CN117756613A - Method for synthesizing polymethoxy dialkyl ether by backpack type continuous reaction rectification - Google Patents
Method for synthesizing polymethoxy dialkyl ether by backpack type continuous reaction rectification Download PDFInfo
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- 238000006243 chemical reaction Methods 0.000 title claims abstract description 45
- 150000001983 dialkylethers Chemical class 0.000 title claims abstract description 34
- 238000000034 method Methods 0.000 title claims abstract description 32
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 9
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 76
- 125000005233 alkylalcohol group Chemical group 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 18
- 239000003054 catalyst Substances 0.000 claims description 24
- 239000000047 product Substances 0.000 claims description 23
- 239000002994 raw material Substances 0.000 claims description 16
- 239000000203 mixture Substances 0.000 claims description 14
- 239000000376 reactant Substances 0.000 claims description 14
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 claims description 13
- 239000011973 solid acid Substances 0.000 claims description 9
- 239000007864 aqueous solution Substances 0.000 claims description 7
- 239000006227 byproduct Substances 0.000 claims description 7
- ZSIAUFGUXNUGDI-UHFFFAOYSA-N hexan-1-ol Chemical compound CCCCCCO ZSIAUFGUXNUGDI-UHFFFAOYSA-N 0.000 claims description 6
- ZXEKIIBDNHEJCQ-UHFFFAOYSA-N isobutanol Chemical compound CC(C)CO ZXEKIIBDNHEJCQ-UHFFFAOYSA-N 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000012856 packing Methods 0.000 claims description 5
- 238000010992 reflux Methods 0.000 claims description 5
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 3
- BWDBEAQIHAEVLV-UHFFFAOYSA-N 6-methylheptan-1-ol Chemical compound CC(C)CCCCCO BWDBEAQIHAEVLV-UHFFFAOYSA-N 0.000 claims description 3
- 239000003729 cation exchange resin Substances 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 238000000066 reactive distillation Methods 0.000 claims description 3
- 230000035484 reaction time Effects 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims 1
- 238000006555 catalytic reaction Methods 0.000 abstract description 8
- 238000000926 separation method Methods 0.000 abstract description 8
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 abstract description 6
- 229930040373 Paraformaldehyde Natural products 0.000 abstract description 2
- 229920002866 paraformaldehyde Polymers 0.000 abstract description 2
- 239000013589 supplement Substances 0.000 abstract description 2
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 description 14
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 12
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 11
- 235000019253 formic acid Nutrition 0.000 description 6
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 5
- 239000000654 additive Substances 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 239000007795 chemical reaction product Substances 0.000 description 5
- NKDDWNXOKDWJAK-UHFFFAOYSA-N dimethoxymethane Chemical compound COCOC NKDDWNXOKDWJAK-UHFFFAOYSA-N 0.000 description 5
- 238000000605 extraction Methods 0.000 description 5
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical group [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 4
- 238000004821 distillation Methods 0.000 description 4
- 239000000446 fuel Substances 0.000 description 4
- 238000009776 industrial production Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229910052760 oxygen Inorganic materials 0.000 description 4
- 239000001301 oxygen Substances 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- DURPTKYDGMDSBL-UHFFFAOYSA-N 1-butoxybutane Chemical compound CCCCOCCCC DURPTKYDGMDSBL-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 description 2
- 150000001298 alcohols Chemical class 0.000 description 2
- 125000000217 alkyl group Chemical group 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- -1 dimethyl ether) Chemical class 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 238000005457 optimization Methods 0.000 description 2
- 238000006116 polymerization reaction Methods 0.000 description 2
- 238000011112 process operation Methods 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- 239000004721 Polyphenylene oxide Substances 0.000 description 1
- 150000001241 acetals Chemical class 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 239000011203 carbon fibre reinforced carbon Substances 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
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- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000018044 dehydration Effects 0.000 description 1
- 238000006297 dehydration reaction Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 150000002170 ethers Chemical class 0.000 description 1
- 239000008098 formaldehyde solution Substances 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
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- 150000002739 metals Chemical class 0.000 description 1
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- 239000012071 phase Substances 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
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- 239000002244 precipitate Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/10—Process efficiency
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a method for synthesizing polymethoxy dialkyl ether by backpack type continuous reaction and rectification. The invention can further react unreacted materials in the front-end reactor, and the externally hung knapsack reactor supplements excessive alkyl alcohol to completely convert the unreacted formaldehyde, thereby solving the problem that the unreacted formaldehyde generates paraformaldehyde to block the tower plates and the pipelines; in addition, the reaction and the rectification in the knapsack catalytic reaction rectification are respectively carried out in a side reactor and a rectification tower which are spatially independent, so that the working conditions of the reaction and the separation can be respectively set, and the reaction and the rectification are carried out under the optimal conditions.
