WO2011072569A1

WO2011072569A1 - Method and device for preparing ethyl t-butyl ether by distillation-extraction coupling separation and purification

Info

Publication number: WO2011072569A1
Application number: PCT/CN2010/079182
Authority: WO
Inventors: 张武平; 张文里; 周山花; 田恒水; 张涵璐; 诸富根; 江兆; 顾京君
Original assignee: 华东理工大学
Priority date: 2009-12-16
Filing date: 2010-11-26
Publication date: 2011-06-23
Also published as: CN101747161A; CN101747161B

Abstract

Disclosed are a method and a device for preparing ethyl t-butyl ether by distillation-extraction coupling separation and purification, wherein the material is to-be-separated mixture of ethyl t-butyl ether which is obtained by carrying out etherification of ethanol with water content from at least more than 1 wt. % to at most 15 wt. % and isoolefin having at least 4 carbon atoms, and the method described is the distillation-extraction coupling separation. The present method improves utilization rate of isoolefin, reduces the circulation of tertiary alcohol and the cost, not only obtains the qualified ethyl t-butyl ether, but also co-produces the corresponding monohydric alcohol.

Description

Method and device for preparing ethyl tertiary alkyl ether by distillation-extraction coupling separation and purification

The present invention relates to a process and apparatus for the preparation of ethyl tertiary alkyl ethers, and in particular to a process and apparatus for the purification of ethyl tertiary alkyl ethers. The purification to prepare ethyl tertiary alkyl ether is carried out by distillation-extraction coupling separation.

Background technology

The development of bio-based fuels based on ethanol (EtOH) produced by fermentation has received increasing attention in many countries around the world.

However, fuel ethanol is one of the most important bio-based alcohol ether fuels. One of the key problems in energy consumption and cost control is that if you want to remove about 5% by weight of azeotropic water to less than 1% by weight, you need to use constant boiling. Special separation methods such as distillation, extractive distillation, adsorption, pervaporation membrane separation, etc., and usually require a small amount of co-dissolving and solubilizing denaturing agents such as fusels, ethers, etc., to compensate for ethanol gasoline to some extent. The disadvantage of phase separation is created. However, despite the lack of its own functions, fuel ethanol is usually sold at a lower price than gasoline, and in some countries its production cost is even higher than that of gasoline (such as China), which is the value of fuel ethanol (ie, function/cost). ) Low, there is an urgent need to find a way to break the game.

It has been agreed that ethyl tertiary alkyl ethers such as ethyl tert-butyl ether (ETBE) or ethyl t-amyl ether (TAEE) can be used as gasoline additives.

Usually, ethyl tertiary alkyl ether used as a gasoline additive: obtained by etherification reaction of isobutylene or isoamylene in a hydrocarbon material such as mixed C ₄ or mixed C ₅ such as steam cracking or catalytic cracking. ETBE is prepared by etherification of ethanol and isobutylene (see US 5248836A, CN 1990443A, CN1772848A, CN101195560A, etc.). It is not difficult to prepare ethyl tertiary alkyl ether, but it has to be isolated and purified to obtain ethyl tertiary alkyl ether (especially ETBE) as a gasoline additive, and many problems remain to be solved.

As a gasoline additive, in order to improve product function and ease of use, especially in order to be directly added in the process of gasoline blending, and without changing the existing storage, transportation and distribution system, it is preferable to be able to prepare the ether-containing product during the preparation process. The ethanol content is strictly controlled, including the ability to control the ethanol content to less than 1% by weight, if necessary. Heretofore, the method for separating and purifying ethyl tertiary alkyl ether (especially ETBE) is to strictly control the content of alcohol in the deparaffin distillation column, including controlling the alcohol/ene reaction ratio to a certain ratio below stoichiometric, Part of the alcohol is removed by pretreatment such as water elution prior to the deparaffin distillation column, and a certain proportion of lighter hydrocarbons are added (see, for example, US Pat. No. 7,141,705 A, US Pat. No. 5,447, 607 A, US Pat. No. 5,536,886, etc.) so that the remaining alcohol can be substantially all The hydrocarbons are azeotropically removed from the top of the dealkylation distillation column, which makes it more difficult to further increase the conversion of isoolefins in some cases, including, for example, reactive distillation, which is often desired, The upper part of the dealkylation distillation column is filled with a certain amount of ethanol, so strictly controlling the content of the alcohol in the deparaffin distillation column may cause difficulty or limitation in increasing the conversion rate of the isoolefin;

However, if the conversion rate of the isoolefin is increased, it is often difficult to strictly control the content of unreacted ethanol in the deparaffin distillation column, so in the dealkylation distillation column (for ETBE: "debutanizer column") The positions of the extracted materials are different, and they are mainly divided into two categories:

One is to extract material from the bottom of the distillation column for subsequent separation (see US 5,158,652A, US 5250156A, US 5, 348, 624A and US 5569787A, etc.);

The second is to take material from the side of the distillation column for subsequent separation (see CN1127243A and US 5, 607, 557A, etc.).

These types of methods have their own advantages, but their common drawbacks are: There are strict requirements on the content of certain components of the material entering the dealkylation distillation column (especially hydrazine, required to enter the "debutanizer" The water content of the material is at most 1% by weight, the content of tert-butyl alcohol (ΤΒΑ) is at most 1% by weight (see CN1127243A and US 5, 607, 557A, etc.), and/or adsorption separation, pervaporation membrane separation is employed. Special separation methods such as azeotropic separation. Such severe operating conditions and/or higher energy separation methods result in a reduction in the commercial value of the existing separation and purification process for preparing ethyl tertiary alkyl ether. Summary of the invention

In order to overcome the above problems, it is an object of the present invention to provide a method and apparatus for the purification of ethyl tertiary alkyl ethers having commercial value (i.e., function/cost). The purification to prepare ethyl tertiary alkyl ether is carried out by distillation-extraction coupling separation. The ethyl tertiary alkyl ether obtained by the method for purifying ethyl tertiary alkyl ether may contain less than 1% by weight of ethanol, gP, so that the obtained ethyl tertiary alkyl ether product can be used as a gasoline additive. Has a very high function.

