CN115819197B - Technological method for synthesizing polymethoxy dimethyl ether - Google Patents
Technological method for synthesizing polymethoxy dimethyl ether Download PDFInfo
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- CN115819197B CN115819197B CN202211137632.3A CN202211137632A CN115819197B CN 115819197 B CN115819197 B CN 115819197B CN 202211137632 A CN202211137632 A CN 202211137632A CN 115819197 B CN115819197 B CN 115819197B
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- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 35
- LCGLNKUTAGEVQW-UHFFFAOYSA-N Dimethyl ether Chemical compound COC LCGLNKUTAGEVQW-UHFFFAOYSA-N 0.000 title claims abstract description 30
- 238000000034 method Methods 0.000 title claims abstract description 29
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims abstract description 102
- 238000006243 chemical reaction Methods 0.000 claims abstract description 93
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 89
- NKDDWNXOKDWJAK-UHFFFAOYSA-N dimethoxymethane Chemical compound COCOC NKDDWNXOKDWJAK-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000000539 dimer Substances 0.000 claims abstract description 40
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 39
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 39
- 238000005086 pumping Methods 0.000 claims abstract description 22
- 239000002994 raw material Substances 0.000 claims abstract description 19
- 230000008569 process Effects 0.000 claims abstract description 13
- 239000007864 aqueous solution Substances 0.000 claims abstract description 12
- 238000000605 extraction Methods 0.000 claims abstract description 9
- 239000007921 spray Substances 0.000 claims abstract description 5
- 238000010521 absorption reaction Methods 0.000 claims abstract description 3
- 238000010992 reflux Methods 0.000 claims description 27
- 238000000926 separation method Methods 0.000 claims description 19
- 239000000203 mixture Substances 0.000 claims description 18
- 239000003054 catalyst Substances 0.000 claims description 16
- TZIHFWKZFHZASV-UHFFFAOYSA-N methyl formate Chemical compound COC=O TZIHFWKZFHZASV-UHFFFAOYSA-N 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 15
- 238000004064 recycling Methods 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 11
- 230000003197 catalytic effect Effects 0.000 claims description 9
- 239000012043 crude product Substances 0.000 claims description 9
- 238000012856 packing Methods 0.000 claims description 8
- 238000005192 partition Methods 0.000 claims description 8
- 238000007670 refining Methods 0.000 claims description 8
- 230000009471 action Effects 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
- 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
- 150000002500 ions Chemical class 0.000 claims description 4
- 238000011084 recovery Methods 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- 102100025342 Voltage-dependent N-type calcium channel subunit alpha-1B Human genes 0.000 claims description 3
- 101710088658 Voltage-dependent N-type calcium channel subunit alpha-1B Proteins 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 150000001768 cations Chemical class 0.000 claims description 2
- 239000000284 extract Substances 0.000 claims description 2
- 238000007667 floating Methods 0.000 claims description 2
- 239000013638 trimer Substances 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
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 19
- 239000000047 product Substances 0.000 description 17
- GZVBAOSNKYQKIT-UHFFFAOYSA-N dimethoxymethane Chemical compound COCOC.COCOC GZVBAOSNKYQKIT-UHFFFAOYSA-N 0.000 description 13
- 238000002360 preparation method Methods 0.000 description 13
- 229930040373 Paraformaldehyde Natural products 0.000 description 5
- 238000007599 discharging Methods 0.000 description 5
- 229920002866 paraformaldehyde Polymers 0.000 description 5
- 229920000642 polymer Polymers 0.000 description 5
- 238000006116 polymerization reaction Methods 0.000 description 5
- 239000002283 diesel fuel Substances 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000007788 liquid 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
- 230000008901 benefit Effects 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 239000008098 formaldehyde solution Substances 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
- 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
- 230000004075 alteration Effects 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012295 chemical reaction liquid Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 208000012839 conversion disease Diseases 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
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- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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 in good quality; the method comprises the steps of pumping reaction raw materials of methanol and formaldehyde aqueous solution into a first pre-reactor according to a certain proportion, carrying out preliminary reaction, conveying the reaction raw materials to the upper part of a reaction section of a methylal synthesizing tower, and continuing to react in the first reaction section in the tower; pumping methylal obtained from the top of the methylal synthesizing tower to a second pre-reactor, reacting with the raw materials which are returned subsequently and mainly comprise dimers, pumping the methylal to an M3-5 synthesizing tower, and deeply reacting again; after the unreacted components at the top of the tower are absorbed by the tower top spray absorption system, part of the components are refluxed, part of the components are recovered by extraction, and uncooled light component methylal is sent to the 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
Polymethoxy dimethyl ether is a recognized clean diesel oil component, and has cetane number of 70 more, no sulfur and no aromatic hydrocarbon. The additive is added into diesel oil according to the proportion of 5-20%, can improve the cetane number of the diesel oil, promote combustion and obviously reduce PM2.5, PM10 and N0 in automobile exhaust x And C0 and other harmful gases.
