Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
The first aspect of the invention provides a method for preparing epsilon-caprolactone, which comprises the following steps:
(I) Mixing an oxidant, a water-carrying agent and a stabilizer in a raw material premixing tank 1, and dehydrating the obtained mixture through a first dehydrating tower 2 to obtain a first product;
(II) mixing the first product and an acid in a first mixer 3, and subjecting the obtained first mixture to a first reaction in a first fixed bed reactor 4, and dehydrating the obtained reaction product through a second dehydrating tower (5) to obtain a second product;
(III) mixing the second product with cyclohexanone in a second mixer 6 and subjecting the resulting second mixture to a second reaction in a third fixed-bed reactor 8 to obtain a crude ester;
(IV) rectifying the crude ester to obtain epsilon-caprolactone.
Aiming at the problems that in the method disclosed by the prior art, peroxide is easy to decompose, epsilon-caprolactone is easy to self-polymerize in rectification, and an added stabilizer is difficult to remove, and the problems of low percarboxylic acid yield, poor safety and low epsilon-caprolactone yield; the inventor of the present invention found through experiments that: the fixed bed reactor filled with the solid acid catalyst can avoid the problems of pollution and difficult separation of impurities caused by the use of the liquid acid catalyst in the prior art; moreover, the method for preparing epsilon-caprolactone by adopting the device provided by the invention has the advantages of stable operation in the whole production process, high product purity and continuous production.
According to the invention, epsilon-caprolactone (epsilon-caprolactone) has the molecule C 6 H 10 O 2 The structural formula is shown as formula (1):
according to the invention, in the step (I), the stabilizer is a compound stabilizer, and the stabilizer is at least two selected from picolinic acid, picoline, lutidine, 8-hydroxyquinoline, tributyl phosphate and dipicolinic acid, and the decomposition of peroxide can be reduced by adopting the compound stabilizer, so that the safety and the economy are improved; in addition, in the present invention, preferably, the stabilizer is selected from two kinds of optional stabilizers selected from picolinic acid, dipicolinic acid, picoline, lutidine, 8-hydroxyquinoline and tributyl phosphate, and the weight ratio of the amounts of the two optional stabilizers in picolinic acid, dipicolinic acid, picoline, lutidine, 8-hydroxyquinoline and tributyl phosphate is 1: (1-20); the weight ratio of the optional three stabilizers in picolinic acid, dipicolinic acid, picoline, lutidine, 8-hydroxyquinoline and tributyl phosphate is 1: (1-20): (1-20), more preferably 1: (1-5): (1-6); more preferably, the stabilizer is dipicolinic acid and picoline; wherein the dipicolinic acid may be a pyridine 2,5 dicarboxylic acid.
According to the present invention, in actual production, the stabilizer must be added to the raw material premix tank 1, so that not only can the stability of the peroxide as a raw material in the reaction system be ensured, but also the stability of the intermediate product in the reactor can be ensured; and its components are recovered to the system after being withdrawn from the top of the first separation column 9 and the bottom of the refining column 11, respectively, so that it is necessary to periodically analyze the content of the components in the stabilizer in the raw material mixing tank 1.
In the invention, the composite stabilizer is adopted, and is added into the raw material premixing tank 1, and in the specific proportion range, the decomposition of intermediate products and target products can be effectively inhibited, and the whole process is safe.
According to the invention, the oxidizing agent is hydrogen peroxide. In the present invention, the concentration of the oxidizing agent is 10 to 70%, preferably 10 to 50%. Hydrogen peroxide (hydrogen peroxide), formula H 2 O 2 . Pure hydrogen peroxide is light blue viscous liquid, can be mixed with water in any proportion, is a strong oxidant, and the aqueous solution is commonly called hydrogen peroxide and is colorless transparent liquid.
In the invention, the water-carrying agent is added while the oxidant is dehydrated, so that the safety can be ensured and the reaction rate can be not reduced.
According to the present invention, the first dehydration tower 2 performs dehydration by using the azeotropic effect of the oxidizing agent and the water-carrying agent, and in the present invention, the water-carrying agent is mixed while the oxidizing agent is concentrated, so that the safety can be ensured to the maximum extent while the concentration of the oxidizing agent is provided.
