阅读说明：本技术 一种连续法合成水杨腈的工艺 (Process for synthesizing salicylonitrile by continuous method ) 是由 汪静莉 胡红一 常亚军 朱光景 夏震宇 宋建均 杨露 于 2019-11-01 设计创作，主要内容包括：本发明涉及一种连续法合成水杨腈的工艺,包括：催化剂填装到二段流化床中,升温活化催化剂；含有水的水杨酸酯以液体形式注入气化室、氨气以气体形式注入气化室,从气化室出来的水杨酸酯和水蒸汽的混合物、氨气分别进入二段流化床在催化剂的作用下反应得到水杨腈气体；水杨腈气体通过控制温度冷却以液体的形式流入接收罐中,得到水杨腈液体；打开尾气回用阀,回用部分尾气至流化床,未回用尾气进入硫酸吸收塔后进行尾气处理。本发明的连续法合成水杨腈的工艺,具有转化率高、传质传热效果好、催化剂寿命长等特点,适于工业化生产。(The invention relates to a process for synthesizing salicylaldehyde by a continuous method, which comprises the following steps: filling the catalyst into a two-stage fluidized bed, and heating to activate the catalyst; salicylic acid ester containing water is injected into a gasification chamber in a liquid form, ammonia gas is injected into the gasification chamber in a gas form, and a mixture of the salicylic acid ester and water vapor and the ammonia gas which are discharged from the gasification chamber respectively enter a two-stage fluidized bed to react under the action of a catalyst to obtain salicylonitrile gas; the salicylonitrile gas flows into a receiving tank in a liquid form through temperature control cooling to obtain salicylonitrile liquid; and opening a tail gas recycling valve, recycling part of tail gas to the fluidized bed, and treating the tail gas after the unrecycled tail gas enters the sulfuric acid absorption tower. The process for synthesizing the salicylonitrile by the continuous method has the characteristics of high conversion rate, good mass and heat transfer effects, long service life of the catalyst and the like, and is suitable for industrial production.)

1. A process for synthesizing salicylonitrile by a continuous method is characterized in that: the method comprises the following steps:

(1) filling the catalyst into a two-stage fluidized bed, and heating to activate the catalyst;

(2) salicylic acid ester containing water is injected into the gasification chamber in a liquid form, ammonia gas is injected into the gasification chamber in a gas form, the mixture of the salicylic acid ester, the water vapor and the ammonia gas from the gasification chamber respectively enter a two-stage fluidized bed and react under the action of the catalyst in the step (1) to obtain salicylonitrile gas;

(3) cooling the salicylonitrile gas obtained in the step (2) by controlling the temperature, and enabling the salicylonitrile gas to flow into a receiving tank in a liquid form to obtain salicylonitrile liquid;

(4) and opening a tail gas recycling valve, recycling part of tail gas to the fluidized bed, and treating the tail gas after the unrecycled tail gas enters the sulfuric acid absorption tower.

2. The process of claim 1, wherein the continuous process for the synthesis of salicylanitrile comprises: the catalyst in the step (1) is a vanadium supported catalyst.

3. The process of claim 2, wherein the continuous process for the synthesis of salicylanitrile comprises: the preparation method of the vanadium supported catalyst is an impregnation method, and specifically comprises the following steps: dissolving a certain amount of precursor in a solvent at 50-100 ℃, adding a carrier, stirring at room temperature for 1-24 hours, drying and roasting at a certain temperature to obtain a supported catalyst, mixing the supported catalyst with an auxiliary agent and water at room temperature, stirring for a period of time, drying and roasting to obtain the vanadium supported catalyst containing the auxiliary agent.

4. The process of claim 3, wherein the continuous process comprises the following steps: the precursor is one or more of ammonium metavanadate, vanadium sulfate and vanadium oxalate, the carrier is one of aluminum oxide, silicon dioxide and a molecular sieve, the auxiliary agent is one or more of phosphoric acid, ammonium phosphate and antimonic acid, and the mass ratio of the precursor to the auxiliary agent is 1: 1-10: 1.

