阅读说明：本技术 一种乙二醇单叔丁基醚的合成反应工艺 (Synthetic reaction process of ethylene glycol mono-tert-butyl ether ) 是由 王红星 李海勇 郑广强 李飞 于越 于 2020-06-04 设计创作，主要内容包括：本发明公开了一种乙二醇单叔丁基醚的合成反应工艺,包括催化精馏塔(T1),一级冷凝器(E1),二级冷凝器(E2),再沸器(E3),通过助溶剂循环式催化精馏合成乙二醇单叔丁基醚(ETB),能够提高乙二醇与异丁烯反应的选择性和ETB产品收率,且通过催化精馏工艺及独到的助溶剂及其添加方式,简化了工艺流程,节能降耗效果显著。(The invention discloses a synthesis reaction process of ethylene glycol mono-tert-butyl ether, which comprises a catalytic rectifying tower (T1), a primary condenser (E1), a secondary condenser (E2) and a reboiler (E3), wherein the ethylene glycol mono-tert-butyl Ether (ETB) is synthesized by cosolvent circulating catalytic rectification, the reaction selectivity of ethylene glycol and isobutene and the yield of ETB products can be improved, and the process flow is simplified by the catalytic rectification process, the unique cosolvent and the addition mode thereof, and the energy-saving and consumption-reducing effects are obvious.)

1. A synthesis reaction process of ethylene glycol mono-tert-butyl ether is characterized by comprising a catalytic rectification tower (T1), a primary condenser (E1), a secondary condenser (E2) and a reboiler (E3), and the ethylene glycol mono-tert-butyl ether is produced by combining the following connection relations:

isobutene (S1) and a supplementary cosolvent (S2) are fed from a catalytic rectifying tower (T1), ethylene glycol (S3) is fed from the top of the tower, the isobutene (S1) and the ethylene glycol (S3) are fully contacted and reacted in a reaction section (R1) of the catalytic rectifying tower (T1) under the action of the cosolvent, the unreacted isobutene and the cosolvent are vaporized and then enter a primary condenser (E1) through an ascending steam pipeline, a first condensate (S4) flows back to the top of the tower through a return line and enters a secondary condenser (E2) without being condensed, and a second condensate (S5) flows back to the tower; liquid in the tower flows into a reboiler (E3) through a stripping section (L1), a tower bottom extracted material flow (S6) flows out of the device, and a tower bottom reflux material flow (S7) returns to a catalytic rectification tower (T1); the material flow extracted from the tower kettle comprises a reaction product of ethylene glycol mono-tert-butyl ether, excessive ethylene glycol and a small amount of byproducts; said column bottoms reflux stream comprises a partial liquid vaporization;

wherein the first-stage condenser (E1) is cooled by circulating water, the second-stage condenser (E2) is cooled by a refrigeration medium with the temperature below-10 ℃, and the reboiler (E3) is heated by steam with the pressure of more than 0.8 Mpa.

2. The synthetic reaction process of claim 1, wherein the reaction section (R1) in the catalytic rectification tower is filled with a catalytic filler formed by combining a catalyst and a mass transfer element, and the catalyst is acidic ion exchange resin, a molecular sieve, a solid acid or a heteropoly acid.

3. The synthetic reaction process according to claim 1, wherein the cosolvent (S2) is dioxane, sulfolane, isophorone and/or dimethyl sulfoxide.

4. The synthesis reaction process according to claim 1, wherein the first condensate (S4) consists of a co-solvent and isobutylene; the first condensate (S4) is totally refluxed and circulated to the top of the catalytic rectifying tower (T1), or part of the first condensate (S4) is refluxed and circulated to the top of the catalytic rectifying tower (T1) and is partially extracted out of the catalytic rectifying tower (T1).

5. The synthetic reaction process according to claim 1, wherein the molar ratio of ethylene glycol (S3) feed to isobutylene (S1) feed is 1-10, the operating pressure of the catalytic distillation column (T1) is 0-2 barg, and the ratio R of the total reflux of the catalytic distillation column (T1) to the isobutylene (S1) feed is 1-10.

Technical Field

The invention belongs to the field of chemical process reinforcement, and particularly relates to a synthesis reaction process of ethylene glycol mono-tert-butyl ether.

Background

Ethylene glycol mono-tert-butyl Ether (ETB) is colorless and transparent liquid at normal temperature, can be mutually soluble with various organic solvents and can be mutually soluble with water at normal temperature. The HLB value (hydrophilic-lipophilic balance value) of ETB is close to 9.0, and the ETB can play the roles of a dispersant, an emulsifier, a rheological agent and a cosolvent in a coating dispersion system and can improve the drying speed, the flatness, the brightness and the adhesion of the water-dispersible coating; and the compound has a tert-butyl structure, and has excellent photochemical stability and safety.

