Purification system and purification method of polyoxymethylene dimethyl ether crude product

Abstract

The invention belongs to the technical field of purification, and particularly relates to a purification system and a purification method of a polyoxymethylene dimethyl ether crude product. The invention provides a purification system for a polyoxymethylene dimethyl ether crude product. The purification system comprises a catalytic rectifying tower, and a deacidification unit, a dehydration unit and a light component removal tower which are sequentially communicated with a tower top discharge port of the catalytic rectifying tower, and a heavy component removal tower communicated with a tower kettle discharge port of the catalytic rectifying tower. According to the purification system provided by the invention, water and acid in the polyoxymethylene dimethyl ether crude product can be more effectively removed, so that polyoxymethylene dimethyl ether of different polymers can be more effectively purified and separated in the subsequent rectification process.

Description

Technical Field

[0001] The invention belongs to the technical field of purification, and in particular relates to a purification system and a purification method for a crude polyoxymethylene dimethyl ether product. Background Art

[0002] Polyoxymethylene dimethyl ether (DMM n , n = 1 ~ 8) is a general term for a class of linear polyether substances, which have only two chemical bonds, CO and CH, in their molecular structure. They have the characteristics of high cetane number, high oxygen content, good volatility, no sulfur and aromatic hydrocarbons, and are a new type of diesel additive. In addition, DMM 2～4 It can dissolve resins (polyester, acrylate, epoxy resin, etc.), oils and waxes, is easily degradable and has low toxicity. It is a good substitute for aromatic hydrocarbons (toluene, xylene), N,N-dimethylformamide, halogenated hydrocarbons and ether solvents, and has great market prospects.

[0003] The raw materials for the synthesis of polyoxymethylene dimethyl ethers are mainly methanol (or dimethyl ether) and formaldehyde derivatives, among which methanol (or dimethyl ether) provides the end-capping methoxyl group (CH 3 -), formaldehyde derivatives provide intermediate methoxy groups (-CH 2 O-). In the process of synthesis, water is inevitably produced as a byproduct. Under acidic conditions, polyoxymethylene dimethyl ether will be hydrolyzed into formaldehyde and methanol during distillation, and formaldehyde will be further disproportionated into formic acid. In addition, the boiling point of water and dioxymethylene dimethyl ether (DMM) 2 ) have similar boiling points and will form an azeotrope, making it difficult to obtain purified DMM. 2 Therefore, before the crude polyoxymethylene dimethyl ether product is distilled and purified, the water and formic acid must be removed.

[0004] Traditional separation methods generally use multi-stage series distillation towers to obtain DMMs with different boiling points. n However, multi-stage series distillation cannot effectively remove water and formic acid in the mixed system, which will affect the subsequent separation efficiency of polyoxymethylene dimethyl ethers with different polymerization degrees. Summary of the invention

[0005] The object of the present invention is to provide a purification system and a purification method for a crude polyoxymethylene dimethyl ether product. The purification system provided by the present invention can effectively remove water and formic acid from the crude product and improve the separation efficiency of polyoxymethylene dimethyl ethers with different polymerization degrees.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The invention provides a purification system for a crude polyoxymethylene dimethyl ether product, comprising a catalytic distillation tower, a deacidification unit, a dehydration unit and a lightness removal tower which are sequentially connected to a tower top discharge port of the catalytic distillation tower, and a heavyness removal tower which is connected to a tower bottom discharge port of the catalytic distillation tower.

[0008] Preferably, the tower body of the catalytic distillation tower comprises a distillation section, a reaction section and a stripping section from top to bottom.

[0009] Preferably, the number of theoretical plates of the catalytic distillation tower is 18 to 30;

[0010] The number of theoretical plates of the rectification section is 1 to 8; the number of theoretical plates of the reaction section is 5 to 25; and the number of theoretical plates of the stripping section is 15 to 30.

[0011] Preferably, the deacidification unit comprises a plurality of fixed-bed deacidification towers connected in parallel;

[0012] Each fixed bed deacidification tower is filled with a deacidification agent; the deacidification agent includes one or more of magnesium oxide, deacidification molecular sieve, deacidification silica gel, solid base and supported solid base;

[0013] Preferably, the dehydration unit comprises a plurality of fixed bed dehydration towers connected in parallel;

[0014] Each fixed bed dehydration tower is filled with a dehydrating agent; the dehydrating agent comprises one or more of dehydrating molecular sieves, dehydrating silica gel, alumina and macroporous resin.

[0015] Preferably, the theoretical plate number of the light-removal tower is 10-20; the theoretical plate number of the heavy-removal tower is 10-20.

[0016] The present invention also provides a method for purifying a crude polyoxymethylene dimethyl ether product, which is purified by using the purification system described in the above technical solution, comprising the following steps:

[0017] Passing the crude polyoxymethylene dimethyl ether product and ethylene oxide into a catalytic distillation tower for reaction, obtaining a first light component from the top of the catalytic distillation tower, and obtaining a first heavy component from the bottom of the catalytic distillation tower;

[0018] The first light component is sequentially introduced into a deacidification unit, a dehydration unit and a lightness removal tower, and deacidification treatment, dehydration treatment and a first distillation are sequentially performed, a second light component is obtained from the top of the lightness removal tower, and a second heavy component is obtained from the bottom of the lightness removal tower; the second light component includes polymethoxy dimethyl ether and methanol, and the second heavy component includes dimerized methoxy dimethyl ether;

[0019] The first heavy component is introduced into a de-weighting tower for a second distillation, a third light component is obtained from the top of the de-weighting tower, and a third heavy component is obtained from the bottom of the de-weighting tower; the third light component includes trimerized methoxydimethyl ether, tetramerized methoxydimethyl ether, pentamerized methoxydimethyl ether and hexamerized methoxydimethyl ether, and the third heavy component includes heptamerized methoxydimethyl ether and octamerized methoxydimethyl ether.