According to the invention, the water carrying agent is selected from one or more of ethyl acetate, ethyl propionate, methyl propionate, isopropyl acetate and propyl formate, preferably ethyl acetate.
According to the invention, the weight ratio of the amounts of the oxidizing agent, the water-carrying agent and the stabilizing agent is 1: (4-15): (0.001-0.02); more preferably, the oxidant, the water-carrying agent and the stabilizer are used in an amount of 1 by weight: (6-12): (0.005-0.01).
According to the invention, in the step (II), an azeotrope of water and the first product is obtained at the top of the first dehydration tower 2, and is layered after condensation, the water carrying agent at the upper layer of the phase separator returns to the first dehydration tower 2, and the water phase at the lower layer is extracted; the first dehydration tower 2 is a mixture of an oxidant and a water-carrying agent, and the mixture is pumped into the first mixer 3 through a pump.
According to the invention, the acid is selected from one or more of formic acid, acetic acid and propionic acid, preferably acetic acid.
According to the invention, the molar ratio of the oxidant to the acid used is 1 (1-5), preferably 1: (1.5-2.5).
According to a preferred embodiment of the present invention, the present invention confirms that the content of the oxidizing agent (hydrogen peroxide) in the second fixed bed reactor (7) is not more than 1wt%, preferably 0.06 to 1wt% by continuous chinese experiment; too high of the two can accelerate the self-polymerization of epsilon-caprolactone in the subsequent process. The content of the peroxy acid is not preferably less than 18wt%, preferably 18 to 22wt%, and too high a content may cause an increase in risk.
According to the invention, in actual production, the first mixer 3 is a three-strand mixer.
According to the invention, the conditions of the first reaction include: the temperature is 30-90 ℃, the pressure is-0.1 MPa to 0MPa, and the time is 0.2-3h; more preferably, the temperature is 40-90 ℃, the pressure is-0.095 MPa to-0.05 MPa, and the time is 0.5-1h.
According to the invention, in step (III), the acid is stored in the acid tank 12. The acid is preheated and then enters a first mixer 3, is mixed with the first product, and then enters a first fixed bed reactor 4 filled with a solid acid catalyst, and part of the reacted material is recycled to the first mixer 3 and the other part enters a second dehydration tower 5.
According to the invention, the molar ratio of the second product to the amount of cyclohexanone is 1: (1-5), preferably 1: (1.5-3).
According to the invention, the conditions of the second reaction include: the temperature is 30-100 ℃, the pressure is 0MPa to 0.1MPa, and the time is 0.2-2h; more preferably, the temperature is 40-90 ℃, the pressure is 0.08MPa to 0.2MPa, and the time is 0.5-1h.
According to the invention, the method further comprises: in step (III), the second product is treated by a second fixed bed reactor 7; preferably, the second fixed bed reactor 7 is charged with the oxidizing agent.
According to the invention, the first fixed bed reactor 4, the second fixed bed reactor 7 and the third fixed bed reactor 8 are all jacketed solid bed reactors; preferably, the first fixed bed reactor 4 and the second fixed bed reactor 7 are filled with a solid acid catalyst; wherein the solid acid catalysts are respectively filled in the tube arrays arranged in the first fixed bed reactor 4; in the present invention, the peripheries of the tube arrays in the first fixed bed reactor 4 and the second fixed bed reactor 7 are filled with a heat medium (circulated hot water), so that the reaction temperature can be rapidly raised, and the reaction can be ensured to be carried out toward the production product by controlling the temperature of the hot water; the periphery of the tube array in the third fixed bed reactor 8 is filled with cold medium (circulating cold water), and the arrangement can effectively draw heat generated by the reaction, control the reaction degree and reduce the decomposition of epsilon-caprolactone.
According to the present invention, the active component-supported molecular sieve catalyst packed in the first fixed bed reactor 4 and the second fixed bed reactor 7, wherein the active component-supported molecular sieve catalyst is a carrier and an active component supported on the carrier, wherein the carrier is selected from the group consisting of B 2 O 3 /γ-Al 2 O 3 One or more of ZSM-5 (H-ZSM-5), modified beta molecular sieve and modified Y molecular sieve, wherein the active component is phosphotungstic heteropolyacid and/or boric acid.
