阅读说明：本技术 一种氯甲酸甲酯的合成方法 (Synthetic method of methyl chloroformate ) 是由 陈斌 陈永贵 过学军 黄中桂 杨镭 刘北战 熊刚 姚翔 于 2021-07-20 设计创作，主要内容包括：本发明公开了一种氯甲酸甲酯的合成方法,属于氯甲酸甲酯生产技术领域。该氯甲酸甲酯的合成方法包括以下步骤：步骤一、甲醇的纯化；步骤二、甲醇的气化；步骤三、光气的合成；步骤四、气相酯化反应。本发明利用甲醇气体和光气的气相反应,利用气相反应分子间的接触比气液反应分子间的接触更加充分,从而提高甲醇的转化率；本发明通过圆形挡板、转轴、循环气管、循环泵的设置,增加甲醇气体和光气之间混合度以及接触时间,使得甲醇反应得更加充分,避免过量的甲醇和氯甲酸甲酯发生副反应,提高氯甲酸甲酯的纯度和甲醇的转化率；本发明中通过批次循环的手段通入甲醇气体和光气,保证光气始终过量,同时不会过量太多,减小尾气处理压力。(The invention discloses a synthesis method of methyl chloroformate, belonging to the technical field of methyl chloroformate production. The synthesis method of methyl chloroformate comprises the following steps: step one, purifying methanol; step two, gasifying the methanol; step three, synthesizing phosgene; step four, carrying out gas-phase esterification reaction. The invention utilizes the gas phase reaction of methanol gas and phosgene, and utilizes the more sufficient contact between gas phase reaction molecules than between gas-liquid reaction molecules, thereby improving the conversion rate of methanol; according to the invention, through the arrangement of the circular baffle, the rotating shaft, the circulating gas pipe and the circulating pump, the mixing degree and the contact time between the methanol gas and the phosgene are increased, so that the methanol reaction is more sufficient, the excessive methanol and the methyl chloroformate are prevented from side reaction, and the purity of the methyl chloroformate and the conversion rate of the methanol are improved; in the invention, methanol gas and phosgene are introduced by means of batch circulation, so that phosgene is always excessive and cannot be excessive, and the pressure for treating tail gas is reduced.)

1. A method for synthesizing methyl chloroformate, which is characterized by comprising the following steps:

step one, purifying methanol: putting methanol into a rectifying tower, and rectifying and purifying the methanol to reduce the occurrence of side reactions in the subsequent esterification reaction;

step two, gasifying the methanol: introducing the purified methanol into a gasification tower, and gasifying the methanol to obtain methanol gas;

step three, phosgene synthesis: introducing carbon monoxide and chlorine into a phosgene generating tower according to the molar ratio of 1:1.05, and carrying out a synthesis reaction under the catalytic action of activated carbon to generate phosgene;

step four, gas-phase esterification reaction: introducing nitrogen for 15min into the esterification tower, driving away air in the esterification tower, controlling the flow of methanol gas and phosgene, circularly entering the esterification tower according to batches, wherein the methanol gas is sprayed out through a first gas automatic nozzle (12), the phosgene is sprayed out through a second automatic nozzle (14), and the methanol gas and the phosgene are subjected to esterification reaction in a mixing zone (10), a main reaction zone (20) and a secondary reaction zone (30) to obtain methyl chloroformate.

2. The method according to claim 1, wherein the temperature of the distillation in the first step is controlled to 65-68 ℃.

3. The method according to claim 1, wherein the vaporization temperature in step two is set to 70-75 ℃.

4. The method of synthesizing methyl chloroformate according to claim 1, wherein the batch recycling in step four is three batches and one cycle.

5. The method of synthesizing methyl chloroformate according to claim 1, wherein the flow molar ratio of the first methanol gas to the phosgene is 1:1.1, the flow molar ratio of the second methanol gas to the phosgene is 1:1.02, and the flow molar ratio of the second methanol gas to the phosgene is 1: 1.06.

6. The method of synthesizing methyl chloroformate according to claim 1, wherein the gas introduction time for each batch is 1 to 2 hours, and the cycle interval time is 1 to 2 hours.