Description
Technical Field
The invention relates to the technical field of polyether synthesis, in particular to a method for synthesizing polymethoxy dialkyl ether by backpack type continuous reaction and rectification.
Background
The polymethoxy dialkyl ether is an oxygen-containing fuel with excellent performance, has the advantages of high cetane number, high oxygen content, high flash point, low condensation point and the like, has good intersolubility with petrochemical diesel at high temperature and low temperature, can be blended with the petrochemical diesel according to a certain proportion or directly and singly used, and is suitable for being used as fuel for diesel vehicles in plateau areas.
At present, the oxygen-containing compound is widely considered to be more suitable for being used as a diesel additive, and the types mainly comprise ethers (such as dimethyl ether), alcohols (such as methanol and ethanol), carbonates (such as ethyl acetate), acetals (such as methylal and polymethoxy dimethyl ether) and the like. The boiling point of dimethyl ether is lower, and the dimethyl ether is in a gaseous state at normal temperature, so that an engine is required to be modified when the dimethyl ether is used, and the application of the dimethyl ether is inconvenient and is greatly limited. Methanol, ethanol and the like can promote the fuel to burn fully and reduce PM emission when being used as additives, but can obviously reduce the flash point and cetane number of the fuel, and the alcohols have certain corrosion to certain nonferrous metals and swelling to plastics and rubber. The methylal (DMM) has no carbon-carbon bond in the molecule, has higher oxygen content and good miscibility with diesel oil, and can obviously reduce PM emission when being used as an additive. But methylal has lower boiling point and flash point, is volatile, reduces the safety of the engine, and requires the optimization of an engine combustion system (Zhu R J, miao H Y, wang X B, huang zuohua, 2013,34 (2): 3013-3020) for practical applications. In contrast, polymethoxy dialkyl ethers are considered to be novel green diesel additives due to their good properties.
After the synthesis of the polymethoxy dialkyl ether, a main product needs to be separated out and used as a diesel additive. The separation of the product is generally carried out by adopting a rectification method (shown in figure 1), and the subsequent experimental results show that no matter what path is adopted to synthesize the polymethoxy dialkyl ether, the reaction product contains formic acid (HCOOH) as a byproduct and unreacted complete formaldehyde. Due to the existence of formaldehyde and formic acid, the product mixture can not obtain qualified target products through direct rectification. Formaldehyde gas evaporated in the rectification gradually polymerizes and adheres to the condensing pipeline until the formaldehyde gas finally accumulates into obvious white solids to block the pipeline, and the rectification cannot be continued. When the reaction product mixture containing formic acid is rectified, the formic acid promotes the hydrolysis of the polymethoxy dialkyl ether and generates substances such as formaldehyde, thereby not only enhancing the polymerization of formaldehyde in a pipeline, but also slowly generating solid precipitate in a tower kettle. Therefore, the reaction product needs to be pretreated before the rectification separation to remove formaldehyde and formic acid as much as possible. The industrial production process for synthesizing the polymethoxy dialkyl ether by the polymerization reaction has the problems of high process optimization difficulty and the like due to the factors, and the industrialization promotion progress of the process is limited.
CN103626640 discloses a method for catalyzing PODE with solid acid resin 1 And a process route for preparing PODE by formaldehyde, firstly, PODE 1 Introducing the mixture into a fixed bed reactor filled with a solid acid resin catalyst according to a certain proportion, decompressing the reacted mixed liquid, introducing the mixed liquid into a flash tank through a pipeline, introducing light components containing methylal and methanol into the reactor to react after flowing out of the top of the flash tank, directly returning the light components into the reactor to be reused as raw materials, introducing other heavy components into a first-stage extraction tower from the bottom of the tower, extracting PODE (point of sale) in the mixture by adopting nonpolar substances such as cyclohexane or aromatic hydrocarbon and the like in the first-stage extraction tower, continuously using raffinate phase as the reaction raw material, introducing an organic phase into a second extraction tower, neutralizing acidic substances in the reaction by taking alkaline water as an extractant in the second extraction tower, taking away a small amount of formaldehyde, introducing the mixture at the top of the tower into a light component removing tower, introducing the mixture at the bottom of the tower into a heavy component removing tower, introducing the mixture at the top of the heavy component removing tower into a product tower, and separating PODE at the bottom of the product tower 3 And PODE 4 Separating PODE from the bottom of the product column 5 The heavy components at the bottom of the heavy component removing tower are returned to the reactor again for recycling. The raw materials used in the process are relatively cheap, the used nonpolar extractant has little harm to the environment, but certain disadvantages still exist, and the extractant lye used in the second extraction tower is easy to generate a large amount of alkaline waste liquid, is difficult to treat and can generate great pollution to the environment.
