阅读说明：本技术 一种高选择性制备1,3-丁二醇的方法和系统 (Method and system for preparing 1, 3-butanediol with high selectivity ) 是由 武金丹 刘喆 邴威瀚 杨光 靳权 王聪 刘新伟 杨克俭 霍瑜姝 梁秀霞 于 2020-07-02 设计创作，主要内容包括：本发明提供一种高选择性制备1,3-丁二醇的方法和系统。所述方案以乙醛为原料、以无机碱为催化剂,pH值11～14的条件下在盘管式反应器中发生缩合反应；调节反应液pH值至中性后,分离未反应的乙醛和3-羟基丁醛粗品溶液；以骨架镍催化剂,60～90℃催化加氢即得1,3-丁二醇粗品溶液。本发明所述的方法和系统采用了极有利于传热的盘管式缩合反应器,能够准确控制反应温度、物料配比和停留时间。同时,在加氢反应步骤中,采用了较低的加氢温度和串联的反应釜,有效减少了副反应的发生。所述反应工艺提高了反应效率、反应稳定性和产品选择性。(The invention provides a method and a system for preparing 1, 3-butanediol with high selectivity. According to the scheme, acetaldehyde is used as a raw material, inorganic base is used as a catalyst, and condensation reaction is carried out in a coil type reactor under the condition that the pH value is 11-14; adjusting the pH value of the reaction liquid to be neutral, and separating unreacted acetaldehyde and a 3-hydroxybutyraldehyde crude product solution; and carrying out catalytic hydrogenation at 60-90 ℃ by using a skeletal nickel catalyst to obtain a 1, 3-butanediol crude product solution. The method and the system adopt the coil type condensation reactor which is extremely beneficial to heat transfer, and can accurately control the reaction temperature, the material ratio and the retention time. Meanwhile, in the hydrogenation reaction step, a lower hydrogenation temperature and a reaction kettle connected in series are adopted, so that the occurrence of side reactions is effectively reduced. The reaction process improves the reaction efficiency, the reaction stability and the product selectivity.)

1. A method for preparing 1, 3-butanediol with high selectivity is characterized in that: taking acetaldehyde as a raw material, taking inorganic base as a catalyst, and carrying out a condensation reaction in a coil type reactor (1) under the condition that the pH value is 11-14 to generate a crude product of 3-hydroxybutyraldehyde; and catalyzing 3-hydroxybutyraldehyde to hydrogenate at 60-90 ℃ by using skeletal nickel as a catalyst to obtain a 1, 3-butanediol crude product solution.

2. The process for producing 1, 3-butanediol according to claim 1, characterized in that: the method comprises the specific steps of carrying out,

s1, preparing a 3-hydroxybutyraldehyde crude product: taking an acetaldehyde aqueous solution as a raw material, and carrying out condensation reaction in a coil type reactor (1) under the catalysis of inorganic base;

s2, recovering acetaldehyde: adding acid into the condensation reaction liquid obtained in the step S1 to adjust the pH value to be neutral, and entering an acetaldehyde recovery tower (3); the distillate at the tower top of the acetaldehyde recovery tower (3) is unreacted acetaldehyde, water is added to continue to be used as a raw material to return to an acetaldehyde raw material tank (9), and the tower bottom of the acetaldehyde recovery tower (3) is a 3-hydroxybutyraldehyde crude product solution;

s3, preparing 1, 3-butanediol by hydrogenation: step S2, feeding the tower bottom effluent of the acetaldehyde recovery tower (3) into a hydrogenation reaction device, wherein the mass ratio of a skeletal nickel catalyst to a 3-hydroxybutyraldehyde crude product solution in the hydrogenation reaction device is 1: 6-12; the hydrogenation reaction time is 10-30 min; and (3) performing solid-liquid separation on the hydrogenation reaction liquid to obtain a mother liquid, namely the generated 1, 3-butanediol crude product solution.

3. The process for producing 1, 3-butanediol according to claim 2, characterized in that: in the step S1, the mass ratio of the added acetaldehyde to the inorganic base is 15-50: 1.

4. The process for producing 1, 3-butanediol according to claim 2, characterized in that: in the step S1, the reaction temperature in the coil of the coil-type reactor (1) is-8 to 8 ℃.

5. The process for producing 1, 3-butanediol according to claim 2, characterized in that: in the step S1, the pH value in the coil of the coil-type reactor (1) is between 11 and 14.

6. The process for producing 1, 3-butanediol according to claim 2, characterized in that: in the step S1, the reaction residence time in the coil of the coil-tube reactor (1) is 5-10 min.

7. The process for producing 1, 3-butanediol according to claim 2, characterized in that: the top temperature of the acetaldehyde recovery tower (3) is 40-55 ℃, and the top pressure is 200-280 kPa; the temperature of the tower bottom is 60-90 ℃, and the pressure of the tower bottom is 300-350 kPa.