7. The method for synthesizing methyl chloroformate according to claim 4, wherein methanol gas and phosgene are not introduced during the circulation interval, and the waste gas outlet (15) is opened to collect waste gas 20-30min before methanol gas and phosgene are introduced at the end of each circulation interval.

Technical Field

The invention belongs to the technical field of methyl chloroformate production, and particularly relates to a synthetic method of methyl chloroformate.

Background

Methyl chloroformate is an important intermediate for synthesizing carbendazim and is generally obtained by reacting phosgene with methanol. Mass production of methyl chloroformate is carried out by charging methanol into reaction tower with glass lining, controlling reaction temperature at 20-30 deg.C, introducing methanol and phosgene from bottom of tower in same direction, and reacting as follows: COCl₂+CH₃OH＝C₂H₃ClO₂+ HCl. The process mainly adopts the gas-liquid reaction of methanol and phosgene, and the generated methyl chloroformate has more byproducts and lower conversion rate of the methanol.

Therefore, the invention provides a synthesis method of methyl chloroformate.

Disclosure of Invention

The invention aims to provide a method for synthesizing methyl chloroformate, which replaces the gas-liquid reaction of methanol and phosgene with the double-gas-phase reaction of the methanol and the phosgene and solves the technical problem of more byproducts in the existing method for synthesizing the methyl chloroformate.

The purpose of the invention can be realized by the following technical scheme:

a method for synthesizing methyl chloroformate, comprising the following steps:

step one, purifying methanol: putting methanol into a rectifying tower, and rectifying and purifying the methanol to reduce the occurrence of side reactions in the subsequent esterification reaction;

step two, gasifying the methanol: introducing the purified methanol into a gasification tower, and gasifying the methanol to obtain methanol gas;

step three, phosgene synthesis: introducing carbon monoxide and chlorine into a phosgene generating tower according to the molar ratio of 1:1.05, and carrying out a synthesis reaction under the catalytic action of activated carbon to generate phosgene;

step four, gas-phase esterification reaction: introducing nitrogen into the esterification tower for 15min to drive away air in the esterification tower, controlling the flow of methanol gas and phosgene by a flow control valve, circularly entering the esterification tower according to batches, spraying the methanol gas out of a first gas automatic nozzle, spraying the phosgene out of a second automatic nozzle, preliminarily mixing the methanol gas and the phosgene in a mixing area to generate esterification reaction, fully mixing the methanol gas and the phosgene in a main reaction area to generate esterification reaction, further mixing the methanol gas and the phosgene in a secondary reaction area to generate esterification reaction, and re-entering the mixing area under the action of a circulating gas pump to repeat the process so as to prolong the contact time of the methanol gas and the phosgene, so that the methanol reaction is more sufficient and methyl chloroformate is obtained, wherein the temperature of the esterification tower is controlled to be 15-25 ℃.

Further, the rectification temperature in the first step is controlled to be 65-68 ℃.

Further, the gasification temperature in the second step is set to 70-75 ℃.

And further, the batch circulation in the fourth step is three batches and one circulation, the flow molar ratio of the methanol gas and the phosgene in the first batch is 1:1.1, the flow molar ratio of the methanol gas and the phosgene in the second batch is 1:1.02, the flow molar ratio of the methanol gas and the phosgene in the second batch is 1:1.06, the gas introducing time of each batch is 1-2h, the methanol gas and the phosgene are not introduced in the circulation interval time, the circulation interval time is 1-2h, 20-30min before the methanol gas and the phosgene are introduced at the end of each circulation interval, an exhaust gas outlet is opened, and the exhaust gas is collected.

Further, the cycle interval time is preferably 1h by measuring the content of methanol gas in the off-gas.

