CN115819197A - Process method for synthesizing polymethoxy dimethyl ether - Google Patents
Process method for synthesizing polymethoxy dimethyl ether Download PDFInfo
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- CN115819197A CN115819197A CN202211137632.3A CN202211137632A CN115819197A CN 115819197 A CN115819197 A CN 115819197A CN 202211137632 A CN202211137632 A CN 202211137632A CN 115819197 A CN115819197 A CN 115819197A
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- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 238000000034 method Methods 0.000 title claims abstract description 27
- 230000008569 process Effects 0.000 title claims abstract description 18
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 14
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 105
- 238000006243 chemical reaction Methods 0.000 claims abstract description 103
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 90
- NKDDWNXOKDWJAK-UHFFFAOYSA-N dimethoxymethane Chemical compound COCOC NKDDWNXOKDWJAK-UHFFFAOYSA-N 0.000 claims abstract description 76
- 239000000539 dimer Substances 0.000 claims abstract description 38
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 35
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 35
- 238000005086 pumping Methods 0.000 claims abstract description 23
- 239000002994 raw material Substances 0.000 claims abstract description 21
- 239000007864 aqueous solution Substances 0.000 claims abstract description 12
- 238000005507 spraying Methods 0.000 claims abstract description 4
- 238000010521 absorption reaction Methods 0.000 claims abstract description 3
- 238000010992 reflux Methods 0.000 claims description 26
- 238000000926 separation method Methods 0.000 claims description 24
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 claims description 16
- 239000003054 catalyst Substances 0.000 claims description 15
- 239000000463 material Substances 0.000 claims description 14
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 12
- 239000006227 byproduct Substances 0.000 claims description 9
- 230000003197 catalytic effect Effects 0.000 claims description 9
- 238000004064 recycling Methods 0.000 claims description 9
- 238000007670 refining Methods 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 8
- 239000012043 crude product Substances 0.000 claims description 8
- 238000012856 packing Methods 0.000 claims description 8
- 238000005192 partition Methods 0.000 claims description 7
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 6
- 150000001768 cations Chemical class 0.000 claims description 6
- 235000019253 formic acid Nutrition 0.000 claims description 6
- 239000011347 resin Substances 0.000 claims description 6
- 229920005989 resin Polymers 0.000 claims description 6
- 239000011973 solid acid Substances 0.000 claims description 6
- 238000001179 sorption measurement Methods 0.000 claims description 6
- 239000011964 heteropoly acid Substances 0.000 claims description 4
- 238000011084 recovery Methods 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 238000007599 discharging Methods 0.000 claims description 3
- -1 polyoxymethylene dimethyl ethers Polymers 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 2
- 102100025342 Voltage-dependent N-type calcium channel subunit alpha-1B Human genes 0.000 claims 1
- 101710088658 Voltage-dependent N-type calcium channel subunit alpha-1B Proteins 0.000 claims 1
- 238000006555 catalytic reaction Methods 0.000 abstract description 4
- 239000000376 reactant Substances 0.000 abstract description 4
- 238000012824 chemical production Methods 0.000 abstract description 2
- 235000019256 formaldehyde Nutrition 0.000 description 26
- 229960004279 formaldehyde Drugs 0.000 description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 239000000203 mixture Substances 0.000 description 18
- 239000000047 product Substances 0.000 description 18
- 229930040373 Paraformaldehyde Natural products 0.000 description 5
- 229920002866 paraformaldehyde Polymers 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 5
- 238000000605 extraction Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 229920000642 polymer Polymers 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
- 230000008901 benefit Effects 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000002283 diesel fuel Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- BLSRGJPGRJBHQK-BUSXIPJBSA-N (2s)-2-amino-1-(2-diphenoxyphosphorylpyrrolidin-1-yl)propan-1-one Chemical compound C[C@H](N)C(=O)N1CCCC1P(=O)(OC=1C=CC=CC=1)OC1=CC=CC=C1 BLSRGJPGRJBHQK-BUSXIPJBSA-N 0.000 description 1
- BGJSXRVXTHVRSN-UHFFFAOYSA-N 1,3,5-trioxane Chemical group C1OCOCO1 BGJSXRVXTHVRSN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 239000003377 acid catalyst Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 208000012839 conversion disease Diseases 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007323 disproportionation reaction Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 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
- 238000000746 purification Methods 0.000 description 1
- 238000000066 reactive distillation Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
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Abstract
The invention relates to a chemical production process, in particular to a process method for synthesizing polymethoxy dimethyl ether, which adopts catalytic reaction to break the reaction balance limit of fixed bed reaction and effectively improve the conversion rate of reactants; the high controllability of the reaction is realized, the conversion rate is greatly improved, and the product selectivity is improved with high quality; pumping reaction raw materials of methanol and formaldehyde aqueous solution into a first pre-reactor according to a certain proportion, sending the reaction raw materials to the upper part of a reaction section of a methylal synthetic tower through a primary reaction, and continuously reacting in the first reaction section in the tower; pumping methylal obtained from the top of the methylal synthetic tower to a second prereactor, reacting with a subsequently returned raw material mainly comprising dimer, pumping to the M3-5 synthetic tower, and carrying out deep reaction again; after the components which are not completely reacted at the top of the tower are absorbed by a spraying absorption system at the top of the tower, part of the components are refluxed and part of the components are extracted and recovered, and the uncooled light component methylal is sent to a dimer synthesis tower through a gas phase pipeline for further reaction and utilization.