It is also an object of the present invention to provide a water content of at least greater than 1% by weight but up to 15% by weight. A method and apparatus for the purification of ethyl tertiary alkyl ethers having commercial value (i.e., function/cost) from ethanol as a raw material. The purification to prepare ethyl tertiary alkyl ether is carried out by distillation-extraction coupling separation. The mono-alcohol produced by the method for purifying the ethyl tertiary alkyl ether can contain less than 1% by weight of water, that is, the obtained ethyl tertiary alkyl ether product can be used as a gasoline additive. While having a high function, it can also significantly reduce its cost, and parallel production of monohydric alcohols (including especially the corresponding tertiary alcohols).

The ethyl tertiary alkyl ether of the present invention is obtained by etherification reaction of ethanol and an isoolefin having at least four carbon atoms. For details, see US 5248836A, US 5258560A, CN 1990443A, CN1772848A, CN101195560A, etc., and ethanol. The water contained can be hydrated with an isoolefin to form a corresponding tertiary alcohol such as t-butanol (TBA) or tert-amyl alcohol (TM).

The method for purifying ethyl tertiary alkyl ether according to the present invention, the main steps of which are: a dealkylation distillation step after the reaction zone in the process for preparing the ethyl tertiary alkyl ether and another distillation - The extraction coupling step is combined. Thus, not only can at least a qualified ethyl tertiary alkyl ether product be obtained at the bottom of the dealkylation distillation column, but also in the subsequent step (ie, the distillation column bottom in the distillation-extraction coupling step) can be co-produced accordingly. Monohydric alcohols (including especially the corresponding tertiary alcohols).

The technical solution of the method of the invention is as follows:

A method for preparing ethyl tertiary alkyl ether by distillation-extraction separation and purification, the method comprising the following steps:

(1) a reaction product obtained by subjecting a reaction zone to an etherification reaction (etherification (hydration) reaction of at least 1% by weight but up to 15% by weight of ethanol and an isoolefin having at least four carbon atoms) (The mixture to be separated, called ethyl tertiary alkyl ether, mainly containing ethanol, tertiary alcohol, ethyl tertiary alkyl ether, water and hydrocarbons, etc.) is introduced into a dealkylation distillation column (abbreviated as the first distillation column) for deparaffinization. Distillation: collecting a hydrocarbon-containing fraction at the top of the first distillation column; collecting an ethyl tertiary alkyl ether fraction (one of the products) at the bottom of the (first distillation column);

(2) introducing a material taken out from the side of the first distillation column into a distillation-extraction coupling zone, wherein the distillation-extraction coupling zone is composed of a second distillation column and an extraction column; in the distillation-extraction coupling zone : The operating pressure of the distillation column (abbreviated as the second distillation column) is lower than the operating pressure of the first distillation column, and the fraction containing aliphatic monohydric alcohol (including especially tertiary alcohol) is collected at the bottom of the second distillation column (product 2) The material obtained from the top of the second distillation column is sent to the extraction column, and the water is extracted as an extractant.

The operating pressure of the extraction column is not lower than atmospheric pressure, and an aqueous solution containing ethanol is collected at the bottom of the extraction column, and the recovered ethanol is recycled for use (for example, recycling to the reaction zone), and 0-100% of the raffinate obtained at the top of the extraction column is obtained. It is recycled to the first distillation column.

When the proportion of the raffinate obtained at the top of the extraction column to the first distillation column is less than 100% by weight, the ethyl tertiary alkyl ether-containing raffinate (one of the products) can be collected from the top of the extraction column.

In a preferred embodiment of the present invention, the ethyl tertiary alkyl ether is ETBE (or TAEE, etc.): that is, obtained by etherification reaction of ethanol and isobutylene (or isopentene, etc.), the method comprising The following steps:

(1) ethanol having a water content of at least 1% by weight but at most 15% by weight, preferably water having a water content of 1.5 to 15% by weight, more preferably 2 to 10% by weight of ethanol. Preferably, the ethanol having a water content of 3 to 10% by weight is obtained by reacting a mixed C ₄ hydrocarbon (or a mixed C ₅ hydrocarbon, etc.) containing isobutylene (or isopentene) in an etherification (hydration) reaction zone. The material (the mixture of ethyl tertiary alkyl ether to be separated) is introduced into the dealkylation distillation column (abbreviated as the first distillation column):

Collecting a fraction containing C ₄ hydrocarbon (or C ₅ -containing hydrocarbon, etc.) at the top of the first distillation column; collecting an ETBE (or TAEE-containing, etc.) fraction (one of the products) at the bottom of the (first distillation column);

(2) a material taken out from the side of the first distillation column described above (the side taken out is located at a side line position below the feeding position of the ethyl tertiary alkyl ether to be separated, more preferably It is located at the side of the tray with the highest ethanol concentration or below, preferably at the plate with the highest ethanol concentration or below the first block - the 15th theoretical plate (including the first and the 15th blocks) a position between the theoretical plates); the vapor phase and/or liquid phase of the material taken out from the side of the first distillation column is taken out to the distillation-extraction coupling zone, wherein the distillation-extraction coupling zone is a distillation tower and an extraction tower;

In the distillation-extraction coupling zone: the operating pressure of the distillation column (abbreviated as the second distillation column) is lower than the operating pressure of the first distillation column, and the aliphatic monohydric alcohol is collected at the bottom of the second distillation column (including special Is a TBA (or TM, etc.) fraction (product 2),

The material obtained from the top of the second distillation column is sent to the extraction column, and a part of the hydrocarbon-containing fraction collected from the top of the first distillation column is taken out and introduced into the extraction column, preferably from the feeding position of the extraction feed, more preferably The extraction tower is introduced from below and extracted with water as an extractant.

The weight ratio is 0. 05-1. 2 : 1, the most suitable weight ratio is 0. 05-1. 2 : 1, the most suitable weight ratio is 0. 1-1. 0: 1, the extraction is carried out under conditions of not lower than atmospheric pressure, collecting an aqueous solution containing ethanol at the bottom of the extraction column, recycling the ethanol and recycling it (for example, recycling to the reaction zone), The 0-100% of the raffinate obtained at the top of the extraction column is recycled to the first distillation column.

