CN110357835B

CN110357835B - Preparation method of epichlorohydrin

Info

Publication number: CN110357835B
Application number: CN201910823367.6A
Authority: CN
Inventors: 孙承宇; 杨琦武; 曹立
Original assignee: FUJIAN TIANCHEN YAOLONG NEW MATERIAL Ltd; China Tianchen Engineering Corp
Current assignee: FUJIAN TIANCHEN YAOLONG NEW MATERIAL Ltd; China Tianchen Engineering Corp
Priority date: 2019-09-02
Filing date: 2019-09-02
Publication date: 2023-04-28
Anticipated expiration: 2039-09-02
Also published as: CN110357835A

Abstract

The invention discloses a preparation method of epichlorohydrin, which comprises the steps of a reaction section, a washing section, a refining section and the like, has simple process and environment friendliness, can realize the recycling of a catalyst, effectively solves the problems of low catalyst activity, poor stability and short service life, has high cost performance, effectively avoids the problem of frequent start and stop, greatly reduces the production cost, and has wide industrial application prospect.

Description

Preparation method of epichlorohydrin

Technical Field

The invention belongs to the technical field of organic chemical synthesis, and particularly relates to a preparation method of epichlorohydrin.

Background

Epichlorohydrin, also called Epichlorohydrin (ECH), is a colorless liquid, is insoluble in water, is a large number of organic chemical raw materials and fine chemical products, is a third largest epoxide with the yield inferior to that of ethylene oxide and propylene oxide, is widely applied to the fields of producing epoxy resin, synthesizing glycerol, chlorohydrin rubber and the like, can also be used for preparing other derivatives, can also be used as a solvent, a plasticizer, a flame retardant, a surfactant and the like, and is an important intermediate of important organic chemical raw materials and petrochemical industry.

At present, the world industrial production methods of epichlorohydrin mainly comprise 3 methods of propylene high-temperature chlorination method, propylene acetate method and glycerol chlorination saponification method. Among them, the propylene high temperature chlorination method is the most main production method at home and abroad. At present, the propylene high-temperature chlorination method using propylene as a raw material accounts for about 90% of the total yield, the glycerol chlorination saponification method accounts for 10% of the total yield, and the propylene acetate method is basically eliminated. The propylene high-temperature chlorination method has the technical advantages of flexible production and mature process, but has the advantages of low yield, high energy consumption, serious equipment corrosion and large discharge of three wastes.

In order to solve the technical defect of the propylene high-temperature chlorination method, US4833260 discloses a method for directly epoxidizing olefin to produce epoxide by taking a titanium-silicon molecular sieve as a catalyst and hydrogen peroxide as an oxidant for the first time. The method has mild reaction conditions, is green and environment-friendly, and only water is used as a byproduct. However, the epoxide is easy to open to generate an ether byproduct due to the existence of a strong polar solvent in the reaction system, so that the selectivity of the epoxide is only about 85%, and the yield is low. In addition, this method has a key problem of short catalyst life.

To further increase the yield of epoxide, patent US4824976, CN1319099a discloses a method for modifying titanium silicalite catalyst in advance by using an acid neutralizer, wherein the acidic groups on the surface and in the pore canal of the catalyst can be neutralized by modifying the titanium silicalite molecular sieve with alkaline substances such as sodium hydroxide, ammonia water, etc., thereby inhibiting the occurrence of side reaction and improving the selectivity of epoxide. However, the catalyst use cost is further increased, which is disadvantageous in terms of atom economy. In addition, patent US5646314 and US5675026 disclose the modification of titanium silicalite catalysts with alkaline adjuvants or the addition of trace amounts of alkaline substances to the reaction system to inhibit the progress of side reactions and increase epoxide selectivity. However, the introduction of alkaline substances can cause unstable hydrogen peroxide, invalid decomposition of the hydrogen peroxide and increase operation danger. It should be noted that none of the above patents propose a solution for the short catalyst life.

