CN115057773A - Preparation method and reaction device for synthesizing ethyl lactate - Google Patents
Preparation method and reaction device for synthesizing ethyl lactate Download PDFInfo
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- CN115057773A CN115057773A CN202210841697.XA CN202210841697A CN115057773A CN 115057773 A CN115057773 A CN 115057773A CN 202210841697 A CN202210841697 A CN 202210841697A CN 115057773 A CN115057773 A CN 115057773A
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Abstract
The invention discloses a preparation method and a reaction device for synthesizing ethyl lactate, wherein the preparation method comprises the following steps: mixing lactic acid and ethanol as reaction raw materials to obtain a mixture; carrying out esterification reaction by using a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product; wherein, the discontinuous resonance and the step-type heating mode are adopted; and (4) obtaining a final ethyl lactate product by adopting a rectification mode. The invention not only improves the yield of the ethyl lactate, but also reduces the occurrence of side reactions, and effectively solves the problem of corrosion to equipment; the water can be removed in the reaction process by adopting a rectification mode, so that the safety problem caused by the residual product of the dehydrating agent is effectively avoided; under the working condition of recycling, the composite catalyst effectively realizes the recycling of the catalyst, reduces the reaction cost and improves the synthesis yield of the ethyl lactate.
Description
Technical Field
The invention belongs to the technical field of ethyl lactate synthesis, and particularly relates to a preparation method and a reaction device for ethyl lactate synthesis.
Background
Ethyl lactate is an important fine chemical raw material, and has traditionally been used as an alcoholic liquor additive, a lubricant for compressed tablets, a pharmaceutical intermediate, and the like. With the increasing requirements of people on the environment, ethyl lactate has great application potential as a green solvent with development value and application prospect, and is used for replacing toxic solvents widely used in industry, such as halogenated solvents, ethers and chlorofluorocarbon solvents, in consideration of the characteristics of no toxicity, good solubility, difficult volatilization, biodegradability and the like.
In the traditional ethyl lactate preparation method: lactic acid and ethanol are used as raw materials and mixed according to a certain proportion, and then concentrated sulfuric acid is used as a catalyst, benzene or toluene is used as a water-carrying agent, and the ethyl lactate is synthesized by catalytic esterification; the above conventional preparation process mainly has the following problems: a plurality of byproducts are generated; the equipment is seriously corroded; the production cost is high.
Aiming at the existing technical problems, a series of researches are carried out at home and abroad, and mainly focus on two aspects:
(1) in the research of the catalyst, silicotungstic acid is adopted as the catalyst for an European jade column and the like, banyan aryl and Jalal J.Jafer and the like adopt p-toluene sulfuric acid as the catalyst, Wanggang and the like adopt metal chlorides as the catalyst, Lifupei and the like adopt rare earth compounds as the catalyst, Kazuhiro Tanaka and the like adopt Amberlyst15 as the catalyst and the like, although the research overcomes the defects of concentrated sulfuric acid catalysts to different degrees, new problems are derived, such as low catalyst activity, catalyst recovery problem, corrosion and the like;
(2) jafer et al uses zeolite A membrane as pervaporation membrane to remove water in reaction system, and Kazuhiro Tanaka et al uses zeolite T membrane for ethyl lactate, which improves conversion rate of lactic acid effectively, but the membrane has high cost; the Argonne national laboratory in the united states uses pervaporation technology to combine reaction and membrane separation, but this technology has a long reaction time and low conversion rate, only 14.5%; halpendd et al, without using a catalyst, take ammonium lactate and ethanol as raw materials, molecular sieves or the like as a desiccant, and nitrogen or other inert fluids as a carrier to carry out the ammonia gas generated by the reaction, and finally, the yield of ethyl lactate is 40%, but the method has the disadvantages that the reaction time is longer, 90-100 hours, and the ammonia gas and the inert gases have separation problems.
Based on the above analysis, the existing ethyl lactate preparation methods have technical defects mainly including:
(1) in the traditional ethyl lactate synthesis, concentrated sulfuric acid is generally used as a catalyst, and the concentrated sulfuric acid and lactic acid are heated together in the reaction process, so that the lactic acid is decomposed into acetaldehyde and formic acid; meanwhile, the existence of the concentrated sulfuric acid can not only cause the concentrated sulfuric acid to react with the dehydrating agent to generate lactide, generate a large amount of side reactions and reduce the synthesis efficiency of the ethyl lactate, but also have strong corrosivity on equipment; in addition, as research continues, many new catalysts are being proposed, such as toluene sulfuric acid, metal chlorides, and rare earth compounds. Although the problem of concentrated sulfuric acid as a catalyst is effectively solved to different degrees, the novel problems of low efficiency, difficult recovery and the like also occur.
(2) The traditional ethyl lactate synthesis method generally adopts benzene or toluene as a dehydrating agent to remove water in the reaction, the ethyl lactate as a green solvent is nontoxic and harmless, and the use of the traditional dehydrating agent can leave a small amount of benzene or toluene in the product, which affects the subsequent application of the ethyl lactate in the aspect of food. The current research shows that some researchers successfully solve the toxicity problem by improving the preparation method to remove the water generated by the reaction, but also generate new problems, such as low efficiency, high cost and the like.
(3) The traditional synthesis process of ethyl lactate has the problems of low product yield, easy side reaction and the like. In recent years, scholars successfully improve the yield of ethyl lactate by adopting different methods, for example, the yield can reach about 77 percent by adopting rare earth compounds as catalysts; the yield can reach more than 92.6 percent by adopting silicotungstic acid for catalysis; the p-toluenesulfonic acid is used as a catalyst, the yield reaches 84.5 percent, and the reaction time is shortened; by utilizing the principle of rectification and high-efficiency separation, the yield can reach 95 percent by taking concentrated sulfuric acid as a catalyst, but the problem of taking the concentrated sulfuric acid as the catalyst still exists.
In conclusion, as the research continues, the improvement of the yield of ethyl lactate is still accompanied by the following problems: the problem of recycling the catalyst; the problem of equipment corrosion; the dehydrating agent still has the problems of safety hazard and the like. The ethyl lactate is used as a green solvent with great prospect, has high efficiency, safety and low cost, realizes the recycling of the catalyst, solves the problem of equipment corrosion and is urgently needed; therefore, it is very important to find a new synthetic preparation method of ethyl lactate.
