Method for preparing fluoorpropane and device thereof

Abstract

The present invention discloses a preparation method for fluoro-propane and the relative device. The tower kettle exit of the first-level fluorination reactor is connected with a first-level circulated pump, a first-level heat-exchanger and the circulating entrance of the first-level fluorination reactor. The tower top exist of the first-level fluorination reactor is connected with the entrance of the first-level refluence tower; the exit of the first-level refluence tower is connected with the entrance of the hydrochloric separated tower; the exit of the hydrochloric separated tower is connected with the tower kettle entrance of the second-level fluorination reactor. The tower kettle exit of the second-level fluorination reactor is connected with the entrance of the second-level refluence tower; the tower kettle exit of the second-level fluorination reactor is connected with a second-level circulated pump, a second-level heat-exchanger and the circulating entrance of the second-level fluorination reactor. The reaction device respectively adopts a circulated pump and a heat-exchanger to form an outer circulation so as to improve the contact condition for the active agent and the catalyzing agent. The method is to prepare the propane. The present invention has the advantages of higher reacting selectivity and conversion ratio, longer using time for the catalyzing agent and lower device investment and so on.

Description

technical field [0001] The invention relates to the preparation of fluoropropane such as HFC-245fa, in particular to a preparation method and device for fluoropropane. Background technique [0002] In the past, the preparation of fluoropropane such as HFC-245fa mainly consisted of two major categories: the hydrogenation reduction method of chloropentafluoropropane (Lianxun Company, CN1128016A) and the fluorination method of pentachloropropane (HCC-240). The former has many reaction steps, and the latter is based on There are different process routes (methods) for fluorination conditions. Lianxun patent CN1063736C uses SbCl n f 5-n As a catalyst, a single reactor is used for liquid-phase fluorination reaction, the yield is only 57%, and the organic phase of the reaction product contains about 84% of HFC-245fa, CF 3 CH 2 CHClF is about 11%; CN1331067A of Atofina Company takes intermediate 1,1,1-trifluoro-3-chloro-2-propene (1233zd) as raw material, and carries out gas-phas...

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Problems solved by technology

Lianxun patent CN1063736C uses SbCl n f 5-n As a catalyst, a single reactor is used for liquid-phase fluorination reaction, the yield is only 57%, and the organic phase of the reaction product contains about 84% of HFC-245fa, CF 3 CH 2 CHClF is about 11%; CN1331067A of Atofina Company takes intermediate 1,1,1-trifluoro-3-chloro-2-propene (1233zd) as raw material, and carries out gas-phase fluorination reaction in the presence of chromium-based catalyst. The raw materials need to undergo complex impurity removal treatment; Ato company CN95117398.7 uses antimony pentachloride as a catalyst, and reacts intermittently in a liquid phase at 120°C to prepare HFC-245fa, and the selectivity of HFC-245fa is 69-91% , the catalyst life of this method is too short to be industrialized

Ato company CN1166479A adopts two-stage fluorination reaction, the first stage uses chromium / nickel-based catalyst to make HCC-240 and AHF undergo gas-phase fluorination reaction, the intermediate product enters the second-stage fluorination reactor, and uses antimony pentachloride as the Catalyst, carry out liquid-phase fluorination reaction, prepare HFC-245fa, and adopt the method of flowing chlorine gas to prolong the service life of catalyst antimony pentachloride; Daikin Company CN1067043C adopts two-step gas-phase fluorination reaction to prepare HFC-245fa, and gas-phase fluorination The preparation requirements of industrial reactors are relatively high, and the investment is large, and the post-treatment process often involves complex processes such as azeotropic distillation

Daikin CN1150146C, on the basis of the single-stage liquid phase fluorination reaction, set up a second reactor for reacting the catalyst (antimony fluoride chloride) with AHF to generate antimony pentafluoride, but in the actual reaction process , to extract the reaction mixture, fluorinate the catalyst in it and then return to the first reactor to work, it is very difficult for industrialization

Solvay company CN1079787C proposes that in the Hastelloy reactor, before the antimony salt catalyst is contacted with HCC-240, it is treated with AHF to improve the activity of the catalyst, but this treatment method will cause the Hastelloy reactor severe corrosion

[0003] Previous technologies have shown that in the single-stage continuous liquid phase fluorination reaction, the content of HFC-245fa in the synthesis gas is below 80%, and there are many intermediates and impurities, which cause difficulties in subsequent separation and are difficult to industrialize; the gas phase fluorination reaction is The preparation requirements of industrial equipment are relatively high, the investment is large, and the post-treatment is more complicated; although the two-stage liquid phase reaction can increase the content of HFC-245fa in the synthesis gas, because the reaction pressure exceeds 1.2MPa, the medium in the reactor has Dangerous media such as HF have the corrosion problem of chlorides, and the catalyst is deactivated and becomes mixed with antimony trichloride (solid) and associated heavy by-products. The catalyst is easy to reduce the activity, and the chlorine gas used as the activator must be increased. However, excessive chlorine gas tends to accumulate near the liquid surface, which will promote some side reactions, make subsequent separation difficult, and aggravate corrosion

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