[0020] Preferably, the operating pressure of the reaction is 0.2-0.8 MPa; the top temperature of the catalytic distillation tower is 70-140° C., the bottom temperature is 150-250° C.; and the reflux ratio is 0.5-3.0.

[0021] Preferably, the operating pressure of the first distillation is 0.1-0.3 MPa; the operating temperature of the first distillation is 40-120° C.; and the reflux ratio is 0.4-0.9.

[0022] Preferably, the operating pressure of the second distillation is 0.01-0.3 MPa; the operating temperature of the second distillation is 100-280° C.; and the reflux ratio is 0.1-1.

[0023] The present invention provides a purification system for a crude polyoxymethylene dimethyl ether product, comprising a catalytic distillation tower, and a deacidification unit, a dehydration unit and a lightness removal tower which are sequentially connected to a tower top discharge port of the catalytic distillation tower, and a heavyness removal tower which is connected to a tower bottom discharge port of the catalytic distillation tower. The purification system provided by the present invention can more effectively remove water and acid from the crude polyoxymethylene dimethyl ether product, thereby enabling polyoxymethylene dimethyl ethers of different polymers to be more effectively purified and separated in a subsequent distillation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the purification system used in Example 1, wherein 1-catalytic distillation tower, 2-fixed bed acid removal tower, 3-fixed bed dehydration tower, 4-light removal tower, 5-heavy removal tower, 11-distillation section, 12-reaction section, and 13-stripping section. DETAILED DESCRIPTION

[0025] The invention provides a purification system for a crude polyoxymethylene dimethyl ether product, comprising a catalytic distillation tower, a deacidification unit, a dehydration unit and a lightness removal tower which are sequentially connected to a tower top discharge port of the catalytic distillation tower, and a heavyness removal tower which is connected to a tower bottom discharge port of the catalytic distillation tower.

[0026] In the present invention, the number of theoretical plates of the catalytic distillation tower is preferably 18-30, more preferably 20-28, and even more preferably 23-25.

[0027] In the present invention, the tower body of the catalytic distillation tower preferably includes a distillation section, a reaction section and a stripping section from top to bottom.

[0028] In the present invention, the number of theoretical plates of the distillation section is preferably 1 to 8, more preferably 2 to 7, and more preferably 3 to 6. In the present invention, the distillation section is preferably filled with a packing; the packing preferably includes a dense packing or a structured packing. The present invention has no particular limitation on the type of the packing, and any type known to those skilled in the art may be used.

[0029] In the present invention, the number of theoretical plates of the reaction section is preferably 5 to 25, more preferably 10 to 20, and more preferably 15 to 18. In the present invention, the reaction section is preferably filled with a structured packing containing a solid acid catalyst. In the present invention, the solid acid catalyst preferably includes a molecular sieve catalyst, a solid superacid or a sulfonic acid type cation exchange resin; the molecular sieve catalyst preferably includes a Zn-SSZ-13 molecular sieve catalyst and a TS-1 molecular sieve catalyst. In the present invention, the mass percentage of the solid acid catalyst in the structured packing containing the solid acid catalyst is preferably 30 to 75%. The present invention does not specifically limit the type of the structured packing, and those known to those skilled in the art may be used.

[0030] In the present invention, the number of theoretical plates of the stripping section is preferably 15 to 30, more preferably 18 to 28, and more preferably 20 to 25. In the present invention, the stripping section is preferably filled with a packing; the packing preferably includes a dense packing or a structured packing. The present invention has no particular limitation on the type of the packing, and any type known to those skilled in the art may be used.

[0031] In the present invention, the deacidification unit preferably includes a plurality of fixed bed deacidification towers connected in parallel; the number of the fixed bed deacidification towers is preferably ≥2. In the present invention, each fixed bed deacidification tower is preferably loaded with a deacidification agent; the deacidification agent preferably includes one or more of magnesium oxide, deacidification molecular sieve, deacidification silica gel, solid base and supported solid base. In the present invention, the deacidification unit also preferably includes a fixed bed regeneration tower connected to each fixed bed deacidification tower. In the present invention, when a single fixed bed deacidification tower reaches a saturated state, the fixed bed deacidification tower is regenerated by a fixed bed regeneration tower.

[0032] In the present invention, the dehydration unit preferably includes a plurality of fixed bed dehydration towers connected in parallel; the number of the fixed bed deacidification towers is preferably ≥2. In the present invention, each fixed bed deacidification tower is preferably filled with a dehydrating agent; the dehydrating agent includes one or more of a dehydrating molecular sieve, a dehydrated silica gel, alumina and a macroporous resin, and the dehydrating molecular sieve is preferably a 3A molecular sieve. In the present invention, the dehydration unit also preferably includes a fixed bed regeneration tower connected to each fixed bed dehydration tower. In the present invention, when a single fixed bed dehydration tower reaches a saturated state, the fixed bed dehydration tower is regenerated by a fixed bed regeneration tower.

[0033] In the present invention, the theoretical plate number of the lightness removal tower is preferably 10-20, more preferably 12-18, and even more preferably 15-16.

[0034] In the present invention, the number of theoretical plates of the deweighting tower is preferably 10-20, more preferably 12-18, and even more preferably 15-16.