Wherein, when the ratio of the raffinate obtained at the top of the extraction column to the first distillation column is less than 100%, A raffinate containing ETBE (or TAEE, etc.) (one of the products) can be collected from the top of the extraction column.

The technical solution of the device of the invention is as follows:

A distillation-extraction coupling separation and purification apparatus for preparing ethyl tertiary alkyl ether, comprising a first distillation column Cl, a second distillation column C2, and an extraction column C3.

A connecting line 3 is provided between the reaction zone R and the first distillation column C1 so that the mixture to be separated of the ethyl tertiary alkyl ether obtained by the etherification reaction enters the first distillation column Cl.

The top of the first distillation column C1 is provided with a condenser E2 for collecting a hydrocarbon-containing fraction, a condensate tank B1, and a line 5.

At the bottom of the first distillation column C1, a heater E3 for collecting an ethyl tertiary alkyl ether fraction and a pipe line 4 are provided.

The side of the first distillation column C1 is provided with a line 6 connecting the second distillation column C2, and the line 6 is provided with a regulating valve D1 and a heat exchanger E4 for introducing the material taken out from the side of the first distillation column C1 to the second distillation column. C2.

At the bottom of the second distillation column C2, a heater E6 and a line 8 for collecting a monohydric alcohol fraction are provided. A condenser E5 for collecting overhead materials, a condensate tank B2 and a line 9 are disposed at the top of the second distillation column C2; and the material obtained from the top of the second distillation column C2 is sent to the extraction column C3 via line 9.

The extractant water enters the extraction column C3 from line 12, and the extract containing ethanol is collected via line 10 at the bottom of the extraction column C3, and the raffinate is collected from the top of the extraction column C3 via line 11.

The apparatus for preparing ethyl tertiary alkyl ether by distillation-extraction coupling separation according to the present invention, the apparatus further comprising: when processing the mixture to be separated of ethyl tert-butyl ether, the second distillation column C2 is provided with a line 14 for For the introduction of recovered ethanol.

The apparatus for preparing ethyl tertiary alkyl ether by distillation-extraction coupling separation according to the present invention further comprises: providing a pump P1 on the line 11, whereby the raffinate obtained at the top of the extraction column C3 is pressurized by the pump P1 It is recycled via line 11 to the first distillation column.

A method and apparatus for preparing an ethyl tertiary alkyl ether by purification according to the present invention, which is carried out by a distillation-extraction coupling separation method. The ethyl tertiary alkyl ether obtained by the method for purifying the ethyl tertiary alkyl ether may contain less than 1% by weight of ethanol, and the obtained monohydric alcohol may contain less than 1% by weight of water. According to the method and apparatus of the present invention, there is no stringent requirement for the material entering the dealkylation distillation column (the mixture of ethyl tertiary alkyl ether to be separated) (including, for example, ethanol content and/or water content and/or tertiary alcohol content, etc.) ), which is beneficial to increase the utilization of isoolefin resources, and greatly reduces the amount of tertiary alcohol that is "harmful" to the reaction zone during the entire separation and purification process. Meanwhile, the method and device according to the present invention The cost can be reduced, in particular, ethanol having a water content of at least 1% by weight but up to 15% by weight, which is a renewable resource, can be used as a raw material for the etherification reaction, and not only a qualified ethyl tertiary alkyl ether product but also a joint can be obtained. The corresponding monohydric alcohols (including in particular the corresponding tertiary alcohols) are produced with high commercial value (function/cost). DRAWINGS

1 is a schematic flow chart of a method and a device for separating and purifying ethyl tertiary alkyl ether (especially ETBE or TAEE, etc.) by distillation-extraction coupling according to the present invention.

2 is a schematic flow chart of another method and apparatus for separating and purifying ethyl tertiary alkyl ether by distillation-extraction according to the present invention. The ethyl tertiary alkyl ether is ethyl tert-butyl ether.

Where: R—reaction zone, C1—first distillation column (desalin distillation column), C2—second distillation column, C3-extraction column, B1-B2—condensate tank, D1-D2—regulating valve, E1-E8 - heat exchanger, P1-P2 - pump, 1-14 - pipeline number or pipeline material stream number. detailed description

Hereinafter, a method and an apparatus for preparing an ethyl tertiary alkyl ether by distillation-extraction coupling separation and purification according to the present invention will be described in detail with reference to Fig. 1, Fig. 2 and Examples. In particular, the ethyl tertiary alkyl alcohol ether is ETBE (or TAEE, etc.).

A method and apparatus for preparing ethyl tertiary alkyl ether (especially ETBE (or TAEE, etc.) by distillation-extraction coupling separation and purification, comprising the following steps:

(1) ethanol having a water content of at least more than 1% by weight but up to 15% by weight or further comprising recovered ethanol, and mixed C ₄ hydrocarbons containing isobutylene (usually containing 10% by mole to 70% by mole of isobutylene, possibly containing isobutylene For lower or higher ratios, see US 5248836A) Entering reaction zone R via lines 1, 7 and 2, respectively, for etherification (for specific reaction conditions for reaction zone R, see: US 5248836A, CN 1990443A, CN1772848A, CN101195560A Etc.), the obtained reaction product (or the mixture of ethyl tertiary alkyl ether to be separated) is passed through line 3 and can be exchanged by heat exchanger E1 to enter the first distillation column C1. A condenser E2 and a condensate tank B1 are disposed at the top of the first distillation column C1, and a C ₄ hydrocarbon fraction is collected via the line 5; a heater E3 is disposed at the bottom of the first distillation column C1, and an ETBE fraction is collected via the line 4. (one of the products).

Wherein: the mixture to be separated of the ethyl tertiary alkyl ether comprises: 1-20% by weight of ethanol (preferably ethanol content of 2-15% by weight), 5-80% by weight of £8 (preferably ETBE) The content is 10-50% by weight), 1-3重量。 The water content of the water is preferably 0. 1-3 weight by weight of the water (preferably the content of the TBA is 1. 5-10% by weight). %), the balance is mainly a hydrocarbon having four carbon atoms (c ₄ ); usually the mixture of the ethyl tertiary alkyl ether to be isolated also contains impurities: up to 1% by weight of diethyl ether, up to 1% by weight Ethyl sec-butyl ether (E2BE), up to 5% by weight (preferably less than 1% by weight) of a hydrocarbon having at least five carbon atoms (C ₅₊ ) and up to 5% by weight of a hydrocarbon having three carbon atoms (C ₃ ).