Disclosure of Invention
The invention aims to provide a preparation method and a reaction device for synthesizing ethyl lactate, so as to solve one or more technical problems. In the preparation method, the composite catalyst which takes the mesoporous silica molecular sieve as the carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as the active components is adopted, so that compared with the traditional catalyst of concentrated sulfuric acid, the yield of ethyl lactate is improved, the occurrence of side reactions is reduced, and the problem of corrosion to equipment is effectively solved; by means of different boiling points of the products, the water can be removed in the reaction process by adopting a rectification mode, so that the safety problem caused by the residual dehydrating agent in the products is effectively avoided; under the working condition of recycling, the composite catalyst effectively realizes the recycling of the catalyst, reduces the reaction cost and improves the synthesis yield of the ethyl lactate.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a preparation method for synthesizing ethyl lactate, which comprises the following steps:
mixing lactic acid and ethanol as reaction raw materials to obtain a mixture;
based on the mixture, carrying out esterification reaction by adopting a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product; wherein, during the esterification reaction, a discontinuous resonance and step-type heating mode is adopted;
based on the initial ethyl lactate product, a final ethyl lactate product is obtained by adopting a rectification mode.
The further improvement of the invention is that in the process of mixing the lactic acid and the ethanol as reaction raw materials to obtain a mixture,
the lactic acid and the ethanol are calculated according to the volume ratio of (1.5-2): 1 in the proportion range.
The invention is further improved in that the discontinuous resonance is realized by adopting an ultrasonic generator; the frequency of the ultrasonic generator is controlled within the range of 20KHz to 40 KHz.
The invention is further improved in that the step-type heating mode is realized by adopting a water bath heater to regulate and control the reaction temperature.
The further improvement of the invention is that the step of obtaining the initial ethyl lactate product based on the mixture by using a composite catalyst with a mesoporous silica molecular sieve as a carrier and phosphomolybdic acid and ammonium phosphomolybdate as active components to perform esterification reaction specifically comprises the following steps:
the mixture is in a non-resonance working condition, and the mixture is heated to the temperature of 60-70 ℃ and is maintained for 40-80 min;
the mixture is in a resonance working condition, and the mixture is heated to 70-90 ℃ and kept for 100-140 min;
the mixture is in a non-resonance working condition and is heated to the temperature of between 90 and 100 ℃ and is kept for 40 to 80 minutes;
and (3) enabling the product to be in a resonance working condition, and naturally cooling for 20-40 min to obtain an initial ethyl lactate product.
The further improvement of the invention is that in the process of obtaining the final ethyl lactate product by adopting a rectification mode based on the initial ethyl lactate product,
the heating temperature range during rectification is 125-135 ℃.
The invention provides a reaction device for synthesizing ethyl lactate, which comprises:
the reaction tank is used for mixing lactic acid and ethanol serving as reaction raw materials to obtain a mixture; based on the mixture, carrying out esterification reaction by adopting a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product;
an ultrasonic generator for effecting further mixing of the lactic acid and ethanol prior to carrying out the esterification reaction; the resonance device is used for realizing discontinuous resonance of lactic acid and ethanol during the esterification reaction and preventing reverse progress of the esterification reaction through resonance after the esterification reaction is carried out;
the water bath heater is provided with a thermocouple and is used for providing stepped heating during the esterification reaction;
a second collecting tank and a temperature control heating rod device arranged in the second collecting tank, wherein the temperature control heating rod device is used for obtaining a final ethyl lactate product by adopting a rectification mode based on the initial ethyl lactate product;
wherein the reaction tank is provided with:
the ethanol feeding tank is used for inputting ethanol raw materials into the reaction tank;
the lactic acid feeding tank is used for inputting a lactic acid raw material into the reaction tank;
the reaction medium input port is used for inputting a composite catalyst which takes the mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components;
the stirrer is used for stirring and mixing the ethanol raw material and the lactic acid raw material;
the catalyst comprises a hollow cubic metal frame, wherein the hollow cubic metal frame is preloaded with a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components;
the volatilization channel and the return pipe are used for realizing the return of the ethanol;
and the discharge channel is provided with a first valve and is used for outputting an initial ethyl lactate product.
The invention further improves the method and also comprises the following steps:
a first collecting tank for collecting volatilized ethanol and refluxing the ethanol to the reaction tank; the collecting tank is provided with a collecting tank inlet and a collecting tank outlet, the collecting tank inlet is communicated with the reaction tank through a condensing pipe and a volatilization channel, and the collecting tank outlet is communicated with the reaction tank through a return pipe.
The invention has the further improvement that the second collecting tank is provided with a second collecting tank inlet, a fractionation component outlet and an ethyl lactate collecting port;
the inlet of the second collecting tank is communicated with the reaction tank through a discharge channel; and the ethyl lactate collecting port is provided with a second valve.
The invention further improves the method and also comprises the following steps:
the third collecting tank is provided with a third collecting tank inlet;
and the inlet of the third collecting tank is communicated with the second collecting tank through a fractionation component outlet and is used for collecting various fractionated components.
Compared with the prior art, the invention has the following beneficial effects:
in the preparation method, the composite catalyst which takes the mesoporous silica molecular sieve as the carrier and takes the phosphomolybdic acid and the ammonium phosphomolybdate as the active components is adopted, so that compared with the traditional catalyst of concentrated sulfuric acid, the yield of the ethyl lactate is improved, the side reaction is reduced, and the problem of corrosion to equipment is effectively solved. Illustratively, the mesoporous silica molecular sieve has a better mesoporous structure, improves the rate of reactant molecules entering pores of the molecular sieve, and has abundant acid sites to promote the esterification reaction. The composite catalyst with mesoporous silica molecular sieve as carrier and ammonium phosphomolybdic acid and ammonium phosphomolybdate as active components is weak acid and has no strong corrosion capacity. According to the thermogravimetric curve, the composite catalyst is almost free of mass attenuation at 100 ℃, has enough thermal stability and can effectively ensure the repeated use of the catalyst. According to the TPD analysis of the catalyst, the catalyst has almost no strong acid sites, mainly medium acid sites. Research shows that the medium and weak acidic sites are beneficial to the synthesis of ethyl lactate, and the more the amount is, the higher the efficiency is. In addition, there is no derivatization reaction between lactic acid and ethanol and the catalyst.
The preparation method disclosed by the invention is carried out under the environment of normal pressure, ultrasonic assistance and stepped heating, the dehydration of the product is realized by virtue of different boiling points of different components and a rectification mode, the use of a dehydrating agent is effectively avoided, the non-toxicity and the harmlessness of the product are successfully realized, and the problem of yield reduction caused by the addition of other dehydrating agents is solved.
In the preparation method, the composite catalyst which takes the mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components is used, so that the catalyst can be recycled for multiple times; the ethyl lactate synthesis reaction is fitted by means of a first-order reaction kinetic equation, and the ethyl lactate synthesis reaction shows higher reaction rate and final reaction yield under the catalysis condition of the composite catalyst. Research shows that the compound catalyst is subjected to a circulation experiment, and the synthetic yield of the ethyl lactate is gradually increased until the third time reaches the highest value, and the yield exceeds 90%. The invention not only realizes the recovery of the catalyst, but also realizes the repeated use, and the efficiency is still maintained at a higher level, thereby successfully reducing the reaction cost and improving the reaction efficiency.
According to the reaction device, the composite catalyst which takes the mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components is loaded on the hollow metal frame, so that the high-efficiency synthesis of ethyl lactate and the recycling of the catalyst can be realized.