In recent years, with the increasingly strict national requirements on environmental protection, the toxicity of ethylene glycol monobutyl ether (BCS) to reproductive systems becomes a key factor restricting the development of industries. Large-scale prohibition is provided abroad, and various large coating manufacturers in China seek for substitutes of BCS. Along with the popularization of domestic ethanol gasoline, MTBE (methyl tert-butyl ether) is greatly reduced, a large amount of isobutene resources are released, and ETB (ethylene-vinyl acetate) is paid renewed attention because the performance of ETB is very close to that of BCS (bulk continuous chain system).

Currently, there are three main ETB technology routes: the first method is an ethylene oxide method, wherein ethylene oxide and alcohol are subjected to etherification reaction to obtain corresponding glycol ether and a small amount of polyol ether; the second is a synthesis gas method, which is realized by the reaction of synthesis gas and acetal or aldehyde and alcohol, wherein the raw material can be various low alkyl aldehydes or alcohols; and thirdly, a carbon-four-ethylene glycol method, which takes C4 and isobutene after butadiene extraction as raw materials, feeds the raw materials into a preheater to be heated to a certain reaction temperature after metering and mixing, and then feeds the raw materials into a reactor filled with a strong acid ion exchange resin catalyst to carry out reaction.

The methods have advantages and disadvantages, when ethylene oxide method is used for producing ethylene glycol mono-tert-butyl ether, the reaction temperature and pressure are lower in the presence of various catalysts such as acid or alkali, and a glass lined pressure kettle or a stainless steel pressure kettle is applied; the reaction temperature and pressure of the synthesis gas method are high; the reaction pressure of the carbon four-ethylene glycol method is slightly lower than that of the synthesis gas method, and the reaction temperature is also slightly lower. The ethylene oxide method is used for producing the glycol ether, the conversion rate of the raw material ethylene oxide can generally reach more than 90 percent, even 100 percent, and the selectivity of the glycol ether is high; the selectivity of glycol ether is 16-60%, the conversion rate of raw material can be up to 70-80%, and the yield can be up to 50-65%. The ethylene oxide method is used for producing glycol ether, and the same set of devices can be utilized, so that the variety of raw material alcohol is changed according to market demands, and different glycol ether products are produced. The ethylene glycol mono-tert-butyl ether selectivity can reach about 90% and the isobutene etherification conversion rate is about 85% by using the carbon-tetra-ethylene glycol method. The method for synthesizing the ethylene glycol mono-tert-butyl ether by the carbon four method is a novel process route, and compared with the common ethylene oxide method, the method has the advantages of simple process flow, convenient product separation, lower cost and the like.

Due to the mass production of the ethylene glycol prepared from coal in China, the selling price of the ethylene glycol is greatly reduced. Meanwhile, the limited application of MTBE limits the outlet of isobutene, so the route for synthesizing ETB by using the carbon-tetraglycol method is extremely economical in China.

In a traditional fixed bed reactor, isobutene and ethylene glycol have the following four complex reactions, the process flow of the reaction is shown in the figure and mainly comprises the working sections of preheating, mixing, reacting, removing C4, azeotropic rectification, monoether concentrating, refluxing, finished product recovering and the like, and the reaction has the advantages of multiple byproducts, long flow and high energy consumption. In particular, the formation of ethylene glycol di-tert-butyl ether (DBE), which azeotropes with the main product ETB, requires the separation by azeotropic distillation, increasing energy consumption. Meanwhile, because DBE cannot be sold as a product, DBE also needs to be returned to the reactor to inhibit the DBE from being generated continuously, and a large amount of material circulation further increases energy consumption.

Main reaction:

(CH3)2C＝CH2+HOCH2CH2OH→(CH3)3COCH2CH2OH(ETB)

side reaction:

(CH3)3COCH2CH2OH+(CH3)2CCH2→(CH3)3COCH2OC(CH3)(DBE)

n (CH3)2C ═ CH2 → [ (CH3)2C-CH2] n n typically 2 or 3

(CH3)2C＝CH2+H2O→(CH3)3COH(TBA)

The traditional technical route is easy to generate dimerization reaction of isobutene, more byproducts are generated, the reaction of ethylene glycol is incomplete, and the reaction efficiency is influenced due to insufficient contact of gas-liquid reaction materials. The reaction has higher requirement on pressure, correspondingly has strict requirement on the material of equipment, and has incomplete reaction of reactants and higher energy consumption for separation.

In large-scale industrial production, it is desirable to shorten the flow as much as possible, improve the product yield, save energy and reduce consumption. Therefore, a new process is urgently needed.

Disclosure of Invention

The invention aims to provide a synthesis reaction process of ethylene glycol mono-tertiary-butyl ether, which synthesizes ethylene glycol mono-tertiary-butyl Ether (ETB) through cosolvent circulating catalytic rectification, can produce ETB products with high conversion rate and high selectivity by adopting the process, and has the obvious effects of simplifying the process, reducing the investment, saving energy and reducing consumption.