The first distillation column C1 can also generally be a reactive distillation column with a reaction section.

The first distillation column C1 is operated at a pressure higher than atmospheric pressure, preferably at a pressure of 5 to 15 bar, and more preferably at a pressure of 7 to 13 bar. The operating temperature of the top of the first distillation column C1 is 30 ° C -10 (TC, the operating temperature of the bottom of the first distillation column C1 is 70 ° C -20 (TC.

(2) The material taken out from the side of the first distillation column C1 (including taken out from the vapor phase and/or the liquid phase) is sent to the second distillation column C2 via line 6 and through the heat exchanger E4 and the pressure reducing valve D1, The operating pressure of the second distillation column C2 is lower than the operating pressure of the first distillation column C1, the heater E6 is provided at the bottom of the second distillation column C2, and the monohydric alcohol-containing (especially TBA-containing) fraction is collected via the line 8 (product 2) .

A condenser E5 and a condensate tank B2 are arranged at the top of the second distillation column C2, and the material obtained from the top of the second distillation column C2 is sent to the extraction column through the line 9 and through the heat exchanger E7 and can be pressurized by the pump P2. C3. The extractant water enters the extraction column C3 from the pipeline 12, and the hydrocarbon-containing fraction collected from the top of the first distillation column C1 can be taken out through the regulating valve D2, and a part of the material can be taken through the pipeline 13 and can be introduced into the extraction tower C3 via the heat exchanger E8. Preferably, the extraction is carried out from the lower side of the extraction feed to the extraction column C3 for extraction. The weight ratio of the introduction amount of the hydrocarbon-containing fraction to the extraction column C3 and the extraction feed amount is 0-2. 0: 1, the more suitable weight ratio is 0. 05-1. 2 : 1, The most suitable weight ratio is 01-1. 0: 1.

An aqueous solution containing ethanol is collected at the bottom of the extraction column C3 via line 10, and the ethanol can be recovered and recycled to the reaction zone R via line 7. It may be more desirable to recover the recovered ethanol (more preferably, it may be up to 80%, more preferably Up to 60%, most preferably up to 30% recovered ethanol) is recycled via line 14 as a feed to the first distillation column C1 (as shown in Figure 2).

The 0-100% of the raffinate obtained at the top of the extraction column C3 is recycled to the first distillation column C1 via the line 11 and through the pump P1 (100% as shown in Fig. 1), wherein the extraction column C3 is recycled to the first When the proportion of the material of the distillation column C1 is less than 100%, the ETBE-containing raffinate (one of the products) can be collected from the top of the extraction column C3 (as shown in Fig. 2), or it can be partially recycled as needed. To the second distillation column C2, more water and/or ethanol is azeotroped from the top of the column.

The operating pressure of the second distillation column C2 is 0. 5 bar - 2 bar (preferably 1 bar - 2 bar), the second distillation column C2 The temperature at the top of the column is from 30 ° C to 80 ° C, and the temperature at the bottom of the second distillation column C 2 is from 70 ° C to 105 ° C.

The operating pressure of the extraction column C3 is 1 bar-15 bar (preferably 1 bar-10 bar), and the operating temperature of the extraction column C3 is 5 ° C -70 ° C (preferably 10 ° C -6 (TC ), extractant water 0-1. 8 : 1。 The most suitable weight ratio is 0. 3-0. 8 : 1。 The weight ratio is 0. 3-0.

The ETBE-containing (or TAEE-containing, etc.) fraction collected from the bottom of the first distillation column C1 (or also includes the ETBE (or TAEE, etc.) raffinate collected from the top of the extraction column C3), the ethanol content of which is related to the process conditions Usually, its ethanol content is less than 1% by weight.

A fraction containing monohydric alcohol (including, in particular, a tertiary alcohol (TBA or TAA, etc.)) is collected from the bottom of the second distillation column C2, the water content of which is related to the process conditions, and usually has a water content of less than 1% by weight. The content of the tertiary alcohol (TBA or TM, etc.) is related to the process operating conditions, preferably the content of the tertiary alcohol (TBA or T, etc.) is more than 30% by weight, more preferably the content of the tertiary alcohol (TBA or TAA, etc.) is more than 50% by weight, most Preferably, the tertiary alcohol (TBA or T, etc.) content is greater than 80% by weight.

When ETBE (or TAEE, etc.) raffinate is collected from the top of the extraction column C3, ETBE (or TAEE, etc.) containing saturated water can be obtained, usually containing only traces of water at room temperature after removal of ethanol, such as ETBE at 2CTC The saturated water content is 0.5 g / 100 g ΕΤΒΕ , generally can not be considered to have to carry out further water removal treatment, of course, if necessary, any suitable water removal methods such as molecular sieves, silica gel and other adsorbents can be further used. Dry and remove water.

Usually, the hydrocarbon-containing fraction collected from the top of the first distillation column C1 also contains a small amount of azeotropically evaporated ethanol, so that the general process for preparing the tertiary alkyl ether is also subjected to alcohol removal, and a recovery tower is provided. Ethanol recovery in the wash water (not shown), and recycling of the recovered ethanol to the reaction zone R, see US 5447607A and the like. Thus, the ethanol-containing aqueous solution collected from the bottom of the extraction column C3 can be recovered by the recovery column in the same manner, and then recycled to the reaction zone R.

Wherein, in the separation and purification of ETBE, it may be more desirable to recycle the recovered ethanol (more preferably up to 80%, more preferably up to 60%, most preferably up to 30% of recovered ethanol) via line 14 Distillation-extraction of the feed to the coupling zone (as shown in Figure 2). Thus, a method for separating and purifying a distillation-extraction of the present invention to prepare ethyl tertiary alkyl ether (the ethyl tertiary alkyl ether is ETBE) can also be used for a water content of more than 1% by weight. But up to 15% by weight of ethanol (preferably water content of 1.5% by weight to 15% by weight of ethanol, more preferably water content of 2% by weight to 10% by weight of ethanol, most preferably water content Alcohol ether is prepared by coupling dehydration from 3% by weight to 10% by weight of ethanol (ie, purified ETBE is produced in parallel to produce monohydric alcohol). One possible advantageous embodiment, the suitable hydrocarbon may be employed as the material containing a mixture of fresh C ₄ isoolefins or a mixed C ₅ hydrocarbons and the like materials, containing an aqueous solution of ethanol collected from the bottom of the extraction column C3 and / or recovered The ethanol, in a separate extraction column, either separately or sequentially, after stripping (not shown) and then as a feed to the etherification reaction (reaction zone R), may be beneficial to save energy and/or reduce ethanol recovery. Azeotropic water content carried by ethanol and a small amount of tertiary alcohol and ethyl tertiary alkyl ether.