5. the process of claim 1, wherein the continuous process for the synthesis of salicylanitrile comprises: in the step (2), the salicylate is methyl salicylate or ethyl salicylate, and the molar ratio of the salicylate to ammonia gas is 1: 3-1: 5, the molar ratio of the salicylate to the water vapor is 1: 0.01-1: 0.5.

6. the process of claim 5, wherein the continuous process comprises the following steps: the salicylate ester is methyl salicylate.

7. The process of claim 1, wherein the continuous process for the synthesis of salicylanitrile comprises: the temperature of the gasification chamber in the step (2) is 250-300 ℃, the reaction temperature of the fluidized bed is 300-450 ℃, the reaction pressure is 0-0.1MPa, and the airspeed of the fluidized bed is 0-2.5h^-1。

8. The process of claim 1, wherein the continuous process for the synthesis of salicylanitrile comprises: and (3) cooling in two stages, wherein the material is cooled by the oil cooler in the first stage, the temperature of the oil cooler is controlled to be 120-180 ℃, and the material is cooled by the circulating water in the second stage, and the temperature is controlled to be 10-50 ℃.

9. The process of claim 1, wherein the continuous process for the synthesis of salicylanitrile comprises: and (4) the recycling rate of the tail gas in the step (4) is 0-100%.

10. The process of claim 9 for the continuous synthesis of salicylanitrile, characterized in that: the recycling rate of the tail gas is 10-50%.

Technical Field

The invention belongs to the technical field of chemical industry, and particularly relates to a process for synthesizing salicylaldehyde by a continuous method.

Background

The salicylaldehyde has the melting point of 95-98 ℃, the boiling point of 149 ℃/14mmHg, certain water solubility, unstable strong alkali or strong oxidizing property, is quickly heated to the boiling point, is decarboxylated and decomposed into phenol, can be used as a key intermediate of products such as buniprolol, azoxystrobin and the like, and can also be used as an intermediate of a plurality of spices and liquid crystal materials.

The current generation methods of the salicylaldehyde mainly comprise: salicylaldoxime dehydration, salicylamide dehydration, o-hydroxyhalobenzene cyanidation, ammonium salicylate, ammoxidation, and the like. Wherein, the salicylaldoxime dehydration method and the salicylamide dehydration method adopt raw materials with high toxicity as dehydrating agents and generate a large amount of acidic wastewater. The cyaniding method uses highly toxic substances such as sodium cyanide and the like as a cyanogen source, so that the safety risk is high. The ammoxidation method is divided into a step ammoxidation method and a one-step ammoxidation method: the method comprises the steps of performing ammoxidation on a precursor o-methyl chlorobenzene or o-methyl phenol ether to generate substituted benzonitrile, and hydrolyzing to obtain the salicylaldehyde, wherein the stepwise process has a long process route, and the second step of hydrolysis can cause the hydrolysis of cyano groups in the salicylaldehyde to corresponding salicylamide and generate a large amount of salt-containing wastewater; the one-step ammoxidation method directly uses salicylic acid or salicylate to directly react with ammonia gas in the presence of a catalyst to obtain the salicylaldehyde in one step, a fixed bed is used as a carrier in the one-step method, and the ammonia oxidation is a strong exothermic reaction, so that the heat of the fixed bed cannot be removed in time, the catalyst is easy to sinter or over-react, the yield is reduced, and the service life of the catalyst is shortened.

Chinese patent CN20111005846.7 discloses an ammonium salicylate process, which comprises reacting salicylic acid with ammonia water to produce ammonium salicylate, and reacting with urea, sulfamic acid and alkaline catalyst at high temperature to produce salicylaronitrile. Although the method avoids the use of dehydrating agents such as phosphorus oxychloride and the like, the process flow is long, the catalyst cannot be recycled, and the industrial application is limited.