8. The process for producing 1, 3-butanediol according to any of claims 2-6, wherein: further comprises the step of refining the product S4, and purifying the obtained 1, 3-butanediol crude product solution.

9. A system for carrying out the process for the production of 1, 3-butanediol as defined in any one of claims 1 to 7, wherein: comprises a coil pipe type reactor (1), an acetaldehyde recovery tower (3), a hydrogenation reaction device and a solid-liquid separator which are connected in sequence.

10. The system for producing 1, 3-butanediol of claim 9, wherein: the coil pipe type reactor (1) consists of a coil pipe and a heat exchange cavity interlayer arranged on the outer wall of the coil pipe; the inner diameter of the coil pipe type reactor (1) is 2.0-4.5 mm, preferably 3.0-4.0 mm; the wall thickness of the reaction tube is 0.8-1.0 mm; the length of the reaction tube is 32-45 m, preferably 35-40 m.

Technical Field

The invention belongs to the technical field of chemical synthesis, and particularly relates to a preparation method and a system of 1, 3-butanediol.

Background

The 1, 3-butanediol has good hygroscopicity and water solubility, no odor and low toxicity, and has the reactivity of dihydric alcohol. The 1, 3-butanediol has wide application, and can be used for producing plasticizers, unsaturated polyester resins, industrial dehydrating agents and the like; can also be used as moisturizer and softener for textiles, tobacco and paper, antibacterial agent for cheese or meat, etc.; can also be used as humectant in cosmetics.

Currently, the acetaldehyde condensation method is the mainstream of the method for producing 1, 3-butanediol. The production process comprises the following steps: in a kettle type reactor, acetaldehyde is subjected to condensation reaction in an alkaline aqueous solution to generate 3-hydroxybutyraldehyde, and after acid is added to neutralize the reaction liquid, the reaction liquid is hydrogenated to generate 1, 3-butanediol. Although the reaction route is short, the traditional method has poor reaction selectivity and unsatisfactory yield; in particular, in the tank reactor, side reactions are likely to occur due to the back-mixing of the fluid in the tank.

The patent CN109422635A analyzes the reason that a kettle type reactor is not suitable for acetaldehyde condensation reaction, 3-hydroxybutyraldehyde is easy to continue to deeply condense with acetaldehyde under an alkaline condition, so that various byproducts are generated, and the reaction selectivity is reduced. In addition, the 3-hydroxybutyraldehyde intermediate is easily decomposed at high temperature, which is also a cause of low product yield.

Patent CN108383684A discloses a preparation method using a tubular reactor instead of a tank reactor to reduce unnecessary back mixing in the preparation process of 1, 3-butanediol and reduce the generation of by-products. However, the material retention time of the method is up to 24 hours at most, 0.51-0.92 ton of 1, 3-butanediol is produced per ton of acetaldehyde, and the yield is unstable.

Therefore, on the basis of the existing preparation process, the side reaction in the acetaldehyde condensation process is reduced, the temperature and the pressure of the hydrogenation reaction are reduced, and the main research direction for improving the selectivity of the 1, 3-butanediol is provided.

Disclosure of Invention

In view of the above, the present invention provides a method for preparing 1, 3-butanediol with high selectivity, so as to solve the problems in the prior art.

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

a method for preparing 1, 3-butanediol with high selectivity takes acetaldehyde as a raw material and takes inorganic base as a catalyst, and a condensation reaction is carried out in a coil type reactor to generate a crude product solution of 3-hydroxybutyraldehyde; the skeletal nickel catalyst catalyzes 3-hydroxybutyraldehyde to hydrogenate to obtain 1, 3-butanediol crude product solution.

The method specifically comprises the following process steps:

s1, preparing a 3-hydroxybutyraldehyde crude product: a40 wt% aqueous solution of acetaldehyde is used as a preferred raw material, condensation reaction is carried out in a coil type reactor under the catalysis of inorganic base, and the material ratio, the reaction temperature and the retention time are accurately controlled.

Wherein the inorganic base is at least one of sodium hydroxide and potassium hydroxide; the mass ratio of the added acetaldehyde to the inorganic base is 15-50: 1.

The reaction temperature in the coil pipe of the coil pipe type reactor is-8 ℃, and preferably-5 ℃; the pH value is controlled to be between 11 and 14.

The reaction residence time in the coil of the coil-type reactor is 5-10 min, preferably 6-8 min.

S2, recovering acetaldehyde: adding acid into the condensation reaction liquid obtained in the step S1 to adjust the pH value to be neutral, and feeding the condensation reaction liquid into an acetaldehyde recovery tower; the distillate at the tower top of the acetaldehyde recovery tower is unreacted acetaldehyde, water is added to prepare 40 wt% of acetaldehyde to be continuously used as a raw material to return to an acetaldehyde raw material tank, and the tower bottom of the acetaldehyde recovery tower is 3-hydroxybutyraldehyde crude product solution.