The following is a brief overview of the embodiment:

The reaction product obtained by subjecting the reaction zone R to an etherification reaction (etherification (hydration) reaction of at least 1% by weight but up to 15% by weight of ethanol and an isoolefin having at least four carbon atoms), a mixture to be separated mainly containing ethyl tert-alkyl ether of ethanol, tertiary alcohol, ethyl tertiary alkyl ether, water and hydrocarbon, which is separated and purified to obtain a hydrocarbon-containing fraction from the top of the first distillation column C1 (almost completely Obtaining no ethyl ether alkyl ether fraction (ethanol content less than 1% by weight) from the bottom thereof, and obtaining a monohydric alcohol (water content less than 1% by weight) fraction from the bottom of the second distillation column C2, The extract flowing out from the bottom of the extraction column C3 can be recycled after recycling ethanol.

The first distillation column C1 is composed of a perforated tray having 80 trays, a stainless steel tower having a plate length of 50 mm and an inner diameter of 100 mm. The second distillation column C2 used in Example 1 was composed of a perforated tray having 20 trays, a glass column having a plate length of 50 mm and an inner diameter of 30 mm. The second distillation column C2 used in Examples 2 - 5 was composed of a perforated tray having 50 trays, a glass column having a plate length of 50 mm and an inner diameter of 50 mm. The extraction column C3 consists of a stainless steel column with 24 perforated plates with a plate spacing of 100 mm and an inner diameter of 30 mm. The three towers are thermally insulated to avoid heat loss, and the trays of the three towers are numbered starting from top to bottom.

Example 1

Process Flow Referring to Figure 1, a material containing about 5% by weight of azeotropic water in ethanol and the recovered ethanol and the mixed C ₅ hydrocarbon containing isopentene in the reaction zone R are subjected to etherification reaction as an ethyl tertiary alkyl ether. The mixture material (line 3) was separated, and after heat exchange to 65 ° C, it was separated in the first distillation column C1.

The first distillation column C1 has a total of 80 trays, the feed position is the 24th tray, the operating pressure at the top of the column is 4 bar, the reflux ratio is 1.5, and the temperature at the top of the column is 85 °C. An unreacted mixed C ₅ hydrocarbon fraction (line 5) is collected from the top of the first distillation column C1, and a TAEE-containing fraction (one of the products, line 4) is obtained from the bottom of the first distillation column C1, and the side take-up position is 45th. The block tray, the material of about 132 ° C (line 6) taken out from the liquid phase is depressurized to 75 ° C and then into the second distillation column C2.

The second distillation column C2 has a total of 20 trays, the feeding position is the sixth tray, the operating pressure of the top of the tower is 1 bar, the reflux ratio is 3.0, the temperature at the top of the tower is 74 ° C, from the second distillation column. CTA bottom obtained with TAA fraction (Product 2, line 8).

The effluent material at the top of the second distillation column C2 (line 9) is then cooled to 38 ° C, from the 24th tray of the extraction column C3, with water as the extractant from the first tray (line 12) The countercurrent extraction operation was carried out at an operating pressure of 3 bar at around 38 °C. The raffinate flowing from the top of the extraction column C3 (line 11) is collected and recycled as the feed to the first distillation column C1, and the extract (line 10) flowing out from the bottom of the extraction column C3 can be recycled to the ethanol and recycled to Reaction zone 1?.

The composition and flow rate of each major pipeline material stream including the mixture of ethyl tertiary alkyl ethers to be separated are shown in Table 1.

Table 1: Material balance table for Example 1 Line 3 Line 4 Line 5 Line 6 Line 8 Line 9 Line 12 Quantity % 10 11

c ₄ 7. 08 <lppm 10. 07 <lppm <lppm <lppm <lppm <lppm <lppm c ₅ 60. 17 <lppm 85. 50 0. 89 <lppm 1. 00 0. 31 2. 09 <lppm

H ₂ 0 0. 46 0. 03 0. 02 3. 12 19ppm 3. 52 0. 71 100. 00

EtOH 9. 48 <lppm 3. 46 46. 50 0. 96 52. 37 inches 45. 11 <lppm <lppm

TAEE 19. 93 99. 45 <lppm 35. 13 0. 07 39. 65 8. 87 95. 73 <lppm

TAA 1. 82 0. 52 <lppm 11. 44 97. 91 0. 31 0. 20 0. 24 <lppm

ETBE 0. 67 <lppm 0. 95 0. 06 <lppm 0. 06 0. 02 0. 13 <lppm

TBA 0. 39 <lppm 4ppm 2. 86 1. 07 3. 09 2. 38 1. 09 <lppm In the stream,

3000 560 2109 455 52 403 468 124 188 g / h

Example 2:

Process Flow Referring to FIG. 1, a material containing about 5% by weight of azeotropic water of ethanol and a recovered ethanol and a mixed C ₄ hydrocarbon in the reaction zone R are subjected to etherification reaction as a mixture of ethyl tertiary alkyl ether to be separated (pipeline) 3), combined with the raffinate from the top of the extraction column C ₃ (line 11) and then used as the feed to the first distillation column C1.