[0035] The present invention also provides a method for purifying a crude polyoxymethylene dimethyl ether product, which is purified by using the purification system described in the above technical solution, comprising the following steps:

[0036] Passing the crude polyoxymethylene dimethyl ether product and ethylene oxide into a catalytic distillation tower for reaction, obtaining a first light component from the top of the catalytic distillation tower, and obtaining a first heavy component from the bottom of the catalytic distillation tower;

[0037] The first light component is sequentially introduced into a deacidification unit, a dehydration unit and a lightness removal tower, and deacidification treatment, dehydration treatment and a first distillation are sequentially performed, a second light component is obtained from the top of the lightness removal tower, and a second heavy component is obtained from the bottom of the lightness removal tower; the second light component includes polymethoxy dimethyl ether and methanol, and the second heavy component includes dimerized methoxy dimethyl ether;

[0038] The first heavy component is introduced into a de-weighting tower for a second distillation, a third light component is obtained from the top of the de-weighting tower, and a third heavy component is obtained from the bottom of the de-weighting tower; the third light component includes trimerized methoxydimethyl ether, tetramerized methoxydimethyl ether, pentamerized methoxydimethyl ether and hexamerized methoxydimethyl ether, and the third heavy component includes heptamerized methoxydimethyl ether and octamerized methoxydimethyl ether.

[0039] In the present invention, unless otherwise specified, all raw materials are commercially available products well known to those skilled in the art.

[0040] The invention introduces a crude polyoxymethylene dimethyl ether product and ethylene oxide into a catalytic distillation tower for reaction, obtains a first light component from the top of the catalytic distillation tower, and obtains a first heavy component from the bottom of the catalytic distillation tower.

[0041] In the present invention, the composition ratio of the crude polyoxymethylene dimethyl ether product is as shown in Table 1;

[0042] Table 1 Composition ratio of crude polyoxymethylene dimethyl ether product

[0043] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 40～50 Dimethoxy dimethyl ether 20～30 Trimethoxy dimethyl ether 8～15 Tetramethoxy dimethyl ether 5～10 Pentamethoxy dimethyl ether 1～5 Hexamethoxydimethyl ether 1～5 Heptamethoxy dimethyl ether 0.2～2 Octamethoxy dimethyl ether 0.1～1.5 Methanol 0.5～5 Formic acid 0.01～1.0 formaldehyde 0.1～10 water 0.1～3 dimethyl ether 0.1～3

[0044] The present invention has no special limitation on the source of the crude polyoxymethylene dimethyl ether product, and any method known to those skilled in the art can be used. In the present invention, the feeding method of the crude polyoxymethylene dimethyl ether product is preferably plate feeding; the number of feeding plates of the crude polyoxymethylene dimethyl ether product is preferably 2 to 8. In the present invention, the feeding amount of the crude polyoxymethylene dimethyl ether product is preferably 40 to 120 kg / h.

[0045] In the present invention, the feeding method of the ethylene oxide is preferably feeding on a plate; the number of feeding plates of the ethylene oxide is preferably 5 to 25. In the present invention, the feeding amount of the ethylene oxide is preferably 1 to 4 kg / h. In the present invention, the ethylene oxide can completely convert water into ethylene glycol or diethylene glycol.

[0046] In the present invention, the crude polyoxymethylene dimethyl ether product and ethylene oxide are preferably preheated before being introduced into the catalytic distillation tower; the temperature of the crude polyoxymethylene dimethyl ether product after preheating is preferably 100-160°C; the temperature of the ethylene oxide after preheating is preferably 30-150°C.

[0047] In the present invention, the operating pressure of the reaction is preferably 0.2-0.8 MPa, more preferably 0.3-0.7 MPa, and more preferably 0.4-0.6 MPa. In the present invention, the top pressure of the catalytic distillation tower is preferably 0.5-0.6 MPa, and the bottom pressure is preferably 0.5-0.6 MPa.

[0048] In the present invention, the top temperature of the catalytic distillation tower is preferably 70-140°C, more preferably 90-130°C, more preferably 100-120°C; the bottom temperature is preferably 150-250°C, more preferably 160-220°C, more preferably 180-200°C.

[0049] In the present invention, the temperature of the rectifying section is preferably 70 to 170°C, more preferably 100 to 150°C, and more preferably 120 to 130°C. In the present invention, the temperature of the reaction section is preferably 140 to 210°C, more preferably 170 to 200°C, and more preferably 180 to 190°C. In the present invention, the temperature of the stripping section is preferably 190 to 240°C, more preferably 200 to 230°C, and more preferably 210 to 220°C.

[0050] In the present invention, the reflux ratio of the reaction is preferably 0.5 to 3.0, more preferably 1.0 to 2.5, and even more preferably 1.5 to 2.0.

[0051] In the present invention, the composition ratio of the first light component is as shown in Table 2;

[0052] Table 2: Composition ratio of the first light component

[0053] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 50～70 Dimethoxy dimethyl ether 20～40 Methanol 1～7 Formic acid 0.05～1.0 formaldehyde 0.01～13.2 water 0.01～1 dimethyl ether 0.01～3

[0054] In the present invention, the composition ratio of the first heavy component is as shown in Table 3;

[0055] Table 3 Composition ratio of the first heavy component

[0056] type Mass percentage / % type Mass percentage / % Trimethoxy dimethyl ether 20～40 Tetramethoxy dimethyl ether 15～30 Pentamethoxy dimethyl ether 10～20 Hexamethoxydimethyl ether 5～10 Heptamethoxy dimethyl ether 2～5 Octamethoxy dimethyl ether 0.1～3

[0057] In the present invention, the recovery rate of the first heavy component is preferably 97-99%.

