A kind of manufacture method of fluoroolefin

Abstract

The invention discloses a preparation method for fluoralkene. The preparation method comprises the following steps: (1) mixing a 2-25% potassium hydroxide water solution with calcium hydroxide or calcium oxide to obtain a saponification liquid, and adding the obtained saponification liquid to a reaction kettle; (2) heating to 30-90 DEG C while stirring, and adding hydrofluoroalkane to the reaction kettle; (3) continuously stirring and keeping the reaction temperature to be 30-90 DEG C to realize defluorination of a liquid-phase hydrofluoroalkane to generate crude fluoralkene; (4) condensing and rectifying the reaction product obtained in the step (3) to obtain fluoralkene. The preparation method has the advantages of simple process, high reaction selectivity, less three-waste discharge and the like, and is suitable for industrialized production.

Description

technical field [0001] The invention relates to a method for producing fluoroolefins, which belongs to the technical field of organic fluorine chemical industry. Background technique [0002] HFO-1234yf is 2,3,3,3-tetrafluoropropene, its ODP is zero, its GWP value is 4, its atmospheric life is only 11 days, it has excellent physical and chemical properties, its molecular weight is similar to that of HFC-134a, and its Its boiling point and high saturated vapor pressure at room temperature, and its density and critical point are similar to HFC-134a, so it is considered as a "direct substitute" for HFC-134a and a potential low-carbon refrigerant. In addition, HFO-1234yf can be used in fire extinguishing agent, heat transfer medium, propellant, foaming agent, gas medium, polymer monomer, carrier gas fluid and other fields. [0003] HFO-1225ye is 1,2,3,3,3-pentafluoropropene, which has low greenhouse effect potential (GWP) and zero ozone depletion potential (ODP), and can also b...

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Problems solved by technology

[0008] The dehydrofluorination of hydrofluoroalkanes to prepare hydrofluoroalkenes conventionally adopts the method of gas-phase catalytic dehydrofluorination and liquid-phase saponification dehydrofluorination, wherein the gas-phase catalytic dehydrofluorination is reacted under the action of a dehydrofluorination catalyst at a temperature greater than 250°C, and the reaction performance is poor, such as CN102884031A As described, the highest selectivity of HFO-1234yf is only 90%, which reduces the reaction yield and brings difficulties to product separation and purification

[0009] Liquid-phase saponification dehydrofluorination needs to be reacted at a higher reaction temperature and lye concentration. As described in CN101962314A, the reaction is carried out at a reaction temperature of about 160°C and an lye concentration of about 60%. This aspect increases energy consumption and is easy to produce Alkynes, on the other hand, the use of high-concentration saponification liquid brings difficulties to the recycling of saponification waste liquid

In order to increase the reaction speed, some patent documents also propose adding an organic solvent to the saponification solution to strengthen the dehydrofluorination process. Although this can reduce the concentration of the lye, it will bring difficulties to the recycling and treatment of the saponification waste solution due to the addition of an organic solution.

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