The first distillation column C1 has a total of 80 trays, the feed temperature is 65 ° C, the feed position is the 40th tray, the operating pressure at the top of the tower is 8 bar, the reflux ratio is 0.75, and the temperature at the top of the tower is 65. °C, collecting unreacted mixed C ₄ hydrocarbon fraction (line 5) from the top of the first distillation column C1, the side draw position is the 64th tray, and the material of about 135 ° C taken from the liquid phase (line 6) After cooling down to 65 ° C, it enters the second distillation column C2. The second distillation column C2 has a total of 50 trays, the feed position is the 12th tray, the operating pressure of the top of the tower is 1 bar, the reflux ratio is 3.0, and the temperature at the top of the tower is 66 °C. Then, the effluent material at the top of the second distillation column C2 (line 9) is cooled to 38 ° C and then fed from the 24th tray of the extraction column C3, and the water is used as the extractant to feed from the first tray (pipeline) 12), operating pressure is 7 bar, operating temperature is 38 °C. After the extraction treatment, the raffinate (line 11) is combined with the mixture of the ethyl tertiary alkyl ether from the reaction zone R (line 3) to be the feed of the first distillation column C1, respectively, from the distillation column C1. The bottom of the column is obtained with an ETBE fraction (one of the products, line 4), and a monohydric alcohol (containing TBA) fraction is obtained from the bottom of the second distillation column C ₂ (product 2, line 8), and flows out from the bottom of the extraction column C3. The extract (line 10) can be recycled to the reaction zone R after recovery of ethanol.

The composition and flow rate of each major pipeline material stream including the mixture of ethyl tertiary alkyl ethers to be separated are shown in Table 2.

Table 2: Material balance table of Example 2

Composition \Heavy: Pipeline Pipeline Pipeline 3 Pipeline 4 Pipeline 5 Pipeline 6 Pipeline 8 Pipeline 9

% 10 11 12 c ₄ 60. 61 <lppm 98. 59 0. 54 <lppm 0. 59 MC 0. 05 0. 68 <lppm

H ₂ 0 0. 35 27ppm 0. 20 1. 53 6ppm 1. 66 73. 19M C 1. 06 100. 00

EtOH 5. 32 0. 03 1. 21 14. 45 9. 13 14. 92 0. 23 <lppm

E2BE 0. 15 0. 37 <lppm 0. 15 1. 50 0. 03 8ppm 0. 03 <lppm

ETBE 30. 74 98. 68 <lppm 73. 72 <lppm 80. 22 2. 46 95. 76 <lppm

TBA 2. 71 0. 67 l lppm 9. 51 88. 03 2. 59 1. 19 2. 23 <lppm

C5+ 0. 11 0. 25 <lppm 0. 11 1. 34 <lppm <lppm <lppm <lppm flow rate, g /

5000 1535 3074 1600 130 1471 937 1208 674 hours

Example 3:

Process Flow Referring to FIG. 1, a material containing about 5% by weight of azeotropic water of ethanol and a recovered ethanol and a mixed C ₄ hydrocarbon in the reaction zone R are subjected to etherification reaction as a mixture of ethyl tertiary alkyl ether to be separated (pipeline) 3), combined with the raffinate from the top of the extraction column C3 (line 11) and then used as the feed to the first distillation column C1.

The first distillation column C1 has a total of 80 trays, the feed temperature is 65 ° C, the feed position is the 40th tray, the operating pressure at the top of the tower is 8 bar, the reflux ratio is 0.75, and the temperature at the top of the tower is 65. °C. From the first distillation column C1 The top of the column collects the unreacted mixed C ₄ hydrocarbon fraction (line 5), the side draw position is the 64th tray, and the material of about 135 ° C (line 6) taken from the liquid phase is reduced to 65 ° by cooling. C then enters the second distillation column C ₂ .

The second distillation column C2 has a total of 50 trays, and the feed position is the 12th tray. The operating pressure at the top of the tower is 1 bar, the reflux ratio is 3. 0, and the temperature at the top of the tower is 66 °C. The effluent from the top of the second distillation column C2 (line 9) was then cooled to 38 ° C and fed from the 16th tray of extraction column C3. The water is used as an extractant to feed from the first tray (line 12), and then part of the material (line 13) is withdrawn from the effluent material at the top of the distillation column C1, and is fed from the 24th tray of the extraction column C3. The operating pressure is 7 bar and the operating temperature is 38 °C. After the extraction treatment, the raffinate (line 11) is combined with the mixture of the ethyl tertiary alkyl ether from the reaction zone R (line 3) to be the feed of the first distillation column C1, and from the extraction column C3. The extract flowing out from the bottom of the column (line 10) can be recovered and recycled to the reaction zone R, and the ETBE-containing fraction (one of the products, the line 4) and the second distillation column C2 are respectively obtained from the bottom of the first distillation column C1. The bottom of the column is obtained with a monohydric alcohol (containing TBA) fraction (product 2, line 8).

The significant difference between this embodiment and Example 2 is that the addition of a portion of the hydrocarbon in the lower portion of the extraction column C3 enhances the recovery of ETBE and TBA, reducing the amount of circulation back to the reaction zone R after recovery of ethanol.

The composition and flow rate of each major pipeline material stream including the mixture of ethyl tertiary alkyl ethers to be separated are shown in Table 3.

Table 3: Material balance table of Example 3

Example 4:

The first distillation column C1 has a total of 80 trays, the feed temperature is 65 ° C, the feed position is the 40th tray, the operating pressure at the top of the tower is 8 bar, the reflux ratio is 0.75, and the temperature at the top of the tower is 65. °C. The unreacted mixed C ₄ hydrocarbon fraction (line 5) is collected from the top of the first distillation column C1, the side draw position is the 60th tray, and the material of about 136 ° C (line 6) taken from the vapor phase is passed through The temperature is lowered to 65 ° C and then into the second distillation column C ₂ .

The second distillation column C2 has a total of 50 trays, and the feed position is the 12th tray. The operating pressure at the top of the tower is 1 bar, the reflux ratio is 3. 0, and the temperature at the top of the tower is 66 °C. Then, the effluent material at the top of the second distillation column C2 (line 9) is cooled to 38 ° C and then fed from the 24th tray of the extraction column C3, and the water is used as the extractant to feed from the first tray (pipeline) 12), operating pressure is 7 bar, operating temperature is 38 °C. After the extraction treatment, the raffinate (line 11) is combined with the mixture of the ethyl tertiary alkyl ether from the reaction zone R (line 3) to be the feed of the first distillation column C1, and from the extraction column C3. The extract flowing out from the bottom of the column (line 10) can be recovered and recycled to the reaction zone R, and the ETBE-containing fraction (one of the products, line 4) is obtained from the bottom of the first distillation column C1, respectively, from the second distillation column C2. The bottom of the column is obtained with a monohydric alcohol (containing TBA) fraction (product 2, line 8).

