembly. The segmented catalytic assembly includes a plurality of catalytic sections spaced apart along the catalytic dehydration direction for performing segmented catalytic dehydration on the gaseous lactic acid. The segmented gasification assembly includes a plurality of heat exchange gasification sections spaced apart along the catalytic dehydration direction for heating and gasifying the liquid lactic acid and transporting it to the fixed bed reactor 20. The plurality of catalytic sections and the plurality of heat exchange gasification sections are cross-distributed. The fixed bed reactor 20 is provided with a heating jacket 216 at positions corresponding to the catalytic units, and a thermocouple 217 is provided in each catalytic unit to monitor the reaction temperature of each catalytic unit in real time. The catalyst sections are a first catalyst layer 201, a second catalyst layer 202 and a third catalyst layer 203. The catalysts in the first catalyst layer 201, the second catalyst layer 202 and the third catalyst layer 203 are all HZSM-5 molecular sieve or phosphate-supported catalysts. The heat exchange and gasification sections are respectively a first heat exchanger 204, a second heat exchanger 205, and a third heat exchanger 206. The inlet of the first heat exchanger 204 is the inlet of liquid lactic acid, and a first connecting pipe 207 is connected between the outlet of the first heat exchanger 204 and the inlet of the second heat exchanger 205. A second connecting pipe 208 is connected between the outlet of the second heat exchanger 205 and the inlet of the third heat exchanger 206. A third connecting pipe 209 is connected between the outlet of the third heat exchanger 206 and the air inlet of the fixed bed reactor 20. A gaseous lactic acid distributor 211 connected to the air inlet of the fixed bed reactor 20 is provided inside the fixed bed reactor 20. When the fixed bed reactor 20 is working, the heating jacket 216 heats each catalytic part to a certain temperature. At this time, the lactic acid gas passes through the first catalyst layer 201, the second catalyst layer 202 and the third catalyst layer 203 in sequence, and gradually undergoes a catalytic dehydration reaction. During this process, the lactic acid gas will also be heated and transfer heat to the first heat exchanger 204, the second heat exchanger 205 and the third heat exchanger 206 when flowing through multiple heat exchange and gasification parts. At this time, the lactic acid gas in the fixed bed reactor 20 can be cooled to prevent its temperature from being too high and coking. At the same time, the external liquid lactic acid also passes through the first heat exchanger 204, the second heat exchanger 205 and the third heat exchanger 206 in sequence and continues to enter the fixed bed reactor 20. During this process, the first heat exchanger 204, the second heat exchanger 205 and the third heat exchanger 206 205 and the third heat exchanger 206 can gradually heat the liquid lactic acid, and after the liquid lactic acid is heated to gaseous lactic acid, it is transported to the gaseous lactic acid distributor 211 on the upper part of the fixed bed reactor 20. At this time, the gaseous lactic acid distributor 211 can evenly spray the gaseous lactic acid downward into the fixed bed reactor 20 and perform a catalytic dehydration reaction. It can be seen that when the catalytic dehydration reaction is performed, the heat absorbed by the lactic acid gas during the reaction can be used to heat and gasify the liquid lactic acid, so that the subsequent added liquid lactic acid can be heated and gasified while the lactic acid gas is cooled. Therefore, there is no need to arrange other special gasification devices, which realizes the reuse of thermal resources, strengthens the coupling of the reaction process, and can reduce the preparation cost to a certain extent and improve the efficiency of production preparation. Moreover, when the liquid lactic acid enters the first heat exchanger 204, due to its low temperature, it will absorb more heat from the first heat exchanger 204. As the temperature of the liquid lactic acid rises, the heat absorbed in the subsequent flow will gradually decrease, and therefore the heat absorption of the second heat exchanger 205 and the third heat exchanger 206 will gradually decrease, so that the temperature of the first heat exchanger 204 is higher than that of the second heat exchanger 205, and the temperature of the second heat exchanger 205 is higher than that of the third heat exchanger 206. Since the first heat exchanger 204 absorbs the heat of the first catalyst layer 201 through the gaseous lactic acid, similarly, the second heat exchanger 205 absorbs the heat of the second catalyst layer 202, and the third heat exchanger 206 absorbs the heat of the third catalyst layer 203. This will correspondingly cause the temperature of the first catalyst layer 201 to be lower than that of the second catalyst layer 202, and the temperature of the second catalyst layer 202 to be lower than that of the third catalyst layer 203, thereby forming a segmented catalytic layer with a temperature increasing from top to bottom inside the fixed bed reactor 20, and then by cooperating with the heating jacket 216 and the thermocouple 217, the purpose of segmented temperature control can be achieved, and thereby the purpose of segmented catalytic dehydration of gaseous lactic acid can be achieved, so that the adsorption and activation of lactic acid is promoted at the low temperature in the front section, and then as the temperature increases, the high temperature in the middle and rear sections will accelerate the dehydration reaction. By optimizing the heating form, the efficiency of the catalytic dehydration reaction can be improved to a certain extent, and therefore it has a positive effect on improving the yield and yield of acrylic acid polymerization.

