RU213929U1 - Tubular reactor for thermal synthesis of 3-methyl-3-buten-1-ol - Google Patents

Abstract

The utility model relates to devices for carrying out physical and chemical processes, namely to the process of synthesis of 3-methyl-3-buten-1-ol, which is the feedstock for the production of synthetic aromatic substances and vitamins A, E. A tubular reactor for thermal synthesis is proposed. 3-methyl-3-buten-1-ol, including a tubular body, nozzles for input of raw materials into the reaction space and output of the product, while the ratio of the length of the reactor to its inner diameter is more than 5000, the nozzle for introducing isobutylene and solvent is located coaxially at the end of the reactor tubular body, the pipe for introducing formaldehyde is located on the wall of the reactor, a pipe for introducing formaldehyde is placed in the pipe for introducing formaldehyde, equipped with a nozzle, the nozzle of the nozzle is installed coaxially with the tubular reactor body.

Description

The utility model relates to devices for carrying out chemical processes, namely to the process of synthesis of 3-methyl-3-buten-1-ol, which is a feedstock for the production of synthetic aromatic substances and vitamins A, E.

The utility model is used in the production of 3-methyl-3-buten-1-ol by the thermal method, by reacting isobutylene and formaldehyde in the absence of a catalyst under supercritical conditions. Most of the existing processes for obtaining 3-methyl-3-buten-1-ol consist in preheating and increasing the pressure of formaldehyde and isobutylene, mixing them homogeneously, and then introducing them into the reactor in a gaseous or liquid state to carry out the reaction. After the mixed feed enters the reactor, it takes some time to reach the temperature and pressure required for the reaction. Since the reaction conditions are not met at the beginning of the reaction zone, some reversible side reactions occur, including self-polymerization and disproportionation of formaldehyde to form formic acid. Side reactions significantly affect the selectivity of the process.

Known tubular reactor for the synthesis of 3-methyl-3-buten-1-ol from formaldehyde and isobutylene in the presence of a solvent, made in the form of a pipe, having a nozzle for entering the reaction space mixture of raw materials and a nozzle for outputting the product [RU 2692801, publ. 07/10/2018]. The tube is made of stainless steel, has an inner diameter of 2 mm and a length of 3180 mm (internal volume 10 ml).

The closest in technical essence is a tubular reactor for the synthesis of 3-methyl-3-buten-1-ol from formaldehyde and isobutylene in the presence of a solvent, made in the form of a pipe, having a branch pipe for introducing a mixture of raw materials into the reaction space and a pipe for outputting the product [JPH 7285899, publ. October 31, 1995]. The tube is made of stainless steel with an inner diameter of 2 mm and a length of 9540 mm (internal volume 30 ml).

In the process of thermal synthesis of 3-methyl-3-buten-1-ol, known reactors have the following disadvantages:

- Reactors are subject to severe corrosion, especially in the input area of the initial components. The corrosion process occurs as a result of exposure to an aggressive environment - formic acid, which is formed as a result of the reaction of the initial components;

- there is frequent clogging of the reactors due to the formation of by-products in the form of solid deposits, which leads to a decrease in the selectivity of the process;

- the performance of the reactors is insufficient.

To eliminate the known shortcomings, a tubular reactor for the thermal synthesis of 3-methyl-3-buten-1-ol from formaldehyde and isobutylene in the presence of a solvent is proposed, including a tubular body, nozzles for input of raw materials into the reaction space and output of the product, with a ratio of the length of the reactor to its inner diameter is more than 5000, while the pipe for introducing isobutylene and solvent is located at the end of the reactor coaxially with the tubular body, the pipe for introducing formaldehyde is located on the wall of the reactor, a pipe for introducing formaldehyde is placed in the pipe for introducing formaldehyde, equipped with a nozzle, the nozzle of the nozzle is installed coaxially to the tubular reactor vessel.