A synthesis reaction process of ethylene glycol mono-tert-butyl ether is characterized by comprising a catalytic rectification tower (T1), a primary condenser (E1), a secondary condenser (E2) and a reboiler (E3), and the ethylene glycol mono-tert-butyl ether is produced by combining the following connection relations:

isobutene (S1) and a supplementary cosolvent (S2) are fed from a catalytic rectifying tower (T1), ethylene glycol (S3) is fed from the top of the tower, the isobutene (S1) and the ethylene glycol (S3) are fully contacted and reacted in a reaction section (R1) of the catalytic rectifying tower (T1) under the action of the cosolvent, the unreacted isobutene and the cosolvent are vaporized and then enter a primary condenser (E1) through an ascending steam pipeline, a first condensate (S4) flows back to the top of the tower through a return line and enters a secondary condenser (E2) without being condensed, and a second condensate (S5) flows back to the tower; the liquid in the tower flows into a reboiler (E3) through a stripping section (L1), a tower bottom produced material flow (S6) comprising reaction product ethylene glycol mono-tert-butyl ether, excessive ethylene glycol and a small amount of by-products flows out of the device, and a tower bottom reflux material flow (S7) comprising part of liquid vaporization returns to the catalytic rectification tower (T1);

wherein the first-stage condenser (E1) is cooled by circulating water, the second-stage condenser (E2) is cooled by a refrigeration medium with the temperature below-10 ℃, and the reboiler (E3) is heated by steam with the pressure of more than 0.8 Mpa.

Furthermore, a reaction section (R1) in the catalytic rectifying tower is filled with a catalytic filler formed by combining a catalyst and a mass transfer element, and the catalyst adopts acidic ion exchange resin, a molecular sieve, solid acid or heteropoly acid.

Further, as the cosolvent (S2), dioxane, sulfolane, isophorone and/or dimethyl sulfoxide is used.

Further, the first condensate (S4) consists of a co-solvent and isobutylene; the first condensate (S4) is totally refluxed and circulated to the top of the catalytic rectifying tower (T1), or part of the first condensate (S4) is refluxed and circulated to the top of the catalytic rectifying tower (T1) and is partially extracted out of the catalytic rectifying tower (T1).

Further, the molar ratio of the ethylene glycol (S3) feed to the isobutene (S1) feed is 1-10, the operating pressure of the catalytic distillation tower (T1) is 0-2 barg, and the ratio R of the total reflux of the catalytic distillation tower (T1) to the isobutene (S1) feed is 1-10.

The invention has the following advantages:

1. the ethylene glycol mono-tertiary butyl ether product with the purity meeting the national standard can be obtained.

2. Different from the prior method, the advanced catalytic rectification process is adopted, the product ETB is removed while the reaction is carried out, the further occurrence of side reaction is reduced, the selectivity is improved, the generation of DTB is avoided, and the conversion rate is higher than that of the traditional fixed bed process.

3. Different from the general catalytic rectification process, the cosolvent is added and continuously circulated in the tower, so that no loss is caused and supplement is hardly required. The existence of the cosolvent greatly improves the complex reaction network of the system, and one is to greatly improve the defects of immiscible isobutene and ethylene glycol and long reaction time, reduce the reaction pressure and the reaction temperature, ensure that the reaction can be carried out under mild low pressure, greatly reduce the equipment investment and increase the process safety. And secondly, the solvent dilutes the isobutene, so that the polymerization reaction of the isobutene is reduced, and the selectivity of the isobutene is improved. Thirdly, the cosolvent is a light solvent, does not need to be discharged from a tower kettle, does not need a subsequent solvent recovery device, and simplifies the flow.

Drawings

FIG. 1 is a prior art schematic of a process for the synthesis of ethylene glycol mono-t-butyl ether.

FIG. 2 is a schematic diagram of the synthesis reaction process of ethylene glycol mono-t-butyl ether according to the present invention.

Wherein, in fig. 2, the numbers are as follows: t1-catalytic rectification tower, E1-primary condenser, E2-secondary condenser, E3-reboiler, R1-reaction section, L1-stripping section, S1-isobutene, S2-cosolvent, S3-glycol, S4-first condensate, S5-second condensate, S6-tower bottom extraction material flow and S7-tower bottom reflux material flow.

Detailed Description

The technical solutions of the present invention will be further described with reference to the drawings and the embodiments, which are not intended to limit the scope of the present invention.

In a traditional fixed bed reactor, isobutene and ethylene glycol have the following four complex reactions, the process flow of the reaction is shown in figure 1, the process mainly comprises the working sections of preheating, mixing, reacting, removing C4, azeotropic distillation, monoether concentration, refluxing, finished product recovery and the like, and the reaction has the advantages of multiple byproducts, long flow path and high energy consumption. In particular, the generation of ethylene glycol di-tert-butyl ether (DBE) which is azeotropic with the main product ETB requires azeotropic distillation for separation, which increases energy consumption. Meanwhile, because DBE cannot be sold as a product, DBE also needs to be returned to the reactor to inhibit the DBE from being generated continuously, and a large amount of material circulation further increases energy consumption.