CN112979413B - Method for preparing trans-1, 3-dichloropropene by using micro-channel photoreactor - Google Patents
Method for preparing trans-1, 3-dichloropropene by using micro-channel photoreactor Download PDFInfo
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Abstract
The invention provides a method for preparing trans-1, 3-dichloropropene by using a microchannel photoreactor, which is used for preparing the trans-1, 3-dichloropropene by using the microchannel photoreactor through continuous transposition without a solvent and an auxiliary agent, and has the advantages of simple subsequent separation, high conversion speed, short reaction time, continuous production, large production capacity and scale and wide application prospect.
Description
Technical Field
The invention relates to the technical field of fine chemical engineering, in particular to a method for preparing trans-1, 3-dichloropropene by utilizing a microchannel photoreactor.
Background
The 1, 3-dichloropropene has two configurations of trans-1, 3-dichloropropene and cis-1, 3-dichloropropene, and the two cis-trans isomers have similar properties, belong to flammable colorless liquids, have strong irritation, have the odor similar to chloroform, are insoluble in water, and are soluble in most organic solvents such as ethanol, diethyl ether, benzene and the like. Wherein, the trans-1, 3-dichloropropene is mainly used for synthesizing intermediates of the cyclohexenone herbicides and synthesizing the antifungal medicine terbinafine hydrochloride. The mixed 1, 3-dichloropropene and cis-1, 3-dichloropropene can be directly used as soil fumigants and soil insecticides and can also be used for producing novel insecticide raw materials.
1, 3-dichloropropene is a byproduct in the chloropropene production process, and 170kg of mixed-type 1, 3-dichloropropene is produced as a byproduct in the industry every 1t of chloropropene, wherein the cis-form accounts for about 56 percent, and the trans-form accounts for about 42 percent. The byproduct of the device for producing 10 ten thousand tons of chloropropene annually is mixed with 1.7 ten thousand tons of dichloropropene, wherein the cis form is about 9000 tons, and the trans form is about 8000 tons. At present, the market price of cis-1, 3-dichloropropene is 4000-8000 yuan/ton, the price is low, and the market demand is small. The market price of the trans-1, 3-dichloropropene is 2-3 ten thousand yuan/ton, the price is high, and the application is wide. The trans-1, 3-dichloropropene is generated by translocating the cis-1, 3-dichloropropene, so that the way of the cis-1, 3-dichloropropene can be increased, the economy of a chloropropene device is improved, and extremely high economic and social benefits are achieved.
Currently, 1, 3-dichloropropene on the market exists in the form of a mixture of cis-1, 3-dichloropropene and trans-1, 3-dichloropropene isomers, trans-1, 3-dichloropropene is mainly obtained by separating and mixing 1, 3-dichloropropene through multi-stage rectification, wherein cis-1, 3-dichloropropene and trans-1, 3-dichloropropene are isomers, cis-1, 3-dichloropropene CAS #10061-01-5 has a molecular weight of 110.97, a melting point of 50 ℃, a boiling point of 104.3 ℃ and a density of 1.225g/ml; trans 1, 3-dichloropropene CAS #10061-02-6, molecular weight 110.97, boiling point 112 ℃, density 1.198g/ml. The boiling point difference of cis/trans-1, 3-dichloropropene is less than 7 ℃, and the separation is carried out by adopting a multi-stage rectification scheme in industry, so that the separation difficulty and the energy consumption are high.
CN1466559A discloses a low-coloring trans-1, 3-dichloropropene and a preparation method thereof, wherein a composition containing cis-1, 3-dichloropropene, trans-1, 3-dichloropropene and a C6 compound is subjected to chlorination and rectification steps to remove low-boiling cis-1, 3-dichloropropene and then to rectify and remove high-boiling C6 chlorinated compounds to obtain the trans-1, 3-dichloropropene with the chroma less than or equal to 200, the method only carries out rectification separation on the mixed 1, 3-dichloropropene and generates trans-related processes without transposition, the separated cis is still mixed with the mixed 1, 3-dichloropropene to be used as a soil fumigant and a pesticide, the economic value is low, and the problem that the cis-1, 3-dichloropropene does not have proper way out is not solved.