[0032] Reference Figure 3 A gas redistribution device 210 is provided between the first heat exchanger 204 and the second catalyst layer 202 and between the second heat exchanger 205 and the third catalyst layer 203 to uniformly transfer the gaseous lactic acid downward; Reference Figure 4 and 5 The gas redistribution device 210 includes a funnel-shaped collecting cover 2101, a cylindrical distributing cover 2102 and a frustum-shaped distributing plate 2103 arranged in the distributing cover 2102. The large-diameter end of the collecting cover 2101 faces in the opposite direction of catalytic dehydration, and the small-diameter end is sealed and connected to one end of the distributing cover 2102. The other end of the distributing cover 2102 is open and faces in the direction of catalytic dehydration, and the inner diameter of the distributing cover 2102 is larger than the inner diameter of the small-diameter end of the collecting cover 2101. The interior of the frustum-shaped distributing plate 2103 is hollow with openings at both ends and is coaxial with the distributing cover 2102. There are a plurality of distributing plates 2103, which are arranged layer by layer from the inside to the outside and their diameters gradually increase. The tapers of the distributing plates 2103 from the inside to the outside gradually increase, and an annular distributing gap 2104 is formed between two adjacent distributing plates 2103. After passing through the first catalyst layer 201 and the first heat exchanger 204, the gaseous lactic acid will continue to be transported downward. However, due to the disturbance of the first catalyst layer 201 and the first heat exchanger 204, the previously evenly distributed gaseous lactic acid will be disrupted, resulting in different concentrations of gaseous lactic acid in different areas. As the gaseous lactic acid continues to flow, it will pass through the first gas redistribution device 210. During this process, the gaseous lactic acid will first enter the funnel-shaped collection cover 2101, and gradually move from the large diameter of the collection cover 2101 to the small diameter, so as to re-concentrate the gaseous lactic acid, and then flow into the uniform distribution cover 2102 with a larger inner diameter. During this process, according to the Venturi effect, since the flow cross-section of the gaseous lactic acid in the collection cover 2101 first decreases from large to small, the gaseous lactic acid will not only be re-concentrated, Moreover, the flow rate will increase, and then after entering the uniform distribution cover 2102, the flow cross-section will increase from small to large. At this time, the gaseous lactic acid will be decelerated in the uniform distribution cover 2102 and diffuse outward at the same time, thereby achieving a certain uniform distribution effect, and then enter the uniform distribution gap 2104 formed by two adjacent uniform distribution plates 2103, and the gaseous lactic acid will be further uniformly distributed under the action of the uniform distribution gap 2104. After uniform distribution, the gaseous lactic acid will continue to flow to the second catalyst layer 202 and the second heat exchanger 205, undergo catalytic dehydration reaction and heat exchange again, and then enter the second gas redistribution device 210, and after uniform distribution again, flow to the third catalyst layer 203 and the third heat exchanger 206, and complete the catalytic dehydration and heat exchange work, and then be discharged from the fixed bed reactor 20; As can be seen from the above, during the process of multi-stage catalytic dehydration of gaseous lactic acid, the gas redistribution device 210 will redistribute the unevenly distributed lactic acid airflow, so that the lactic acid airflow can pass through each catalyst layer evenly, avoiding the lactic acid airflow being too concentrated or too dispersed at a certain place in the catalyst layer, thereby ensuring that the lactic acid contacts the catalyst evenly in the gaseous state, and thereby making the catalytic dehydration reaction more uniform and efficient, which is undoubtedly also helpful to improve the yield of acrylic acid polymer.