[0058] After obtaining the first light component, the present invention sequentially passes the first light component into a deacidification unit, a dehydration unit and a light-removing tower, sequentially performs deacidification treatment, dehydration treatment and a first distillation, obtains a second light component from the top of the light-removing tower, and obtains a second heavy component from the bottom of the light-removing tower; the second light component includes polymethoxydimethyl ether and methanol, and the second heavy component includes dimerized methoxydimethyl ether.

[0059] In the present invention, the temperature of the deacidification treatment is preferably 60 to 120° C. In the present invention, the temperature of the dehydration treatment is preferably 25 to 60° C. The present invention has no particular limitation on the deacidification treatment and dehydration treatment processes, and the processes well known to those skilled in the art can be used.

[0060] In the present invention, the feeding method of the material introduced into the lightness removal tower is preferably plate feeding; the number of feeding plates of the material is preferably 7-12.

[0061] In the present invention, the operating pressure of the first distillation is preferably 0.1-0.3 MPa, more preferably 0.1-0.2 MPa. In the present invention, the top pressure of the lightness removal tower is preferably 0.1-0.16 MPa, and the bottom pressure is preferably 0.2-0.26 MPa.

[0062] In the present invention, the operating temperature of the first distillation is preferably 40-120° C. In the present invention, the top temperature of the lightness removal tower is preferably 14-60° C., more preferably 40-55° C., more preferably 45-50° C.; the bottom temperature is preferably 80-120° C.

[0063] In the present invention, the reflux ratio of the first distillation is preferably 0.4 to 0.9, more preferably 0.5 to 0.7, and even more preferably 0.5 to 0.6.

[0064] In the present invention, the second light component preferably comprises 90-99% polyoxymethylene dimethyl ether and 1-10% methanol in terms of mass percentage. In the present invention, the second light component is preferably returned to the first distillation process as a raw material for recycling.

[0065] In the present invention, the recovery rate of the dimethoxy dimethyl ether is preferably 95 to 99.5%.

[0066] After obtaining the first heavy component, the present invention passes the first heavy component into a de-weighting tower for second distillation, obtains a third light component from the top of the de-weighting tower, and obtains a third heavy component from the bottom of the de-weighting tower; the third light component includes trimerized methoxydimethyl ether, tetramerized methoxydimethyl ether, pentamerized methoxydimethyl ether and hexamerized methoxydimethyl ether, and the third heavy component includes heptamerized methoxydimethyl ether and octamerized methoxydimethyl ether.

[0067] In the present invention, the feeding method of the material introduced into the deweighting tower is preferably plate feeding; the number of feeding plates of the material is preferably 7-10.

[0068] In the present invention, the operating pressure of the second distillation is preferably 0.01-0.3 MPa, more preferably 0.02-0.2 MPa, and more preferably 0.03 MPa. In the present invention, the top pressure of the deweighting tower is preferably 0.01-0.03 MPa, and the bottom pressure is preferably 0.15-0.04 MPa.

[0069] In the present invention, the operating temperature of the second distillation is preferably 100-280°C. In the present invention, the top temperature of the deweighting tower is preferably 65-135°C, more preferably 80-130°C, more preferably 90-120°C; the bottom temperature is preferably 160-280°C. In the present invention, the reflux ratio of the second distillation is preferably 0.1-1, more preferably 0.2-0.8, more preferably 0.3-0.5.

[0070] In the present invention, the third light component preferably comprises 20-50% of trimerized methoxy dimethyl ether, 15-30% of tetramerized methoxy dimethyl ether, 10-20% of pentamerized methoxy dimethyl ether and 5-10% of hexamerized methoxy dimethyl ether in terms of mass percentage. In the present invention, the recovery rate of the third light component is preferably 95-99.3%.

[0071] In the present invention, the third heavy component preferably includes 50-70% heptamethoxy dimethyl ether and 20-40% octamethoxy dimethyl ether in terms of mass percentage. In the present invention, the recovery rate of the third heavy component is preferably 95-99%.

[0072] In order to further illustrate the present invention, a purification system and a purification method for a crude polyoxymethylene dimethyl ether product provided by the present invention are described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0073] Example 1

[0074] use Figure 1 The purification system shown purifies polyoxymethylene dimethyl ether;

[0075] The composition ratio of the crude polyoxymethylene dimethyl ether product in this embodiment is shown in Table 4:

[0076] Table 4 Composition ratio of crude polyoxymethylene dimethyl ether product

[0077]

[0078]

[0079] The crude polyoxymethylene dimethyl ether product was preheated to 150°C and then introduced into a catalytic distillation tower (theoretical plate number is 20) at a flow rate of 100 kg / h, and the number of feed plates was 4 (where the plates are numbered incrementally from top to bottom); ethylene oxide was preheated to 30°C and then introduced into the catalytic distillation tower at a flow rate of 2.4 kg / h, and the number of feed plates was 13. The reaction was carried out in the catalytic distillation tower at an operating pressure of 0.6 MPa (where the top pressure was 0.6 MPa and the bottom pressure was 0.6 MPa). The pressure is 0.6MPa), the temperature of the rectification section is 107-130°C, the temperature of the reaction section (wherein the solid acid catalyst is TS-1, and the mass percentage of the solid acid catalyst is 72%) is 136-202°C, the temperature of the stripping section is 203-238°C, the tower top temperature is 107°C, the tower bottom temperature is 238°C, and the reflux ratio is 1.5 to obtain a first light component and a first heavy component (with a recovery rate of 99%); the composition ratio of the first light component is shown in Table 5;

[0080] Table 5: Composition ratio of the first light component

[0081] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 59.92 Dimethoxy dimethyl ether 35.47 Methanol 2.63 Formic acid 0.13 formaldehyde 0.05 water 0.01 dimethyl ether 0.13