In the present invention, the active component-supporting molecular sieve catalyst is packed in the first fixed bed reactor 4 and the second fixed bed reactor 7, wherein the first fixed bed reactor 4 is provided with a pump capable of self-circulation, and the second fixed bed reactor 7 is provided with a dehydration column capable of removing product water. The arrangement of the device can effectively reduce the water content in the second product and ensure that the reaction is carried out towards the direction of the production product, so that the production can be continuous.
According to the present invention, the third fixed bed reactor 8 is filled with an organic acid synthetic resin catalyst.
Wherein the organic acid synthetic resin catalyst is one of Amberlyst-15, 001×7 strong acid styrene cation exchange resin and D001 macroporous strong acid styrene cation exchange resin, wherein the D001 macroporous strong acid styrene cation exchange resin is preferable.
Wherein Amberlyst-15, which is a solid acid catalyst, belongs to ion exchange resin, and is a strongly acidic catalyst formed by sulfonation on the basis of macroporous styrene divinylbenzene copolymer. The detailed parameters are as follows: the mass total exchange capacity is more than or equal to 4.60, and the specific surface area is 30-50m 2 Per g, pore volume is 0.2-0.4ml/g, and granularity (0.315-1.25 mm) is more than or equal to 96%.
Wherein the 001×7 strongly acidic styrene cation exchange resin has sulfonic acid group (-SO) on the polymer matrix with styrene-divinylbenzene copolymer cross-linked structure 3 H) Styrene-divinylbenzene with resin structure, functional group-SO 3 H, brown to tan spherical particles. The detailed parameters are as follows: the mass total exchange capacity is more than or equal to 4.80, the uniformity coefficient is 1.6, the ball rate after grinding is more than or equal to 90 percent, and the granularity (0.315-1.25 mm) is more than or equal to 95 percent.
Wherein, the D001 macroporous strong acid styrene cation exchange resin has a resin structure of styrene-divinylbenzene and a functional group-SO 3 H, light hump opaque spherical particles, other parameters are: the mass total exchange capacity is more than or equal to 4.70, and the specific surface area is 35-58m 2 Per g, pore volume is 0.2-0.4ml/g, and granularity (0.315-1.25 mm) is more than or equal to 95%.
According to the present invention, the third fixed bed reactor 8 is filled with the organic acid synthetic resin catalyst and provided with a self-circulation device, and this arrangement can maintain the components in the separation column 1 stable, which is advantageous for continuous production.
According to the invention, in step (III), in a second mixer 6, the second product is fed into a third fixed bed reactor 8 with cyclohexanone and unreacted material in a certain ratio, and after reaction, part of the material is taken out and fed into a rectifying device.
In actual production, the residence time of the material (the second product) in the fixed bed reactor at the catalyst surface is measured in terms of weight hourly space velocity, defined as 1m in 1h 3 Volume of material (m) through which the catalyst flows 3 /(m 3 H), i.e., h -1 。
In the present invention, in the step (II), the weight hourly space velocity is from 0.5 to 2h -1 Preferably 0.6-1.5h -1 More preferably0.6-0.8h -1 An initial weight hourly space velocity of 0.5h -1 The circulation ratio is 10, and according to the content of the target product, the circulation amount can be gradually reduced while the airspeed is increased.
In the present invention, in the step (III), the weight hourly space velocity is 1 to 3 hours -1 Preferably 2 to 2.5h -1 An initial weight hourly space velocity of 1h -1 The circulation ratio is 5, and according to the content of the target product, the circulation amount can be gradually reduced while the airspeed is increased.
In addition, the "recycle ratio" is the ratio of the flow rate of the material returned to the inlet in the outlet of the third fixed bed reactor to the flow rate of the portion of the separation column 1.
According to the present invention, more preferably, the oxidizing agent is hydrogen peroxide, the water-carrying agent is ethyl acetate, and in the present invention, the reaction for obtaining peracetic acid by performing the first reaction in the first fixed bed reactor 4 is:
in the present invention, the reaction in the first fixed bed reactor 4 is an endothermic reaction, and the shell side is hot water.
In the present invention, the second reaction in the third fixed bed reactor 8 gives epsilon-caprolactone as follows:
in the present invention, the reaction in the third fixed bed reactor 8 is exothermic and the shell side is cold water.