In 2005, it was reported that cis-isomer has high internal energy and poor thermal stability, and can be translocated under certain conditions to form trans-isomer having low internal energy and high thermal stability, and the mechanism of cis-isomerization to form trans-isomer includes photoisomerization, thermolsomerization and catalytic isomerization (see "cis-trans isomerization process and mechanism", plum front, etc., cis-trans isomerization process and mechanism, phase 1, pages 21-23).
US3914167 discloses a method for isomerizing trans-1, 3-dichloropropene into cis-1, 3-dichloropropene by adding a certain amount of photocatalyst under the irradiation of ultraviolet light to generate free radicals which can efficiently catalyze the isomerization of the trans-1, 3-dichloropropene to a cis-structure, wherein the cis-trans isomerization mechanism is that the free radicals generated under the irradiation of ultraviolet light can induce double bonds to generate double radicals, so that the double radicals are twisted to obtain an isomeric structure. The process provides a concept for the preparation of cis-1, 3-dichloropropene, but does not mention how to prepare trans-1, 3-dichloropropene.
CN109694308A discloses a method for in situ inversion of trans-1, 3-dichloropropene into cis-1, 3-dichloropropene, comprising adding trans-1, 3-dichloropropene into an alcohol solvent, adding a light promoter to carry out ultraviolet irradiation, and obtaining cis-1, 3-dichloropropene after reaction. The method also provides a concept for preparing cis-1, 3-dichloropropene, and does not mention how to prepare trans-1, 3-dichloropropene.
Therefore, it is required to develop a method for continuously and industrially preparing trans-1, 3-dichloropropene, which can improve the economic benefits in the chloropropene production process.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for preparing trans-1, 3-dichloropropene by using a microchannel photoreactor, the method prepares the trans-1, 3-dichloropropene by using the microchannel photoreactor through continuous transposition, a solvent and an auxiliary agent are not needed, the subsequent separation is simple, the conversion speed is high, the reaction time is short, the continuous production can be realized, the capacity and the scale are large, and the application prospect is wide.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a process for preparing trans-1, 3-dichloropropene using a microchannel photoreactor, the process comprising: feeding reaction raw materials and a catalyst into a micro-channel photoreactor, sequentially passing through a 1 st module to an nth module of the micro-channel photoreactor under the condition of illumination, and discharging to obtain a reaction product containing trans-1, 3-dichloropropene;
wherein the reaction raw material contains cis-1, 3-dichloropropene, n is a natural number of not less than 1, and may be, for example, 1, 2, 3, 4, 5, 6 or 7, etc., but is not limited to the above-mentioned values, and other values not shown in the above-mentioned range are also applicable.
The method for preparing the trans-1, 3-dichloropropene by using the microchannel photoreactor can strengthen reaction mass transfer and heat transfer, reduce catalyst consumption and improve reaction selectivity, and can be used for industrial large-scale production.
Preferably, the catalyst comprises any one or a combination of at least two of nano titanium dioxide, nano alumina, chlorine, bromine or iodine, wherein typical but non-limiting combinations are a combination of nano titanium dioxide and nano alumina, a combination of nano titanium dioxide and chlorine, a combination of nano alumina and chlorine, a combination of chlorine and bromine, and a combination of bromine and iodine.
The catalyst selected by the invention can be suitable for a micro-channel photoreactor and is beneficial to the reaction.
Preferably, the mass ratio of the reaction raw material to the catalyst is 1 (0.001 to 0.03), and may be, for example, 1.
The mass ratio of the reaction raw materials to the catalyst can be reduced to 1 (0.001-0.03), so that a better catalytic effect can be achieved, and the selectivity and the conversion rate are both remarkably improved.
Preferably, the mass fraction of cis-1, 3-dichloropropene in the reaction feed is from 50 to 100wt%, and may be, for example, 50wt%, 56wt%, 62wt%, 67wt%, 73wt%, 78wt%, 84wt%, 89wt%, 95wt%, or 100wt%, but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the reaction raw material contains trans-1, 3-dichloropropene.
Preferably, the mass fraction of trans-1, 3-dichloropropene in the reaction feed is 1 to 50wt%, and may be, for example, 1wt%, 7wt%, 12wt%, 18wt%, 23wt%, 29wt%, 34wt%, 40wt%, 45wt%, or 50wt%, but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, n.gtoreq.3.