The composition and flow rate of each major pipeline stream including the mixture of ethyl tertiary alkyl ethers are shown in Table 4.

Table 4: Material Balance Table of Example 4

Composition \ Weight Pipeline Pipeline Pipeline 3 Pipeline 4 Pipeline 5 Pipeline 6 Pipeline 8 Pipeline 9

% 10 11 12 c ₄ 60. 61 <lppm 98. 59 0. 70 <lppm 0. 83 0. 09 0. 97 <lppm

H ₂ 0 0. 35 2ppm 0. 18 1. 75 0. 03 2. 09 65. 87 1. 14 100

EtOH 5. 32 26ppm 1. 23 19. 22 36. 36 15. 9 29. 21 1. 29 <lppm

E2BE 0. 15 0. 49 <lppm 0. 11 <lppm 0. 13 61ppm 0. 16 <lppm

ETBE 30. 74 99. 01 <lppm 66. 41 <lppm 79. 24 3. 82 94. 86 <lppm

TBA 2. 71 0. 19 lOppm 11. 73 63. 10 1. 80 1. 01 1. 58 <lppm

C5+ 0. 11 0. 30 <lppm 0. 08 0. 51 <lppm <lppm <lppm <lppm flow rate, g /

5000 1532 3074 1244 201 1043 530 850 337 hours Example 5:

Referring to FIG. 2, a material containing ethanol of about 5% by weight of azeotropic water or a mixture of partially recovered ethanol and mixed C ₄ hydrocarbons in the reaction zone R is used as a mixture of ethyl tertiary alkyl ether to be separated. The material (line 3) was used as the feed to the first distillation column C1.

The first distillation column C1 has a total of 80 trays, the feed temperature is 65 ° C, the feed position is the 40th tray, the operating pressure at the top of the tower is 8 bar, the reflux ratio is 0.75, and the temperature at the top of the tower is 65 ° C. . The unreacted mixed C ₄ hydrocarbon fraction (line 5) is collected from the top of the first distillation column C1, the side draw position is the 68th tray, and the material (line 6) taken from the liquid phase at about 135 ° C is passed through The temperature was lowered to 65 ° C and used as a feed to the second distillation column C ₂ together with the partially recovered ethanol (line 14).

The second distillation column C2 has a total of 50 trays, and the feed position is the 12th tray. The operating pressure at the top of the tower is 1 bar, the reflux ratio is 3.0, and the temperature at the top of the tower is 66 °C. Then, the effluent material at the top of the second distillation column C2 (line 9) is cooled to 38 ° C and then fed from the 24th tray of the extraction column C3, and the water is used as an extractant to feed from the first tray (pipeline) 12), operating pressure is 1 bar, operating temperature is 38 °C. The ethyl tertiary alkyl ether-containing raffinate (line 11) flowing out from the top of the extracting column C3 is collected, and the extract (line 10) flowing out from the bottom of the extracting column C3 is recovered and partially recycled to the reaction zone R. And a portion (about 66% of the recovered ethanol, line 14) is used for the feed of the second distillation column C2, and an ethyl tertiary alkyl ether (ETBE) fraction is obtained from the bottom of the first distillation column C1 (product) One, line 4) and an ethyl tertiary alkyl ether (ETBE) raffinate (one of the products, line 11) obtained from the top of the extraction column C3, and a monohydric alcohol-containing fraction obtained from the bottom of the second distillation column C2 ( Product 2, pipeline 8).

The significant difference between this example and Examples 2-4 is that by using partially recovered ethanol as the feed to the second distillation column C2, more monohydric alcohols which substantially remove the azeotropic water can be obtained.

The composition and flow rate of each major pipeline material stream including the mixture of ethyl tertiary alkyl ethers to be separated are shown in Table 5.

Table 5: Material balance table of Example 5

A method and apparatus for preparing an ethyl tertiary alkyl ether by purification according to the present invention, which is carried out by a distillation-extraction coupling separation method. The ethyl tertiary alkyl ether obtained by the method for purifying the ethyl tertiary alkyl ether may contain less than 1% by weight of ethanol, and the obtained monohydric alcohol may contain less than 1% by weight of water. According to the method and apparatus of the present invention, there is no stringent requirement for the material entering the dealkylation distillation column (the mixture of ethyl tertiary alkyl ether to be separated) (including, for example, ethanol content and/or water content and/or tertiary alcohol content, etc.) ), which is beneficial to increase the utilization of isoolefin resources, and greatly reduces the amount of tertiary alcohol that is "harmful" to the reaction zone during the entire separation and purification process. At the same time, the method and the device according to the invention can reduce the cost, in particular, ethanol having a water content of at least 1% by weight but up to 15% by weight, which is a renewable resource, can be used as a raw material for the etherification reaction, and not only a qualified ethyl group can be obtained. Tertiary alkyl ether products, and can co-produce the corresponding monohydric alcohols (including especially the corresponding tertiary alcohols), thus having high commercial value (function/cost).

Claims

Claim

A process for the preparation of ethyl tertiary alkyl ether by distillation-extraction coupling separation and purification, which is carried out by ether having an aqueous content of at least more than 1% by weight but up to 15% by weight of ethanol and an isoolefin having at least four carbon atoms The mixture to be separated of the ethyl tertiary alkyl ether obtained by the reaction is a raw material, characterized in that the method comprises: introducing a mixture of the ethyl tertiary alkyl ether to be separated into the first distillation column for dealkylation distillation, at the first Collecting a hydrocarbon-containing fraction at the top of the distillation column, collecting an ethyl tertiary alkyl ether fraction at the bottom of the first distillation column; and introducing the material withdrawn from the side of the first distillation column into a distillation-extraction coupling zone, wherein the distillation - the extraction coupling zone is composed of a second distillation column and an extraction column, and the operating pressure of the second distillation column is lower than the operating pressure of the first distillation column;

Collecting an aliphatic monohydric alcohol fraction at the bottom of the second distillation column, and feeding the material obtained at the top of the second distillation column as an extract feed to the extraction column for extraction;

The ethanol-containing extract is collected at the bottom of the extraction column, and 0-100% of the raffinate obtained at the top of the extraction column is recycled to the first distillation column.