In actual production, the circulating water passes through the third fixed bed reactor 8 and then goes to the first fixed bed reactor 4.
In the present invention, the second fixed bed reactor 7 is used as a supplement to the first fixed bed reactor 4 in order to reduce the hydrogen peroxide content and ensure efficient subsequent reactions.
In the present invention, the reaction in the second fixed bed reactor 7 is an endothermic reaction, and the shell side is hot water.
In actual production, the circulating water passes through the third fixed bed reactor 8 and then goes to the first fixed bed reactor 4 and the second fixed bed reactor 7.
According to the invention, in the step (IV), the material to be rectified sequentially enters a first separation tower 9 and a second separation tower 10, and water preparation agent and cyclohexanone are removed respectively; meanwhile, the first separation tower 9 and the second separation tower 10 form a multi-effect rectifying system, so that energy consumption can be effectively reduced.
According to the invention, the material in the tower bottom of the second separation tower 10 enters a refining tower, light components are separated from the tower top under certain vacuum and temperature, and epsilon-caprolactone with the content of not less than 99.4% is obtained from the tower top, and heavy components are separated from the tower bottom.
According to the invention, the first separation column 9 is operated at a temperature of 80 to 130 ℃, preferably 90 to 120 ℃; the operating pressure is 1 to 30kPa, preferably 4 to 25kPa.
According to the invention, the second separation column 10 is operated at a temperature of 80-130 ℃, preferably 100-120 ℃; the operating pressure is from 0.1 to 10kPa, preferably from 0.3 to 5kPa.
Through strict analog calculation and Chinese experiments, in actual production, the first separation tower 9 and the second separation tower 10 form a double-effect rectifying tower system adopting a concurrent flow process, namely, the top steam of the first separation tower 9 is used as a heating medium of a reboiler of the second separation tower 10; the preliminary estimation saves about 38% of energy compared with the traditional system.
According to the invention, the operating temperature of the refining column 11 is between 90 and 140 ℃, preferably between 110 and 130 ℃; the operating pressure is from 0.5 to 10kPa, preferably from 1 to 8kPa.
The second aspect of the invention provides a device for preparing epsilon-caprolactone, wherein the device comprises a pretreatment system, a reaction system and a rectification system which are sequentially connected;
wherein the pretreatment system comprises a raw material premixing tank 1, a first dehydration tower 2 and a first mixer 3; the first dehydration tower 2 is respectively connected with the raw material premixing tank 1 and the first mixer 3 through a circulating pump;
wherein the reaction system comprises a first fixed bed reactor 4, a second dehydration tower 5, a second mixer 6 and a third fixed bed reactor 8; the first mixer 3 is respectively connected with an acid tank 12 and the first fixed bed reactor 4; the second dehydration tower 5 is respectively connected with the first fixed bed reactor 4 and the third fixed bed reactor 8;
the rectification system comprises a rectification device, and the third fixed bed reactor 8 is connected with the rectification device.
According to the invention, the rectifying device comprises a first separation tower 9, a second separation tower 10 and a refining tower 11 which are connected in sequence.
According to the present invention, the first separation column 9, the second separation column 10 and the refining column 11 each include a condenser, a reboiler, a condensing tank and a bottom discharge pump.
According to the invention, the plant also comprises a second fixed-bed reactor 7, and the second fixed-bed reactor 7 is connected to the first fixed-bed reactor 4 and the third fixed-bed reactor 8, respectively.
The method and the device provided by the invention have the advantages of wide raw material selection range, high safety coefficient, low system energy consumption and low waste discharge, and can realize industrialized continuous production. Meanwhile, the expansion production can be performed according to actual production conditions.
The present invention will be described in detail by examples.
Example 1
This example is intended to illustrate the preparation of epsilon-caprolactone using the apparatus and method of the present invention.
In the apparatus for producing epsilon-caprolactone shown in fig. 1, epsilon-caprolactone was produced by the following steps:
the tubes arranged in the first fixed bed reactor 4 and the second fixed bed reactor 7 are filled with H-ZSM-5 catalyst loaded with heteropolyacid.