The invention preferably adopts more than 3 modules of micro-channel photoreactors, and can better control the operating conditions of different reaction stages, thereby further improving the selectivity and the conversion rate of the reaction.
The reaction temperature in the 1 st block is preferably 10 to 60 ℃, and may be, for example, 10 ℃, 16 ℃, 22 ℃, 27 ℃, 33 ℃, 38 ℃, 44 ℃, 49 ℃, 55 ℃ or 60 ℃, but is not limited to the values listed, and other values not listed in the range are also applicable, and preferably 30 to 50 ℃.
The reaction temperature in the 2 nd to nth modules is preferably 30 to 100 ℃, and may be, for example, 30 ℃, 38 ℃, 46 ℃, 54 ℃, 62 ℃, 69 ℃, 77 ℃, 85 ℃, 93 ℃ or 100 ℃ or the like, but is not limited to the recited values, and other values not recited in the range are also applicable, and preferably 40 to 80 ℃.
Preferably, the light source for illumination comprises any one of or a combination of at least two of a visible light source, an ultraviolet light source or a natural light source.
Preferably, the wavelength of the illumination light is in the range of 10 to 780nm, for example, 10nm, 96nm, 182nm, 267nm, 353nm, 438nm, 524nm, 609nm, 695nm or 780nm, etc., but is not limited to the recited values, and other values not recited in this range are also applicable.
Preferably, the intensity of the light is 5 to 2000W, and may be, for example, 5W, 60W, 115W, 170W, 225W, 280W, 335W, 390W, 445W, 500W, 600W, 800W, 1000W, 1200W, 1500W or 2000W, but is not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the reaction temperature of the nth module is greater than or equal to the reaction temperature of the (n-1) th module.
The reaction temperature in the preferred microchannel photoreactor is set to be the setting, which can reduce the generation of byproducts, improve the selectivity of the reaction and achieve higher reaction efficiency in shorter retention time.
Preferably, the residence time of the reaction raw materials in the microchannel photoreactor is 10 to 300s, for example, 10s, 43s, 75s, 107s, 139s, 172s, 204s, 236s, 268s or 300s, etc., but not limited to the recited values, and other values not recited in the range are also applicable, preferably 20 to 200s.
Preferably, cooling is carried out after the discharge to obtain a reaction product containing trans-1, 3-dichloropropene.
Preferably, the reaction product is rectified and separated to obtain the trans-1, 3-dichloropropene product.
Preferably, the cis-1, 3-dichloropropene obtained by the rectification separation is recycled to the reaction raw material.
The distillation separation step and parameters are not particularly limited in the present invention, and the separation conditions for separating cis-1, 3-dichloropropene and trans-1, 3-dichloropropene, which are well known to those skilled in the art, may be used, and may be adjusted according to the actual process.
Preferably, the degree of vacuum of the rectification separation is-0.065 to-0.075 MPa, and may be, for example, -0.065MPa, -0.066MPa, -0.068MPa, -0.069MPa, -0.070MPa, -0.071MPa, -0.072MPa, -0.073MPa or-0.075 MPa, but the degree is not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the temperature of the bottom of the rectification column is 70 to 77 ℃, and may be, for example, 70 ℃, 71 ℃, 72 ℃, 73 ℃, 74 ℃, 75 ℃, 76 ℃ or 77 ℃, but is not limited to the values listed, and other values not listed in the range are also applicable.
Preferably, the top temperature of the rectification separation is 64 to 68 ℃, and may be, for example, 64 ℃, 64.5 ℃, 64.9 ℃, 65.4 ℃, 65.8 ℃, 66.3 ℃, 66.7 ℃, 67.2 ℃, 67.6 ℃ or 68 ℃ or the like, but is not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the reflux ratio of the rectification separation is 3 to 5, and for example, 3.