The top temperature of the acetaldehyde recovery tower is 40-55 ℃, and the top pressure is 200-280 kPa; the temperature of the tower bottom is 60-90 ℃, and the pressure of the tower bottom is 300-350 kPa.

S3, preparing 1, 3-butanediol by hydrogenation: step S2, enabling the bottom effluent of the acetaldehyde recovery tower to enter a hydrogenation reaction device, wherein the mass ratio of a skeletal nickel catalyst to a 3-hydroxybutyraldehyde crude product solution in the reaction device is 1: 6-12, the reaction temperature is 60-90 ℃, and the preferable temperature is 70-80 ℃; the hydrogenation reaction time is 10-30 min. The catalyst separated from the hydrogenation reaction liquid by the solid-liquid separator returns to the hydrogenation reaction device, and the mother liquid obtained by the solid-liquid separation is the generated 1, 3-butanediol crude product solution.

Further, the preparation method of the 1, 3-butanediol further comprises the step of refining the product S4.

The invention also aims to provide a system for realizing the preparation method of the 1, 3-butanediol, which comprises a coil type reactor, an acetaldehyde recovery tower, a hydrogenation reaction device and a solid-liquid separator which are connected in sequence.

The coil pipe type reactor consists of a coil pipe and a heat exchange cavity interlayer arranged on the outer wall of the coil pipe; the coil pipe is provided with two feed inlets which are respectively connected with an acetaldehyde raw material tank and an inorganic alkali raw material tank; the coil type reactor also comprises a discharge hole which is connected with a downstream acetaldehyde recovery tower. The interlayer of the heat exchange cavity of the coil-type reactor is provided with a circulating medium inlet and a circulating medium outlet, the reaction temperature in the coil is controlled by controlling the temperature of the circulating medium, and the circulating medium can be a mixed solution of glycol and water. The inlet of the circulating medium is close to the feed inlet of the coil pipe, and the outlet of the circulating medium is close to the discharge outlet of the coil pipe.

The inner diameter of the coil pipe type reactor is 2.0-4.5 mm, preferably 3.0-4.0 mm; the wall thickness of the reaction tube is 0.8-1.0 mm; the length of the reaction tube is 32-45 m, preferably 35-40 m.

Furthermore, a flow meter and a valve are arranged between the acetaldehyde raw material tank and the inorganic alkali raw material tank and the tubular reactor, so that the amount of the solution entering the tubular reactor can be controlled.

Further, a neutralization kettle is arranged between the coil pipe type reactor and the acetaldehyde recovery tower, a feeding hole is formed in the top of the neutralization kettle, and a discharging hole in the bottom of the neutralization kettle is connected with the middle part of the acetaldehyde recovery tower.

The top discharge port of the acetaldehyde recovery tower is connected with the feed inlet of the acetaldehyde raw material tank or the coil pipe type reactor, the bottom of the acetaldehyde recovery tower is connected with the feed inlet of the hydrogenation reaction device, and preferably, two hydrogenation reaction kettles are connected in series for hydrogenation reaction.

A discharge port of the hydrogenation reaction device is connected with a solid-liquid separator, and a liquid outlet of the solid-liquid separator is connected with a filtrate tank and used for storing a 1, 3-butanediol crude product solution; the solid outlet is connected with the feed inlet of the hydrogenation reaction kettle, and the skeletal nickel catalyst is sent back to the hydrogenation reaction device. Preferably, a material buffer tank is arranged between the hydrogenation reaction device and the solid-liquid separator.

Further, the outlet of the filtrate tank is connected with a subsequent refining unit for treatment.

Compared with the prior art, the method and the system for preparing the 1, 3-butanediol with high selectivity have the following advantages: the coil type condensation reactor which is extremely beneficial to heat transfer is adopted, and the reaction temperature, the material ratio and the residence time can be accurately controlled. Meanwhile, in the hydrogenation reaction step, a lower hydrogenation temperature and a reaction kettle connected in series are adopted, so that the occurrence of side reactions is effectively reduced. The reaction process improves the reaction efficiency, the reaction stability and the product selectivity.

Drawings

FIG. 1 is a schematic view of a system for producing 1, 3-butanediol according to an embodiment of the present invention.

Description of reference numerals:

1-a coil-type reactor; 2-a neutralization kettle; a 3-acetaldehyde recovery column; 4-a first hydrogenation reaction kettle; 5-a second hydrogenation reaction kettle; 6-material buffer tank; 7-a centrifuge; 8-a filtrate tank; a 9-acetaldehyde feed tank; 10-inorganic base raw material tank.

Detailed Description

Unless defined otherwise, technical terms used in the following examples have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs.