Because of the excellent performance of the polymethoxy dimethyl ether, the synthesis process of the polymethoxy dimethyl ether has become a popular direction for domestic and foreign research. The polymethoxy dimethyl ether is produced by reacting one or more of methanol or methylal with formaldehyde aqueous solution/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 low, formaldehyde can be disproportionated to generate a large amount of formic acid when the temperature of water is high, and the formic acid not only corrodes equipment, but also can decompose the product, so that the subsequent separation is more difficult.
The main reason for low product synthesis conversion rate in the prior art is that by-products and products cannot be separated from a reaction bed layer, so that the reaction raw materials are utilized in a low-efficiency mode, 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 formaldehyde solution with high concentration has the risk of polymerization, and the polymerization blockage of related equipment such as a pipeline, a reactor, a condenser and the like is easily caused, so that the production cannot be normally carried out.
Furthermore, although the low water content paraformaldehyde minimizes the water content, the depolymerization requires a higher temperature and the increase of the formic acid content is unavoidable. Meanwhile, as the polymerization of the paraformaldehyde contains a small amount of extremely high polymer, the complete decomposition of the paraformaldehyde takes quite a long time, so that the product contains a small amount of paraformaldehyde, and the quality of the product is affected.
Because the polymethoxy dimethyl ether is a compound of a homolog, different polymers are obtained according to different amounts of polymerized formaldehyde, and a certain concentration gradient proportion is needed in the polymerization process, in a system for synthesizing dimers by methylal, the reaction efficiency is lower because the amount of the dimers is insufficient for synthesizing M3-5 products with higher polymerization degree.
Disclosure of Invention
The technical problem to be solved by the invention is to overcome the existing defect, and provide 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 reaction system is independently arranged by M1, M2 and M3-5, the reaction is independent and stepwise, 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 method for synthesizing polymethoxy dimethyl ether comprises the following steps,
step one, the methanol and formaldehyde aqueous solution serving as reaction raw materials are pumped into a first pre-reactor according to a certain proportion, are sent to the upper part of a reaction section of a methylal synthesizing tower through preliminary reaction, and are continuously reacted in the first reaction section in the tower, and methylal with the concentration of 88-94% is obtained at the top of the tower;
pumping methylal obtained from the top of the methylal synthesizing tower to a pre-reactor II, reacting with the raw materials which are returned subsequently and mainly comprise dimers together, pumping the methylal to an M3-5 synthesizing tower, and deeply reacting again; after the unreacted components at the tower top are absorbed by the tower top spray absorption system, part of the components are refluxed, part of the components are recovered by extraction, and uncooled light component methylal is 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 a methylal synthesizing tower and a high-concentration formaldehyde aqueous solution, performing preliminary reaction by a pre-reactor II, pumping into the top of a reaction section III on the left side of a dimer synthesizing tower with a partition wall reactor, further participating in the reaction, and collecting byproduct methanol from a side line of a rectifying section on the right side and delivering the byproduct methanol to a separating tower for recovery;
through the refining action of the rectifying section III at the top of the tower, methylal cooled by the condenser II at the top of the tower is partially returned through the reflux tank II, and partially sent to the middle lower part of the reaction section III of the dimer synthesizing tower through the reflux pump II for recycling in the system;
after the third stripping action of the stripping section at the bottom 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, rectifying to obtain a crude product at the tower bottom, and sending the tower top byproduct to a recovery unit by a reflux pump III for further refining and recycling;
the reaction equation involved in this paragraph is as follows:
rectifying the methylal which is not completely reacted to a higher concentration in a rectifying section I at the tower top, extracting the methylal by a reflux pump I through a condenser I and a reflux tank I, taking part of the methylal as reflux at the tower top, pumping part of methylal into the tower for recycling, and pumping a small amount of methylal into a methyl formate tower for recycling methyl formate to realize the recycling of raw materials and the internal balance of formic acid;
and step six, a side stream extraction pump of the separation tower extracts the dimer which is not completely converted, and sends the dimer to the front end of a second pre-reactor of the M3-5 synthesis tower to continuously participate in the reaction.