Description
Technical Field
The invention relates to a chemical production process, in particular to a process method for synthesizing polymethoxy dimethyl ether.
Background
Polyoxymethylene dimethyl ethers are recognized as clean diesel components with a cetane number of up to 70, no sulfur, and no aromatics. The additive is added into diesel oil according to the proportion of 5-20 percent, can improve the cetane number of the diesel oil, promote combustion and obviously reduce the tail gas of automobilesMiddle PM2.5, PM10, N0 x And C0 and the like.
Because of the excellent performance of polyoxymethylene dimethyl ethers, the synthesis process has become the popular direction of domestic and foreign research. The polymethoxy dimethyl ether is generated by the reaction of one or more of methanol or methylal and aqueous solution of formaldehyde/trioxymethylene/paraformaldehyde under the catalysis of an acid catalyst. The reaction product can be decomposed under the acidic condition of water, the reaction conversion rate is not high, and the disproportionation reaction of formaldehyde can be carried out to generate a large amount of formic acid when the temperature of the water is higher, so that the formic acid not only corrodes equipment, but also decomposes the product, and great difficulty is brought to subsequent separation.
The main reasons for low product synthesis conversion rate in the prior art are that by-products and products cannot be separated from a reaction bed layer, so that low-efficiency utilization of reaction raw materials is caused, the circulating materials in a system are large, and finally, the product energy consumption is high and the economic benefit of enterprises is low.
Meanwhile, the high-concentration formaldehyde solution has polymerization risk, which easily causes polymerization blockage of related equipment such as pipelines, reactors, condensers and the like, so that the production cannot be normally carried out.
Furthermore, paraformaldehyde with low water content reduces the water content to the maximum extent, but depolymerization requires higher temperature, and the increase of formic acid content is inevitable. Meanwhile, because the polymerization of the paraformaldehyde contains a small amount of extremely high polymers, the complete decomposition of the paraformaldehyde needs a long time, so that the product contains a small amount of paraformaldehyde, and the product quality is influenced.
Because polymethoxy dimethyl ether is a compound of homologous compounds, different polymers are obtained according to different amounts of polymeric formaldehyde, and a certain concentration gradient proportion is needed in the polymerization process, in a system for synthesizing dimers from methylal, because the amount of dimers is not enough to synthesize M3-5 products with higher polymerization degree, the reaction efficiency is lower.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the existing defects, and provide a process method for synthesizing polymethoxy dimethyl ether, wherein a catalytic reaction is adopted, the reaction balance limitation of a fixed bed reaction is broken, and the conversion rate of reactants is effectively improved; the step-by-step product conversion is realized, the reaction systems are independently arranged by the M1, the M2 and the M3-5, the reaction is independent and step-by-step, the mutual interference is eliminated, the high controllability of the reaction is realized, the conversion rate is greatly improved, and the product selectivity is improved with high quality.