Preferably, the method comprises the steps of:
(1) Feeding a reaction raw material containing cis-1, 3-dichloropropene and a catalyst into a microchannel photoreactor, wherein the wavelength range of illumination is 10-780 nm and the intensity is 5-2000W under the illumination condition, the reaction raw material sequentially passes through a 1 st module to an nth module of the microchannel photoreactor, the reaction temperature of the 1 st module is 10-60 ℃, the reaction temperature of the 2 nd module to the nth module is 30-100 ℃, the residence time of the reaction raw material in the microchannel photoreactor is 10-300 s, and discharging to obtain a reaction product containing the trans-1, 3-dichloropropene;
the mass ratio of the reaction raw material to the catalyst is 1 (0.001-0.03), and the catalyst comprises any one or combination of at least two of nano titanium dioxide, nano alumina, chlorine, bromine or iodine;
(2) And rectifying and separating the reaction product to obtain a trans-1, 3-dichloropropene product, and recycling the cis-1, 3-dichloropropene obtained by rectifying and separating into the reaction raw material.
As a preferred technical scheme of the invention, the method comprises the following steps:
(1) Feeding a reaction raw material containing cis-1, 3-dichloropropene and a catalyst into a microchannel photoreactor, wherein the wavelength range of illumination is 10-780 nm and the intensity is 5-2000W under the illumination condition, the reaction raw material sequentially passes through a 1 st module to an nth module of the microchannel photoreactor, the reaction temperature of the 1 st module is 10-60 ℃, the reaction temperature of the 2 nd module to the nth module is 30-100 ℃, the retention time of the reaction raw material in the microchannel photoreactor is 10-300 s, and discharging to obtain a reaction product containing the trans-1, 3-dichloropropene;
the mass ratio of the reaction raw material to the catalyst is 1 (0.001-0.03), and the catalyst comprises any one or combination of at least two of nano titanium dioxide, nano alumina, chlorine, bromine or iodine;
(2) The reaction product is rectified and separated, the vacuum degree of the rectification separation is-0.065 to-0.075 MPa, the temperature of the top of the tower is 64 to 68 ℃, the temperature of the bottom of the tower is 70 to 77 ℃, the reflux ratio is 3 to 5, cis-1, 3-dichloropropene and trans-1, 3-dichloropropene products are sequentially extracted, and the cis-1, 3-dichloropropene obtained by the rectification separation is circulated to the reaction raw material.
In the present invention, "%" is "% by mass" unless otherwise specified.
Compared with the prior art, the invention at least has the following beneficial effects:
(1) The method for preparing the trans-1, 3-dichloropropene by utilizing the microchannel photoreactor takes the cis-1, 3-dichloropropene as a raw material, controls the temperature and the retention time in a gradient way through the microchannel reactor, changes the type and the strength of a light source, strengthens the mass transfer and heat transfer of reaction, reduces the consumption of a catalyst, and ensures that the conversion rate of the cis-1, 3-dichloropropene reaches more than 60 percent and the selectivity of the trans-1, 3-dichloropropene reaches more than 99.5 percent;
(2) The method for preparing the trans-1, 3-dichloropropene by using the microchannel photoreactor does not need other solvents, has low separation energy consumption, ensures that the purity of the trans-1, 3-dichloropropene after separation is more than or equal to 99wt percent, has mild reaction conditions and simple process, and is easy for industrial implementation;
(3) The method for preparing the trans-1, 3-dichloropropene by using the microchannel photoreactor can realize continuous production of the trans-1, 3-dichloropropene, and has the advantages of rapid industrialized production, small occupied area and large production capacity.
Detailed Description
For the purpose of facilitating an understanding of the present invention, the present invention will now be described by way of examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
1. Examples of the invention
Example 1
This example provides a continuous process for preparing trans-1, 3-dichloropropene using a microchannel photoreactor, comprising the steps of:
(1) Uniformly mixing reaction raw materials (75.4 wt% of cis-1, 3-dichloropropene and 13.5wt% of trans-1, 3-dichloropropene) with a catalyst of nano titanium dioxide, wherein the mass ratio of the reaction raw materials to the catalyst is 1;
(2) And (2) rectifying and separating the reaction product, wherein the vacuum degree of the rectifying and separating is-0.065 to-0.068 MPa, the temperature of the top of the tower is 64 to 65 ℃, the temperature of the bottom of the tower is 70 to 72 ℃, the reflux ratio is 4.