The reaction device disclosed by the invention is carried out under the environment of normal pressure, ultrasonic assistance and stepped water bath heating, the dehydration of the product is realized by virtue of different boiling points of different components and a rectification mode, the use of a dehydrating agent is effectively avoided, the non-toxicity and harmless treatment of the product is successfully realized, and the problem of yield reduction caused by the addition of other dehydrating agents is solved. Wherein, the ultrasonic assistance is used for effectively promoting the full mixing of reaction substrates, enhancing the generation of free radicals, reducing the activation energy of esterification reaction, promoting the esterification reaction and reducing the generation of byproducts; the step-type water bath heating promotes the breakage of covalent bonds, and simultaneously, the ethanol reflux of one of the reaction raw materials and the recovery of the final product material both promote the utilization efficiency of the raw materials and increase the yield of the ethyl lactate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art are briefly introduced below; it is obvious that the drawings in the following description are some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.
FIG. 1 is a schematic flow diagram of a method for preparing ethyl lactate by synthesis according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a reaction apparatus for synthesizing ethyl lactate according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a reaction system for the synthesis of ethyl lactate according to an embodiment of the present invention;
in the figure, 1, a thermocouple; 2. a water bath heater; 3. an ultrasonic generator; 4. a reaction tank; 5. a lactic acid feed tank; 6. an ethanol feed tank; 7. a reaction medium input port; 8. a pressure relief valve; 9. a blender; 10. a volatilization channel; 11. a return pipe; 12. a straight condenser tube; 13. a water level gauge; 14. a hollow cubic metal frame; 15. a first valve; 16. a discharge passage; 17. a temperature control heating rod device; 18. a second collecting tank; 19. a ethyl lactate collection port; 20. a second valve; 21. a fractionation component outlet; 22. collecting tank III; 23. collecting tank I.
Detailed Description
The present invention is further illustrated below with reference to specific examples, which are intended to be illustrative only and not to limit the scope of the invention.
The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.
It is to be understood that the processing equipment or apparatus not specifically identified in the following examples is conventional in the art.
Furthermore, it is to be understood that one or more method steps mentioned in the present invention does not exclude that other method steps may also be present before or after the combined steps or that other method steps may also be inserted between these explicitly mentioned steps, unless otherwise indicated; it is also to be understood that a combined connection between one or more devices/apparatus as referred to in the present application does not exclude that further devices/apparatus may be present before or after the combined device/apparatus or that further devices/apparatus may be interposed between two devices/apparatus explicitly referred to, unless otherwise indicated. Moreover, unless otherwise indicated, the numbering of the method steps is only a convenient tool for identifying each method step, and is not intended to limit the order of the method steps or the scope of the invention, and changes or modifications in the relative relationship thereof may be regarded as the scope of the invention without substantial change in the technical content.
Example one
Referring to fig. 1, a preparation method for synthesizing ethyl lactate according to an embodiment of the present invention includes the following steps:
mixing reaction raw materials of lactic acid and ethanol to obtain a mixture;
based on the mixture, carrying out esterification reaction by adopting a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product; wherein, during the esterification reaction, intermittent resonance and step heating are adopted; illustratively, the realization mode of the discontinuous resonance adopts an ultrasonic generator, and the frequency of the ultrasonic generator is controlled in the range of 20KHz to 40 KHz; after the materials are added, starting an ultrasonic generator for 20-40 min to realize full mixing; the stepped heating is realized by regulating and controlling the reaction temperature through a water bath heater to realize temperature stepped reaction;
based on the initial ethyl lactate product, a final ethyl lactate product is obtained by adopting a rectification mode.
In the embodiment of the invention, preferably, the lactic acid (with the purity of more than 80%) and the ethanol (with the purity of more than 90%) are mixed according to the volume ratio of (1.5-2): 1 in the proportion range; the proportioning scheme can save cost and improve the esterification reaction efficiency.
In the embodiment of the invention, based on the mixture, the step of performing esterification reaction by using a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product comprises the following steps:
the mixture is in a non-resonance working condition, and the mixture is heated to the temperature of 60-70 ℃ and is maintained for 40-80 min;
the mixture is in a resonance working condition and is heated to a temperature range of 70-90 ℃ and kept for 100-140 min;
the mixture is in a non-resonance working condition and is heated to the temperature of between 90 and 100 ℃ and is kept for 40 to 80 minutes;
and (3) enabling the mixture to be in a resonance working condition, and naturally cooling for 20-40 min to ensure that the substrate forwards in the synthesis reaction of the ethyl lactate and obtain an initial ethyl lactate product.
In the preferred embodiment of the invention, the heating temperature range during rectification is 125-135 ℃.
According to the preparation method, lactic acid and ethanol are subjected to esterification reaction under the condition that a mesoporous silica molecular sieve is used as a carrier and phosphomolybdic acid and ammonium phosphomolybdate are used as active components to efficiently obtain an ethyl lactate target product, and the raw materials are recycled; ultrasonic assistance and stirring effect fully guarantee the contact between reaction medium and the reactant, promoted catalytic efficiency, cascaded heating promotes the fracture of covalent bond, and the ethanol backward flow of one of the reaction raw materials and the recovery of final product material have all promoted the utilization efficiency of raw materials simultaneously, have increased ethyl lactate's yield.
Example two
Referring to fig. 2, a reaction apparatus for synthesizing ethyl lactate according to an embodiment of the present invention includes a reaction tank 4, a hollow cubic metal frame 14, an ultrasonic generator 3, a first collecting tank 23, a second collecting tank 18, and a third collecting tank 22.
The reaction tank 4 is used for mixing lactic acid and ethanol and performing esterification reaction, and is provided with an ethanol feeding groove 6, a lactic acid feeding groove 5, a reaction medium inlet 7, a pressure release valve 8, a water level meter 13 and a stirrer 9; in addition, the reaction tank 4 is provided with a volatilization channel 10 and a return pipe 11 for realizing the return of ethanol; the reaction tank 4 is provided with a discharge channel 16, the discharge channel 16 being provided with a first valve 15.
The hollow cubic metal frame 14 is used for loading a mesoporous silica molecular sieve loaded with active components, and the appearance of the hollow cubic metal frame is of a matrix frame three-dimensional structure; the hollow cubic metal frame 14 is used for loading the mesoporous silica molecular sieve attached with the active component, so that the substrate and the reaction medium are in full contact, and the recovery after the reaction is finished is facilitated.
The ultrasonic generator 3 is arranged at the bottom of the reaction tank 4; the frequency range of the ultrasonic generator 3 is in the range of 20KHz to 40 KHz; the ultrasonic generator 3 is used for fully mixing two substrates before reaction; the ultrasonic generator 3 is used for forming free radicals in the reaction process, promoting the esterification reaction and reducing the generation of intermediate products; the ultrasonic generator 3 is used for preventing the reverse proceeding of the esterification reaction after the heating is finished, and reducing the generation of byproducts.