In order to solve the technical problems, the invention specifically provides the following technical scheme: a process for synthesizing polymethoxy dimethyl ether comprises the following steps,
pumping reaction raw materials of methanol and formaldehyde aqueous solution into a first pre-reactor according to a certain ratio, sending the mixture to the upper part of a reaction section of a methylal synthetic tower through a primary reaction, and continuously reacting in the reaction section I in the tower to obtain methylal with the concentration of 88-94% at the tower top;
pumping the methylal obtained from the top of the methylal synthetic tower to a second prereactor, performing common reaction with the subsequently returned raw materials mainly comprising the dimer, pumping the mixture to an M3-5 synthetic tower, and performing deep reaction again; after the components which are not completely reacted at the top of the tower are absorbed by a spraying absorption system at the top of the tower, part of the components are refluxed and part of the components are extracted and recovered, and uncooled light components, namely methylal, are sent to a dimer synthesis tower through a gas phase pipeline for further reaction and utilization;
step three, uniformly mixing methylal from the top of the methylal synthetic tower and a high-concentration formaldehyde aqueous solution, then carrying out primary reaction in a pre-reactor II, pumping into the top of a reaction section III on the left side of a dimer synthetic tower with a partition wall reactor, further participating in reaction, and collecting a byproduct methanol from the lateral line of a rectifying section on the right side and sending the methanol to a separation tower for recycling;
through the refining action of the rectification section III at the top of the tower, part of methylal cooled by the condenser II at the top of the tower passes through the reflux tank II, part of methylal participates in reflux, and part of methylal is sent to the middle lower part of the reaction section III of the dimer synthesis tower through the reflux pump II and is recycled in the system;
after the third stripping action of the bottom stripping section of the dimer synthesis tower, pumping the crude product to a separation tower;
pumping the material extracted from the side line into the upper half part of the separation tower by a side line discharge pump, pumping the material at the bottom of the dimer synthesis tower into the lower half part of the separation tower by a reboiler II, obtaining a crude product at the tower kettle under the rectification action, and sending the byproduct at the tower top to a recovery unit by a reflux pump III for further refining and recycling;
the reaction equations involved in this section are as follows:
fifthly, rectifying incompletely reacted methylal to a high concentration by a first rectifying section at the top of the tower, extracting by a first reflux pump through a first condenser and a first reflux tank, taking part of the incompletely reacted methylal as reflux at the top of the tower, pumping part of the incompletely reacted methylal into the tower for recycling, and pumping a small amount of the incompletely reacted methylal into a methyl formate tower to recycle methyl formate, so that the reutilization of raw materials and the balance in a formic acid system are realized;
and step six, extracting incompletely converted dimers by a side line extraction pump of the separation tower, conveying the dimers to the front end of a pre-reactor II of the M3-5 synthetic tower, and continuing to participate in the reaction.
Preferably, the mass ratio of the methanol to the formaldehyde aqueous solution in the first step is as follows: (1-2.5): 1, wherein the concentration of the formaldehyde aqueous solution is 35-85%.
Preferably, the concentration of the methylal supplemented by the M3-5 synthesis tower in the second step is 85-99%.
Preferably, the usage amount of the low-temperature type cation adsorption resin catalyst of the first prereactor is 50-300Kg/M 3 The medium-temperature type cation adsorption resin of the pre-reactor II is catalyzedThe dosage of the agent is 60-280Kg/M 3 The dosage of the medium-temperature type cation adsorption resin catalyst of the third prereactor is 60-200Kg/M 3 。
Preferably, the use amount of the medium-temperature solid acid catalyst in the catalytic section of the methylal synthesis tower is 80-280Kg/M 3 (ii) a The dosage of the high-temperature solid acid catalyst in the catalytic section of the M3-5 synthetic tower is 80-180Kg/M 3 (ii) a Solid heteropoly acid catalyst 10-90Kg/M 3 (ii) a The usage amount of the low-temperature solid acid catalyst at the catalytic section of the dimer synthetic tower is 50-250Kg/M 3 (ii) a 60-100Kg/M of solid heteropoly acid catalyst 3 。
Preferably, the first rectifying section, the second rectifying section and the third rectifying section can adopt regular packing, the first stripping section, the second stripping section and the third stripping section can adopt bubble cap trays or float valve plates, the third reaction section of the left partition wall can adopt regular packing, and the rectifying and separating section of the right partition wall preferably adopts regular packing or bulk packing.
The invention has the beneficial effects that: the technological method for synthesizing the polymethoxy dimethyl ether adopts catalytic reaction to break the reaction balance of fixed bed reaction; the synthesis of 1, 2 and 3 polymers is independently designed for reaction, so that the controllability of product selectivity is efficiently realized, and the conversion rate is improved; a small amount of water reacts with methylal to generate methanol and formaldehyde, so that the hydrolysis effect of the water on the product is greatly reduced. Solves a series of problems caused by selecting formaldehyde with higher concentration, and greatly expands the selection range of raw materials.
