Preparation method of 1,3,3,3-tetrafluoropropene

Abstract

The invention discloses a preparation method of 1,3,3,3-tetrafluoropropene; the preparation method includes the steps: a, in the presence of a composite catalyst, carrying out a gas phase fluorination reaction of a compound represented by the general formula of CF3-xClxCHClCHF2-yCly with hydrogen fluoride through two series-connection reactors with different reaction temperatures to generate 2,3-dichloro-1,1,1,3-tetrafluoropropane, wherein in the compound general formula, x=0, 1, 2 or 3, y=1 or 2, and 2<=(x+y)<=5; and b, in the presence of a dechloridation catalyst, carrying out a gas phase dechloridation reaction of 2,3-dichloro-1,1,1,3-tetrafluoropropane with hydrogen gas to generate 1,3,3,3-tetrafluoropropene. The preparation method is mainly used for preparation of 1,3,3,3-tetrafluoropropene.

Description

technical field [0001] The invention relates to a method for preparing hydrofluoroolefins, in particular to a method for preparing 1,3,3,3-tetrafluoropropene (HFO-1234ze). Background technique [0002] Compared with chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs), hydrofluoroolefins (HFOs) do not contain chlorine, do not pose a threat to the earth's ozone layer, and have low greenhouse effect potential. At present, it has become the focus of industrial research on fluorocarbons. 1,3,3,3-Tetrafluoropropene, namely HFO-1234ze, as a kind of hydrofluoroolefin, has an ozone depletion potential of 0 and a greenhouse effect potential of 6, and can be used as a refrigerant, blowing agent, gas Sol propellants, fire extinguishing agents, heat transfer media, propellants, gaseous dielectrics, sterilizing agent carriers, polymer monomers, and pharmaceutical and pesticide intermediates are widely used in the fields of chemical industry, fire p...

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Problems solved by technology

[0004] Fluorine-chlorine exchange method is the most, Japanese patent JP10007604, US patent US6472573, European patent EP486333 reported that 1-chloro-3,3,3-trifluoropropene (HCFC-1233zd) was used as raw material to synthesize HCFC-1233zd by one-step gas phase fluorination The method of HFO-1234ze, but the reaction raw material HCFC-1233zd in the method is expensive and difficult to obtain, and the catalyst used is a chromium-containing catalyst. These chromium-containing compounds and catalysts will cause damage to the human digestive tract and kidneys, especially high-priced chromium It has a strong carcinogenic effect, is unfriendly to people and the environment during production and use, and will cause serious harm; Chinese patent CN200810000765. -240fa) as a raw material, the method for preparing HFO-1234ze by gas-phase fluorination, but the selectivity of HFO-1234ze is poor in the method, only about 50%; -1243) is the method for synthesizing HFO-1234ze as a raw material, but the raw material of this synthetic method is expensive, the route is complicated, and the addition reaction process is difficult to control

[0005] For the dehydrohalogenation method, U.S. Patent US7592494, European Patent EP2014637, European Patent EP0974571, Chinese Patent CN101265155, Chinese Patent CN101466656 and Japanese Patent JP10007605 have reported the use of 1,1,1,3,3-pentafluoropropane (HFC-245fa ) is a method for synthesizing HFO-1234ze as a raw material, but the reaction raw material HFC-245fa is expensive; U.S. Patent UA20090278075 has reported a method for preparing HFO- 1234ze and HFO-1234yf method, but HFO-1234ze is less selective in this method

[0006] For the telomerization method, U.S. Patents US20050245773 and US20050245774 reported using methyl halide and vinyl halide as raw materials to obtain HFO-1234ze through continuous fluorination after telomerization, but the synthesis method is complicated, and the catalyst is expensive and easy to coke Inactivation, and many by-products, low conversion rate

[0007] For the preparation method of carbene reaction, U.S. Patent US20050245774 reported that above the cracking temperature of difluorocarbene precursor, HFO-1234ze was prepared by high-temperature reaction of difluorocarbene and vinylidene fluoride monomer in the same reactor. The reaction temperature of this synthesis method High, low yield, harsh reaction conditions, no industrial application value

[0008] Although there are many methods for preparing HFO-1234ze disclosed at present, there are deficiencies such as expensive raw materials, not easy to obtain, catalysts that are not friendly to the environment, and harsh reaction conditions. Therefore, there is continuous improvement and demand for more effective preparation methods

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