The first collecting tank 23 is used for collecting volatilized ethanol and enabling the volatilized ethanol to flow back to the reaction tank 4, and the first collecting tank 23 is provided with an inlet of the straight condensing pipe 12 and an outlet of the first collecting tank 23; the inlet of the straight condensing pipe 12 is communicated with the volatilizing channel 10 and is used for collecting volatilized ethanol; the outlet of the first collecting tank 23 is communicated with the reaction tank 4 through a return pipe 11 and is used for returning ethanol which is one of raw materials. Specifically, for example, the inlet of the first collecting tank 23 is communicated with the outlet of the reaction tank 4 through a straight condensing pipe 12 and a volatilization channel 10, wherein the volatilization channel 10 extends into one end of the reaction tank 4 and is positioned at the top of the reaction tank 4; an inlet of the first collecting tank 23 is communicated with an outlet of the reaction tank 4 through a return pipe 11, and the return pipe 11 extends into one end of the first collecting tank 23 and is positioned at the bottom of the first collecting tank 23; the inlet of the straight condensing pipe 12 extends into one end of the first collecting groove 23 and is positioned at the top of the first collecting groove 23. The first collection tank 23 should be at a height equal to or higher than the height at which the top of reaction tank 4 is located.
A temperature control heating rod device 17 is arranged in the second collecting tank 18 and is used for fractionating inflow products after reaction to obtain pure ethyl lactate target products, and an inlet of the second collecting tank 18, a fractionation component outlet 21 and an ethyl lactate collecting port 19 are arranged; an inlet of the second collecting tank 18 is communicated with the reaction tank 4 through a discharge channel 16 and is used for introducing a mixed product after the reaction is finished; a fractionation component outlet 21 for discharging components other than ethyl lactate; the ethyl lactate collecting port 19 is provided with a second valve 20 for outputting the target product ethyl lactate. In a specific example, an inlet of the second collecting tank 18 is communicated with an outlet of the reaction tank 4 through a discharge passage 16, and extends into one end of the second collecting tank 18, and is located in the middle of the second collecting tank 18; the temperature control heating rod device 17 controls the heating temperature to be 125-135 ℃; the temperature control heating rod device 17 is arranged at the bottom of the second collecting tank 18. The fractionated component outlet 21 extends into one end of the second holding tank 18 at the top of the second holding tank 18.
The third collecting tank 22 is provided with a third collecting tank 22 inlet, and the third collecting tank 22 inlet is communicated with the second collecting tank 18 through a fractionation component outlet 21 and is used for collecting various fractionated components. Specifically, for example, the inlet of collection tank number three 22 extends into one end of collection tank number three 22 and is located at the bottom of collection tank number three 22.
The water bath heater 2 is used for heating the reaction tank 4, and a thermocouple 1 is arranged in the water bath heater and used for controlling the temperature of water bath heating.
Further preferably in the embodiment of the present invention, the reaction tank 4 is a hollow cylinder; the volume ratio range (1.5-2) of the lactic acid and the ethanol in the reaction tank 4 during mixing is 1.
Further preferably in the embodiment of the present invention, the ethanol feeding tank 6 and the lactic acid feeding tank 5 are located at the side of the reaction tank 4; the reaction medium input port 7 extends into one end of the reaction tank 4 and is positioned at the top of the reaction tank 4; the stirrer 9 extends into the middle of the reaction tank 4.
In a particularly preferred embodiment of the present invention, the exterior of the hollow cubic metal frame 14 belongs to a matrix frame three-dimensional structure, and micropores exist on the surface of the metal frame.
In the reaction device provided by the embodiment of the invention, the ultrasonic generator is mixed and stirred along with the stirrer, so that the contact between a reaction medium and a reactant is promoted, the catalytic efficiency is ensured, meanwhile, the ethanol reflux of one of reaction raw materials and the recovery of a final product material both promote the utilization efficiency of the raw materials, and the yield of ethyl lactate is increased. Under the environment of normal pressure, ultrasonic assistance and stepped heating, lactic acid and ethanol are directly contacted for esterification reaction by virtue of active components such as phosphomolybdic acid, ammonium phosphomolybdate and the like without adding a water removal agent; the ultrasonic assistance effectively promotes the full mixing of reaction substrates, enhances the generation of free radicals, reduces the activation energy of esterification reaction, promotes the esterification reaction, reduces the generation of byproducts, and reduces the harm of the reaction process to the corrosion of equipment.
EXAMPLE III
The operation flow of the reaction device provided by the above embodiment of the present invention includes the following steps:
respectively introducing reaction raw materials of lactic acid and ethanol into a reaction tank 4 through a lactic acid feeding groove 5 and an ethanol feeding groove 6, putting a hollow cubic metal frame 14 loaded with a mesoporous silica molecular sieve attached with active components of phosphomolybdic acid and ammonium phosphomolybdate into the bottom of the reaction tank 4, and simultaneously introducing a little mesoporous silica molecular sieve attached with active components of phosphomolybdic acid and ammonium phosphomolybdate into the reaction tank 4 through a reaction medium inlet 7; the water level meter 13 monitors the height of the water level in the reaction tank 4; carrying cooling substance water by an outer pipe of the straight condensing pipe 12; turning on a switch of the ultrasonic generator 3, and turning off the ultrasonic generator 3 after the preset time is continued; the switch of the water bath heater 2 is turned on, and the heating temperature of the reaction tank 4 is regulated and controlled by the thermocouple 1 to present step-type temperature heating; turning on a switch of the stirrer 9, and uniformly mixing the reaction raw materials and the reaction medium; after the water bath heater 2 is turned off, the ultrasonic generator 3 is turned on, and is turned off after the preset time is continued; after the esterification reaction is finished, the stirrer 9 is closed, the first valve 15 is opened, and the esterification reaction product materials are discharged into a second collecting tank 18; after discharging, closing the first valve 15, opening the switch of the temperature control heating rod device 17, and controlling the temperature within the range of 125-135 ℃; and after the product material does not generate bubbles any more, closing the temperature control heating rod device 17, and opening the second valve 20 to complete the synthesis of the ethyl lactate to obtain the target product of the ethyl lactate. The ethanol condensed in the first collecting tank 23 enters the reaction tank 4 through the return pipe 11, so that the raw materials are efficiently utilized; in the fractionation process, the fractionation components enter a third collecting tank 22 through a fractionation component outlet 21, and are liquefied at normal temperature to realize the collection of raw materials.