The invention has the beneficial effects that:

the method utilizes methanol gasification to enable methanol gas and phosgene to generate gas phase reaction, and compared with the traditional gas-liquid reaction, the method utilizes the contact between gas phase reaction molecules to be more sufficient than the contact between gas phase reaction molecules, thereby improving the conversion rate of the methanol; in addition, the invention increases the mixing degree and the contact time between the methanol gas and the phosgene by controlling the flow of the methanol gas and the phosgene and arranging the circular baffle, the rotating shaft, the circulating gas pipe and the circulating pump, so that the methanol is reacted more fully, the excessive methanol and the methyl chloroformate are prevented from generating side reaction, and the purity of the methyl chloroformate and the conversion rate of the methanol are improved; on the other hand, in the invention, the methanol gas and the phosgene are introduced by a batch circulation method, so that the condition that the phosgene in the esterification tower is always excessive but not too much is ensured, excessive phosgene waste gas is avoided, the pressure of tail gas treatment is reduced, and the waste gas in the esterification tower is discharged at the tail of a circulation interval, so that the excessive methanol gas and the excessive phosgene are prevented from being discharged, on the other hand, the excessive pressure in the esterification tower is prevented, and the continuous reaction of the methanol gas and the phosgene is kept.

In conclusion, the synthesis method of methyl chloroformate provided by the invention is simple to operate, can be used for continuous production, and has high purity of the obtained methyl chloroformate and high conversion rate of methanol.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a scheme showing the synthesis of methyl chloroformate according to the present invention;

FIG. 2 is a schematic structural diagram of a methyl chloroformate synthesizing apparatus according to the present invention;

FIG. 3 is a schematic diagram of the structure of an esterification column in a methyl chloroformate synthesizing apparatus according to the present invention;

fig. 4 is a schematic top view of a circular baffle in a methyl chloroformate synthesizing apparatus according to the present invention.

In the drawings, the components represented by the respective reference numerals are listed below:

10. a mixing zone; 11. a methanol gas line; 12. a first gas auto-injector; 13. a phosgene conduit; 14. a second automatic nozzle; 15. an exhaust gas outlet; 16. a methyl chloroformate outlet; 20. a primary reaction zone; 30. a secondary reaction zone; 40. a drive motor; 41. a coupling; 42. a rotating shaft; 43. a circular baffle; 50. a circulating gas pipe; 51. a circulating air pump; 52. and circulating the valve.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-4, the synthesis method of methyl chloroformate according to the present invention is synthesized in the apparatus for synthesizing methyl chloroformate, which comprises the following steps:

step one, purifying methanol: putting methanol into a rectifying tower, and rectifying and purifying the methanol to reduce the occurrence of side reactions in subsequent esterification reaction, wherein the rectifying temperature is controlled to be 65-68 ℃;

step two, gasifying the methanol: putting the purified methanol into a gasification tower, and gasifying the methanol to obtain methanol gas, wherein the gasification temperature is set to be 70-75 ℃;

step three, phosgene synthesis: introducing carbon monoxide and chlorine into a phosgene generating tower according to the molar ratio of 1:1.05, and carrying out a synthesis reaction under the catalytic action of activated carbon to generate phosgene;

step four, gas-phase esterification reaction: introducing nitrogen for 15min into the esterification tower to drive away air in the esterification tower, controlling the flow of methanol gas and phosgene by a flow control valve, circularly entering the esterification tower according to batches, wherein the methanol gas is sprayed out by a first gas automatic nozzle 12, the phosgene is sprayed out by a second automatic nozzle 14, the methanol gas and the phosgene are preliminarily mixed in a mixing zone 10 to generate esterification reaction, are fully mixed in a main reaction zone 20 to generate esterification reaction, are further mixed in a secondary reaction zone 30 to generate esterification reaction, and can enter the mixing zone 10 again under the action of a circulating air pump 51, repeating the process, prolonging the contact time of the methanol gas and the phosgene, leading the methanol reaction to be more full and obtaining methyl chloroformate, wherein the temperature of the esterification tower is controlled at 15-25 ℃.

The methyl chloroformate synthesizing device comprises a rectifying tower, a gasification tower, an esterification tower and a phosgene generating tower, wherein the rectifying tower, the gasification tower and the esterification tower are sequentially connected, a liquid pump (not shown in the figure) is arranged on a communication pipeline between the rectifying tower and the gasification tower, the esterification tower is connected with the phosgene generating tower through a gas pipe, a methanol gas tank and a flow regulating valve are connected between the gasification tower and the esterification tower, a phosgene tank and a flow regulating valve are connected between the esterification tower and the phosgene generating tower, and the flow regulating valve is close to the esterification tower;