[0082] The composition ratio of the first component is shown in Table 6;

[0083] Table 6 Composition ratio of the first heavy component

[0084] type Mass percentage / % type Mass percentage / % Trimethoxy dimethyl ether 37.41 Tetramethoxy dimethyl ether 22.72 Pentamethoxy dimethyl ether 15.15 Hexamethoxydimethyl ether 7.04 Heptamethoxy dimethyl ether 3.78 Octamethoxy dimethyl ether 1.89

[0085] The first light component is sequentially passed into a deacidification tower (deacidification agent is MgO), a dehydration tower (dehydration agent is 3A molecular sieve) and a lightness removal tower (theoretical plate number is 18, feed plate number is 9), and deacidification treatment (deacidification temperature is 80° C.), dehydration treatment (dehydration temperature is 25° C.) and a first rectification treatment are sequentially performed, the operating temperature of the first rectification is 110° C. (tower top temperature is 45° C., tower bottom temperature is 111.5° C.), the operating pressure is 0.26 MPa (tower top pressure is 0.15 MPa, tower bottom pressure is 0.26 MPa), and the reflux ratio is 0.5, to obtain a second light component (comprising 94.39% of polymethoxy dimethyl ether and 2.41% of methanol) and dimerized methoxy dimethyl ether (with a recovery rate of 98.6%);

[0086] The first heavy component is passed into a deweighting tower (theoretical plate number is 20, feed plate number is 10), and a second distillation is performed, wherein the operating temperature of the second distillation is 258.1° C. (tower top temperature is 87° C., tower bottom temperature is 258° C.), the operating pressure is 0.02 MPa (tower top pressure is 0.01 MPa, tower bottom pressure is 0.02 MPa), and the reflux ratio is 0.1, to obtain a third light component (comprising 39.67% of trimerized methoxy dimethyl ether, 24.10% of tetramerized methoxy dimethyl ether, 16.10% of pentamerized methoxy dimethyl ether and 7.39% of hexamerized methoxy dimethyl ether, with a recovery rate of 99%) and a third heavy component (65.62% of heptamerized methoxy dimethyl ether and 33.14% of octamerized methoxy dimethyl ether, with a recovery rate of 98.8%).

[0087] Example 2

[0088] The composition ratio of the crude polyoxymethylene dimethyl ether product in this example is shown in Table 7.

[0089] Table 7 Composition ratio of crude polyoxymethylene dimethyl ether product

[0090] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 40.2 Dimethoxy dimethyl ether 21.3 Trimethoxy dimethyl ether 8.1 Tetramethoxy dimethyl ether 5.5 Pentamethoxy dimethyl ether 3.4 Hexamethoxydimethyl ether 1.9 Heptamethoxy dimethyl ether 1.1 Octamethoxy dimethyl ether 0.50 Methanol 5 Formic acid 1 formaldehyde 10 water 1.00 dimethyl ether 1.00

[0091] The crude polyoxymethylene dimethyl ether product was preheated to 150°C and then introduced into a catalytic distillation tower (theoretical plate number is 20) at a flow rate of 100 kg / h, and the number of feed plates was 4 (where the plates were numbered in ascending order from top to bottom); ethylene oxide was preheated to 30°C and then introduced into the catalytic distillation tower at a flow rate of 2.4 kg / h, and the number of feed plates was 13. The reaction was carried out in the catalytic distillation tower at an operating pressure of 0.6 MPa (where the tower top pressure was 0.6 MPa and the tower bottom pressure was 0.6 MPa). Pa), the temperature of the rectification section is 72.3-129.0°C, the temperature of the reaction section (wherein the solid acid catalyst is TS-1, and the mass percentage of the solid acid catalyst is 72%) is 141-154°C, the temperature of the stripping section is 155.9-219.8°C, the tower top temperature is 72.3°C, the tower bottom temperature is 219.8°C, and the reflux ratio is 1.5 to obtain a first light component and a first heavy component (with a recovery rate of 97.2%); the composition ratio of the first light component is shown in Table 8;

[0092] Table 8 Composition ratio of the first light component

[0093] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 52.9 Dimethoxy dimethyl ether 25.7 Methanol 6.5 Formic acid 0.07 formaldehyde 13.1 water 0.06 dimethyl ether 1.3

[0094] The composition ratio of the first component is shown in Table 9;

[0095] Table 9: Composition ratio of the first heavy component

[0096] type Mass percentage / % type Mass percentage / % Trimethoxy dimethyl ether 30.6 Tetramethoxy dimethyl ether 20.8 Pentamethoxy dimethyl ether 12.9 Hexamethoxydimethyl ether 7.2 Heptamethoxy dimethyl ether 4.2 Octamethoxy dimethyl ether 1.9

[0097] The first light component is sequentially passed into a deacidification tower (deacidification agent is MgO), a dehydration tower (dehydration agent is 3A molecular sieve) and a lightness removal tower (theoretical plate number is 21, and feed plate number is 11), and deacidification treatment (deacidification temperature is 80° C.), dehydration treatment (dehydration temperature is 25° C.) and a first rectification treatment are sequentially performed, the operating temperature of the first rectification is 110° C. (tower top temperature is 14.1° C., and tower bottom temperature is 105.9° C.), the operating pressure is 0.26 MPa (tower top pressure is 0.15 MPa, and tower bottom pressure is 0.26 MPa), and the reflux ratio is 0.39, to obtain a second light component (comprising 93.7% of polymethoxy dimethyl ether and 5.3% of methanol) and dimerized methoxy dimethyl ether (with a recovery rate of 99.5%);