Wherein, the switch of the ultrasonic generator 3 is turned on, and the ultrasonic generator 3 is turned off after the preset time; the switch of the water bath heater 2 is turned on, and the heating temperature of the reaction tank 4 is regulated and controlled by the thermocouple 1 to present step-type temperature heating; turning on a switch of the stirrer 9, and uniformly mixing the reaction raw materials and the reaction medium; after the water bath heater 2 is turned off, the ultrasonic generator 3 is turned on, and is turned off after the preset time is continued; after the esterification reaction is completed, the stirrer 9 is closed, the first valve 15 is opened, and the esterification reaction product material is discharged into a second collecting tank 18, which specifically comprises the following steps:
after the materials are fully mixed, adjusting the temperature of the reaction tank 4 to be within the temperature range of 60-70 ℃ by using the water bath heater 2 and maintaining for 40-80 min;
step two, the ultrasonic generator 3 is started, the temperature of the reaction tank 4 is adjusted from the temperature range of 60-70 ℃ to the temperature range of 70-90 ℃ by using the water bath heater 2, and the temperature is kept for 100-140 min, so that the generation of free radicals is effectively realized, the esterification reaction is promoted, and the generation of byproducts is reduced;
turning off the ultrasonic generator 3, and regulating the temperature of the reaction tank 4 from the temperature range of 70-90 ℃ to the temperature range of 90-100 ℃ by using the water bath heater 2 to keep the temperature for 40-80 min;
and stage four, closing the water bath heater 2, and starting the ultrasonic generator 3 for 20-40 min to ensure the forward progress of the substrate in the ethyl lactate synthesis reaction.
In the technical scheme provided by the embodiment of the invention, a dehydrating agent is not required to be added in the esterification reaction process, and the dehydration of the product is realized by virtue of a temperature control heating rod device of a second collecting tank; after the reaction is finished, the product can be directly discharged into a second collecting tank for rectification and purification, so that the energy consumption is reduced; after the reaction is finished, the active components of phosphomolybdic acid and ammonium phosphomolybdate and the mesoporous silica molecular sieve carrier can be recovered by recovering the hollow cubic metal frame.
Example four
In the reaction device for synthesizing ethyl lactate provided by the embodiment of the invention, the ethanol volatilization outlet of the reaction tank 4 is communicated with the volatilized ethanol inlet of the first collecting tank 23 through the volatilization channel 10 and the inlet of the straight condensing pipe 12; an ethanol reflux inlet of the reaction tank 4 is communicated with a reflux ethanol outlet of the first collecting tank 23 through the reflux pipe 11. The material outlet of the reaction tank 4 is communicated with the material inlet of a second collecting tank 18 through a discharge channel 16. The volatiles outlet of collection tank No. two 18 is in communication with the composition inlet of collection tank No. three 22 via a fractionated composition outlet 21.
The volatilization channel 10 extends into one end of the reaction tank 4 and is positioned at the top of the reaction tank 4. The return pipe 11 is used for communicating the reaction tank 4 with the first collecting tank 23; the return pipe 11 extends into one end of the first collecting tank 23 and is positioned at the bottom of the first collecting tank 23; the return pipe 11 extends into one end of the reaction tank 4, and is positioned at the top of the reaction tank 4. The inlet of the straight condensing pipe 12 extends into one end of the first collecting tank 23 and is positioned at the top of the first collecting tank 23. The first collection tank 23 should be located at a height equal to or higher than the height of the reaction tank 4. The inlet of the second collecting groove 18 extends into one end of the second collecting groove 18 and is positioned in the middle of the second collecting groove 18. The fractionated component outlet 21 extends into one end of the second holding tank 18 at the top of the second holding tank 18. The ethyl lactate collecting port 19 is positioned at the side of the second collecting tank 18. The inlet of the third collecting groove 22 extends into one end of the third collecting groove 22 and is positioned at the bottom of the third collecting groove 22.
EXAMPLE five
The reaction device for synthesizing ethyl lactate provided by the embodiment of the invention comprises: the device comprises a water bath heater 2, an ultrasonic generator 3, a reaction tank 4, a lactic acid feed tank 5, an ethanol feed tank 6, a reaction medium input port 7, a stirrer 9, a hollow cubic metal frame 14, a first collecting tank 23, a temperature control heating rod device 17, a second collecting tank 18, an ethyl lactate collecting port 19 and a third collecting tank 22.
In the present embodiment, the reaction tank 4 is a hollow cylinder; one end of the lactic acid feeding groove 5 is communicated with the side surface of the reaction tank 4, and the other end is arranged outside the reaction tank 4; one end of the ethanol feeding groove 6 is communicated with the side surface of the reaction tank 4, and the other end is arranged outside the reaction tank 4; one end of the reaction medium input port 7 is arranged at the top end of the reaction tank 4, and the other end is arranged outside the reaction tank 4; the hollow cubic metal frame 14 is arranged at the bottom of the reaction tank 4; a water level meter 13 is arranged on the side surface of the reaction tank 4, and a pressure release valve 8 is arranged at the top end of the reaction tank; a first valve 15 is arranged on the side surface of the middle lower end of the reaction tank 4 and used for controlling discharging; the hollow cubic metal frame 14 is arranged at the bottom of the reaction tank 4 to fully ensure the contact reaction between the reaction medium and the reaction substrate.
In the present embodiment, the second collecting groove 18 is a hollow cube; the applicable temperature range of the second collecting tank 18 is 125-135 ℃; a second valve 20 is arranged at the position communicated with the ethyl lactate collecting port 19.
In the present embodiment, the third collecting groove 22 is a hollow cube; preferably, the entire cube is in a sealed state.
In the embodiment of the invention, the applicable temperature range of the reaction tank 4 is 50-110 ℃.
EXAMPLE six
The preparation method for synthesizing the ethyl lactate provided by the embodiment of the invention comprises the following steps:
mixing lactic acid and ethanol as reaction raw materials to obtain a mixture;
based on the mixture, carrying out esterification reaction by adopting a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product; wherein, during the esterification reaction, a discontinuous resonance and step-type heating mode is adopted;
based on the initial ethyl lactate product, a final ethyl lactate product is obtained by adopting a rectification mode;
wherein in the process of mixing lactic acid and ethanol as reaction raw materials to obtain a mixture, the volume ratio of lactic acid to ethanol is 1.5: 1 in the proportion range. The discontinuous resonance is realized by adopting an ultrasonic generator; the frequency of the ultrasonic generator is controlled to be 20 KHz. The step-type heating mode is realized by adopting a water bath heater to regulate and control the reaction temperature.
The method comprises the following steps of performing esterification reaction by using a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components based on the mixture to obtain an initial ethyl lactate product:
heating the mixture to 60 deg.C for 40min under non-resonance condition;
keeping the mixture in resonance condition, heating the mixture to 70 deg.C, and maintaining for 100 min;
heating the mixture to 90 deg.C for 40min under non-resonance condition;
and (3) enabling the product to be in a resonance working condition, and naturally cooling for 20min to obtain an initial ethyl lactate product.
In the process of obtaining the final ethyl lactate product by adopting a rectification mode based on the initial ethyl lactate product, the heating temperature range during rectification is 125 ℃.