CN107188789B discloses a method for producing polymethoxy dialkyl ether by catalytic reaction distillation, which can effectively overcome the equilibrium conversion rate by adopting the reaction distillation, promote the equilibrium to proceed forward, and improve the equilibrium conversion rate of formaldehyde. However, the problem of clogging of the reaction apparatus by the formation of paraformaldehyde from formaldehyde at high temperatures is not completely solved. The alkyl alcohol and formaldehyde can generate a large amount of water in the reaction process, and form an azeotrope with the raw materials, so that the rectification dehydration time is too long, the energy consumption is high, the production efficiency is low, the production cost is not ideal, and the industrial production scale and the wide application of the polymethoxy dialkyl ether are limited.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for synthesizing polymethoxy dialkyl ether by backpack type continuous reaction rectification, unreacted reactants in a reactor can be further reacted in a reaction rectification section by a backpack type catalytic reaction rectification device, formaldehyde which is a participated reactant is completely converted, polymethoxy dialkyl ether is produced, the yield is improved, and the production cost is reduced.
The invention adopts the following technical scheme:
the invention provides a method for synthesizing polymethoxy dialkyl ether by backpack type continuous reaction rectification, which takes alkyl alcohol and formaldehyde aqueous solution as raw materials, and under the action of a catalyst, unreacted reactants in a reaction section can be further reacted in an externally hung reactor by using a backpack type catalytic reaction rectification device, and the externally hung reactor supplements excessive alkyl alcohol to completely convert the participated reactants formaldehyde, thereby producing part of polymethoxy dialkyl ether and improving the yield.
Chemical reaction formula:
the 'knapsack' catalytic reaction rectifying device comprises a pre-reactor 1, a rectifying tower 2 and a knapsack reactor 4, wherein the pre-reactor 1, the knapsack reactor 4 and the rectifying tower 2 are connected through pipelines, and the pre-reactor 1 and the knapsack reactor 4 are arranged outside the rectifying tower.
Preferably, the method for synthesizing the polymethoxy dialkyl ether by backpack type continuous reaction rectification provided by the invention comprises the following steps:
s1, alkyl alcohol and formaldehyde aqueous solution with a specific proportion enter a pre-reactor 1 through a raw material inlet 11 to react, and the reacted mixed material of polymethoxy dialkyl ether, byproducts, alkyl alcohol and formaldehyde aqueous solution enters a reaction section 22 of a rectifying tower 2 from the middle part of the rectifying tower 2;
s2, the mixed materials in the reaction section 22 enter the knapsack reactor 4 through the lower part of the knapsack reactor 4 by a pipe under the action of the circulating pump 3, contact and react with the catalyst in the knapsack reactor 4, and the reacted materials are output from the upper part of the knapsack reactor 4 and enter the rectifying tower 2 through a pipeline;
s3, pumping the materials in the rectifying tower 2 into the knapsack reactor 4 again under the action of the circulating pump 3, further reacting with sufficient alkyl alcohol replenished into the knapsack reactor 4 through the replenishing feeding device 6, outputting the reacted materials from the upper part of the knapsack reactor 4, and entering the rectifying tower 2 through a pipeline;
s4, repeatedly circulating the mixed solution of the raw material and the product polymethoxy dialkyl ether between the rectifying tower 2 and the knapsack reactor 4 until all formaldehyde in the raw material is reacted, finally extracting the product polymethoxy dialkyl ether from a stripping section 23 at the bottom of the rectifying tower 2, and processing the product polymethoxy dialkyl ether after the mixture enters a rectifying section 21 at the top of the rectifying tower 2 and is distilled and condensed by the rectifying section 21, wherein the components are alkyl alcohol and water and light components of partial reaction byproducts.