the bottom end of the esterification tower is provided with a driving motor 40, the output end of the driving motor 40 penetrates through the bottom wall of the esterification tower and is fixedly connected with a rotating shaft 42 through a coupler 41, two circular baffles 43 are fixedly arranged on the outer peripheral wall of the rotating shaft 42, the circular baffles 43 protrude upwards, and a plurality of leaf-shaped holes are symmetrically arranged along the center of a circle, the driving motor 40 drives the rotating shaft 42 to rotate, so that the circular baffles 43 are driven to rotate, convection of surrounding gas is accelerated by the circular baffles 43, and contact between methanol gas and phosgene is promoted to be more sufficient;

the circular baffle 43 divides the inner cavity of the esterification tower into the mixing zone 10, the main reaction zone 20 and the secondary reaction zone 30, the circular baffle 43 can prevent the gas from moving downwards, and the retention time of the gas in the mixing zone 10 and the main reaction zone 20 is prolonged, so that the esterification reaction of the methanol gas and the phosgene is more sufficient;

a methanol gas pipeline 11 and a phosgene pipeline 13 are arranged in the mixing area 10, the methanol gas pipeline 11 is arranged above the phosgene pipeline 13, the methanol gas pipeline 11 is communicated with a methanol gas tank, the phosgene pipeline 13 is communicated with the phosgene tank, a plurality of first automatic gas nozzles 12 are arranged on the methanol gas pipeline 11, a plurality of second automatic gas nozzles 14 are arranged on the phosgene pipeline 13, and the first automatic gas nozzles 12 and the second automatic gas nozzles 14 are oppositely arranged, so that the methanol gas and the phosgene are relatively sprayed out, and the better mixing between the methanol gas and the phosgene is promoted;

the mixing zone 10 is connected with the secondary reaction zone 30 through a circulating gas pipe 50, a circulating gas pump 51 and a circulating valve 52 are arranged on the circulating gas pipe 50, and the circulating gas pump 51 pumps gas in the secondary reaction zone 30 and leads the gas into the mixing zone 10, so that the methanol reaction is more thorough;

the bottom of the inner cavity of the esterification tower is provided with a waste gas outlet 15 and a methyl chloroformate outlet 16, and the bottom of the inner cavity of the esterification tower is conical, so that the generated methyl chloroformate liquid can flow out of the esterification tower along the inclined inner wall.

The use principle of the methyl chloroformate synthesis device is as follows:

the methanol is purified in a rectifying tower, the methanol purified by the action of a liquid pump flows into a gasification tower to form methanol gas, the methanol gas flows into a methanol gas tank to facilitate the storage of the methanol gas in the subsequent batch circulation, the methanol gas flows into an esterification tower through a flow regulating valve, meanwhile, phosgene gas generated in a phosgene generating tower flows into a phosgene tank to facilitate the storage of the phosgene in the subsequent batch circulation, the methanol gas flows into the esterification tower through the flow regulating valve, the methanol gas is sprayed out through a first gas automatic nozzle 12, the phosgene is sprayed out through a second automatic nozzle 14, the methanol gas and the phosgene are primarily mixed in a mixing area 10 to generate esterification reaction, the methanol gas and the phosgene are fully mixed in a main reaction area 20 to generate esterification reaction, the methanol gas and the phosgene in a secondary reaction area 30 are further mixed to generate esterification reaction, the methanol gas and the phosgene in the secondary reaction area 30 can enter the mixing area 10 again under the action of a circulating air pump 51, the process is repeated, and the contact time of the methanol gas and the phosgene is prolonged, so that the methanol is reacted more fully to obtain methyl chloroformate, the produced methyl chloroformate liquid is collected through a methyl chloroformate outlet 16, and the produced hydrogen chloride gas and excess phosgene waste gas are collected through a waste gas outlet 15.