Patent CN101486690B discloses a method for preparing epichlorohydrin by epoxidation of chloropropene, which is technically characterized in that a small amount of methanol is added as a solvent in a kettle/slurry bed reactor, the reaction liquid is in a phase-separated state, and under the condition of sufficient stirring, a micron-sized catalyst is highly dispersed in an oil phase and an aqueous phase, and the epoxidation reaction is carried out by three-phase contact to produce epichlorohydrin. Because the alcohol solvent is less in dosage and is dissolved in the water phase, a large amount of epichlorohydrin is distributed in the oil phase, the byproduct is prevented from being easily generated when alcohol, water and epichlorohydrin are separated, the oil phase is separated by normal pressure rectification, and the separation yield of epichlorohydrin is high. However, the reaction system is divided into oil-water phases, so that the concentration of the substrate is too high, and compared with a homogeneous system, the reaction is more severe and difficult to control. In addition, the methanol solvent has the functions of promoting the mutual dissolution of chloropropene and hydrogen peroxide, eliminating diffusion resistance and affecting the catalytic action process. For the epoxidation of olefins with hydrogen peroxide, the catalytic mechanism of TS-1 is generally considered to be a five membered ring mechanism. When the organic solvent is not used, water in the hydrogen peroxide solution serves as the solvent, and the generated five-membered ring transition state active species are unstable, so that the TS-1 cannot fully exert the chemical effect. In addition, chloropropene and hydrogen peroxide are mutually insoluble, and the reaction activity is also influenced, so the process has the technical defects of low conversion rate and effective utilization rate of hydrogen peroxide and short service life of the catalyst.

Patent CN1249042C discloses a suspension catalytic distillation process for the direct epoxidation of olefins. The method is characterized in that a titanium-silicon molecular sieve catalyst, a solvent, hydrogen peroxide and olefin enter a reaction section of a distillation tower together, and the catalyst and liquid materials are mixed and flow in the tower so as to catalyze the materials to react. The olefin is gasified and separated by utilizing reaction heat release, the solvent is recycled, after the catalyst and unvaporized liquid materials are separated, the obtained catalyst is recycled to a reaction section for use, and the epoxide is separated from tower top or tower bottom materials. The method has high reaction heat utilization rate, greatly reduces energy consumption, and can effectively inhibit side reaction. However, the method also has the problem of short catalyst life, and the problem of catalyst tower blocking occurs with the recycling of the catalyst.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for preparing epichlorohydrin, which effectively solves the problems of short service life and easy deactivation of the catalyst. The catalyst slurry separated and concentrated after the reaction is purified and washed on line, macromolecular organic matters adsorbed on the surface and inside of the catalyst are timely removed, and catalyst pore channels are evacuated, so that the catalyst has good stability, no deactivation problem, and is circularly economical, and frequent operations such as starting and stopping are avoided.

In order to achieve the above purpose, the technical scheme of the invention is realized as follows:

a preparation method of epichlorohydrin specifically comprises the following steps:

step 1: continuously and quantitatively adding chloropropene, hydrogen peroxide and a pH regulator into a reactor, mixing a catalyst and a solvent, and then adding the mixture into the reactor for reaction to obtain a mixed solution containing epichlorohydrin;

step 2: separating and concentrating the mixed solution containing the epichlorohydrine obtained in the step 1 through a separator to obtain catalyst slurry and clear liquid;

step 3: the catalyst slurry obtained in the step 2 enters a washing kettle and is washed by a detergent to obtain a purified catalyst and clear liquid containing a small amount of epichlorohydrine, and the catalyst after washing and purification is recycled by a separator and is circularly injected into a reactor;

step 4: and (3) feeding the clear liquid obtained in the step (2) and the clear liquid containing a small amount of epichlorohydrine obtained in the step (3) into a subsequent rectification working section for product refining to obtain epichlorohydrine products, and separating unreacted chloropropene and solvent in the clear liquid and then directly returning the separated chloropropene and solvent to a reactor for recycling.

The preparation process comprises an online continuous washing and purifying process, macromolecular organic matters adsorbed on the surface and inside of the catalyst can be removed through online washing of the catalyst, and the washed and purified catalyst returns to the reactor, so that the catalyst has no deactivation problem, the problems of short service life and poor stability of the catalyst are solved, and frequent start-stop operation is avoided.

Further, the mol ratio of chloropropene to hydrogen peroxide in the reactor in the step 1 is 1:1-30:1, and the mol ratio of solvent to chloropropene is 3:1-30:1;

the mass concentration of the catalyst in the reactor is 2-30%, and the mass concentration of the catalyst in the washing kettle is 1-50%.