[0098] The first heavy component is passed into a deweighting tower (theoretical plate number is 18, feed plate number is 9), and a second distillation is performed, wherein the operating temperature of the second distillation is 258.1°C (tower top temperature is 65°C, tower bottom temperature is 258°C), the operating pressure is 0.02MPa (tower top pressure is 0.01MPa, tower bottom pressure is 0.02MPa), and the reflux ratio is 0.1, to obtain a third light component (comprising 32.6% of trimerized methoxy dimethyl ether, 22.2% of tetramerized methoxy dimethyl ether, 13.7% of pentamerized methoxy dimethyl ether and 7.6% of hexamerized methoxy dimethyl ether, with a recovery rate of 99%) and a third heavy component (67.8% of heptamerized methoxy dimethyl ether and 33.1% of octamerized methoxy dimethyl ether, with a recovery rate of 98.8%).

[0099] Example 3

[0100] The composition ratio of the crude polyoxymethylene dimethyl ether product in this example is shown in Table 10.

[0101] Table 10 Composition ratio of crude polyoxymethylene dimethyl ether product

[0102] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 49.2 Dimethoxy dimethyl ether 21.0 Trimethoxy dimethyl ether 10.4 Tetramethoxy dimethyl ether 6.4 Pentamethoxy dimethyl ether 3.1 Hexamethoxydimethyl ether 1.8 Heptamethoxy dimethyl ether 1.2 Octamethoxy dimethyl ether 0.8 Methanol 2 Formic acid 0.3 formaldehyde 1.8 water 1.00 dimethyl ether 1.00

[0103] After the crude polyoxymethylene dimethyl ether product is preheated to 150°C, it is passed into a catalytic distillation tower (theoretical plate number is 20) at a flow rate of 100 kg / h, and the number of feed plates is 4 (where the plate numbers are numbered incrementally from top to bottom); after the ethylene oxide is preheated to 30°C, it is passed into the catalytic distillation tower at a flow rate of 2.4 kg / h, and the number of feed plates is 13. The reaction is carried out in the catalytic distillation tower, and the operating pressure is 0.4 MPa (where the top pressure is 0.6 MPa and the bottom pressure is 0.6 MPa). Pa), the temperature of the rectification section is 96-137°C, the temperature of the reaction section (wherein the solid acid catalyst is TS-1, and the mass percentage of the solid acid catalyst is 72%) is 158.7-201.1°C, the temperature of the stripping section is 202.9-237.4°C, the tower top temperature is 96.7°C, the tower bottom temperature is 237.4°C, and the reflux ratio is 1.2 to obtain a first light component and a first heavy component (with a recovery rate of 99%); the composition ratio of the first light component is shown in Table 11;

[0104] Table 11 Composition ratio of the first light component

[0105] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 64.7 Dimethoxy dimethyl ether 27.6 Methanol 2.63 Formic acid 0.13 formaldehyde 2.3 water 0.01 dimethyl ether 0.13

[0106] The composition ratio of the first component is shown in Table 12;

[0107] Table 12 Composition ratio of the first heavy component

[0108]

[0109]

[0110] The first light component is sequentially passed into a deacidification tower (deacidification agent is MgO), a dehydration tower (dehydration agent is 3A molecular sieve) and a lightness removal tower (theoretical plate number is 19, feed plate number is 10), and deacidification treatment (deacidification temperature is 60°C), dehydration treatment (dehydration temperature is 40°C) and a first distillation treatment are sequentially performed, the operating temperature of the first distillation is 110°C (tower top temperature is 36.1°C, tower bottom temperature is 111.0°C), the operating pressure is 0.26MPa (tower top pressure is 0.15MPa, tower bottom pressure is 0.26MPa), and the reflux ratio is 0.5, to obtain a second light component (including 91.8% of polymethoxy dimethyl ether and 2.1% of methanol) and dimerized methoxy dimethyl ether (recovery rate is 99.1%);

[0111] The first heavy component is passed into a deweighting tower (theoretical plate number is 18, feed plate number is 10), and a second distillation is performed, wherein the operating temperature of the second distillation is 258.1°C (tower top temperature is 86.7°C, tower bottom temperature is 261°C), the operating pressure is 0.02MPa (tower top pressure is 0.01MPa, tower bottom pressure is 0.02MPa), and the reflux ratio is 0.1, to obtain a third light component (comprising 40.8% of trimerized methoxy dimethyl ether, 26.2% of tetramerized methoxy dimethyl ether, 12.7% of pentamerized methoxy dimethyl ether and 7.3% of hexamerized methoxy dimethyl ether, with a recovery rate of 99%) and a third heavy component (59.2% of heptamerized methoxy dimethyl ether and 39.8% of octamerized methoxy dimethyl ether, with a recovery rate of 99%).

[0112] Example 4

[0113] The composition ratio of the crude polyoxymethylene dimethyl ether product in this example is shown in Table 13.