Preferably, in the first step, the mass ratio of the methanol to the formaldehyde aqueous solution is: (1-2.5): 1, wherein the concentration of the formaldehyde aqueous solution is 35-85%.
Preferably, the concentration of methylal supplemented by the M3-5 synthesis tower in the second step is 85-99%.
Preferably, the low-temperature cation adsorption resin catalyst of the first pre-reactor is used in an amount of 50-300Kg/M 3 The using amount of the medium Wen Xingyang ion adsorption resin catalyst in the second pre-reactor is 60-280Kg/M 3 The using amount of the catalyst of the ion adsorption resin Wen Xingyang in the third prereactor is 60-200Kg/M 3 。
Preferably, the medium-temperature solid acid catalyst in the catalytic section of the methylal synthesizing tower is 80-280Kg/M 3 The method comprises the steps of carrying out a first treatment on the surface of the The usage amount of the high-temperature solid acid catalyst at the catalytic section of the M3-5 synthetic tower is 80-180Kg/M 3 The method comprises the steps of carrying out a first treatment on the surface of the 10-90Kg/M solid heteropolyacid catalyst 3 The method comprises the steps of carrying out a first treatment on the surface of the The dosage of the low-temperature solid acid catalyst in the catalytic section of the dimer synthesis tower is 50-250Kg/M 3 The method comprises the steps of carrying out a first treatment on the surface of the 60-100Kg/M solid heteropolyacid catalyst 3 。
Preferably, the first rectifying section, the second rectifying section and the third rectifying section can adopt structured packing, the first stripping section, the second stripping section and the third stripping section can adopt bubble cap plates or floating valve plates, the third reaction section of the left partition wall can adopt structured packing, and the right partition wall rectifying and separating section is preferably structured 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 the 1, 2 and 3 polymers is independently designed and reacted, the controllability of the product selectivity is realized efficiently, and the conversion rate is improved; a small amount of water reacts with methylal to generate methanol and formaldehyde, so that the hydrolysis of water to products is greatly reduced. Solves a series of problems caused by the necessity of selecting formaldehyde with higher concentration, and greatly expands the selection range of raw materials.
Meanwhile, methanol and a product M2-3 which are reaction byproducts are timely and laterally extracted, 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 process of producing polymethoxy dimethyl ether is finally and 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 tower; C. a first reflux tank; D. a first condenser; E. a first reflux pump; F. a reboiler I; G. a first tower kettle discharging pump; H. a second pre-reactor; J. m3-5 synthesis tower; K. a spray tower; l, a second cooler; m, a reflux pump II; n, reboiler II; o, a tower kettle discharging pump II; p, a pre-reactor III; q, a dimer synthesis tower; r, a second condenser; s, a second reflux tank; t, a reflux pump II; u, side line discharging pump; v, reboiler II; w, a tower kettle discharging pump II; x, a separation tower; y, a condenser III; z, reflux drum III; ZA, reflux pump three; ZB, side draw pump; ZC, reboiler III; ZD, knockout tower discharge pump; BI. Rectifying section I; BII, reaction section I; BIII and stripping section I; JI. Rectifying section II; j II, a second reaction section; j III, stripping section II; QI, rectifying section III; q II and a reaction section III; q IV, right side partition wall rectifying separation section; q III, stripping section III.
Description of chemical formula:
methylal (M) 1 )：CH 3 O-[CH 2 O] 1 -CH 3 The method comprises the steps of carrying out a first treatment on the surface of the Formaldehyde: CH (CH) 2 O;2 Polymer (M) 2 )：CH 3 O-[CH 2 O] 2 -CH 3 The method comprises the steps of carrying out a first treatment on the surface of the 3 Polymer (M) 3 )：CH 3 O-[CH 2 O] 3 -CH 3 The method comprises the steps of carrying out a first treatment on the surface of the 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 below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.