Example 2
This example provides a continuous process for preparing trans-1, 3-dichloropropene using a microchannel photoreactor, comprising the steps of:
(1) Uniformly mixing reaction raw materials (88.6 wt% of cis-1, 3-dichloropropene and 11.3wt% of trans-1, 3-dichloropropene) with a catalyst of nano-alumina, wherein the mass ratio of the reaction raw materials to the catalyst is 1;
(2) And (2) rectifying and separating the reaction product, wherein the vacuum degree of the rectifying and separating is-0.070 to-0.075 MPa, the temperature of the top of the tower is 64 to 66 ℃, the temperature of the bottom of the tower is 70 to 73 ℃, the reflux ratio is 3, sequentially extracting cis-1, 3-dichloropropene and trans-1, 3-dichloropropene products, and recycling the cis-1, 3-dichloropropene obtained by the rectifying and separating into the reaction raw material.
Example 3
This example provides a continuous process for preparing trans-1, 3-dichloropropene using a microchannel photoreactor, comprising the steps of:
(1) Uniformly mixing reaction raw materials (60.4 wt% of cis-1, 3-dichloropropene and 37.4wt% of trans-1, 3-dichloropropene) with a catalyst of an iodine simple substance, wherein the mass ratio of the reaction raw materials to the catalyst is 1.03, feeding the mixture into a microchannel photoreactor, pumping the mixture into a 1 st module of the microchannel photoreactor at a temperature of 10 ℃, wherein a light source is a 10W200nmLED light source, discharging the 1 st template into a 2 nd module of the microchannel photoreactor at a temperature of 30 ℃, wherein the light source is a 50W350nmLED light source, discharging the 2 nd template into a 3 rd reaction module of the microchannel photoreactor at a temperature of 50 ℃, wherein the light source is a natural light source, discharging the 3 rd template into a 4 th reaction module of the microchannel photoreactor at a temperature of 80 ℃, wherein the light source is a natural light source, the total reaction module number is 4, the total reaction residence time is 160s, cooling the discharging the 4 th module to obtain a reaction liquid, and discharging the reaction product containing the trans-1, 3-dichloropropene;
(2) And (2) rectifying and separating the reaction product, wherein the vacuum degree of the rectifying and separating is-0.070 to-0.075 MPa, the temperature of the top of the tower is 66 to 68 ℃, the temperature of the bottom of the tower is 75 to 77 ℃, the reflux ratio is 5, sequentially extracting cis-1, 3-dichloropropene and trans-1, 3-dichloropropene products, and recycling the cis-1, 3-dichloropropene obtained by the rectifying and separating into the reaction raw material.
Example 4
This example provides a process for the continuous production of trans-1, 3-dichloropropene using a microchannel photoreactor, comprising the steps of:
(1) Uniformly mixing reaction raw materials (95.8 wt% of cis-1, 3-dichloropropene and 3.4wt% of trans-1, 3-dichloropropene) and a catalyst of a bromine simple substance, wherein the mass ratio of the reaction raw materials to the catalyst is 1.005, feeding the mixture into a microchannel photoreactor, pumping the mixture into a 1 st module of the microchannel photoreactor, controlling the temperature to be 30 ℃, controlling a light source to be 50W100nmLED light source, feeding the discharge of the 1 st module into a 2 nd module of the microchannel photoreactor, supplementing 0.5wt% of the bromine simple substance into the 2 nd module, controlling the temperature to be 70 ℃, controlling the light source to be 100W650nmLED light source, feeding the discharge of the 2 nd module into a 3 rd module of the microchannel reactor, supplementing 0.5wt% of the bromine simple substance into the 3 rd module, controlling the temperature to be 100 ℃, controlling the light source to be a natural light source, controlling the total number of the reaction modules to be 3, controlling the total reaction time to be 45s, cooling the discharge of the 3 rd module to obtain a reaction liquid and discharging to obtain a reaction product containing the trans-1, 3-dichloropropene;
(2) And (2) rectifying and separating the reaction product, wherein the vacuum degree of the rectifying and separating is-0.068 to-0.072 MPa, the temperature of the top of the tower is 66 to 67 ℃, the temperature of the bottom of the tower is 72 to 75 ℃, the reflux ratio is 3.5, sequentially extracting cis-1, 3-dichloropropene and trans-1, 3-dichloropropene products, and recycling the cis-1, 3-dichloropropene obtained by the rectifying and separating into the reaction raw material.
Example 5
This example provides a continuous process for the preparation of trans-1, 3-dichloropropene using a microchannel photoreactor, which process is identical to example 1 except that the number of reaction modules in step (1) is 1, the process is carried out using the process parameters of module 1 in example 1, and the residence time is 60 s.