[0114] Table 13 Composition ratio of crude polyoxymethylene dimethyl ether product

[0115] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 42.5 Dimethoxy dimethyl ether 25.6 Trimethoxy dimethyl ether 12.8 Tetramethoxy dimethyl ether 6.4 Pentamethoxy dimethyl ether 3.2 Hexamethoxydimethyl ether 1.6 Heptamethoxy dimethyl ether 0.8 Octamethoxy dimethyl ether 0.4 Methanol 3.0 Formic acid 0.2 formaldehyde 0.8 water 1.5 dimethyl ether 1.2

[0116] After the crude polyoxymethylene dimethyl ether product is preheated to 150°C, it is passed into a catalytic distillation tower (theoretical plate number is 21) at a flow rate of 100 kg / h, and the number of feed plates is 4 (where the plate numbers are numbered incrementally from top to bottom); after the ethylene oxide is preheated to 60°C, it is passed into the catalytic distillation tower at a flow rate of 1.2 kg / h, and the number of feed plates is 15. The reaction is carried out in the catalytic distillation tower, and the operating pressure is 0.6 MPa (where the tower top pressure is 0.6 MPa and the tower bottom pressure is 0.6 MPa) , the temperature of the rectification section is 105.8-150.3°C, the temperature of the reaction section (wherein the solid acid catalyst is TS-1, and the mass percentage of the solid acid catalyst is 72%) is 170-201.6°C, the temperature of the stripping section is 202.2-230.1°C, the tower top temperature is 105.8°C, the tower bottom temperature is 230.1°C, the reflux ratio is 1.4, and the first light component and the first heavy component are obtained (the recovery rate is 98.9%); the composition ratio of the first light component is shown in Table 14;

[0117] Table 14 Composition ratio of the first light component

[0118] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 55.9 Dimethoxy dimethyl ether 33.6 Methanol 3.9 Formic acid 0.26 formaldehyde 1.05 water 1.3 dimethyl ether 1.6

[0119] The composition ratio of the first component is shown in Table 15;

[0120] Table 15 Composition ratio of the first heavy component

[0121] type Mass percentage / % type Mass percentage / % Trimethoxy dimethyl ether 44.1 Tetramethoxy dimethyl ether 25.4 Pentamethoxy dimethyl ether 12.7 Hexamethoxydimethyl ether 6.3 Heptamethoxy dimethyl ether 3.1 Octamethoxy dimethyl ether 1.5

[0122] The first light component is sequentially passed into a deacidification tower (deacidification agent is MgO), a dehydration tower (dehydration agent is 3A molecular sieve) and a lightness removal tower (theoretical plate number is 18, feed plate number is 10), and deacidification treatment (deacidification temperature is 80° C.), dehydration treatment (dehydration temperature is 30° C.) and a first rectification treatment are sequentially performed, the operating temperature of the first rectification is 113.5° C. (tower top temperature is 40.1° C., tower bottom temperature is 113.8° C.), the operating pressure is 0.20 MPa (tower top pressure is 0.12 MPa, tower bottom pressure is 0.20 MPa), and the reflux ratio is 0.9, to obtain a second light component (comprising 91.2% of polymethoxy dimethyl ether and 3.9% of methanol) and dimerized methoxy dimethyl ether (recovery rate is 99%);

[0123] The first heavy component is passed into a deweighting tower (theoretical plate number is 18, feed plate number is 10), and a second distillation is performed, wherein the operating temperature of the second distillation is 258.7° C. (tower top temperature is 82.4° C., tower bottom temperature is 258.7° C.), the operating pressure is 0.04 MPa (tower top pressure is 0.02 MPa, tower bottom pressure is 0.04 MPa), and the reflux ratio is 0.3, to obtain a third light component (comprising 46.3% of trimerized methoxy dimethyl ether, 26.6% of tetramerized methoxy dimethyl ether, 13.3% of pentamerized methoxy dimethyl ether and 6.6% of hexamerized methoxy dimethyl ether, with a recovery rate of 99.1%) and a third heavy component (65.6% of heptamerized methoxy dimethyl ether and 33.1% of octamerized methoxy dimethyl ether, with a recovery rate of 98.7%).

[0124] Example 5

[0125] The composition ratio of the crude polyoxymethylene dimethyl ether product in this example is shown in Table 16.

[0126] Table 16 Composition ratio of crude polyoxymethylene dimethyl ether product

[0127] type Mass percentage / % type Mass percentage / % Polyoxymethylene dimethyl ether 46.1 Dimethoxy dimethyl ether 25.3 Trimethoxy dimethyl ether 10.6 Tetramethoxy dimethyl ether 5.4 Pentamethoxy dimethyl ether 3.8 Hexamethoxydimethyl ether 1.8 Heptamethoxy dimethyl ether 0.9 Octamethoxy dimethyl ether 0.5 Methanol 2.3 Formic acid 0.2 formaldehyde 1.1 water 1.2 dimethyl ether 0.8

[0128] After the crude polyoxymethylene dimethyl ether product is preheated to 140°C, it is passed into a catalytic distillation tower (theoretical plate number is 19) at a flow rate of 100 kg / h, and the number of feed plates is 4 (where the plate numbers are numbered incrementally from top to bottom); after the ethylene oxide is preheated to 70°C, it is passed into the catalytic distillation tower at a flow rate of 1.8 kg / h, and the number of feed plates is 13. The reaction is carried out in the catalytic distillation tower, and the operating pressure is 0.5 MPa (where the tower top pressure is 0.5 MPa and the tower bottom pressure is 0.5 MPa). The temperature of the rectification section is 102.5-128.2° C., the temperature of the reaction section (wherein the solid acid catalyst is TS-1, and the mass percentage of the solid acid catalyst is 72%) is 130.7-174.6° C., the temperature of the stripping section is 182.6-235.4° C., the tower top temperature is 102.5° C., the tower bottom temperature is 235.4° C., and the reflux ratio is 0.5, to obtain a first light component and a first heavy component (with a recovery rate of 97.2%); the composition ratio of the first light component is shown in Table 17;

[0129] Table 17 Composition ratio of the first light component

[0130]

[0131]

[0132] The composition ratio of the first component is shown in Table 18;