Meanwhile, a reaction byproduct methanol and a product M2-3 are timely extracted from the side line, so that the forward movement of the reaction is promoted, the conversion rate of reactants is improved, the repeated circulation of reaction raw materials which do not participate in the reaction is reduced, the steam consumption in the production process of the polymethoxy dimethyl ether is finally efficiently reduced, the economic value is improved, and the process has the advantages of simple process flow, compact equipment, simplicity in operation, low energy consumption and the like.
Drawings
FIG. 1 is a schematic diagram of the reaction principle of the present invention.
Description of the drawings: A. a first pre-reactor; B. a methylal synthesis column; C. a first reflux tank; D. a first condenser; E. a first reflux pump; F. a first reboiler; G. a first tower kettle discharge pump; H. a second prereactor; J. a M3-5 synthesis tower; K. a spray tower; l, a second cooler; m, a reflux pump II; n, a reboiler II; o, a tower kettle discharge pump II; p, a prereactor III; q, a dimer synthesis tower; r, a second condenser; s, a second reflux tank; t, a reflux pump II; u, a lateral line discharging pump; v, a reboiler II; w, a tower kettle discharge pump II; x, a separation tower; y, a condenser III; z, a reflux tank III; ZA, reflux pump III; ZB, a side draw pump; ZC and a reboiler III; ZD, a discharge pump of the separation tower; BI. A first rectifying section; b II, a reaction section I; b III, stripping section I; JI. A second rectifying section; j II, a reaction section II; j III, a stripping section II; QI, rectifying section III; q II and a third reaction section; QIV, right side bulkhead rectification separation section; and QIII, a stripping section III.
Description of the chemical formula:
methylal (M) 1 )：CH 3 O-[CH 2 O] 1 -CH 3 (ii) a Formaldehyde: CH (CH) 2 O; 2-mer (M) 2 )：CH 3 O-[CH 2 O] 2 -CH 3 (ii) a 3-mer (M) 3 )：CH 3 O-[CH 2 O] 3 -CH 3 (ii) a 4-mer (M) 4 )：CH 3 O-[CH 2 O] 4 -CH 3 。
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
The invention discloses a process method for synthesizing polymethoxy dimethyl ether, which comprises a methylal synthetic tower B, an M3-5 synthetic tower J, a dimer synthetic tower Q, a separation tower X and accessory equipment thereof.
The reaction raw materials of methanol and formaldehyde aqueous solution are pumped into a pre-reactor A according to a certain proportion, are sent to the upper part of the reaction section of a methylal synthetic tower B through a primary reaction, and continue to react in the reaction section in the tower. Meanwhile, the middle lower part of the catalytic section is respectively supplemented with methanol with a certain proportion so as to ensure the equilibrium concentration of reaction raw materials in the reaction equilibrium and promote the formaldehyde to be thoroughly converted as much as possible.
Through the refining action of the first BI of the rectification section at the top of the tower, part of methylal condensed and cooled at the top of the tower is pumped to a subsequent synthesis unit, and the methylal comprises a second H pre-reactor of an M3-5 synthesis tower, a lower half section of a J reaction section of the M3-5 synthesis tower and a third P pre-reactor of a dimer synthesis tower.
Wherein the selected feed (stream 001) is methylal (85-99%) and (35-85%) aqueous formaldehyde (stream 002). After the reaction in the prereactor A, a prereacted liquid (stream 003) is obtained.
The experimental data are as follows:
and (3) material flow 001:
| logistics, 001 | Mass, kg | Is proportion% |
| Methanol | 1460 | 100％ |
| Methylal | 0 | 0％ |
Material flow 002:
| logistics, 002 | Mass, kg | Is proportion% |
| Formaldehyde (formol) | 688 | 55％ |
| Water (W) | 563 | 45％ |
And (3) material flow 003:
| stream flow, 003 | Mass, kg | Is proportion% |
| Formaldehyde (I) | 16 | 1.1％ |
| Water (W) | 958 | 62.5％ |
| Methanol | 53 | 3.5％ |
| Methylal | 465 | 30.3％ |
| M2 | 41 | 2.7％ |
| M3 | 0 | 0.0％ |
| M4 | 0 | 0.0％ |
The make-up methanol chosen was (stream 004):
| logistics, 004 | Mass, kg | Is proportion% |
| Methanol | 450 | 100％ |
| Methylal | 0 | 0％ |
Part methylal extraction system is as material balance in the system, commodity circulation 006, and this experimentation, the top of the tower (commodity circulation 006) extraction volume is less, but the intermittent type is extracted.