Example 6
This example provides a continuous process for the preparation of trans-1, 3-dichloropropene using a microchannel photoreactor, which is the same as in example 1 except that the temperature of the 2 nd module is 30 ℃.
Example 7
This example provides a continuous process for the preparation of trans-1, 3-dichloropropene using a microchannel photoreactor, which is the same as in example 1 except that the temperature of the 2 nd module is 90 ℃.
Example 8
This example provides a continuous process for the preparation of trans-1, 3-dichloropropene using a microchannel photoreactor, which is the same as in example 3 except that the temperature of the 2 nd module is 70 ℃.
2. Comparative example
Comparative example 1
This comparative example provides a process for preparing trans-1, 3-dichloropropene comprising the steps of:
(1) Uniformly mixing reaction raw materials (75.4 wt% of cis-1, 3-dichloropropene and 13.5wt% of trans-1, 3-dichloropropene) with a catalyst of nano titanium dioxide, wherein the mass ratio of the reaction raw materials to the catalyst is 1.01, feeding the mixture into a reaction kettle, reacting at 40 ℃ for 60s by using a 20W400nmLED light source, and discharging to obtain a reaction product containing the trans-1, 3-dichloropropene;
(2) And (2) rectifying and separating the reaction product, wherein the vacuum degree of the rectifying and separating is-0.065 to-0.068 MPa, the temperature of the top of the tower is 64 to 65 ℃, the temperature of the bottom of the tower is 70 to 72 ℃, the reflux ratio is 4.
Comparative example 2
This comparative example provides a process for producing trans-1, 3-dichloropropene similar to example 1, except that in step (1), a methanol solvent is added in a mass ratio of the methanol solvent to the reaction starting materials of 1.
The above examples and comparative examples show slight fluctuations in temperature and pressure during actual operation and are therefore represented by temperature and pressure ranges.
3. Test and results
The test method comprises the following steps: and (3) testing the compositions of the reaction product in the step (1) and the trans-1, 3-dichloropropene product obtained in the step (2) by adopting a gas spectrum quantitative method, and calculating the selectivity of the trans-1, 3-dichloropropene, the conversion rate of the cis-1, 3-dichloropropene and the purity of the product.
The test results of the above examples and comparative examples are shown in table 1.
TABLE 1
From table 1, the following points can be seen:
(1) Compared with the traditional kettle type, the method for synthesizing the trans-1, 3-dichloropropene by using the microchannel photoreactor has the advantages of high conversion rate, selectivity and product quality, the purity of the trans-1, 3-dichloropropene product is more than or equal to 99wt%, the selectivity is more than or equal to 99.5wt%, the reaction condition is milder, the microchannel continuous flow synthesis is used, the capacity is large in scale, and the intrinsic safety is high;
(2) Combining example 1 with comparative example 1, it can be seen that the preparation of trans-1, 3-dichloropropene in example 1 using a microchannel photoreactor has a conversion rate of cis-1, 3-dichloropropene of 70.3wt%, a selectivity of trans-1, 3-dichloropropene of 99.7wt%, and a purity of trans-1, 3-dichloropropene of 99.52wt% in example 1 compared to the preparation of trans-1, 3-dichloropropene in comparative example 1 using a reaction vessel, and the conversion rate is only 42.1wt% and the purity of the final product is only 99.1wt% in comparative example 1, thus indicating that the conversion rate and the selectivity are improved by the preparation of trans-1, 3-dichloropropene using a microchannel photoreactor;
(3) By combining the example 1 and the comparative example 2, the conversion rate, the selectivity and the product purity of the reaction in the example 1 are higher than those of the reaction in the comparative example 2 when no solvent is added in the example 1 compared with the methanol added in the comparative example 2, so that the method has the advantages that the subsequent separation is simple, the product purity is high, and the reaction selectivity and the conversion rate are high by adopting a solvent-free mode;
(4) It can be seen from the combination of examples 6-8 that the temperature of the 2 nd module in example 8 is 70 ℃, the final purity of the product in example 8 is 99.58wt% and the conversion and selectivity of the reaction are both higher compared to the second modules in examples 6-7 of 30 and 90 ℃, respectively, whereas the conversion of the reaction in example 6 is only 62.1wt% and the purity of the product in example 7 is 99.45wt%, thus indicating that the present invention improves both the conversion and the selectivity of the reaction through reasonable temperature settings.