The technological process for synthesizing polymethoxy dimethyl ether includes methylal synthesizing tower B, M-5, dimer synthesizing tower Q, separating tower X and its accessory equipment.
The methanol and formaldehyde aqueous solution as reaction raw materials are pumped into a first pre-reactor A according to a certain proportion, and are sent to the upper part of a reaction section of a methylal synthesizing tower B through preliminary reaction, and are continuously reacted in the reaction section in the tower. Meanwhile, the middle and lower parts of the catalytic section are respectively supplemented with methanol with a certain proportion, so that the equilibrium concentration of reaction raw materials in the reaction equilibrium is ensured, and the complete conversion of formaldehyde is promoted as much as possible.
And under the refining action of the first BI of the rectifying 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 except part of methylal which participates in reflux, and the methylal comprises a second pre-reactor H of the M3-5 synthesis tower and a third pre-reactor P of the M3-5 synthesis tower J reaction section at the lower half section of the M3-5 synthesis tower.
Wherein the selected starting materials (stream 001) are methylal (85-99%) and (35-85%) aqueous formaldehyde solution (stream 002). The pre-reaction liquid (material flow 003) is obtained after the reaction in the first pre-reactor A.
Experimental data are as follows:
stream 001:
| logistics, 001 | Mass, kg | Duty ratio of% |
| Methanol | 1460 | 100％ |
| Methylal (methylal) | 0 | 0％ |
Stream 002:
| logistics, 002 | Mass, kg | Duty ratio of% |
| Formaldehyde | 688 | 55％ |
| Water and its preparation method | 563 | 45％ |
Stream 003:
| logistics, 003 | Mass, kg | Duty ratio of% |
| Formaldehyde | 16 | 1.1％ |
| Water and its preparation method | 958 | 62.5％ |
| Methanol | 53 | 3.5％ |
| Methylal (methylal) | 465 | 30.3％ |
| M2 | 41 | 2.7％ |
| M3 | 0 | 0.0％ |
| M4 | 0 | 0.0％ |
The make-up methanol selected was (stream 004):
| logistics 004 | Mass, kg | Duty ratio of% |
| Methanol | 450 | 100％ |
| Methylal (methylal) | 0 | 0％ |
Part of methylal extraction system is used as material balance in the system, material flow 006 is used, the extraction amount of the top of the tower (material flow 006) is less in the experimental process, and intermittent extraction can be realized.
And (3) uniformly mixing methylal from the methylal synthesis tower B with an intermediate from the dimer synthesis tower Q, conveying the mixture to a pre-reactor II, carrying out preliminary reaction by the pre-reactor, and pumping the mixture to the bottom of a rectifying section III of the dimer synthesis tower Q, the top of a reaction section, and continuously reacting in a reaction section II to a target product. The liquid absorbed by spraying at the top of the dimer synthesis tower Q is used as reflux of the tower, partial liquid is extracted to maintain dynamic balance of liquid level, and the uncondensed light component (mainly methylal) automatically flows to the middle lower part of the reaction section of the dimer synthesis tower Q from a gas phase state as a reaction raw material to participate in synthesis of dimer.
The feed to pre-reactor two H comprises (stream 009), (stream 030) with the following composition:
(Logistics 009)
| Logistics 009 | Mass, kg | Duty ratio of% |
| Formaldehyde | 3.4 | 0.6％ |
| Water and its preparation method | 3.9 | 0.7％ |
| Methanol | 20.3 | 3.6％ |
| Methylal (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 | Duty ratio of% |
| Formaldehyde | 168.3 | 25％ |
| Water and its preparation method | 40.4 | 6％ |
| Methanol | 52.6 | 8％ |
| Methylal (methylal) | 10.6 | 2％ |
| M2 | 388.5 | 57％ |
| M3 | 21.3 | 3％ |
| M4 | 0.0 | 0％ |
After reaction in pre-reactor II, stream (stream 012) is pumped to the top of the reaction section of M3-5 synthesis column J, wherein (stream 012) consists of the following, actual operating temperature: 60-80 ℃ and the operating pressure is 0.5-0.6Mpa.