Chinese patent CN201410849943.1 discloses a novel preparation process of salicylaldehyde, which is mainly characterized in that a fixed bed process is adopted, three wastes are not generated basically in the whole reaction process, the reaction yield is high, and the like, but when the reaction is carried out for about 500 hours, the activity of a catalyst is sharply reduced and cannot be recovered, so that the industrial application of the catalyst is limited.

Disclosure of Invention

The invention aims to provide a process for synthesizing salicylonitrile by a continuous method, which has the characteristics of high conversion rate, good mass and heat transfer effects, long service life of a catalyst and the like and is suitable for industrial production.

The technical scheme adopted by the invention for solving the problems is as follows: a process for synthesizing salicylonitrile by a continuous method comprises the following steps:

(1) the catalyst is filled into the two-stage fluidized bed, and the catalyst is activated by heating.

(2) And (2) injecting salicylate containing water into the gasification chamber in a liquid form, injecting ammonia gas into the gasification chamber in a gas form, and respectively introducing the mixture of the salicylate and the water vapor and the ammonia gas from the gasification chamber into a two-stage fluidized bed to react under the action of the catalyst in the step (1) to obtain the salicylalonitrile gas.

(3) And (3) cooling the salicylonitrile gas obtained in the step (2) by controlling the temperature, and enabling the salicylonitrile gas to flow into a receiving tank in a liquid form to obtain a salicylonitrile liquid.

(4) And opening a tail gas recycling valve, recycling part of tail gas to the fluidized bed, and treating the tail gas after the unrecycled tail gas enters the sulfuric acid absorption tower.

Further, the catalyst in the step (1) is a vanadium-supported catalyst.

Further, the preparation method of the vanadium-supported catalyst is an impregnation method, and specifically comprises the following steps: dissolving a certain amount of precursor in a solvent at 50-100 ℃, adding a carrier, stirring at room temperature for 1-24 hours, drying and roasting at a certain temperature to obtain a supported catalyst, mixing the supported catalyst with an auxiliary agent and water at room temperature, stirring for a period of time, drying and roasting to obtain the vanadium supported catalyst containing the auxiliary agent.

Further, the precursor is one or more of ammonium metavanadate, vanadium sulfate and vanadium oxalate, the carrier is one or more of aluminum oxide, silicon dioxide and a molecular sieve, the auxiliary agent is one or more of phosphoric acid, ammonium phosphate and antimonic acid, and the mass ratio of the precursor to the auxiliary agent is 1:1 ~ 10: 1.

Further, in the step (2), the salicylate is methyl salicylate or ethyl salicylate, the molar ratio of the salicylate to ammonia gas is 1:3 ~ 1: 5, and the molar ratio of the salicylate to water vapor is 1: 0.01-1: 0.5.

Still further, the salicylate is methyl salicylate.

Further, the temperature of the gasification chamber in the step (2) is 250-^-1。

Further, the cooling in the step (3) is two-stage cooling, wherein the material is cooled by the oil cooler in the first stage, the temperature of the oil cooler is controlled to be 120-.

Further, the recycling rate of the tail gas in the step (4) is 0-100%.

Further, the exhaust gas reuse rate is 10-50%.

Compared with the prior art, the invention has the advantages that:

(1) the two-stage fluidized bed technology is adopted, and a continuous method replaces an intermittent method, so that the generating capacity is improved, and the labor intensity is reduced.

(2) And a tail gas recycling device is adopted, so that the ammonia gas consumption is reduced, the tail gas emission is reduced, and the process is environment-friendly.

(3) Less generation of three wastes, economy and environmental protection.

(4) The reaction device has continuous preparation process, good heat transfer of the two-stage fluidized bed and easy temperature control, ensures that the reacted materials are quickly mixed in the fluidized bed and the reaction heat is removed in time, can overcome the defects of uneven concentration distribution and local overheating in the traditional reactor, and can effectively control the mixing, mass transfer and heat transfer processes of the reacted materials.

Drawings

FIG. 1 is a process flow diagram of a continuous process for synthesizing salicylaldehyde.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

As shown in figure 1, the process flow chart of the invention for synthesizing the salicylonitrile by a continuous method.