The invention is described in detail below with reference to embodiments and the accompanying drawings.

In the following examples 1 and 2, the 1, 3-butanediol production system used was: the device comprises a coil pipe type reactor 1, a neutralization kettle 2, an acetaldehyde recovery tower 3, a first hydrogenation reaction kettle 4 and a second hydrogenation reaction kettle 5 of two hydrogenation reaction kettles connected in series, a material buffer tank 6, a centrifuge 7 and a filtrate tank 8.

The coil pipe type reactor 1 consists of a coil pipe and a heat exchange cavity interlayer arranged on the outer wall of the coil pipe; the coil pipe is provided with two feed inlets which are respectively connected with an acetaldehyde raw material tank 9 and an inorganic alkali raw material tank 10; the coil type reactor also comprises a discharge port which is connected with a downstream acetaldehyde recovery tower 3. The interlayer of the heat exchange cavity of the coil-type reactor 1 is provided with a circulating medium inlet and a circulating medium outlet, the reaction temperature in the coil is controlled by controlling the temperature of the circulating medium, and the circulating medium is a mixed solution of glycol and water. The inlet of the circulating medium is close to the feed inlet of the coil pipe, and the outlet of the circulating medium is close to the discharge outlet of the coil pipe.

Flow meters and valves are arranged between the acetaldehyde raw material tank 9 and the inorganic alkali raw material tank 10 and the coil type reactor 1, and the amount of the solution entering the coil type reactor 1 can be controlled.

And a neutralization kettle 2 is arranged between the coil pipe type reactor 1 and the acetaldehyde recovery tower 3, a feed inlet is arranged at the top of the neutralization kettle 2, and a discharge outlet at the bottom of the neutralization kettle 2 is connected with the middle part of the acetaldehyde recovery tower 3.

The top discharge port of the acetaldehyde recovery tower 3 is connected with an acetaldehyde raw material tank 9, and the bottom of the acetaldehyde recovery tower 3 is connected with a first hydrogenation reaction kettle 4 and a second hydrogenation reaction kettle 5 which are connected in series.

A centrifuge 7 is used as a solid-liquid separator, a discharge hole of the second hydrogenation reaction kettle 5 is connected with the centrifuge 7, and a liquid outlet of the centrifuge 7 is connected with a filtrate tank 8 for storing a 1, 3-butanediol crude product solution; the solid outlet is connected with the feed inlet of the first hydrogenation reactor 4, and the skeletal nickel catalyst is sent back to the first hydrogenation reactor 4. And a material buffer tank 6 is arranged between the second hydrogenation reaction kettle 5 and the centrifuge 7.

The specific preparation process of the 1, 3-butanediol comprises the following steps:

s1, preparing a 3-hydroxybutyraldehyde crude product: pumping 40 wt% acetaldehyde water solution material and inorganic base into the coil type reactor 1 for condensation reaction, and accurately controlling material ratio, reaction temperature and residence time.

S2, recovering acetaldehyde: adding acetic acid into the neutralization kettle 2, neutralizing the condensation reaction liquid obtained in the step S1 until the pH value is 7.0, and entering an acetaldehyde recovery tower 3; the temperature of the top of the acetaldehyde recovery tower 3 is 46-47 ℃, and the pressure is 220-240 kPa; the temperature of the tower bottom is 66-68 ℃, and the pressure is 320-340 kPa. Adding water into unreacted acetaldehyde distilled from the top of the acetaldehyde recovery tower 3 to prepare 40 wt% of acetaldehyde to be continuously used as a raw material to return to an acetaldehyde raw material tank 9, and pumping the 3-hydroxybutyraldehyde crude product solution at the bottom of the acetaldehyde recovery tower 3 into a first hydrogenation reactor 4.

S3, preparing 1, 3-butanediol by hydrogenation: two hydrogenation reaction kettles are connected in series, the crude product solution of the 3-hydroxybutyraldehyde flowing out from the bottom of the acetaldehyde recovery tower 3 in the step S2 enters a first hydrogenation reaction kettle 4, and a skeletal nickel catalyst returned by a solid-liquid separator in the first hydrogenation reaction kettle 4 is mixed uniformly and then enters a second hydrogenation reaction kettle 5 for continuous reaction. The mixture of the skeleton nickel 3-hydroxybutyraldehyde stays in the first hydrogenation reactor 4 and the second hydrogenation reactor 5 for 20-50min respectively. A centrifuge 7 was used as the solid-liquid separator.

And pumping the reaction liquid into a centrifugal machine 7 through a pump, wherein the centrifugal speed is 10000rpm, the centrifugal time is 3min, returning the finally obtained catalyst solid to the first hydrogenation reaction kettle 4, pumping the mother liquid into a 1, 3-butanediol crude product tank through the pump, and treating the mother liquid by a subsequent refining unit.