(stream 012):
in order to maintain the concentration of the reaction raw material, a part of methylal is supplemented from the lower half of the reaction section of the M3-5 synthesis tower J to the catalytic bed layer, and the composition of the material flow 010 is as follows:
| logistics 010 | Mass, kg | Duty ratio of% |
| Formaldehyde | 2.8 | 0.6％ |
| Water and its preparation method | 3.3 | 0.7％ |
| Methanol | 17.1 | 3.6％ |
| Methylal (methylal) | 445.4 | 94.8％ |
| M2 | 1.4 | 0.3％ |
| M3 | 0.0 | 0.0％ |
| M4 | 0.0 | 0.0％ |
Unreacted methylal in the M3-5 synthesis tower J overflows from the top of the spray tower K through reactive rectification and reaches the lower half section of the dimer synthesis tower Q. Actual operating temperature: 50-60 ℃, operating pressure: 0.05-0.11Mpa.
(stream 017) has the following composition:
the crude product (material flow 018) mainly containing M3-5 is sent out of the system for further refining and purification through stripping action of a stripping section of an M3-5 synthesis tower J, and the product with relevant required purity is obtained at the actual operation temperature: 120-160 ℃, operating pressure: 0.1-0.2Mpa.
(stream 018) has the following composition:
| logistics 018 | Mass, kg | Duty ratio of% |
| Formaldehyde | 1.2 | 0.2％ |
| Water and its preparation method | 0.6 | 0.1％ |
| Methanol | 2.1 | 0.4％ |
| Methylal (methylal) | 1.3 | 0.2％ |
| M2 | 23.6 | 4.0％ |
| M3 | 410.3 | 69.7％ |
| M4 | 149.6 | 25.4％ |
The methylal as the reaction material and high concentration formaldehyde aqua are pumped into the pre-reactor III P in certain proportion, and the mixture is first reacted and then fed to the upper part of the reaction section of the dimer synthesizing tower Q to react continuously in the reaction section. Meanwhile, methylal with a certain proportion is respectively supplemented at the middle and lower parts of the catalytic section, so that the reaction balance is ensured to be always carried out in the forward and reverse directions.
The composition of (stream 019) is as follows:
| logistics, 019 | Mass, kg | Duty ratio of% |
| Formaldehyde | 375 | 75％ |
| Water and its preparation method | 125 | 25％ |
(stream 007) the composition is as follows:
after the reaction of the three pre-reactors, the actual operating temperature: 60-80 ℃, operating pressure: 0.5-0.6Mpa. The composition obtained (stream 020) is as follows:
| logistics 020 | Mass, kg | Duty ratio of% |
| Formaldehyde | 318.2 | 27.0％ |
| Water and its preparation method | 84.0 | 7.1％ |
| Methanol | 187.4 | 15.9％ |
| Methylal (methylal) | 191.6 | 16.2％ |
| M2 | 263.5 | 22.3％ |
| M3 | 100.6 | 8.5％ |
| M4 | 34.7 | 2.9％ |
Rectifying section three QI of dimer synthetic tower Q rectifies the methylal which is not fully reacted to higher concentration, and then the methylal is extracted by a pump through a condenser and a reflux tank, part of methylal is used as reflux at the top of the tower, and the reflux is partially pumped into the tower for recycling, and a small amount of methylal is pumped into a methyl formate tower for recycling methyl formate, so that the recycling of raw materials and the internal balance of formic acid are realized.
The composition of the overhead methyl formate recovery (stream 023) is as follows:
| logistics, 023 | Mass, kg | Duty ratio of% |
| Methyl formate | 3.3 | 2.6％ |
| Water and its preparation method | 0.5 | 0.1％ |
| Methanol | 102.7 | 74.6％ |
| Methylal (methylal) | 31.3 | 23.4％ |
The material with the byproduct mainly methanol is extracted by a side stream discharging pump U under the rectifying action of a rectifying and separating section QIV at the right side of the reaction section, so that the reaction products and the byproducts are moved out of the reaction system, and the reaction is promoted. After stripping in stripping section three QIII, crude product mainly M2-3 is obtained in the tower bottom and pumped to a separation tower X for further refining and separation.
The reaction equation involved in this paragraph is as follows:
as can be seen from the reaction (3), the methanol as a reaction byproduct is a limiting factor for limiting the forward progress of the reaction, and the product M of the reaction is extracted from the tower kettle 2-3 Enriched methanol is extracted from the right side of the partition wall reaction section. Thereby realizing efficient forward movement of the reaction.