And after the methylal from the methylal synthetic tower B and the intermediate from the dimer synthetic tower Q are uniformly mixed, the mixture is sent to a pre-reactor II H, and is subjected to preliminary reaction by the pre-reactor, and then is pumped to the bottom of a rectifying section III QI of the dimer synthetic tower Q, and the top of a reaction section, and the reaction continues to react to a target product in the reaction section II J II. The liquid absorbed by spraying at the top of the dimer synthesis tower Q is used as the reflux of the tower, part of the liquid is extracted to maintain the dynamic balance of the liquid level, and the uncondensed light components (mainly methylal) automatically flow to the middle lower part of the reaction section of the dimer synthesis tower Q from a gas phase state to be used as reaction raw materials to participate in the synthesis of the dimer.
The feed to prereactor two H comprised (stream 009), (stream 030), the composition was as follows:
(stream 009)
| Logistics, 009 | Mass, kg | Is proportion% |
| Formaldehyde (I) | 3.4 | 0.6％ |
| Water (W) | 3.9 | 0.7％ |
| Methanol | 20.3 | 3.6％ |
| Methylal | 530.7 | 94.8％ |
| M2 | 1.6 | 0.3％ |
| M3 | 0.0 | 0.0％ |
| M4 | 0.0 | 0.0％ |
(Logistics 030)
| Logistics, 030 | Mass, kg | Is proportion% |
| Formaldehyde (I) | 168.3 | 25％ |
| Water (W) | 40.4 | 6％ |
| Methanol | 52.6 | 8％ |
| Methylal | 10.6 | 2％ |
| M2 | 388.5 | 57％ |
| M3 | 21.3 | 3％ |
| M4 | 0.0 | 0％ |
After the reaction in the prereactor II H, a stream (stream 012) is pumped to the top of the reaction section of the M3-5 synthesis column J, wherein (stream 012) has the following composition, actual operating temperature: 60-80 deg.C, and operating pressure 0.5-0.6MPa.
(stream 012):
in order to maintain the concentration of the reaction raw material, the composition of the material flow 010 of the supplemented partial methylal from the lower half catalytic bed layer of the J reaction section of the M3-5 synthetic tower is as follows:
| logistics, 010 | Mass, kg | Is proportion% |
| Formaldehyde (I) | 2.8 | 0.6％ |
| Water (W) | 3.3 | 0.7％ |
| Methanol | 17.1 | 3.6％ |
| Methylal | 445.4 | 94.8％ |
| M2 | 1.4 | 0.3％ |
| M3 | 0.0 | 0.0％ |
| M4 | 0.0 | 0.0％ |
The unreacted methylal in the M3-5 synthetic tower J overflows from the top of the spray tower K to the lower half section of the dimer synthetic tower Q through reactive distillation. Actual operating temperature: 50-60 ℃, operating pressure: 0.05-0.11MPa.
(stream 017) the composition was as follows:
through the stripping action of the stripping section of the M3-5 synthetic tower J, a crude product (material flow 018) mainly comprising M3-5 is obtained at the tower bottom and sent out of the system for further refining and purification, and a product with the purity required by the relevant is obtained, wherein the actual operation temperature is as follows: 120-160 ℃, operating pressure: 0.1-0.2Mpa.
(stream 018) has the following composition:
| logistics, 018 | Mass, kg | Is proportion% |
| Formaldehyde (formol) | 1.2 | 0.2％ |
| Water (W) | 0.6 | 0.1％ |
| Methanol | 2.1 | 0.4％ |
| Methylal | 1.3 | 0.2％ |
| M2 | 23.6 | 4.0％ |
| M3 | 410.3 | 69.7％ |
| M4 | 149.6 | 25.4％ |
The reaction raw materials methylal and high-concentration formaldehyde aqueous solution are pumped into a pre-reactor III P according to a certain proportion, are sent to the upper part of the reaction section of the dimer synthesis tower Q through primary reaction, and continue to react in the reaction section in the tower. And simultaneously, methylal with a certain proportion is respectively supplemented at the middle lower part of the catalytic section so as to ensure that the reaction equilibrium is always carried out in the positive reaction direction.