EXAMPLE seven
The preparation method for synthesizing ethyl lactate provided by the embodiment of the invention is different from the sixth embodiment only in that in the process of mixing lactic acid and ethanol as reaction raw materials to obtain a mixture, the volume ratio of lactic acid to ethanol is 1.8: 1 in the proportion range. The frequency of the ultrasonic generator is controlled to be 30 KHz.
The method comprises the following steps of performing esterification reaction by using a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components based on the mixture to obtain an initial ethyl lactate product:
heating the mixture to 65 deg.C for 60min under non-resonance condition;
keeping the mixture in resonance condition, heating the mixture to 80 deg.C, and maintaining for 120 min;
heating the mixture to 95 deg.C for 60min under non-resonant condition;
and (3) enabling the product to be in a resonance working condition, and naturally cooling for 30min to obtain an initial ethyl lactate product.
In the process of obtaining the final ethyl lactate product by adopting a rectification mode based on the initial ethyl lactate product, the heating temperature range during rectification is 130 ℃.
Example eight
The preparation method for synthesizing ethyl lactate provided by the embodiment of the invention is different from the sixth embodiment only in that in the process of mixing lactic acid and ethanol as reaction raw materials to obtain a mixture, the volume ratio of lactic acid to ethanol is 2: 1 in the proportion range. The frequency of the ultrasonic generator is controlled to be 40 KHz.
The method comprises the following steps of performing esterification reaction by using a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components based on the mixture to obtain an initial ethyl lactate product:
heating the mixture to 70 deg.C for 80min under non-resonant condition;
enabling the mixture to be in a resonance working condition, and heating the mixture to be in a temperature range of 90 ℃ for 140 min;
heating the mixture to 100 deg.C for 80min under non-resonance condition;
and (5) enabling the product to be in a resonance working condition, and naturally cooling for 40min to obtain an initial ethyl lactate product.
In the process of obtaining the final ethyl lactate product by adopting a rectification mode based on the initial ethyl lactate product, the heating temperature range during rectification is 135 ℃.
Example nine
A reaction system for synthesizing ethyl lactate comprises a plurality of reaction devices disclosed by the embodiment of the invention; the reaction devices are arranged in series and are used for realizing the continuous synthesis of the ethyl lactate.
Referring to fig. 3, specifically, when the number of reaction devices is three: the reaction system comprises a No. 1 reaction tank, a No. 2 reaction tank, a No. 3 reaction tank, a No. 1 ultrasonic generator, a No. 2 ultrasonic generator, a No. 3 ultrasonic generator, a total volatilization channel, a total return pipe, a total discharge channel, a No. 1 collecting tank, a No. 2 collecting tank and a No. 3 collecting tank; the ethanol volatilization outlet of the reaction tank No. 1 is communicated with the ethanol inlet of the collection tank No. 1 through a volatilization channel No. 1, a total volatilization channel and a straight condensation pipe; an ethanol reflux inlet of the reaction tank No. 1 is communicated with an ethanol outlet of the collecting tank No. 1 through a reflux pipe No. 1 and a main reflux pipe; the material outlet of the No. 1 reaction tank is communicated with the material inlet of the No. 2 collecting tank through the No. 1 discharge channel and the total discharge channel; the ethanol volatilization outlet of the No. 2 reaction tank is communicated with the ethanol inlet of the No. 1 collecting tank through a No. 2 volatilization channel, a total volatilization channel and a straight condensing pipe; an ethanol reflux inlet of the No. 2 reaction tank is communicated with an ethanol outlet of the No. 1 collecting tank through a No. 2 reflux pipe and a total reflux pipe; the material outlet of the No. 2 reaction tank is communicated with the material inlet of the No. 2 collecting tank through the No. 2 discharge channel and the total discharge channel; an ethanol volatilization outlet of the No. 3 reaction tank is communicated with an ethanol inlet of the No. 1 collecting tank through a No. 3 volatilization channel, a total volatilization channel and a straight condensing pipe; an ethanol reflux inlet of the No. 3 reaction tank is communicated with an ethanol outlet of the No. 1 collecting tank through a No. 3 reflux pipe and a main reflux pipe; the material outlet of the No. 3 reaction tank is communicated with the material inlet of the No. 2 collecting tank through a No. 3 discharge channel and a total discharge channel; the total volatilization channel is used for transmitting volatilized ethanol and is communicated with the No. 1 volatilization channel, the No. 2 volatilization channel and the No. 3 volatilization channel; the main reflux pipe is used for refluxing ethanol which is one of raw materials and is communicated with a No. 1 reflux pipe, a No. 2 reflux pipe and a No. 3 reflux pipe; the main discharge channel is used for conveying product materials and is communicated with the No. 1 discharge channel, the No. 2 discharge channel and the No. 3 discharge channel; the volatile component outlet of the No. 2 collecting tank is communicated with the inlet of the No. 3 collecting tank through a fractionation component outlet.
In the embodiment of the invention, the reaction tank No. 1, the reaction tank No. 2 and the reaction tank No. 3 are respectively provided with an ethanol feeding groove, a lactic acid feeding groove, a reaction medium input port, a pressure release valve, a water level meter and a stirrer; the No. 1 reaction tank is provided with a No. 1 volatilization channel, and the No. 1 volatilization channel is provided with a fourth valve; the No. 1 return pipe is provided with a fifth valve; the device is provided with a No. 1 discharge channel, and the No. 1 discharge channel is provided with a first valve; the No. 2 reaction tank is provided with a No. 2 volatilization channel, and the No. 2 volatilization channel is provided with a sixth valve; a No. 2 return pipe is arranged, and the No. 2 return pipe is provided with a seventh valve; a No. 2 discharge channel is arranged, and a second valve is arranged in the No. 2 discharge channel; the No. 3 reaction tank is provided with a No. 3 volatilization channel, and the No. 3 volatilization channel is provided with an eighth valve; a No. 3 return pipe is arranged, and the No. 3 return pipe is provided with a ninth valve; a No. 3 discharge channel is arranged, and a third valve is arranged in the No. 3 discharge channel; the No. 1 ultrasonic generator is arranged at the bottom of the No. 1 reaction tank; the No. 2 ultrasonic generator is arranged at the bottom of the No. 2 reaction tank; the No. 3 ultrasonic generator is arranged at the bottom of the No. 3 reaction tank; the frequency ranges of the No. 1 ultrasonic generator, the No. 2 ultrasonic generator and the No. 3 ultrasonic generator are 20-40 KHz. No. 1 collecting vat is provided with straight condenser pipe import and No. 1 collecting vat export, and straight condenser pipe import is linked together with total volatilization passageway, and No. 1 collecting vat export is linked together with total back flow. The No. 2 collecting tank is provided with a temperature control heating rod device, the heating temperature range of the temperature control heating rod device is 125-135 ℃, and the temperature control heating rod device is positioned at the bottom of the No. 2 collecting tank; no. 2 collecting vat is provided with No. 2 collecting vat import, cuts apart composition export and ethyl lactate and collects the mouth, and No. 2 collecting vat import is linked together with total discharge passage, and ethyl lactate collects the mouth and is provided with the tenth valve. No. 3 collecting vat is provided with No. 3 collecting vat import, and No. 3 collecting vat import is linked together through fractionating composition export and No. 2 collecting vat. The reaction tanks No. 1, No. 2 and No. 3 are hollow cylinders, and the volume ratio range of lactic acid to ethanol in the reaction tanks (1.5-2) is 1; phosphomolybdic acid and ammonium phosphomolybdate are used as active components to be attached to the mesoporous silica molecular sieve, and are introduced into the reaction tank through the reaction medium inlet. And an inlet of the straight condensing pipe extends into one end of the No. 1 collecting tank and is positioned at the top of the No. 1 collecting tank. The height of the No. 1 collecting tank is equal to or higher than the height of the tops of the No. 1 reaction tank, the No. 2 reaction tank and the No. 3 reaction tank. The first valve, the second valve, the third valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, the eighth valve and the ninth valve can be controlled by computer programs, so that automatic operation is realized; the fourth valve and the fifth valve are a first group of valves, and the switches are kept consistent; the sixth valve and the seventh valve are a second group of valves, and the switches are kept consistent; and the eighth valve and the ninth valve are a third group of valves, and the switches are kept consistent.