The composition of the side draw (stream 025) is as follows:
| logistics, 025 | Mass, kg | Duty ratio of% |
| Formaldehyde | 48.2 | 8.9％ |
| Water and its preparation method | 36.3 | 6.7％ |
| Methanol | 298.6 | 55.0％ |
| Methylal (methylal) | 128.6 | 23.7％ |
| M2 | 26.0 | 4.8％ |
| M3 | 5.0 | 0.9％ |
| M4 | 0.0 | 0.0％ |
| Summing up | 543 | 100.0％ |
The top of stripping section tri-Q III 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 reaction section tri-Q II is increased, and the forward movement of the reaction is promoted.
Extracting and distilling the stripping section at the bottom of the dimer synthesizing tower Q, extracting a crude product mainly comprising M2-5 from the tower kettle, and pumping the crude product into a separation tower to purify the target product. Actual operating temperature: 90-120 deg.c and 0.1-0.25MPa.
(stream 026) the composition is as follows:
| logistics, 026 | Mass, kg | Duty ratio of% |
| Formaldehyde | 126.0 | 9.2％ |
| Water and its preparation method | 6.0 | 0.4％ |
| Methanol | 152.0 | 11.2％ |
| Methylal (methylal) | 42.3 | 3.1％ |
| M2 | 450.5 | 33.1％ |
| M3 | 373.3 | 27.4％ |
| M4 | 212.5 | 15.6％ |
The feed to separation column X was in two parts, one part from the middle section of the dimer bulkhead column and the other part from the bottom of the dimer bulkhead column. With the feed being predominantly at 5-8 plates and 10-12 plates.
The enriched methanol and a small amount of methylal are rectified to higher concentration in the separation tower X, the methanol and the methylal are extracted by a pump through a condenser and a reflux tank, part of the methanol and the methylal are used as reflux at the top of the tower, and the part of the methylal is pumped out of the system to be recycled as raw materials for synthesizing methylal after being recovered and refined.
(stream 028) the composition is as follows:
the material mainly comprising dimer is extracted from the middle section of the separation tower X and is pumped to a pre-reactor II H of the M3-5 synthesis tower J through a side extraction pump ZB to be used as a main raw material for synthesizing M3-5. Preferred operating temperature: 90-120 ℃.
(stream 030) the composition is as follows:
| logistics 030 | Mass, kg | Duty ratio of% |
| Formaldehyde | 167.3 | 25％ |
| Water and its preparation method | 40.1 | 6％ |
| Methanol | 52.7 | 8％ |
| Methylal (methylal) | 10.1 | 2％ |
| M2 | 388.5 | 57％ |
| M3 | 21.3 | 3％ |
| M4 | 0.0 | 0％ |
After the stripping section of the separation tower X plays a role in stripping, the crude product mainly comprising 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 the product with higher purity. Preferred operating temperature: 130-170 ℃ and the operating pressure is 0.1-0.35Mpa.
(stream 031) the composition is as follows:
the final stream 031 is combined with stream 018 and then stream 032 is sent out of the system for further separation or collection as desired.
The composition of the target product (stream 032) is as follows:
| logistics 032 | Mass, kg | Duty ratio of% |
| Formaldehyde | 1.2 | 0.1％ |
| Water and its preparation method | 0.6 | 0.1％ |
| Methanol | 2.1 | 0.2％ |
| Methylal (methylal) | 1.3 | 0.1％ |
| M2 | 27.2 | 2.3％ |
| M3 | 767.3 | 66.0％ |
| m4 | 362.1 | 31.2％ |
The above is a preferred embodiment of the present invention, and a person skilled in the art can also make alterations and modifications to the above embodiment, therefore, the present invention is not limited to the above specific embodiment, and any obvious improvements, substitutions or modifications made by the person skilled in the art on the basis of the present invention are all within the scope of the present invention.
