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Method for preparing fluorinated alkene by high temperature wet-cracking

A technology of fluorine-containing olefins and wet method, which is applied in the field of high-temperature wet cracking to prepare fluorine-containing olefins

Active Publication Date: 2012-06-27
泉州宇极新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] So far, no catalyst-free method for the preparation of fluorine-containing alkenes from hydrofluoroalkanes with three carbon atoms in high yields has been reported.

Method used

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  • Method for preparing fluorinated alkene by high temperature wet-cracking
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  • Method for preparing fluorinated alkene by high temperature wet-cracking

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Example 1: Comparison of dehydrofluorination reaction and dry cracking reaction for HFC-236fa steam wet cracking.

[0029] The parameters of wet cracking: the temperature of the inner tube of the reactor is the reaction temperature, the reactant CF 3 CH 2 CF 3 The intake flow rate is 30ml / min, the water vapor flow rate is calculated based on the evaporation rate of 0.6g / min, and the reaction time is 0.04s. The experimental results are listed in Table 1, the main by-products are CO, CO2.

[0030] CF 3 CH 2 CF 3 ——→ CF 3 CH=CF 2 +HF

[0031] Table 1 Experimental results of wet cracking HFC-236fa

[0032]

[0033] Take the cracking dehydrofluorination reaction without adding water vapor or ammonia water vapor as a control:

[0034] The temperature of the inner tube of the reactor is the reaction temperature, the inlet flow rate of the reactant CF3CH2CF3 is 30ml / min, and the reaction time is 0.04s. The experimental results are listed in Table 2. The main by-pro...

Embodiment 2

[0039] Example 2 Influence of the amount of water vapor at 850°C on the dehydrofluorination reaction of wet cracking HFC-236fa

[0040] The reactor is the same as above, the temperature of the inner tube of the reactor is the reaction temperature, the inlet flow rate of the reactant CF3CH2CF3 is 30ml / min, the water vapor flow rate is calculated by evaporation per minute, and the reaction time is about 0.04s. The reaction conditions and corresponding experimental results are listed in Table 3. The main by-products are CO, CO2.

[0041] Table 3 Experimental results of steam wet cracking of HFC-236fa at 850℃

[0042]

[0043] The results show that within the selected water vapor flow rate range of the present invention, the conversion rate does not change substantially at 850°C, and the selectivity slightly increases with the increase of the water vapor amount.

Embodiment 3

[0044] Embodiment 3. The influence of reaction temperature on steam wet cracking HFC-245fa de-HF reaction

[0045] The reaction process is as follows:

[0046]

[0047] The temperature of the inner tube of the reactor is the reaction temperature, the inlet flow of the reactant CF3CH2CHF2 is 30ml / min, the water vapor flow is calculated based on the evaporation of 0.6g / min, and the reaction time is 0.04s. The reaction conditions and results are shown in Table 4, and the main by-products are CO and CO2.

[0048] Table 4 Effect of reaction temperature on experimental results of steam wet cracking of HFC-245fa

[0049]

[0050] The experimental results show that under the above conditions, as the temperature increases, the conversion rate of wet cracking HFC-245fa increases gradually, and the selectivity of trans and cis tetrafluoropropene decreases gradually. At 750-800°C, the conversion rate reaches more than 95%, and the by-products are about 0.2-1.1%. The obtained resul...

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Abstract

The invention relates to a method for preparing fluorinated alkene by high temperature wet-cracking, belonging to the field of organic synthesis. The method is characterized in that under the condition of normal pressure and the temperature of 600-1000DEG C, hydrogen fluoride alkane with the molecular formula of HnFmC3 (n +m=8, n is more than or equal to 1 and less than or equal to 8, and m is more than or equal to 2 and less than 8) is taken as raw gas to have cracking reaction in the environment of water vapor or ammonia water vapor; no catalyst is used in the method, so that the generation cost is reduced, by-products are few, the selectivity of the product is high, subsequent purification and separation are convenient, the whole technique is easy to control, and the method is very suitable for producing the fluorinated alkene in industrialization-scale.

Description

technical field [0001] The invention relates to the field of organic compound synthesis, in particular to a method for preparing fluorine-containing olefins by high-temperature wet cracking. Background technique [0002] Hydrochlorofluorocarbons (CFCs), such as difluorodichloromethane and trifluorochloromethane, are widely used as diluents for refrigerants, blowing agents and gas bactericides due to their excellent performance. In recent years, it has been found that chlorofluorocarbons have a destructive effect on the earth's atmosphere and also produce a greenhouse effect, and this issue has received widespread attention. Therefore, worldwide efforts are being made to find alternatives to halogenated hydrocarbons with short lifespan and low greenhouse effect. According to the current situation, the preparation of hydrofluorocarbons (HFCs) or compounds containing only carbon, hydrogen and fluorine elements has become a very popular topic. Research and provide environmental...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C21/18C07C17/25C09K5/04C08K5/02
Inventor 贾晓卿杨光成郭艳红鲍鹏
Owner 泉州宇极新材料科技有限公司
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