(stream 019) has the following composition:
| logistics, 019 | Mass, kg | Is proportion% |
| Formaldehyde (I) | 375 | 75％ |
| Water (W) | 125 | 25％ |
The composition of (stream 007) was as follows:
after the reaction of the three-P pre-reactor, the actual operating temperature is as follows: 60-80 ℃, operating pressure: 0.5-0.6MPa. The composition obtained (stream 020) was as follows:
| logistics, 020 | Mass, kg | By weight percent% |
| Formaldehyde (I) | 318.2 | 27.0％ |
| Water (W) | 84.0 | 7.1％ |
| Methanol | 187.4 | 15.9％ |
| Methylal | 191.6 | 16.2％ |
| M2 | 263.5 | 22.3％ |
| M3 | 100.6 | 8.5％ |
| M4 | 34.7 | 2.9％ |
Rectifying the incompletely reacted methylal to a higher concentration by a rectifying section three QI of the dimer synthetic tower Q, extracting by a pump through a condenser and a reflux tank, taking part of methylal as reflux of the tower top, pumping part of methylal into the tower for recycling, and pumping a small amount of methylal into a methyl formate tower to recycle methyl formate, thereby realizing the reutilization of raw materials and the system balance of formic acid.
The composition of the overhead methyl formate recovery (stream 023) is as follows:
| logistics, 023 | Mass, kg | Is proportion% |
| Formic acid methyl ester | 3.3 | 2.6％ |
| Water (W) | 0.5 | 0.1％ |
| Methanol | 102.7 | 74.6％ |
| Methylal | 31.3 | 23.4％ |
Through the rectification action of the rectification separation section QIV of the right partition wall of the reaction section, a material with a byproduct mainly comprising methanol is extracted by the side line discharging pump U, so that a reaction product and the byproduct are moved out of the reaction system, and the reaction is promoted to be carried out. After the three Q III is stripped in the stripping section, a crude product with M2-3 as the main component is obtained in the tower kettle and is pumped to a separation tower X for further refining and separation.
The reaction equations involved in this section are as follows:
as can be seen from the reaction (3), the reaction by-product methanol is a limiting factor for the forward progress of the reaction, and the product M of the reaction is extracted from the tower bottom 2-3 And the right side of the next reaction section is used for extracting the enriched methanol.Thereby achieving efficient forward movement of the reaction.
The composition of the side draw (stream 025) was as follows:
| logistics, 025 | Mass, kg | Is proportion% |
| Formaldehyde (I) | 48.2 | 8.9％ |
| Water (W) | 36.3 | 6.7％ |
| Methanol | 298.6 | 55.0％ |
| Methylal | 128.6 | 23.7％ |
| M2 | 26.0 | 4.8％ |
| M3 | 5.0 | 0.9％ |
| M4 | 0.0 | 0.0％ |
| Summing | 543 | 100.0％ |
The top of the stripping section III Q at the bottom of the dimer synthesis tower Q is connected with gas-phase methylal from the top of the M3-5 synthesis tower J, so that the concentration of reactants in the reaction section III Q is increased, and the forward movement of the reaction is promoted.
After being stripped at the stripping section at the bottom of the dimer synthetic tower Q, a crude product mainly containing M2-5 is extracted from the tower bottom and pumped into a separation tower to purify a target product. Actual operating temperature: 90-120 deg.C, and operating pressure 0.1-0.25Mpa.
(stream 026) the composition was as follows:
| physical distribution 026 | Mass, kg | Is proportion% |
| Formaldehyde (I) | 126.0 | 9.2％ |
| Water (I) | 6.0 | 0.4％ |
| Methanol | 152.0 | 11.2％ |
| Methylal | 42.3 | 3.1％ |
| M2 | 450.5 | 33.1％ |
| M3 | 373.3 | 27.4％ |
| M4 | 212.5 | 15.6％ |
The feed to the separation column X is divided into two portions, one from the middle section of the dimer dividing wall column and the other from the bottom of the dimer dividing wall column. While the feed is predominantly at 5-8 plates and 10-12 plates.
And (3) rectifying the enriched methanol and a small amount of methylal to a higher concentration in the separation tower X, extracting by a pump through a condenser and a reflux tank, taking part of the methanol and the small amount of methylal as reflux on the top of the tower, pumping part of the methanol and the small amount of methylal out of a system, and recycling and refining the methanol and the small amount of methylal to be used as raw materials for synthesizing methylal.