Claims (1)
1. A process method for synthesizing polymethoxy dimethyl ether is characterized by comprising the following steps,
step one, pumping reaction raw materials of methanol and formaldehyde aqueous solution into a pre-reactor I (A) according to a certain proportion, specifically 85-99% methylal and 35-85% formaldehyde aqueous solution; sending the mixture to the upper part of a reaction section of a methylal synthesizing tower (B) through preliminary reaction, and continuously reacting in a reaction section I (BII) in the tower to obtain methylal with concentration of 88-94% at the top of the tower;
pumping methylal obtained from the top of the methylal synthesizing tower (B) to a pre-reactor II (H), jointly reacting with a raw material which is returned subsequently and mainly comprises dimer, pumping to an M3-5 synthesizing tower (J), and deeply reacting again; after the unreacted components at the tower top are absorbed by the tower top spray absorption system, part of the components are refluxed, part of the components are recovered by extraction, 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 a methylal synthesizing tower (B) and a high-concentration formaldehyde aqueous solution, performing preliminary reaction in a pre-reactor II (P), pumping into the top of a reaction section III (QII) on the left side of a dimer synthesizing tower with a partition wall reactor, further participating in the reaction, and taking byproduct methanol out from a side line of a rectifying section on the right side and delivering the byproduct methanol to a separating tower (X) for recycling;
through the refining action of the rectifying section III (Q I) at the top of the tower, methylal cooled by the condenser II (R) at the top of the tower is partially in reflux through the reflux tank II (S), and partially sent to the middle lower part of the reaction section III (Q II) of the dimer synthesizing tower (Q) through the reflux pump II (T) for recycling in the system;
after stripping action of a stripping section III (QIII) at the bottom of the dimer synthesis tower (Q), pumping the crude product into a separation tower (X);
pumping the material extracted from the side line into the upper half part of a separation tower (X) by a side line discharge pump (U), pumping the bottom material of a dimer synthesis tower (Q) into the lower half part of the separation tower (X) by a reboiler II (V), rectifying to obtain a crude product at the tower bottom, and sending the tower top byproduct to a recovery unit by a reflux pump III (ZA) for further refining and recycling;
the reaction equation involved in this paragraph is as follows:
CH 2 O + M 1 (methylal) ⟺ M 2 (dimer) (1)
CH 2 O + M 2 (dimer) ⟺ M 3 (trimer) (2)
H 2 O + M 1 (methylal) ⟺ CH 2 O + 2CH 3 OH ③
H 2 O + 2M 1 (methylal) ⟺ M 2 (dimer) +2CH 3 OH ④
Rectifying the methylal which is not completely reacted to a higher concentration in a rectifying section I (BI) at the tower top, extracting the methylal by a reflux pump I (E) through a condenser I (D) and a reflux tank I (C), partially pumping the methylal serving as reflux at the tower top into the tower for recycling, and pumping a small amount of methylal into a methyl formate tower for recycling methyl formate to realize the recycling of raw materials and the system internal balance of formic acid;
step six, a side line extraction pump (ZB) of the separation tower (X) extracts the dimer which is not completely converted, and sends the dimer to the front end of a second pre-reactor (H) of the M3-5 synthesis tower (J) to continuously participate in the reaction;
in the first step, the mass ratio of the methanol to the formaldehyde aqueous solution is (1-2.5): 1, wherein the concentration of the formaldehyde aqueous solution is 35-85%;
the concentration of methylal supplemented by the M3-5 synthesis tower (J) in the second step is 85-99%;
the low-temperature type cation adsorption resin catalyst of the first pre-reactor (A) is used in an amount of 50-300Kg/M, the medium Wen Xingyang ion adsorption resin catalyst of the second pre-reactor (H) is used in an amount of 60-280Kg/M, and the medium Wen Xingyang ion adsorption resin catalyst of the third pre-reactor (P) is used in an amount of 60-200 Kg/M;
the using amount of the medium-temperature solid acid catalyst in the catalytic section of the methylal synthesizing tower (B) is 80-280 Kg/M; the usage amount of the high-temperature solid acid catalyst in the catalytic section of the M3-5 synthesis tower (J) is 80-180 Kg/M; 10-90Kg/M of solid heteropolyacid catalyst; the dosage of the low-temperature solid acid catalyst in the catalytic section of the dimer synthesis tower (Q) is 50-250 Kg/M; 60-100Kg/M of solid heteropolyacid catalyst;
the first rectifying section (BI), the second rectifying section (BI) and the third rectifying section (QI) can adopt structured packing, the first stripping section (BIII), the second stripping section (BIII) and the third stripping section (QIII) can adopt bubble cap trays or floating valve plates, the third reaction section (QII) of the left partition wall can adopt structured packing, and the right partition wall rectifying and separating section (QIV) can adopt structured packing or bulk 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 |
| 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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