The molar ratio of the alkyl alcohol to formaldehyde added in the step S1 is 1: (0.5-1.4), the reaction temperature of the mixture of alkyl alcohol and formaldehyde aqueous solution in the raw material pre-reactor 1 is 80-120 ℃, the catalyst is a solid acid catalyst, and the amount of the loaded catalyst is 2-4% of the total mass of reactants.
Preferably, the solid acid catalyst is a macroporous cation exchange resin.
The knapsack reactors 4 in the steps S2-S4 comprise n knapsack reactors which are arranged in parallel, the lower part of each knapsack reactor is communicated with the rectifying tower 2 through a circulating pump, and the number of the knapsack reactors is consistent with that of the circulating pumps, wherein n is more than or equal to 3.
Preferably, the backpack reactor 4 includes 3 backpack reactors, namely, a first backpack reactor 41, a second backpack reactor 42 and a third backpack reactor 43, which are arranged in parallel, and the corresponding circulation pumps are also 3, namely, a first circulation pump 31, a second circulation pump 32 and a third circulation pump 33.
The catalyst filled in the knapsack reactor 4 in the steps S2-S4 is a solid acid catalyst, and the amount of the filled catalyst is 2% -4% of the total mass of reactants.
Preferably, the solid acid catalyst is a macroporous cation exchange resin.
The reaction pressure of the materials in the knapsack reactor 4 is 0.1MPa-3.0MPa, the reaction temperature is 80-120 ℃, and the reaction time is 2-10 h.
The alkyl alcohol added in the step S1 and the step S2 is one of n-butanol, isobutanol, n-hexanol or isooctanol.
The temperature of the stripping section 23 at the bottom of the rectifying tower 2 in the step S4 is 100-300 ℃, and the temperature of the rectifying section 21 at the top of the rectifying tower 2 is 50-200 ℃;
the flow rate of the reactant entering the rectifying tower 2 is 80-200kg/h.
Preferably, the flow rate of the reactants into the rectification column 2 is from 100 to 120kg/h.
The circulation amount of the knapsack reactor 4 is 500-700kmol/hr.
The backpack reactor 4 consists of a tower wall and catalyst packing, wherein the catalyst is packed in the tower in the form of random packing.
The rectifying tower 2 is a plate type tower and comprises tower walls and tower plates, the total number of the tower plates of the rectifying tower is 24-32, the number of the tower plates of the rectifying section is 5-7, the number of the tower plates of the stripping section is 2-3, the reflux ratio of the tower top is 3-5, and the reflux ratio is the ratio of the flow of reflux liquid returned from the tower top of the rectifying tower to the flow of the product at the tower top.
In the step S3, the alkyl alcohol supplemented by the supplementing feeding device 6 is branched by the splitter 5 and then added into each knapsack reactor 4.
The stripping section 23 in the step S4 is used for collecting the product of polymethoxy dialkyl ether with the same alkyl groups at two ends and different alkyl groups at two ends (one end is CH 3 ) Is a polymethoxy dialkyl ether.
Compared with the prior art, the technical scheme of the invention has the following advantages:
A. the invention relates to a knapsack catalytic reaction rectifying device and a plurality of other separating units in a polymethoxy dialkyl ether generation process. The unreacted reactants in the reactor can be further reacted in the reaction rectifying section through a knapsack catalytic reaction rectifying device, the knapsack reactor is supplemented with excessive alkyl alcohol, formaldehyde which is a participated reactant is completely converted to generate polymethoxy dialkyl ether, and the yield is improved. The reaction and rectification in the knapsack catalytic reaction rectification are respectively carried out in a knapsack reactor and a rectification tower which are spatially independent, so that the working conditions of the reaction and the separation can be respectively set, and the reaction and the rectification are carried out under the optimal conditions.
