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Method for preparing 1,1-difluoroethylene by cracking of 1,1,1-difluoro-1-chloroethane

A technology of difluoro-chloroethane and difluoroethylene, applied in the direction of dehydrohalogenation preparation, etc., can solve the problems of limited improvement effect, easy deactivation, catalyst loss, etc., to improve gas flow and heat distribution, and eliminate local Overheating phenomenon, the effect of improving the reaction conversion rate

Inactive Publication Date: 2015-01-28
LINHAI LIMIN CHEM +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0017] (1) The empty tube cracking process requires high temperature to obtain a high reaction conversion rate, and the cracking of 1,1,1-difluorochloroethane is prone to carbon formation and coking under high temperature conditions
[0018] (2) The dilution cracking process can improve the carbon formation and coking phenomenon in the cracking process, but the addition of a large amount of diluent will reduce the production capacity, increase energy consumption, and the load of the subsequent separation process will be large
[0019] (3) Accelerators can reduce the cracking temperature, but the improvement effect is limited, and side reactions are intensified at the same time
[0020] (4) The catalyst can reduce the cracking temperature, but the catalyst used for cracking 1,1,1-difluorochloroethane generally suffers from catalyst loss and easy deactivation

Method used

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  • Method for preparing 1,1-difluoroethylene by cracking of 1,1,1-difluoro-1-chloroethane
  • Method for preparing 1,1-difluoroethylene by cracking of 1,1,1-difluoro-1-chloroethane
  • Method for preparing 1,1-difluoroethylene by cracking of 1,1,1-difluoro-1-chloroethane

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Evenly fill the internal components in the Ф32×1200mm quartz cracking tube, and the filling volume is 500m3 of the external area of ​​the internal components per cubic meter of reaction tube volume 2 (Internal component composition: nickel content 100%); put the cracking tube into the electric heating furnace, turn on the electric heating, and preheat the cracking tube to 500°C. Maintain the temperature of the cracking tube at 500°C, control the flow rate of the raw material 1,1,1-difluoromonochloroethane so that the residence time in the effective constant temperature heating section of the cracking tube (length 570mm) is 200s; mix the reacted The gas is rapidly cooled to below 100°C by a water cooler, and then the acid gas produced by cracking is washed away by the secondary water washing tower and the first alkali washing tower, and then the moisture is removed by freeze drying. After the gas is collected, the composition is detected by gas chromatography.

[0049] T...

Embodiment 2

[0052] Evenly fill the internal components in the Ф32×1200mm quartz cracking tube, and the filling amount is 100m3 of the external area of ​​the internal components per cubic meter of reaction tube volume 2 (Internal component composition: nickel content 100%); put the cracking tube into the electric heating furnace, turn on the electric heating, and preheat the cracking tube to 580°C. Maintain the temperature of the cracking tube at 580°C, control the flow rate of the raw material 1,1,1-difluorochloroethane so that the residence time in the effective constant temperature heating section of the cracking tube (length 570mm) is 100s; mix the reacted The gas is rapidly cooled to below 100°C by a water cooler, and then the acid gas produced by cracking is washed away by the secondary water washing tower and the first alkali washing tower, and then the moisture is removed by freeze drying. After the gas is collected, the composition is detected by gas chromatography.

[0053] The m...

Embodiment 3

[0056] Evenly fill the internal components in the Ф32×1200mm quartz cracking tube, and the filling amount is 300m3 of the external area of ​​the internal components per cubic meter of reaction tube volume 2 (Internal component composition: 90% nickel, 10% iron); put the cracking tube into the electric heating furnace, turn on the electric heating, and preheat the cracking tube to 560°C. Maintain the temperature of the cracking tube at 560°C, control the flow rate of the raw material 1,1,1-difluorochloroethane so that the residence time in the effective constant temperature heating section of the cracking tube (length 570mm) is 80s; mix the reacted The gas is rapidly cooled to below 100°C by a water cooler, and then the acid gas produced by cracking is washed away by the secondary water washing tower and the first alkali washing tower, and then the moisture is removed by freeze drying. After the gas is collected, the composition is detected by gas chromatography.

[0057] The m...

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Abstract

The invention discloses a method for preparing 1,1-difluoroethylene by cracking of 1,1,1-difluoro-1-chloroethane. The method includes steps of uniformly mounting inner metal components with catalysis effect in a cracking tube made of an inert material according to the filling quantity that the surface area of the inner metal components in each cubic meter of cracking tube is 100-500 square meters; placing the cracking tube into an electric heating furnace, controlling the temperature of the cracking tube within the range of 500-580 DEG C, leading 1,1,1-difluoro-1-chloroethane and retaining the same in a reaction section of the cracking tube for 20-400 seconds; quenching reaction products at an outlet of the cracking tube to below 100 DEG C through a water cooler, absorbing acid gas such as hydrogen chloride therein through a secondary washing absorption tower and a primary alkali cleaning absorption tower, freezing and drying to obtain cracked products. The method has the advantages that crack reaction temperature is low, conversion rate of raw materials is high, reaction selectivity is good, the service life of the cracking tube is long, and the method is applicable to industrial production.

Description

technical field [0001] The invention relates to a method for preparing 1,1-difluoroethylene by cracking 1,1,1-difluorochloroethane, in particular to using internal components as catalytic materials to catalytically crack 1,1,1-difluorochloroethane Cracking of alkane to produce 1,1-difluoroethylene. technical background [0002] 1,1-Difluoroethylene, also known as vinylidene fluoride (Vinylidene Fluoride, VDF) is an important fluorine-containing monomer, polyvinylidene fluoride can be prepared by homopolymerization, and can be prepared by copolymerization with hexafluoropropylene and tetrafluoroethylene Fluorine resin and fluororubber. Polyvinylidene fluoride has good corrosion resistance, weather resistance and thermal processing performance, and is widely used in coatings, lithium batteries, water treatment and other industries. [0003] 1,1-difluoroethylene is mainly prepared by thermal cracking of 1,1,1-difluorochloroethane (R142b). The cracking process can be carried o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C21/18C07C17/25
Inventor 尹红郑海峰何甫长王林光袁慎峰陈志荣刘乘风
Owner LINHAI LIMIN CHEM
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