(stream 028) has the following composition:
the material mainly containing dimer is extracted from the middle section of the separation tower X and pumped to a pre-reactor II H of the M3-5 synthetic tower J through a side extraction pump ZB to be used as the main raw material for synthesizing the M3-5. Preferred operating temperatures are: 90-120 ℃.
The composition of (stream 030) is as follows:
| logistics, 030 | Mass, kg | By weight percent% |
| Formaldehyde (I) | 167.3 | 25％ |
| Water (W) | 40.1 | 6％ |
| Methanol | 52.7 | 8％ |
| Methylal compound | 10.1 | 2％ |
| M2 | 388.5 | 57％ |
| M3 | 21.3 | 3％ |
| M4 | 0.0 | 0％ |
After the separation of the X stripping section of the separation tower, the crude product mainly containing M3-4 obtained from the tower bottom is merged with the material flow from the tower bottom of the M3-5 synthesis tower and then sent to a refining unit to obtain a product with higher purity. Preferred operating temperatures are: 130-170 deg.C, and operating pressure 0.1-0.35Mpa.
(stream 031) has the following composition:
and finally, after the stream 031 and the stream 018 are merged, the stream 032 is sent out of the system and is further separated or collected according to requirements.
The composition of the target product (stream 032) is as follows:
| logistics, 032 | Mass, kg | By weight percent% |
| Formaldehyde (I) | 1.2 | 0.1％ |
| Water (W) | 0.6 | 0.1％ |
| Methanol | 2.1 | 0.2％ |
| Methylal | 1.3 | 0.1％ |
| M2 | 27.2 | 2.3％ |
| M3 | 767.3 | 66.0％ |
| m4 | 362.1 | 31.2％ |
The above embodiments are preferred embodiments of the present invention, and those skilled in the art can make variations and modifications to the above embodiments, therefore, the present invention is not limited to the above embodiments, and any obvious improvements, substitutions or modifications made by those skilled in the art based on the present invention are within the protection scope of the present invention.
Claims (6)
1. A process method for synthesizing polymethoxy dimethyl ether is characterized by comprising the following steps,
pumping reaction raw materials of methanol and formaldehyde aqueous solution into a pre-reactor I (A) according to a certain ratio, sending the reaction raw materials to the upper part of a reaction section I (BII) of a methylal synthetic tower B through a primary reaction, and continuously reacting in the reaction section I (BII) in the tower to obtain methylal with the concentration of 88-94% at the tower top;
pumping methylal obtained from the top of the methylal synthetic tower (B) to a pre-reactor II (H), reacting with a subsequently returned raw material mainly comprising dimer, pumping to an M3-5 synthetic tower (J), and carrying out deep reaction again; after the components which are not completely reacted at the top of the tower are absorbed by a spraying absorption system at the top of the tower, part of the components are refluxed and part of the components are extracted and recovered, and uncooled light component methylal is sent to a dimer synthesis tower (Q) through a gas phase pipeline for further reaction and utilization;
step three, uniformly mixing methylal from the top of the methylal synthetic tower (B) and a high-concentration formaldehyde aqueous solution, then carrying out primary reaction in a pre-reactor II, pumping into the top of a reaction section III (QII) at the left side of the dimer synthetic tower with a partition wall reactor, further participating in the reaction, and collecting a byproduct methanol from the lateral line of a rectifying section at the right side and sending the methanol to a separation tower (X) for recovery;
through the refining action of a rectification section III (Q I) at the top of the tower, part of methylal cooled by a condenser II (R) at the top of the tower participates in reflux through a reflux tank II (S), and part of methylal is sent to the middle lower part of a reaction section III (Q II) of a dimer synthesis tower (Q) through a reflux pump II (T) and is recycled in the system;
after stripping in the bottom stripping section III (QIII) of the dimer synthesis column (Q), the crude product is pumped to a separation column (X);
pumping the material extracted from the side line into the upper half part of the separation tower (X) by a side line discharging pump (U), pumping the material at the bottom of the dimer synthesis tower (Q) to the lower half part of the separation tower (X) by a reboiler II (V), obtaining a crude product at the tower kettle under the rectification action, and sending the byproduct at the tower top to a recovery unit for further refining and recycling by a reflux pump III (ZA);
the reaction equations involved in this section are as follows:
fifthly, rectifying incompletely reacted methylal to a higher concentration by a rectifying section I (BI) at the tower top, extracting by a reflux pump I (E) through a condenser I (D) and a reflux tank I (C), taking part of the unreacted methylal as reflux at the tower top, pumping part of the unreacted methylal into the tower for recycling, pumping a small amount of unreacted methylal into a methyl formate tower for recycling methyl formate, and realizing the recycling of raw materials and the balance of formic acid in a system;
and sixthly, withdrawing incompletely converted dimer by a side draw pump (ZB) of the separation tower (X), sending the dimer to the front end of a pre-reactor II (H) of the M3-5 synthesis tower (J), and continuing to participate in the reaction.