[0033] In the present invention, cellulosic biomass is first hydrolyzed and fermented to obtain bio-based lactic acid, and then the bio-based lactic acid is transported to the distillation tower 10 for purification to remove impurities. The purified bio-based lactic acid is then transported to the feed pipe 212 by the metering pump 90 and enters the first heat exchanger 204. Since the heating jacket 216 has previously heated the first catalyst layer 201, the second catalyst layer 202, and the third catalyst layer 203, when the temperature of each catalyst layer rises, the first heat exchanger 204, the second heat exchanger 205, and the third heat exchanger 206 are also heated through heat transfer. Therefore, the liquid lactic acid entering the first heat exchanger 204 is heated for the first time, and then enters the second heat exchanger 205 through the first connecting pipe 207 and is heated again. Then, it enters the third heat exchanger 206 through the second connecting pipe 208 for the final heating. After three heatings, the liquid lactic acid can be vaporized into gaseous lactic acid and transported to the gaseous lactic acid distributor 211 through the third connecting pipe 209. The gaseous lactic acid distributor 211 can evenly transport the heated gaseous lactic acid into the fixed bed reactor 20, and thus flow through the first catalyst layer 201, the second catalyst layer 202 and the third catalyst layer 203 to undergo catalytic dehydration reaction. During this period, the gaseous lactic acid will also contact the first heat exchanger 204, the second heat exchanger 205 and the third heat exchanger 206 for a certain amount of cooling, thereby transferring heat to the three heat exchangers. The three heated heat exchangers will continue to heat and vaporize the liquid lactic acid flowing through them. While the gaseous lactic acid undergoes a multi-stage reaction in the fixed bed reactor 20, an inert gas and water vapor are introduced into the fixed bed reactor 20 through the inert gas inlet pipe 214 and the steam inlet pipe 215, respectively, to perform an auxiliary catalytic dehydration reaction, ultimately forming a gaseous product. Under the action of the vacuum pump 50, the gaseous product enters the condenser 30 through the discharge pipe 213. The reaction gas is condensed and separated into liquid acrylic acid and unreacted lactic acid. The unreacted lactic acid and other waste gases are discharged through the recovery pipe 100 and recycled. The liquid acrylic acid flows through the buffer tank 40 and the vacuum pump 50 and enters the vacuum distillation tower 60 to be separated into acrylic acid and low-boiling point impurities. Finally, the liquid acrylic acid is transported to the adsorption column 70 to adsorb residual impurities, thereby achieving the preparation and purification of acrylic acid. Finally, the purified acrylic acid can be transported to a polymerization reactor 80 with stirring and temperature control for polymerization reaction. At the same time, potassium persulfate as an initiator is added. Under its action, the acrylic acid undergoes free radical polymerization in aqueous solution or bulk to obtain an acrylic acid polymer.

[0034] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

[0035] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

Claims

1. A method for preparing acrylic acid polymer based on biorefining solid waste, characterized in that: The process of producing lactic acid using cellulosic biomass as raw material includes the following steps: Obtaining bio-based lactic acid through hydrolysis and fermentation of cellulosic biomass; Purify bio-based lactic acid to remove impurities; The purified bio-based lactic acid, inert gas, and water vapor are introduced into a fixed bed reactor (20) respectively, and the bio-based lactic acid is gasified and subjected to a multi-stage catalytic dehydration reaction under a slightly negative pressure condition to obtain acrylic acid reaction gas; Separating and purifying the acrylic acid reaction gas to obtain purified acrylic acid; The purified acrylic acid is polymerized to obtain an acrylic acid polymer.