The column tube arranged in the third fixed bed reactor 8 is filled with organic acid resin catalyst D001 macroporous strong acid styrene cation exchange resin.
Wherein the first fixed bed reactor 4, the second fixed bed reactor 7 and the third fixed bed reactor 8 are all jacketed solid bed reactors; the peripheries of the tubes in the first fixed bed reactor 4 and the second fixed bed reactor 7 are filled with a heat medium (circulated hot water); the periphery of the tube array in the third fixed bed reactor 8 is filled with a cold medium (circulated cold water).
The first step: preparation of the first product
Mixing oxidant hydrogen peroxide, water-carrying agent ethyl acetate and a composite stabilizer in a raw material premixing tank 1, and dehydrating the obtained mixture through a first dehydrating tower 2 to obtain a first product;
wherein the weight ratio of the usage amount of the oxidant, the water-carrying agent and the stabilizer is 1:6:0.008; the selected composite stabilizer is lutidine, 8-hydroxyquinoline and pyridine 2,5 dicarboxylic acid according to the proportion of 1:4:5, mixing, wherein the mass fraction of the raw material hydrogen peroxide is 50%.
And a second step of: preparation of the second product
Mixing acetic acid and a first product in a first mixer 3, carrying out a first reaction on the obtained first mixture in a first fixed bed reactor 4, and dehydrating the obtained reaction product through a second dehydrating tower 5 to obtain a second product;
wherein the weight ratio of acetic acid to the first product is 1:1, and the molar ratio of the oxidant to the acid is 1:3, acid excess, space velocity of the catalyst of 1m 3 /(m 3 H) initial airspeed of 0.5m 3 /(m 3 H) the circulation ratio is 10; wherein the conditions of the first reaction include: the temperature is 60 ℃, the pressure is-0.08 MPa, and the time is 1h.
The materials are fully circulated in the first dehydration tower 2 and the second fixed bed reactor 7, and the components of the tower bottom materials of the analysis dehydration tower after 60min are as follows:
the peroxyacetic acid mixed solution mainly comprises the following components (weight percent, excluding catalysts and stabilizers):
peracetic acid 20.05%
Acetic acid 51.6%
Ethyl acetate 28.2%
Hydrogen peroxide 0.06%
The conversion of hydrogen peroxide was 99.3% and the selective yield of peroxyacetic acid was 96.5%.
And a third step of: preparation of epsilon-caprolactone
Mixing the second product and cyclohexanone according to a molar ratio of 1:2.5, then entering a third fixed bed reactor 8, simultaneously starting to inject cold water into a jacket for heat extraction, and carrying out a second reaction in the third fixed bed reactor 8 to obtain crude ester; the outlet material was fully circulated and after 120min the outlet composition was analyzed.
Wherein the conditions of the second reaction include: the temperature is 70 ℃, the pressure is 0.04MPa, and the time is 1h; weight hourly space velocity of 2h -1 ;
The epsilon-caprolactone mixed solution mainly comprises the following components (weight percent, excluding catalysts and stabilizers):
epsilon-caprolactone 21.2%
Cyclohexanone 0.16%
Peracetic acid 2.22%
Acetic acid 53.3%
Ethyl acetate 23.1%
Hydrogen peroxide 0.01%
The conversion of cyclohexanone was 99.2% and the selectivity yield of epsilon-caprolactone was 99.8%. The conversion of peroxy acid was 86.4% and the selectivity yield to epsilon-caprolactone was 99.9%.
Fourth step: epsilon-caprolactone
The materials sequentially pass through a first separation tower 9, a second separation tower 10 and a refining tower 11.
Obtaining epsilon-caprolactone with the content of 99.9 weight percent at the outlet of a reflux tank at the top of the refining tower 11; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is calculated to be 96.4 percent.
Example 2
Epsilon-caprolactone was prepared in the same manner as in example 1 except that the catalyst was filled in the same manner as in example 1: the raw materials and the proportions are changed, in particular:
the first step: preparation of the first product
Mixing oxidant hydrogen peroxide, water-carrying agent ethyl propionate and a composite stabilizer in a raw material premixing tank 1, and dehydrating the obtained mixture through a first dehydrating tower 2 to obtain a first product;
wherein the weight ratio of the usage amounts of the oxidant, the water-carrying agent and the stabilizer is 1:8:0.006; the selected composite stabilizer is 8-hydroxyquinoline and pyridine 2,5 dicarboxylic acid according to the proportion of 1:1, mixing, wherein the mass fraction of the raw material hydrogen peroxide is 30%.