Preferably, the mol ratio of chloropropene to hydrogen peroxide in the reactor in the step 1 is 3:1; preferably, the molar ratio of solvent to chloropropene is 4:1; preferably, the mass concentration of catalyst in the reactor is 10%; preferably, the mass concentration of catalyst in the wash tank is 10%.

Further, the solvent is acetonitrile and lower alcohols. Wherein the lower alcohols are methanol, ethanol, isopropanol or tert-butanol, etc. The solvent is preferably methanol.

Further, the pH regulator is one of ammonia water, methylamine, dimethylamine, trimethylamine, ethylamine and triethylamine. The pH value of the reaction system in the step 1 is controlled to be 6-7, and the pH regulator is preferably ammonia water, so that the method has good economical efficiency.

Further, the catalyst is:

molecular sieve or zeolite catalyst with Si to Ti molar ratio of 10-500;

or an amorphous catalyst corresponding to the empirical formula (TiO ₂ ) _X (SiO ₂ ) _1-X Wherein X is between 0.0001 and 0.5.

The catalyst is a titanium-containing catalyst, and may be a crystal (zeolite), an amorphous or a mixture thereof. Crystals mainly refer to various zeolite molecular sieves containing titanium, such as titanium-containing zeolite having an MFI topology similar to that of ZSM-5 zeolite (i.e., TS-1), titanium-containing zeolite having an MEL topology similar to that of ZSM-11 zeolite (i.e., TS-2), and titanium-containing molecular sieves having a beta zeolite, mordenite (natural or synthetic), ZSM-12, MCM-22, ZSM-48 structure, etc.; the amorphous material mainly refers to mesoporous molecular sieve with titanium and regular pore canal and oxide with irregular pore canal, such as titanium-containing material with isomorphic structure with MCM-41, SBA-15 and titanium dioxide loaded by silicon dioxide. Preferably, the molar ratio of Si to Ti of the molecular sieve to the zeolite catalyst is 10-200. Preferably, the amorphous catalyst has a molecular structure corresponding to the empirical formula (TiO ₂ ) _X (SiO ₂ ) _1-X Wherein X is 0.01 to 0.125.

Further, the catalyst is catalyst raw powder or catalyst after spraying, extruding and granulating, and the average particle size of the catalyst is 0.15-100 mu m. Preferably, the catalyst has an average particle size of 0.2 to 0.4. Mu.m.

Further, the mass concentration of the hydrogen peroxide is 27.5%, 50% or 70%. Preferably, the mass concentration of the hydrogen peroxide is 27.5%, so that the use safety is improved.

Further, the detergent is composed of one or two of methanol and alkylphenol ethoxylates. Preferably, the detergent is a mixture of methanol and alkylphenol ethoxylates, wherein the mass concentration of the alkylphenol ethoxylates is 0.1% -1%, preferably 0.3% -0.5%. The mixture of the methanol and the alkylphenol ethoxylates can be used as a detergent to effectively improve the cleaning effect of the catalyst, so that the reaction activity and the reaction efficiency of the catalyst are improved, and the reaction is more sufficient.

Further, the reaction is operated under the following conditions: the reaction temperature is 30-110 ℃, the reaction pressure is normal pressure-3.0 MPa, the reaction residence time is 10-60 min, the catalyst washing temperature is 30-200 ℃, and the washing time is 2-72 h. The reaction temperature is preferably 50 ℃; the reaction pressure is preferably 0.3MPa; the reaction residence time is preferably 20min; the catalyst wash temperature is preferably 180 ℃; the washing time is preferably 48 hours.

Further, the reactor is a slurry bed reactor, and the slurry bed reactor is a loop reactor or a curing kettle with a stirring device. The reactor is preferably a slurry bed curing tank.

Compared with the prior art, the preparation method of the epichlorohydrin has the following advantages:

(1) According to the invention, the catalyst slurry separated and concentrated after the reaction is subjected to online purification and washing, macromolecular organic matters adsorbed on the surface and inside of the catalyst are timely removed, and catalyst pore channels are evacuated, so that the catalyst has good stability, no deactivation problem, only a trace amount of catalyst is needed to be added, the recycling is realized, and the operations such as frequent start and stop are avoided.