B. According to the invention, the polymethoxy dialkyl ether is synthesized by 'knapsack' catalytic distillation, and the number of externally hung knapsack reactors, the distance between the feeding and discharging positions of the knapsack reactors and the distance between the knapsack reactors and the feeding position are reasonably set, so that better reaction and separation effects can be obtained. The method has the advantages of simple process operation and high safety, and is suitable for general popularization and industrial production; the method has the advantages that byproducts which are difficult to separate are not present, the operation difficulty of the process is greatly reduced in the further product refining process, the separation efficiency is high, the cost is reduced, and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention, the drawings that are required for the embodiments will be briefly described, and it will be apparent that the drawings in the following description are some embodiments of the present invention and that other drawings may be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart for the synthesis of polymethoxy dimethyl ether using methanol and formaldehyde as examples;
FIG. 2 is a schematic illustration (I) of a backpack reactor replenishment feed backpack type reactive distillation flow chart of the present invention;
FIG. 3 is a schematic diagram of a backpack reactor replenishment feed backpack type reactive distillation flow chart (II) of the present invention;
the figures are identified as follows:
1-a pre-reactor, 11-a raw material inlet; 2-rectifying tower, 21-rectifying section, 22-reaction section, 23-stripping section; 3-circulation pump, 31-first circulation pump, 32-second circulation pump, 33-third circulation pump, 34-fourth circulation pump; 4-knapsack reactor, 41-first knapsack reactor, 42-second knapsack reactor, 43-third knapsack reactor, 44-fourth knapsack reactor; 5-a shunt; 6-a supplementary feeding device; 7-tower kettle.
Detailed Description
This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1
N-butanol: formaldehyde is prepared according to the following steps of 1: mixing in a proportion of 0.8, pumping the mixture into a raw material pre-reactor for reaction, then sending the mixture into a reactive rectifying tower 2, mixing a reaction product of polymethoxy dibutyl ether, an unreacted raw material aqueous formaldehyde solution and butanol, and then sending the mixture into the rectifying tower 2, wherein the reaction product is shown in figure 3. Simultaneously, materials in the rectifying tower 2 are pumped into a first knapsack reactor 41, a second knapsack reactor 42, a third knapsack reactor 43 and a fourth knapsack reactor 44 through a first circulating pump 31, a second circulating pump 32, a third circulating pump 33 and a fourth circulating pump 34 respectively, alkyl alcohol is also added into the knapsack reactor 4 through a flow divider 5, and the materials reacted by the knapsack reactor 4 are returned into the rectifying tower 2. On the basis of knapsack type reaction rectification, n-butanol material is directly added into a knapsack reactor 4 through a flow divider 5, so that the problem of low efficiency of the knapsack reactor 4 is solved. The number of the knapsack reactors 4 was 4, the side circulation amount was 600kmol/hr, the number of trays in the rectifying section was 6, the number of trays in the reaction section was 16, the number of trays in the stripping section was 2, the total number of trays was 24, the molar reflux ratio was 4, and the recovery rate was 110kmol/hr. After formaldehyde, n-butanol, polymethoxy dibutyl ether and water quaternary material are rectified in a rectifying tower 2, light component water and butanol are obtained at the top of the tower, polymethoxy dibutyl ether is obtained at the bottom of the tower through a tower kettle 7, and the total yield of the product is 87%.
In the invention, a circulation and dynamic balance process is adopted between the rectifying tower 2 and the knapsack reactor 4, and the mixed solution of raw materials and products repeatedly circulates between the rectifying tower 2 and the knapsack reactor 4, and the generated products are continuously evaporated into the rectifying tower 2 instead of a simple single-way flow direction. The yield (total yield of product) is given as the cumulative yield, i.e. the product obtainable per 1Kg of feed.
Examples 2 to 4
The knapsack catalytic rectification technology for producing polymethoxy dialkyl ether with isobutanol, n-hexanol and isooctanol.
Examples 2-4 were identical to the reaction steps of example 1, except for the reactants, the catalysts used and the reaction conditions, as shown in Table 1.
Examples 1-4 Synthesis of polymethoxy dialkyl ether conditions and product yield
According to the invention, the polymethoxy dialkyl ether is synthesized by 'knapsack' catalytic distillation, and the number of externally hung knapsack reactors, the distance between the feeding and discharging positions of the knapsack reactors and the distance between the knapsack reactors and the feeding position are reasonably set, so that better reaction and separation effects can be obtained. The method has the advantages of simple process operation and high safety, and is suitable for general popularization and industrial production; the method has the advantages that byproducts which are difficult to separate are not present, the operation difficulty of the process is greatly reduced in the further product refining process, the separation efficiency is high, the cost is reduced, and the like.
The invention is applicable to the prior art where nothing is said.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While obvious variations or modifications are contemplated as falling within the scope of the present invention.