The pipe for introducing formaldehyde is located on the wall of the reactor at a distance of 300-1000 mm from the beginning of the reactor.

The pipe with a nozzle for supplying formaldehyde consists of two straight pipes connected to each other by a bend at an angle of 90 °.

The nozzle diameter is at least 10 times smaller than the reactor diameter.

The tubular reactor and nozzles are made of stainless steel. The reactor may be provided with an external heating jacket, but is not required. Heating of the reactor can be carried out either in one zone of the reactor, or along the entire length.

Branch pipes for input of initial components are supplied with temperature sensors.

The reactor is equipped with temperature and pressure sensors and a device for determining the consumption of reagents at the inlet.

The reactor operates in a mode close to the ideal displacement mode: there is no mixing in the direction of the flow axis; in each individual section, perpendicular to the flow axis, the process parameters are aligned.

When formaldehyde is sprayed through a nozzle into the center of the isobutylene and solvent stream, the formation of formic acid is reduced, as a result of which there is practically no corrosion, and no solid by-products are formed. When using a reactor for the thermal synthesis of 3-methyl-3-buten-1-ol with a ratio of its length to the inner diameter of more than 5000, the selectivity of the process increases.

The use of the utility model is illustrated in Fig. one.

In FIG. 1 schematically shows the proposed tubular reactor, which includes:

1 - reactor;

2 - branch pipe for entering a mixture of isobutylene with a solvent;

3 - branch pipe for introducing formalin;

4 - branch pipe for the withdrawal of reaction products;

5 - pipe with nozzle.

The reactor works as follows. The heated mixture of isobutylene with the solvent is fed into the reactor (1) through the nozzle (2). Heated formalin is sprayed through a pipe with a nozzle (5) installed in the formalin inlet (3) in a mixture of isobutylene with a solvent. The resulting reaction product is removed through the reaction product outlet (4).

The example describes a possible use of the utility model.

Example 1

The experiment was carried out on a pilot plant.

The reaction mixture consisting of 22.96 g of 98 wt.% isobutylene and 5.71 g of 99.9 wt.% methanol in the amount of 28.67 g/h is fed into a heat exchanger, where it is heated to a temperature of 280°C, the heated mixture is fed into a tubular reactor (1) made of stainless steel through a branch pipe (2) at the end of the reactor. The tubular reactor has an inner diameter of 2 mm and a length of 10,000 mm. 4.50 g of 40% formalin at a temperature of 70°C is fed into the heated solution through the pipe (3) on the reactor wall, which is located at a distance of 300 mm from the beginning of the reactor, through the nozzle (5). The injector nozzle is installed coaxially with the reactor tube. The process is carried out in a reactor at a temperature of 250°C and a pressure of 30 MPa for 0.5 h. temperature 30-60°C, reduce the pressure by a pressure reducing valve to 0.5 MPa and, then, sent to a container to collect the reaction mass.

As a result of using the proposed reactor, the formaldehyde conversion was 95.0%, the selectivity of 3-methyl-3-buten-1-ol in terms of formaldehyde was 95.7%. The content of formic acid and formic acid ester as by-products was 0.05 wt.% and 0.1 wt.%, respectively.

The inventive tubular reactor for the production of 3-methyl-3-buten-1-ol undergoes slight corrosion when organizing a special order for introducing mixed starting components and works more efficiently at certain ratios of its length to the inner diameter and the location of the input points of the feedstock.

Claims (2)

1. A tubular reactor for the thermal synthesis of 3-methyl-3-buten-1-ol from formaldehyde and isobutylene in the presence of a solvent, including a tubular body, an isobutylene and solvent inlet, a formaldehyde inlet and a product outlet, characterized in that that the ratio of the length of the reactor to its inner diameter is more than 5000; installed coaxially with the tubular reactor vessel. 2. Tubular reactor according to claim 1, characterized in that the formaldehyde injection pipe consists of two straight pipes connected to each other by an elbow at an angle of 90°.

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