The operation method of the reaction system of the above embodiment of the present invention includes the steps of:
a charging stage: respectively introducing reaction raw materials of lactic acid and ethanol into a specific reaction tank through a lactic acid feeding groove and an ethanol feeding groove, and introducing a mesoporous silica molecular sieve loaded with phosphomolybdic acid and ammonium phosphomolybdate into the reaction tank through a reaction medium inlet; turning on corresponding ultrasonic generator for 60min, and turning off ultrasonic generator; turning on a switch of the stirrer, and uniformly mixing the reaction raw materials and the reaction medium; carrying cooling substance water by an outer pipe of the straight condensing pipe; the water level gauge monitors the height of the water level in the reaction tank.
A reaction stage: opening a specific group of valves; starting a corresponding water bath heater, and regulating and controlling the heating temperature through a thermocouple to realize stepped heating of a corresponding reaction tank; adjusting the temperature of the corresponding reaction tank to 60-70 ℃ by using a water bath heater for 60 min; adjusting the temperature of the corresponding reaction tank from 60-70 ℃ to 70-90 ℃ by using a water bath heater, simultaneously starting the corresponding ultrasonic generator for 120min, and then closing the ultrasonic generator; adjusting the temperature of the corresponding reaction tank from 70-90 ℃ to 90-100 ℃ by using a water bath heater for 60 min; and (4) turning off the water bath heater, simultaneously turning on the corresponding ultrasonic generator for 30min, and then turning off the corresponding ultrasonic generator.
A discharging stage: after the esterification reaction is finished, closing the stirrer, opening a specific valve, and discharging the esterification reaction product into a second collecting tank through a main discharge channel; after discharging is finished, closing a specific valve, opening a switch of a temperature control heating rod device, and controlling the temperature within the range of 125-135 ℃; and after the reaction product does not generate foam any more, closing the temperature control heating rod device, and opening a tenth valve to complete the synthesis of the ethyl lactate to obtain the target product of the ethyl lactate.
When the reaction tank No. 1 is in a charging stage, the reaction tank No. 2 and the reaction tank No. 3 are ready to be determined, and the first group of valves, the second group of valves and the third group of valves are all closed; when the reaction tank No. 1 is in a reaction stage, the reaction tank No. 2 is in a charging stage, the reaction tank No. 3 is undetermined, the first group of valves are opened, and the second group of valves and the third group of valves are closed; when the reaction tank No. 1 is in a discharging stage, the reaction tank No. 2 is in a reaction stage, the reaction tank No. 3 is in a charging stage, the second group of valves is opened, and the first group of valves and the third group of valves are closed; and the reaction tanks 1, 2 and 3 sequentially react according to the rule to realize the continuous synthesis of the ethyl lactate.
In summary, the embodiment of the invention discloses a preparation method and a reaction device for synthesizing ethyl lactate and an operation method thereof, wherein the device comprises a reaction tank, an ultrasonic generator, a hollow cubic metal frame, a first collecting tank, a second collecting tank, a third collecting tank, a water bath heater and a temperature control heating rod device; the reaction tank is a hollow cylinder; the hollow cubic metal is arranged at the bottom of the reaction tank; the ultrasonic generator is arranged at the bottom of the reaction tank; one end of the lactic acid feeding groove is communicated with the side surface of the reaction tank, and the other end of the lactic acid feeding groove is arranged outside the reaction tank; one end of the ethanol feeding groove is communicated with the side surface of the reaction tank, and the other end of the ethanol feeding groove is arranged outside the reaction tank; one end of the reaction medium input port is arranged at the top end of the reaction tank, and the other end of the reaction medium input port is arranged outside the reaction tank; a water level gauge is arranged on the side surface of the reaction tank, and a pressure release valve is arranged at the top end of the reaction tank; a first valve is arranged on the side surface of the middle lower end of the reaction tank; the second collecting tank is a hollow cube, and a second valve is arranged at the position communicated with the ethyl lactate collecting port; the second collecting tank is provided with a temperature control heating rod device; the third collecting groove is a hollow cube, and the whole cube is in a sealed state. According to the method, the lactic acid and the ethanol are subjected to esterification reaction under the conditions that the mesoporous silica molecular sieve is used as a carrier and the phosphomolybdic acid and the ammonium phosphomolybdate are used as active components to efficiently obtain the target product of the ethyl lactate, and the raw materials are recycled. The invention has the advantages that: 1. under the environment of normal pressure, ultrasonic assistance and stepped heating, lactic acid and ethanol are directly contacted to carry out esterification reaction, and meanwhile, reaction media such as phosphomolybdic acid, ammonium phosphomolybdate and the like are added, so that the activation energy of the esterification reaction is reduced, the esterification reaction is promoted to be carried out, the generation of byproducts is reduced, and the harm of the reaction process to equipment corrosion is reduced. 2. The ultrasonic generator is used for mixing and stirring along with the stirrer, so that the contact between a reaction medium and reactants is promoted, the catalytic efficiency is ensured, meanwhile, the ethanol reflux of one of reaction raw materials and the recovery of final product materials both promote the utilization efficiency of the raw materials and increase the yield of ethyl lactate.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.
Claims (10)
1. A preparation method for synthesizing ethyl lactate is characterized by comprising the following steps:
mixing lactic acid and ethanol as reaction raw materials to obtain a mixture;
based on the mixture, carrying out esterification reaction by adopting a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product; wherein, during the esterification reaction, a discontinuous resonance and step-type heating mode is adopted;
based on the initial ethyl lactate product, a final ethyl lactate product is obtained by adopting a rectification mode.