2. The process method for synthesizing polymethoxy dimethyl ether according to claim 1, wherein the mass ratio of methanol to the formaldehyde aqueous solution in the first step is (1-2.5): 1, wherein the concentration of the formaldehyde aqueous solution is 35-85%.
3. The process for the synthesis of polyoxymethylene dimethyl ethers according to claim 1, wherein in step two the concentration of methylal supplied to the M3-5 converter (J) is 85-99%.
4. The process for the synthesis of polymethoxy dimethyl ether according to claim 1, wherein the amount of the catalyst of the low temperature type cation adsorption resin used in the pre-reactor one (A) is 50 to 300Kg/M 3 The using amount of the medium-temperature type cation adsorption resin catalyst of the pre-reactor II (H) is 60-280Kg/M 3 The using amount of the medium-temperature type cation adsorption resin catalyst of the pre-reactor III (P) is 60-200Kg/M 3 。
5. The process for synthesizing polymethoxy dimethyl ether according to claim 1, wherein the amount of the medium temperature type solid acid catalyst used in the catalytic stage of the methylal synthesis column (B) is 80-280Kg/M 3 (ii) a The use amount of the high-temperature solid acid catalyst in the catalytic section of the M3-5 synthetic tower (J) is 80-180Kg/M 3 (ii) a Solid heteropoly acid catalyst 10-90Kg/M 3 (ii) a The dosage of the low-temperature solid acid catalyst in the catalytic section of the dimer synthesis tower (Q) is 50-250Kg/M 3 (ii) a 60-100Kg/M of solid heteropoly acid catalyst 3 。
6. The process for the synthesis of polymethoxy dimethyl ether according to claim 1, wherein the first rectification section (BI), the second rectification section (JI) and the third rectification section (QI) are made of structured packing, the first stripping section (BIII), the second stripping section (JIII) and the third stripping section (QII) are made of bubble cap trays or float valve plates, the third reaction section (QII) on the left partition wall is made of structured packing, and the rectifying and separating section (QIV) on the right partition wall is preferably made of structured packing or loose packing.
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| CN107522602A (en) * | 2017-09-08 | 2017-12-29 | 青岛迈特达新材料有限公司 | A kind of technique and system for preparing DMM2 |
| CN107721831A (en) * | 2017-11-08 | 2018-02-23 | 江苏道尔顿石化科技有限公司 | A kind of polymethoxy dimethyl ether synthesizes the plug-in reaction system of bubble type and synthetic method |
| CN107739301A (en) * | 2017-11-08 | 2018-02-27 | 江苏道尔顿石化科技有限公司 | A kind of polymethoxy dimethyl ether synthesis system and technique |
| CN110496576A (en) * | 2019-09-17 | 2019-11-26 | 无锡赫利邦化工科技有限公司 | A kind of synthesis of polymethoxy dimethyl ether and separation system |
| CN110642687A (en) * | 2019-11-11 | 2020-01-03 | 无锡赫利邦化工科技有限公司 | Synthesis device and synthesis process for polymethoxy dimethyl ether |
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| CN107522602A (en) * | 2017-09-08 | 2017-12-29 | 青岛迈特达新材料有限公司 | A kind of technique and system for preparing DMM2 |
| CN107721831A (en) * | 2017-11-08 | 2018-02-23 | 江苏道尔顿石化科技有限公司 | A kind of polymethoxy dimethyl ether synthesizes the plug-in reaction system of bubble type and synthetic method |
| CN107739301A (en) * | 2017-11-08 | 2018-02-27 | 江苏道尔顿石化科技有限公司 | A kind of polymethoxy dimethyl ether synthesis system and technique |
| CN110496576A (en) * | 2019-09-17 | 2019-11-26 | 无锡赫利邦化工科技有限公司 | A kind of synthesis of polymethoxy dimethyl ether and separation system |
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