(2) The invention is green and environment-friendly, the technological process is short, and low-carbon alcohol is used as a solvent, so that on one hand, the system materials are uniform, the reaction efficiency is improved, the reaction activity is high, and the reaction is more complete; on the other hand, the reaction heat can be taken out by evaporating the solvent, and the reaction temperature is easy to control.

(3) The invention adopts the slurry bed reactor, the heat generated in the reaction process is easy to remove in time, the temperature uniformity in the whole reaction process is ensured, and the catalyst material returning operation is simple.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:

FIG. 1 is a flow chart showing the process for producing epichlorohydrin according to examples 2 to 11 of the present invention.

Detailed Description

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other.

Example 1 (comparative example):

this example is where the catalyst is not subjected to continuous on-line wash clean-up.

Firstly, TS-1 raw powder is adopted as a catalyst, the average particle size of the catalyst is 0.2-0.4 mu m, and the catalyst and a methanol solvent are mixed and then added into a slurry bed curing kettle reactor for stirring. Secondly, chloropropene, 27.5% hydrogen peroxide and ammonia water are quantitatively and continuously added into the reactor, and the pH value of the reaction system is regulated to 6-7. The mol ratio of chloropropene to hydrogen peroxide is 3:1, the mol ratio of methanol to chloropropene is 4:1, and the mass concentration of TS-1 catalyst in the reactor is 10%. The reaction condition is that the reaction temperature is 50 ℃, the reaction pressure is 0.3MPa, the reaction residence time is 20min, the product mixed solution containing the epichlorohydrine is obtained after full reaction, the catalyst slurry and clear liquid are obtained after concentration by a separator, the clear liquid is refined by a subsequent rectification working section to obtain the epichlorohydrine product, unreacted chloropropene and solvent in the clear liquid are directly returned to the reactor for continuous recycling after separation, and the concentrated catalyst slurry also enters a curing kettle reactor for recycling. The data are shown in table 1.

Table 1:

as can be seen from example 1 (comparative example), the catalyst was not subjected to continuous on-line washing purification, and had poor stability, short life, and greatly reduced activity after 1000 hours of operation.

Example 2:

this example is a continuous on-line wash clean of the catalyst.

Firstly, TS-1 raw powder is adopted as a catalyst, the average particle size of the catalyst is 0.2-0.4 mu m, and the catalyst and a methanol solvent are mixed and then added into a slurry bed curing kettle reactor for stirring. Secondly, chloropropene, 27.5% hydrogen peroxide and ammonia water are quantitatively and continuously added into the reactor, and the pH value of the reaction system is regulated to 6-7. The mol ratio of chloropropene to hydrogen peroxide is 3:1, the mol ratio of methanol to chloropropene is 4:1, and the mass concentration of TS-1 catalyst in the reactor is 10%. The reaction condition is that the reaction temperature is 50 ℃, the reaction pressure is 0.3MPa, the reaction residence time is 20min, the product mixed solution containing the epichlorohydrine is obtained after full reaction, and the catalyst slurry and the clear liquid are obtained after concentration by a separator. The clear liquid is refined in a subsequent rectification working section to obtain an epichlorohydrin pure product, and unreacted chloropropene and solvent in the clear liquid are directly returned to the reactor for continuous recycling after being separated. The concentrated catalyst slurry enters a washing kettle and is purified and washed by a mixture of methanol and alkylphenol ethoxylate, the mass concentration of the alkylphenol ethoxylate is 0.3-0.5 percent, macromolecular organic matters adsorbed on the surface and inside a pore canal of the catalyst are removed, a purified catalyst and clear liquid containing a small amount of epichlorohydrin are obtained, the purified catalyst is recycled by a separator and is input into a reactor, the mass concentration of the catalyst in the washing kettle is 10 percent, the washing temperature of the catalyst is 180 ℃, the washing time is 48 hours, and the clear liquid containing a small amount of epichlorohydrin enters a rectifying section for refining and purifying. The data are shown in table 2.

Table 2:

as can be seen from example 2, the catalyst is subjected to continuous on-line washing and purification, and has high stability and strong activity, and the activity after 8000 hours of operation is consistent with that of the fresh catalyst.