2. The method according to claim 1, wherein the extraction is performed using water as an extracting agent; and when the ratio of the raffinate obtained at the top of the extraction column to the first distillation column is less than 100%, the content is collected from the top of the extraction column. A raffinate of ethyl tertiary alkyl ether.

3. The method according to claim 1, further comprising: extracting a portion of the hydrocarbon-containing fraction collected from the top of the first distillation column into the extraction column, wherein the introduction amount of the hydrocarbon-containing fraction and the extraction feed The weight ratio of the amount is 0. 05-1. 2 : 1.

4. The method according to claim 3, wherein extraction is performed using water as an extracting agent; a part of the hydrocarbon-containing fraction collected from the top of the first distillation column is taken out from the feed position of the extraction feed or is introduced into the extraction tower.

The method according to any one of claims 1 to 4, wherein the ethyl tertiary alkyl ether in the mixture to be separated of the ethyl tertiary alkyl ether is ethyl tert-butyl ether. The ethanol-containing extract collected from the bottom of the extraction column recovers the ethanol therein and serves as a feed for the distillation-extraction coupling zone.

The method according to any one of claims 1 to 4, wherein the mixture of the ethyl tertiary alkyl ether to be separated has a water content of 2 to 10% by weight of ethanol and contains isobutylene or isoprene The material of the mixed C ₄ hydrocarbon or mixed C ₅ hydrocarbon of the alkene is obtained by etherification reaction.

The method according to any one of claims 1 to 4, wherein the ethyl tertiary alkyl ether in the mixture to be separated of the ethyl tertiary alkyl ether is ethyl tert-butyl ether, which comprises : 1-20% by weight of ethanol, 5-80% by weight of ethyl tert-butyl ether, more than 1% by weight but up to 20% by weight of tert-butanol, 0.1 to 5% by weight of water, the balance being a hydrocarbon of four carbon atoms.

The method according to any one of claims 1 to 4, wherein the position at which the material is taken out from the side of the first distillation column is located at a side line position of a tray having substantially the highest ethanol concentration or below The material is withdrawn from the vapor phase and/or liquid phase at the location where the material is withdrawn from the side of the first distillation column.

9. The method according to claim 8, wherein the material taken out from the side of the first distillation column is located at the tray having substantially the highest ethanol concentration or the first block of the first block - the 15th theoretical plate The location between.

A method for preparing an ethyl tertiary alkyl ether by distillation-extraction separation and purification, characterized in that the method comprises:

a) feeding a material having a water content of at least more than 1% by weight but at most 15% by weight of ethanol and a mixed C ₄ hydrocarbon containing isobutylene to the reaction zone (R) for reaction under etherification reaction conditions;

b) feeding the mixture to be separated from the reaction zone (R) containing the ethyl tertiary alkyl ether to the first distillation column for dealkylation distillation, collecting the C ₄ hydrocarbon fraction at the top of the first distillation column, at the first Collecting a ethyl tertiary alkyl ether fraction at the bottom of the distillation column;

c) introducing a material withdrawn from the side of the first distillation column into a distillation-extraction coupling zone, wherein the distillation-extraction coupling zone is composed of a second distillation column and an extraction column, and the operating pressure of the second distillation column is lower than An operating pressure of a distillation column; collecting an aliphatic monohydric alcohol fraction at the bottom of the second distillation column, feeding the material obtained at the top of the second distillation column as an extraction feed to the extraction column, using water as an extractant for extraction, and extracting the column The operating pressure is not lower than atmospheric pressure; the ethanol-containing extract is collected at the bottom of the extraction column, and 0-100% of the raffinate obtained at the top of the extraction column is recycled to the first distillation column, wherein the raffinate circulation obtained at the top of the extraction column is recycled. When the proportion to the first distillation column is less than 100% by weight, the raffinate containing ethyl tertiary alkyl ether is collected from the top of the extraction column.

d) For the ethanol-containing extract collected from the bottom of the extraction column, recover the ethanol and recycle it as a feed to the reaction zone (R) or as a feed to the distillation-extraction coupling zone.

11. A distillation-extraction coupling separation and purification apparatus for preparing ethyl tertiary alkyl ether, comprising: a first distillation column (Cl), a second distillation column (C2) and an extraction column (C3), characterized in that: A connection line (3) is provided between the zone (R) and the first distillation column (C1) to make the etherification reaction The mixture to be separated of the ethyl tertiary alkyl ether to be prepared is introduced into the first distillation column (ci),

The top of the first distillation column (C1) is provided with a condenser (E2) for collecting hydrocarbon-containing fractions, a condensate tank (B1) and a line (5);

A heater (E3) and a line (4) for collecting an ethyl tertiary alkyl ether fraction are provided at the bottom of the first distillation column (C1),

The side of the first distillation column (C1) is provided with a line (6) connected to the second distillation column (C2), and a regulating valve (D1) and a heat exchanger (E4) are provided on the line (6) for the first distillation The side (C1) side take-out material is introduced into the second distillation column (C2).

A heater (E6) and a pipe line (8) for collecting the monohydric alcohol fraction are provided at the bottom of the second distillation column (C2).

The top of the second distillation column (C2) is provided with a condenser (E5) for collecting overhead materials, a condensate tank (B2) and a line (9); the material obtained from the top of the second distillation column (C2) is passed through a line (9) It is sent to the extraction column (C3), the extractant water enters the extraction column (C3) from the line (12), and the ethanol-containing extract is collected from the bottom of the extraction column (C3) via the line (10), from the top of the extraction column (C3). The raffinate is collected via line (11).

The apparatus according to claim 11, wherein in the treatment of the mixture to be separated of ethyl tert-butyl ether, the second distillation column (C2) is provided with a line (14) for introducing the recovered ethanol.

13. Apparatus according to claim 11 or 12, characterized in that a pump (Pl) is arranged on the line (11), whereby the raffinate obtained at the top of the extraction column (C3) is pressurized by the pump (P1) It is recycled to the first distillation column via line (11).