Example 1:

a method for synthesizing methyl chloroformate, comprising the following steps:

step one, purifying methanol: putting methanol into a rectifying tower, and rectifying and purifying the methanol to reduce the occurrence of side reactions in subsequent esterification reaction, wherein the rectifying temperature is controlled to be 65 ℃;

step two, gasifying the methanol: putting the purified methanol into a gasification tower, and gasifying the methanol to obtain methanol gas, wherein the gasification temperature is set to be 70 ℃;

step three, phosgene synthesis: introducing carbon monoxide and chlorine into a phosgene generating tower according to the molar ratio of 1:1.05, and carrying out a synthesis reaction under the catalytic action of activated carbon to generate phosgene;

step four, gas-phase esterification reaction: introducing nitrogen for 15min into an esterification tower to drive away air in the esterification tower, controlling the flow of methanol gas and phosgene by a flow control valve, circularly entering the esterification tower according to three batches and one batch, wherein the methanol gas is sprayed out by a first gas automatic nozzle 12, the phosgene is sprayed out by a second automatic nozzle 14, the methanol gas and the phosgene are preliminarily mixed in a mixing zone 10 to generate esterification reaction, are fully mixed in a main reaction zone 20 to generate esterification reaction, are further mixed in a secondary reaction zone 30 to generate esterification reaction, the methanol gas and the phosgene in the secondary reaction zone 30 can enter the mixing zone 10 again under the action of a circulating air pump 51, repeating the process, prolonging the contact time of the methanol gas and the phosgene, leading the methanol reaction to be more sufficient and obtaining methyl chloroformate, wherein the temperature of the esterification tower is controlled at 15 ℃, the flow molar ratio of the first batch of the methanol gas to the phosgene is 1:1.1, the flow molar ratio of the methanol gas and the phosgene of the second batch is 1:1.02, the flow molar ratio of the methanol gas and the phosgene of the second batch is 1:1.06, the gas introducing time of each batch is 1h, the methanol gas and the phosgene are not introduced in the circulation interval time, the circulation interval time is 1h, 20min before the methanol gas and the phosgene are introduced at the end of the circulation interval time of each batch, an exhaust gas outlet is opened, and the exhaust gas is collected by using an air pump.

The purity of methyl chloroformate was found to be 97.1% and the conversion of methanol was 96.4%.

Example 2:

a method for synthesizing methyl chloroformate, comprising the following steps:

step one, purifying methanol: putting methanol into a rectifying tower, rectifying and purifying the methanol to reduce the occurrence of side reactions in subsequent esterification reaction, and controlling the rectifying temperature to be 68 ℃;

step two, gasifying the methanol: putting the purified methanol into a gasification tower, and gasifying the methanol to obtain methanol gas, wherein the gasification temperature is set to be 75 ℃;

step three, phosgene synthesis: introducing carbon monoxide and chlorine into a phosgene generating tower according to the molar ratio of 1:1.05, and carrying out a synthesis reaction under the catalytic action of activated carbon to generate phosgene;

step four, gas-phase esterification reaction: introducing nitrogen for 15min into an esterification tower to drive away air in the esterification tower, controlling the flow of methanol gas and phosgene by a flow control valve, circularly entering the esterification tower according to three batches and one batch, wherein the methanol gas is sprayed out by a first gas automatic nozzle 12, the phosgene is sprayed out by a second automatic nozzle 14, the methanol gas and the phosgene are preliminarily mixed in a mixing zone 10 to generate esterification reaction, are fully mixed in a main reaction zone 20 to generate esterification reaction, are further mixed in a secondary reaction zone 30 to generate esterification reaction, the methanol gas and the phosgene in the secondary reaction zone 30 can enter the mixing zone 10 again under the action of a circulating air pump 51, repeating the process, prolonging the contact time of the methanol gas and the phosgene, leading the methanol reaction to be more sufficient and obtaining methyl chloroformate, wherein the temperature of the esterification tower is controlled at 25 ℃, the flow molar ratio of the first batch of the methanol gas to the phosgene is 1:1.1, the flow molar ratio of the methanol gas and the phosgene of the second batch is 1:1.02, the flow molar ratio of the methanol gas and the phosgene of the second batch is 1:1.06, the gas introducing time of each batch is 2 hours, the methanol gas and the phosgene are not introduced in the circulation interval time, the circulation interval time is 2 hours, 30min before the methanol gas and the phosgene are introduced at the end of the circulation interval time of each batch, an exhaust gas outlet is opened, and the exhaust gas is collected by a gas pump.

The purity of methyl chloroformate was found to be 96.3% and the conversion of methanol was found to be 95.4%.

Comparative example 1: example 1 in CN 201811058095.7.

The purity of methyl chloroformate was found to be 92.2% and the conversion of methanol was 83.4%.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.