Example 3:

example 2 was repeated except that the raw material feed ratio and the reaction conditions were changed. Wherein the mol ratio of chloropropene to hydrogen peroxide is 1:1, the mol ratio of methanol to chloropropene is 3:1, and the mass concentration of TS-1 catalyst in the reactor is 2%. The reaction conditions were as follows: the reaction temperature is 30 ℃, the reaction is normal pressure, and the reaction residence time is 10min. The catalyst washing conditions were as follows: the mass concentration of the catalyst in the washing kettle is 1%, the temperature is 30 ℃, the washing time is 2 hours, and the data are shown in Table 3:

table 3:

example 4:

example 2 was repeated except that the raw material feed ratio and the reaction conditions were changed. Wherein the mol ratio of chloropropene to hydrogen peroxide is 1:1, the mol ratio of methanol to chloropropene is 30:1, and the mass concentration of TS-1 catalyst in the reactor is 30%. The reaction conditions were as follows: the reaction temperature is 110 ℃, the reaction pressure is 3.0MPa, and the reaction residence time is 60min. The catalyst washing conditions were as follows: the mass concentration of the catalyst in the washing kettle is 50%, the temperature is 200 ℃, the washing time is 72 hours, and the data are shown in Table 4:

table 4:

example 5:

example 2 was repeated, the feed ratio and the reaction conditions were maintained unchanged, except that TS-2 raw powder was used as a catalyst, 50% hydrogen peroxide by mass was used as an oxidant, and the data are shown in Table 5:

table 5:

example 6:

example 2 was repeated, maintaining the feed ratio and reaction conditions unchanged, except that TiO was used ₂ The powder was the catalyst and the data are shown in table 6:

table 6:

example 7:

example 2 was repeated, the feed ratio and the reaction conditions were maintained, except that the catalyst was TS-1 after spray granulation, the average particle diameter of the catalyst was 40. Mu.m, and the data are shown in Table 7:

table 7:

example 8:

example 2 was repeated except that the solvent methanol was replaced with acetonitrile and the data are shown in table 8:

table 8:

example 9:

example 2 was repeated except that the pH adjuster aqueous ammonia was replaced with trimethylamine, and the data are shown in table 9:

table 9:

example 10:

example 2 was repeated except that the slurry bed curing tank reactor was replaced with a fixed bed tube reactor, the TS-1 raw powder was replaced with TS-1 extruded catalyst, and the data are shown in Table 10:

table 10:

example 11:

example 2 was repeated except that the detergent methanol and alkylphenol ethoxylate mixture was replaced with methanol and the data are shown in table 11:

table 11:

the foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.

Claims

1. A process for the preparation of epichlorohydrin, characterized in that: the method specifically comprises the following steps:

step 4: the clear liquid obtained in the step 2 and the clear liquid containing a small amount of epichlorohydrine obtained in the step 3 enter a subsequent rectification working section to carry out product refining to obtain epichlorohydrine products, and unreacted chloropropene and solvent in the clear liquid are directly returned to a reactor for recycling after being separated;

the mol ratio of chloropropene to hydrogen peroxide in the reactor in the step 1 is 1:1-30:1, and the mol ratio of solvent to chloropropene is 3:1-30:1; the mass concentration of the catalyst in the reactor is 2-30%, and the mass concentration of the catalyst in the washing kettle is 1-50%;

the catalyst is as follows: TS-1 catalyst or TS-2 catalyst;

the catalyst is catalyst raw powder or sprayed, extruded and granulated;

the mass concentration of the hydrogen peroxide is 27.5%, 50% or 70%;

the detergent consists of methanol and alkylphenol ethoxylates;

the operating conditions of the reaction are: the reaction temperature is 30-110 ℃, the reaction pressure is normal pressure-3.0 MPa, the reaction residence time is 10-60 min, the catalyst washing temperature is 30-200 ℃, and the washing time is 2-72 h;

the solvent is low-carbon alcohols;

the pH regulator is one of ammonia water, methylamine, dimethylamine, trimethylamine, ethylamine and triethylamine.

2. A process for the preparation of epichlorohydrin according to claim 1, characterized in that: the reactor is a slurry bed reactor, and the slurry bed reactor is a loop reactor.

3. A process for the preparation of epichlorohydrin according to claim 1, characterized in that: the reactor is a curing kettle with a stirring device.