2. The method for preparing an acrylic acid polymer based on biorefining solid waste according to claim 1, characterized in that: The fixed bed reactor (20) is provided with a segmented catalytic component and a segmented gasification component. The segmented catalytic component includes a plurality of catalytic parts distributed at intervals along the catalytic dehydration direction, and is used for segmented catalytic dehydration of gaseous lactic acid. The segmented gasification component includes a plurality of heat exchange gasification parts distributed at intervals along the catalytic dehydration direction, and is used for heating and gasifying liquid lactic acid and transporting it to the fixed bed reactor (20). The plurality of catalytic parts and the plurality of heat exchange gasification parts are cross-distributed.

3. The method for preparing an acrylic acid polymer based on biorefining solid waste according to claim 2, characterized in that: The catalytic parts are respectively a first catalyst layer (201), a second catalyst layer (202) and a third catalyst layer (203), and the catalysts in the first catalyst layer (201), the second catalyst layer (202) and the third catalyst layer (203) are all HZSM-5 molecular sieves or phosphate-loaded catalysts.

4. The method for preparing an acrylic acid polymer based on biorefining solid waste according to claim 3, characterized in that: The heat exchange and gasification sections are respectively a first heat exchanger (204), a second heat exchanger (205) and a third heat exchanger (206); the inlet of the first heat exchanger (204) is the inlet of liquid lactic acid, and a first connecting pipe (207) is connected between the outlet of the first heat exchanger (204) and the inlet of the second heat exchanger (205); a second connecting pipe (208) is connected between the outlet of the second heat exchanger (205) and the inlet of the third heat exchanger (206); a third connecting pipe (209) is connected between the outlet of the third heat exchanger (206) and the air inlet of the fixed bed reactor (20); and a gaseous lactic acid distributor (211) connected to the air inlet of the fixed bed reactor (20) is provided inside the fixed bed reactor (20).

5. The method for preparing acrylic acid polymer based on biorefining solid waste according to claim 4, characterized in that: A gas redistribution device (210) is provided between the first heat exchanger (204) and the second catalyst layer (202), and between the second heat exchanger (205) and the third catalyst layer (203).

6. The method for preparing acrylic acid polymer based on biorefining solid waste according to claim 5, characterized in that: The gas redistribution device (210) comprises a funnel-shaped collecting cover (2101), a cylindrical distributing cover (2102), and a frustum-shaped distributing plate (2103) disposed in the distributing cover (2102). The collecting cover (2101) has a large-diameter end facing in the opposite direction to the catalytic dehydration direction, and a small-diameter end is sealedly connected to one end of the distributing cover (2102). The other end of the distributing cover (2102) is open and faces in the catalytic dehydration direction, and the inner diameter of the distributing cover (2102) is greater than The inner diameter of the small-diameter end of the collecting cover (2101), the interior of the truncated cone-shaped uniform distribution plate (2103) is hollow with both ends open and coaxial with the uniform distribution cover (2102), and there are multiple uniform distribution plates (2103), which are arranged layer by layer from the inside to the outside and the diameters gradually increase. The taper of the multiple uniform distribution plates (2103) from the inside to the outside gradually increases, and an annular uniform distribution gap (2104) is formed between two adjacent uniform distribution plates (2103).

7. The method for preparing acrylic acid polymer based on biorefining solid waste according to claim 2, characterized in that: Heating jackets (216) are provided on the outside of the fixed bed reactor (20) at positions corresponding to the plurality of catalytic parts, and thermocouples (217) are provided inside the plurality of catalytic parts.

8. The method for preparing acrylic acid polymer based on biorefining solid waste according to claim 1, characterized in that: The inert gas in step c is nitrogen or carbon dioxide, the feed volume ratio of water vapor to gasified bio-based lactic acid is 5-10%, and the slightly negative pressure is 0.5-0.8 atm.

9. The method for preparing acrylic acid polymer based on biorefining solid waste according to claim 1, characterized in that: The separation and purification in step d includes condensation recovery, distillation purification and adsorption purification.

10. An acrylic acid polymer based on biorefining solid waste, prepared by the method according to any one of claims 1 to 9.

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