Claims (10)
1. The method for synthesizing the polymethoxy dialkyl ether by backpack type continuous reactive distillation is characterized by comprising the following steps of:
s1, alkyl alcohol and formaldehyde aqueous solution with a specific proportion enter a pre-reactor (1) through a raw material inlet (11) to carry out pre-reaction, and the reacted polymethoxy dialkyl ether, byproducts, alkyl alcohol and formaldehyde aqueous solution mixture enters a reaction section (22) of a rectifying tower (2) from the middle part of the rectifying tower (2);
s2, enabling mixed materials in the reaction section (22) to enter the knapsack reactor (4) from the lower part of the knapsack reactor (4) through a pipeline under the action of a circulating pump (3), enabling the mixed materials to react with a catalyst in the knapsack reactor (4) in a contact manner, outputting the reacted materials from the upper part of the knapsack reactor (4), and enabling the reacted materials to enter the rectifying tower (2) through the pipeline;
s3, pumping the materials in the rectifying tower (2) into the knapsack reactor (4) again under the action of the circulating pump (3), further reacting with sufficient alkyl alcohol replenished into the knapsack reactor (4) through the replenishing feeding device (6), outputting the reacted materials from the upper part of the knapsack reactor (4), and re-entering the rectifying tower (2) through a pipeline;
s4, repeatedly circulating the mixed solution of the raw material and the product polymethoxy dialkyl ether between the rectifying tower (2) and the knapsack reactor (4) until all formaldehyde in the raw material is reacted, finally extracting the product polymethoxy dialkyl ether from a stripping section (23) at the bottom of the rectifying tower (2), and introducing the product polymethoxy dialkyl ether into a rectifying section (21) at the top of the rectifying tower (2) to be separated into alkyl alcohol, water and light components of partial reaction byproducts, and evaporating and condensing the light components from the rectifying section (21) for treatment.
2. The method according to claim 1, wherein the molar ratio of the alkyl alcohol and formaldehyde added in the step S1 is 1: (0.5-1.4), the reaction temperature of the mixture of alkyl alcohol and formaldehyde aqueous solution in the pre-reactor (1) is 80-120 ℃, the packed catalyst is a solid acid catalyst, and the catalyst packing amount is 2-4% of the total mass of reactants.
3. The method according to claim 1, wherein the backpack reactors (4) in the steps S2-S4 comprise n backpack reactors which are arranged in parallel, the lower part of each backpack reactor is communicated with the rectifying tower (2) through a circulating pump, and the number of the backpack reactors is consistent with the number of the circulating pumps, wherein n is more than or equal to 3.
4. A method according to claim 3, characterized in that the backpack reactor (4) comprises 3 backpack reactors arranged in parallel, namely a first backpack reactor (41), a second backpack reactor (42) and a third backpack reactor (43), respectively, and the corresponding circulation pumps are also 3, namely a first circulation pump (31), a second circulation pump (32) and a third circulation pump (33), respectively.
5. The method according to claim 1, wherein the catalyst packed in the backpack reactor (4) in steps S2-S4 is a solid acid catalyst, the amount of packed catalyst being 2% -4% of the total mass of reactants.
6. The method of claims 2 and 5, wherein the solid acid catalyst is a macroporous cation exchange resin.
7. The method according to claim 5, wherein the reaction pressure of the material in the backpack reactor (4) is 0.1MPa-3.0MPa, the reaction temperature is 80-120 ℃ and the reaction time is 2-10 h.
8. The method according to claim 1, wherein the alkyl alcohol added in step S1 and step S2 is one of n-butanol, isobutanol, n-hexanol or isooctanol.
9. The method according to claim 1, wherein the temperature set in the bottom stripping section (23) of the rectifying column (2) in step S4 is 100 ℃ to 300 ℃, and the temperature set in the top rectifying section (21) of the rectifying column (2) is 50 ℃ to 200 ℃; the flow rate of the reactant entering the rectifying tower (2) is 80-200kg/h.
10. The method according to claim 1, characterized in that the backpack reactor (4) consists of a column wall and catalyst packing, wherein the catalyst is packed in the column in the form of random packing;
the rectifying tower (2) is a plate type tower and comprises tower walls and tower plates, the total number of the tower plates of the rectifying tower is 24-32, the number of the tower plates of the rectifying section is 5-7, the number of the tower plates of the stripping section is 2-3, and the reflux ratio of the tower top is 3-5.
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