And a second step of: preparation of the second product
The molar ratio of the propionic acid to the hydrogen peroxide used was 1:1.5, and the space velocity of the catalyst was 1m 3 /(m 3 H) initial airspeed of 0.6m 3 /(m 3 H) the circulation ratio is 15; wherein the conditions of the first reaction include: the temperature was 75℃and the pressure-0.09 MPa for 1.5h.
The materials are fully circulated in the first dehydration tower 2 and the second fixed bed reactor 7, and the components of the tower bottom materials of the analysis dehydration tower after 90 minutes are as follows:
peroxypropionic acid 19.6%
Propionic acid 52.04%
Ethyl propionate 28.3%
Hydrogen peroxide 0.06%
The conversion of hydrogen peroxide was 99.3% and the selective yield of peroxypropionic acid was 94.3%.
And a third step of: preparation of epsilon-caprolactone
Mixing a second product and cyclohexanone according to a molar ratio of 1:2 in a second fixed bed reactor 8, simultaneously starting to inject cold water into a jacket for heating, and performing a second reaction in a third fixed bed reactor 8 to obtain crude ester; the outlet material was fully circulated and after 120min the outlet composition was analyzed.
Wherein the conditions of the second reaction include: the temperature is 80 ℃, the pressure is 0.06MPa, and the time is 1.5h; weight hourly space velocity of 2h -1 ;
The calculated conversion of cyclohexanone was 98.5% and the selective yield to epsilon-caprolactone was 92.5%;
reference example 1 gave an epsilon-caprolactone content of 99.7% by weight at the outlet of the reflux drum at the top of the rectifying column 11; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is calculated to be 95.2 percent.
Example 3
Epsilon-caprolactone was prepared in the same manner as in example 1 except that the catalyst was filled in the same manner as in example 1:
the first step: preparation of the first product
Mixing oxidant hydrogen peroxide, water-carrying agent propyl formate and a composite stabilizer in a raw material premixing tank 1, and dehydrating the obtained mixture through a first dehydration tower 2 to obtain a first product;
wherein the weight ratio of the usage amount of the oxidant, the water-carrying agent and the stabilizer is 1:8:0.01; the selected composite stabilizer is picoline and lutidine according to the proportion of 2:3, mixing, wherein the mass fraction of the raw material hydrogen peroxide is 50%.
And a second step of: preparation of the second product
As shown in example 1, is different in that
The molar ratio of the amounts of formic acid and hydrogen peroxide used was 1:2, the space velocity of the catalyst was 1m 3 /(m 3 H) initial airspeed of 0.5m 3 /(m 3 H) the circulation ratio is 10; wherein the conditions of the first reaction include: the temperature is 55 ℃, the pressure is-0.06 MPa, and the time is 1.5h.
The materials are fully circulated in the first dehydration tower 2 and the second fixed bed reactor 7, and the components of the tower bottom materials of the analysis dehydration tower after 60min are as follows:
the peroxyformic acid mixed solution mainly comprises the following components (weight percent, excluding catalysts and stabilizers):
peroxyformic acid 18.2%
Formic acid 51.9%
Propyl formate 29.3%
Hydrogen peroxide 0.6%
The calculated conversion of hydrogen peroxide was 99%.
And a third step of: preparation of epsilon-caprolactone
Mixing a second product and cyclohexanone according to a molar ratio of 1:1.8, then in a second fixed bed reactor 8, simultaneously starting a jacket to be filled with cold water for heat extraction, and carrying out a second reaction in a third fixed bed reactor 8 to obtain crude ester; the outlet material was fully circulated and after 120min the outlet composition was analyzed.
Wherein the conditions of the second reaction include: the temperature is 65 ℃, the pressure is 0.09MPa, and the time is 1h; weight hourly space velocity of 2h -1 ;
The calculated conversion of cyclohexanone was 99% and the selective yield to epsilon-caprolactone was 82.2%; the conversion of peroxy acid was 86.4% and the selectivity yield to epsilon-caprolactone was 84.2%.