[0133] Table 18 Composition ratio of the first heavy component

[0134] type Mass percentage / % type Mass percentage / % Trimethoxy dimethyl ether 39.7 Tetramethoxy dimethyl ether 20.4 Pentamethoxy dimethyl ether 14.4 Hexamethoxydimethyl ether 6.8 Heptamethoxy dimethyl ether 3.4 Octamethoxy dimethyl ether 1.8

[0135] The first light component is sequentially passed into a deacidification tower (deacidification agent is MgO), a dehydration tower (dehydration agent is 3A molecular sieve) and a lightness removal tower (theoretical plate number is 13, feed plate number is 7), and deacidification treatment (deacidification temperature is 70°C), dehydration treatment (dehydration temperature is 40°C) and a first rectification treatment are sequentially performed, the operating temperature of the first rectification is 89.0°C (tower top temperature is 27.8°C, tower bottom temperature is 89.0°C), the operating pressure is 0.26MPa (tower top pressure is 0.10MPa, tower bottom pressure is 0.26MPa), and the reflux ratio is 0.4, to obtain a second light component (comprising 91.2% of polymethoxy dimethyl ether and 2.2% of methanol) and dimerized methoxy dimethyl ether (recovery rate is 95.4%);

[0136] The first heavy component is passed into a deweighting tower (theoretical plate number is 18, feed plate number is 10), and a second distillation is performed, wherein the operating temperature of the second distillation is 253.4°C (tower top temperature is 84.6°C, tower bottom temperature is 253.4°C), the operating pressure is 0.02MPa (tower top pressure is 0.01MPa, tower bottom pressure is 0.02MPa), and the reflux ratio is 0.15 to obtain a third light component (comprising 41.9% of trimerized methoxy dimethyl ether, 21.9% of tetramerized methoxy dimethyl ether, 15.2% of pentamerized methoxy dimethyl ether and 6.8% of hexamerized methoxy dimethyl ether, with a recovery rate of 96.7%) and a third heavy component (59.1% of heptamerized methoxy dimethyl ether and 34.5% of octamerized methoxy dimethyl ether, with a recovery rate of 95.3%).

[0137] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A purification system for a crude polyoxymethylene dimethyl ether product, characterized in that: The invention comprises a catalytic distillation tower, a deacidification unit, a dehydration unit and a lightness removal tower which are sequentially connected to the tower top discharge port of the catalytic distillation tower, and a heavyness removal tower which is connected to the tower bottom discharge port of the catalytic distillation tower.

2. The purification system according to claim 1, characterized in that The tower body of the catalytic distillation tower comprises a distillation section, a reaction section and a stripping section in sequence from top to bottom.

3. The purification system according to claim 1, characterized in that: The number of theoretical plates of the catalytic distillation tower is 18 to 30; The number of theoretical plates of the rectification section is 1 to 8; the number of theoretical plates of the reaction section is 5 to 25; and the number of theoretical plates of the stripping section is 15 to 30.

4. The purification system according to claim 1, characterized in that: The deacidification unit comprises a plurality of fixed-bed deacidification towers connected in parallel; Each fixed bed deacidification tower is filled with a deacidification agent; the deacidification agent includes one or more of magnesium oxide, deacidification molecular sieve, deacidification silica gel, solid alkali and supported solid alkali.

5. The purification system according to claim 1, characterized in that: The dehydration unit comprises a plurality of fixed bed dehydration towers connected in parallel; Each fixed bed dehydration tower is filled with a dehydrating agent; the dehydrating agent comprises one or more of dehydrating molecular sieves, dehydrating silica gel, alumina and macroporous resin.

6. The purification system according to claim 1, characterized in that The theoretical plate number of the light removal tower is 10 to 20; the theoretical plate number of the heavy removal tower is 10 to 20.

7. A method for purifying a crude polyoxymethylene dimethyl ether product, characterized in that: Purification using the purification system according to any one of claims 1 to 6 comprises the following steps: Passing the crude polyoxymethylene dimethyl ether product and ethylene oxide into a catalytic distillation tower for reaction, obtaining a first light component from the top of the catalytic distillation tower, and obtaining a first heavy component from the bottom of the catalytic distillation tower; The first light component is sequentially introduced into a deacidification unit, a dehydration unit and a lightness removal tower, and deacidification treatment, dehydration treatment and a first distillation are sequentially performed, a second light component is obtained from the top of the lightness removal tower, and a second heavy component is obtained from the bottom of the lightness removal tower; the second light component includes polymethoxy dimethyl ether and methanol, and the second heavy component includes dimerized methoxy dimethyl ether; The first heavy component is introduced into a de-weighting tower for a second distillation, a third light component is obtained from the top of the de-weighting tower, and a third heavy component is obtained from the bottom of the de-weighting tower; the third light component includes trimerized methoxydimethyl ether, tetramerized methoxydimethyl ether, pentamerized methoxydimethyl ether and hexamerized methoxydimethyl ether, and the third heavy component includes heptamerized methoxydimethyl ether and octamerized methoxydimethyl ether.

8. The purification method according to claim 7, characterized in that: The operating pressure of the reaction is 0.2-0.8 MPa; the top temperature of the catalytic distillation tower is 70-140° C., the bottom temperature is 150-250° C.; and the reflux ratio is 0.5-3.

0.

9. The purification method according to claim 7, characterized in that: The operating pressure of the first distillation is 0.1-0.3 MPa; the operating temperature of the first distillation is 40-120° C.; and the reflux ratio is 0.4-0.

9.

10. The purification method according to claim 7, characterized in that: The operating pressure of the second distillation is 0.01-0.3 MPa; the operating temperature of the second distillation is 100-280° C.; and the reflux ratio is 0.1-1.

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