In conclusion, the method for preparing the trans-1, 3-dichloropropene by using the microchannel photoreactor realizes the continuous production of the trans-1, 3-dichloropropene, does not need a solvent or an auxiliary agent, and has the advantages of simple subsequent separation, high conversion speed, short reaction time and wide application prospect.
The applicant states that the present invention is illustrated by the above examples to show the details of the process equipment and process flow of the present invention, but the present invention is not limited to the above details of the process equipment and process flow, which means that the present invention must not be implemented by relying on the above details of the process equipment and process flow. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (16)
1. A process for preparing trans-1, 3-dichloropropene using a microchannel photoreactor, comprising: feeding reaction raw materials and a catalyst into a microchannel photoreactor, wherein the catalyst comprises any one or combination of at least two of nano titanium dioxide, nano alumina, chlorine, bromine or iodine, sequentially passes through a 1 st module to an nth module of the microchannel photoreactor under the condition of illumination, the reaction temperature of the 1 st module is 10-60 ℃, the reaction temperature of the 2 nd module to the nth module is 30-100 ℃, the reaction temperature of the nth module is greater than or equal to the reaction temperature of the n-1 st module, and discharging to obtain a reaction product containing trans-1, 3-dichloropropene;
wherein the reaction raw material contains cis-1, 3-dichloropropene, and n is a natural number not less than 3.
2. The method according to claim 1, wherein the mass ratio of the reaction raw material to the catalyst is 1 (0.001 to 0.03).
3. The method according to claim 1, wherein the mass fraction of cis-1, 3-dichloropropene in the reaction feed is 50 to 100wt%.
4. The method of claim 1, wherein the reaction feed comprises trans-1, 3-dichloropropene.
5. The method according to claim 4, wherein the mass fraction of trans-1, 3-dichloropropene in the reaction feed is 1 to 50wt%.
6. The method of claim 1, wherein the reaction temperature of the 1 st module is 30 to 50 ℃.
7. The method of claim 1, wherein the reaction temperature of the 2 nd to nth modules is 40 to 80 ℃.
8. The method of claim 1, wherein the source of illumination comprises any one or a combination of at least two of a visible light source, an ultraviolet light source, or a natural light source.
9. The method of claim 1, wherein the illumination is in the wavelength range of 10 to 780nm.
10. The method of claim 1, wherein the intensity of the illumination is between 5 and 2000W.
11. The method of claim 1, wherein the residence time of the reaction raw materials in the microchannel photoreactor is 10 to 300s.
12. The method of claim 11, wherein the residence time of the reaction raw materials in the microchannel photoreactor is 20 to 200s.
13. The process of claim 1, wherein the discharge is followed by cooling to obtain a reaction product comprising trans-1, 3-dichloropropene.
14. The method as claimed in claim 1, wherein the reaction product is separated by rectification to obtain trans-1, 3-dichloropropene product.
15. The method as claimed in claim 14, wherein the cis-1, 3-dichloropropene obtained by the rectification separation is recycled to the reaction raw material.
16. Method according to claim 1, characterized in that it comprises the following steps:
(1) Feeding a reaction raw material containing cis-1, 3-dichloropropene and a catalyst into a microchannel photoreactor, wherein the wavelength range of illumination is 10-780 nm and the intensity is 5-2000W under the illumination condition, the reaction raw material sequentially passes through a 1 st module to an nth module of the microchannel photoreactor, the reaction temperature of the 1 st module is 10-60 ℃, the reaction temperature of the 2 nd module to the nth module is 30-100 ℃, the residence time of the reaction raw material in the microchannel photoreactor is 10-300 s, and discharging to obtain a reaction product containing the trans-1, 3-dichloropropene;
the mass ratio of the reaction raw material to the catalyst is 1 (0.001-0.03), and the catalyst comprises any one or the combination of at least two of nano titanium dioxide, nano alumina, chlorine, bromine or iodine;
(2) And rectifying and separating the reaction product to obtain a trans-1, 3-dichloropropene product, and recycling the cis-1, 3-dichloropropene obtained by rectifying and separating into the reaction raw material.
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