Fourth step: epsilon-caprolactone
The materials sequentially pass through a first separation tower 9, a second separation tower 10 and a refining tower 11.
Obtaining epsilon-caprolactone with the content of 99.5 weight percent at the outlet of a reflux tank at the top of the refining tower 11; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is calculated to be 90.2 percent.
Example 4
Epsilon-caprolactone was prepared by the same equipment and method as in example 1 except that: in the first step, the weight ratio of the usage amount of the oxidant, the water-carrying agent and the stabilizer is 1:4, a step of; 0.01 is selected from the compound stabilizer of lutidine and dipicolinate according to the proportion of 1:3, mixing, wherein the mass fraction of the raw material hydrogen peroxide is 50%.
As a result, epsilon-caprolactone was obtained in an amount of 99.4% by weight; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is calculated to be 90.5 percent.
Example 5
Epsilon-caprolactone was prepared by the same equipment and method as in example 1 except that:
in the first step, the weight ratio of the usage amount of the oxidant, the water-carrying agent and the stabilizer is 1:3:0.05; the selected composite stabilizer is picolinic acid, picolinic acid and tributyl phosphate according to a proportion of 1:1:3, mixing, wherein the mass fraction of the raw material hydrogen peroxide is 50%.
In the second step, the use of acetic acid and hydrogen peroxideThe molar ratio of the amounts is 1:2, space velocity of the catalyst is 1m 3 /(m 3 H) initial airspeed of 0.6m 3 /(m 3 H) the circulation ratio is 10; wherein the conditions of the first reaction include: the temperature is 50 ℃, the pressure is-0.08 MPa, and the time is 0.8h.
As a result, epsilon-caprolactone was obtained in an amount of 99.4% by weight; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is calculated to be 91.2 percent.
Comparative example 1
Epsilon-caprolactone was prepared by the same equipment and method as in example 1 except that:
the stabilizer is selected from lutidine;
in the second step, the third step was identical to example 1.
As a result, epsilon-caprolactone was obtained in an amount of 98.1% by weight; the yield of epsilon-caprolactone during purification was calculated to be 80.3%.
Comparative example 2
Epsilon-caprolactone was prepared by the same equipment and method as in example 1 except that:
the stabilizer is pyridine 2,5 dicarboxylic acid;
in the second step, the third step was identical to example 1.
As a result, epsilon-caprolactone was obtained in an amount of 99.1% by weight; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is 84.3 percent.
Comparative example 3
Epsilon-caprolactone was prepared by the same equipment and method as in example 1 except that:
the first fixed bed reactor 4 and the third fixed bed reactor 7 are catalyst exchanged for Amberlyst-15.
As a result, epsilon-caprolactone was obtained in an amount of 99.2% by weight; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is calculated to be 83.3 percent.
Comparative example 4
Epsilon-caprolactone was prepared by the same equipment and method as in example 1 except that:
the first fixed bed reactor 4 and the third fixed bed reactor 7 were replaced with 001×7 strongly acidic styrene-based cation exchange resins.
As a result, epsilon-caprolactone was obtained in an amount of 99.3% by weight; according to the molar ratio, the yield of epsilon-caprolactone in the purification process is calculated to be 85.1 percent.
The results show that the device and the method can continuously prepare high-quality epsilon-caprolactone, have little by-product yield, and have the advantages of high yield, low consumption of oxidant and cyclohexanone, good safety and the like.
Whereas comparative examples 1 and 2, because they do not use a complex stabilizer, do not have high yields due to decomposition of epsilon-caprolactone in a fixed bed reactor and column system during the reaction.
In comparative example 3, amberlyst-15 was packed in the column tubes provided in the first fixed bed reactor 4 and the third fixed bed reactor 7, and it was preliminarily judged that Amberlyst-15 was relatively small in mass total exchange capacity, resulting in a lower yield of epsilon-caprolactone.
The tubes arranged in the first fixed bed reactor 4 and the third fixed bed reactor 7 in comparative example 4 were filled with 001X 7 strongly acidic styrene-based cation exchange resin, and the reaction proceeded to a relatively low extent due to the relatively high water content thereof, so that the epsilon-caprolactone yield was low.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.