2. The preparation method for synthesizing ethyl lactate according to claim 1, wherein in the process of mixing lactic acid and ethanol as reaction raw materials to obtain a mixture,
the lactic acid and the ethanol are calculated according to the volume ratio of (1.5-2): 1 in the proportion range.
3. The preparation method for synthesizing ethyl lactate according to claim 1, wherein the discontinuous resonance is realized by using an ultrasonic generator; the frequency of the ultrasonic generator is controlled within the range of 20KHz to 40 KHz.
4. The preparation method for synthesizing ethyl lactate according to claim 1, wherein the stepwise heating is realized by regulating the reaction temperature with a water bath heater.
5. The preparation method of claim 1, wherein the step of performing esterification reaction based on the mixture by using a composite catalyst with a mesoporous silica molecular sieve as a carrier and phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product specifically comprises:
the mixture is in a non-resonance working condition, and the mixture is heated to the temperature of 60-70 ℃ and is maintained for 40-80 min;
the mixture is in a resonance working condition, and the mixture is heated to the temperature of between 70 and 90 ℃ and is kept for 100 to 140 minutes;
the mixture is in a non-resonance working condition, and the mixture is heated to the temperature of between 90 and 100 ℃ and is kept for 40 to 80 minutes;
and (3) enabling the product to be in a resonance working condition, and naturally cooling for 20-40 min to obtain an initial ethyl lactate product.
6. The preparation method for synthesizing ethyl lactate according to claim 1, wherein in the process of obtaining the final ethyl lactate product by adopting a rectification mode based on the initial ethyl lactate product,
the heating temperature range during rectification is 125-135 ℃.
7. A reaction device for synthesizing ethyl lactate is characterized by comprising:
the reaction tank (4) is used for mixing lactic acid and ethanol serving as reaction raw materials to obtain a mixture; based on the mixture, carrying out esterification reaction by adopting a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components to obtain an initial ethyl lactate product;
an ultrasonic generator (3), the ultrasonic generator (3) being for effecting further mixing of the lactic acid and ethanol prior to carrying out the esterification reaction; the device is used for realizing discontinuous resonance of lactic acid and ethanol during the esterification reaction and preventing reverse progress of the esterification reaction through resonance after the esterification reaction is carried out;
the water bath heater (2), the said water bath heater (2) has thermocouple (1), is used for providing the ladder-type heating while carrying on the esterification reaction;
a second collecting tank (18) and a temperature control heating rod device (17) arranged in the second collecting tank (18) and used for obtaining a final ethyl lactate product by adopting a rectification mode based on the initial ethyl lactate product;
wherein the reaction tank (4) is provided with:
an ethanol feeding groove (6) for inputting ethanol raw materials into the reaction tank (4);
a lactic acid feed tank (5) for feeding a lactic acid raw material to the reaction tank (4);
a reaction medium input port (7) for inputting a composite catalyst which takes the mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components;
the stirrer (9) is used for stirring and mixing the ethanol raw material and the lactic acid raw material;
the catalyst comprises a hollow cubic metal frame (14), wherein the hollow cubic metal frame (14) is preloaded with a composite catalyst which takes a mesoporous silica molecular sieve as a carrier and takes phosphomolybdic acid and ammonium phosphomolybdate as active components;
the volatilization channel (10) and the return pipe (11) are used for realizing the return of the ethanol;
a discharge channel (16), the discharge channel (16) being provided with a first valve (15) for enabling output of an initial ethyl lactate product.
8. The reaction device for synthesizing ethyl lactate according to claim 7, further comprising:
a first collecting tank (23), wherein the first collecting tank (23) is used for collecting volatilized ethanol and enabling the ethanol to flow back to the reaction tank (4); the first collecting tank (23) is provided with a first collecting tank inlet and a first collecting tank outlet, the first collecting tank inlet is communicated with the reaction tank (4) through a condensing pipe and a volatilization channel (10), and the first collecting tank outlet is communicated with the reaction tank (4) through a return pipe (11).
9. The reaction device for synthesizing ethyl lactate as recited in claim 7, wherein the second collecting tank (18) is provided with a second collecting tank inlet, a fractionation component outlet (21) and an ethyl lactate collecting port (19);
the inlet of the second collecting tank is communicated with the reaction tank (4) through a discharge channel (16); the ethyl lactate collecting port (19) is provided with a second valve (20).
10. The reaction device for synthesizing ethyl lactate according to claim 9, further comprising:
a third collecting tank (22), wherein the third collecting tank (22) is provided with a third collecting tank inlet;
the third collecting tank inlet is communicated with the second collecting tank (18) through a fractionation component outlet (21) and is used for collecting various fractionated components.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN206033624U (en) * | 2016-08-25 | 2017-03-22 | 江苏九天高科技股份有限公司 | Vapor permeation dehydration techniques is used for synthetic ethyl lactate's device |
| CN112844249A (en) * | 2020-12-24 | 2021-05-28 | 河南金丹乳酸科技股份有限公司 | Process for preparing ethyl lactate by catalytic esterification |
| US20220009872A1 (en) * | 2018-11-23 | 2022-01-13 | Gs Caltex Corporation | Method for preparing alkyl carboxylic acid ester and apparatus for preparing alkyl carboxylic acid ester |
| CN114100644A (en) * | 2021-10-29 | 2022-03-01 | 中国科学院金属研究所 | Solid acid catalytic separation integrated filler and preparation method and application thereof |
-
2022
- 2022-07-18 CN CN202210841697.XA patent/CN115057773A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN206033624U (en) * | 2016-08-25 | 2017-03-22 | 江苏九天高科技股份有限公司 | Vapor permeation dehydration techniques is used for synthetic ethyl lactate's device |
| US20220009872A1 (en) * | 2018-11-23 | 2022-01-13 | Gs Caltex Corporation | Method for preparing alkyl carboxylic acid ester and apparatus for preparing alkyl carboxylic acid ester |
| CN112844249A (en) * | 2020-12-24 | 2021-05-28 | 河南金丹乳酸科技股份有限公司 | Process for preparing ethyl lactate by catalytic esterification |
| CN114100644A (en) * | 2021-10-29 | 2022-03-01 | 中国科学院金属研究所 | Solid acid catalytic separation integrated filler and preparation method and application thereof |
Non-Patent Citations (4)
| Title |
|---|
| 严学芬 等: "快速合成乳酸乙酯", 贵阳学院学报（自然科学版）, vol. 5, no. 4, pages 60 - 61 * |
| 于海云 等: "磷钨钼杂多酸催化合成乳酸正丁酯", 内蒙古民族大学学报（自然科学版）, vol. 27, no. 1, pages 15 - 17 * |
| 李斌 等: "Mo/HZSM-5分子筛催化合成乳酸酯的研究", 广西化工, vol. 28, no. 1, pages 6 - 8 * |
| 钟立群 等: "二氧化硅负载硅钨钼酸催化合成乳酸正戊酯", 化工中间体, no. 07, pages 51 - 52 * |
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