A method for preparing 3,3,3-trifluoropropene

Abstract

A preparation method of 3,3,3-trifluoropropylene belongs to the field of organic fluorine chemical technology. The present invention uses cis-1-chloro-3,3,3-trifluoropropylene as a raw material, hydrazine hydrate as a reducing agent, and performs a dehalogenation reduction reaction under the action of a reaction solvent and a mixture catalyst of aluminum-nickel-chromium alloy and palladium-carbon, and then purifies the product to obtain 3,3,3-trifluoropropylene. Nickel-containing catalytic hydrazine hydrate is used to disproportionately decompose to generate a highly active reducing component-N2H2, and then N2H2 is used as a hydrogen donor, and dechlorination is catalyzed by Pd / C without destroying double bonds. The starting raw material cis-1-chloro-3,3,3-trifluoropropylene is a by-product in the production process of trans-1-chloro-3,3,3-trifluoropropylene, and the raw material input cost is low; the reaction conditions are mild, the raw material conversion rate is high, the product selectivity is high, and the over-hydrogenation by-product is low. The catalyst can be recycled and applied, and the catalytic cost is low; using hydrazine hydrate as a raw material is relatively safer than using hydrogen, the reaction conditions are mild, the process is simple and easy to control, and industrialization is easy to implement.

Description

Technical Field

[0001] The invention belongs to the technical field of organic fluorine chemical industry, and specifically relates to a method for preparing 3,3,3-trifluoropropylene. Background Art

[0002] 3,3,3-trifluoropropene, referred to as HFO-1243zf or TFP, has an ozone depletion value (ODP) of 0 and a greenhouse effect potential (GWP) of 0.29. It can be used as the basic raw material for the synthesis of environmentally friendly refrigerant 2,3,3,3-tetrafluoropropene (HFO-1234yf), and can also be used to prepare mixed refrigerants to replace R22, R134a and R410A. It can also be used as a monomer to synthesize polymer materials such as fluorosilicone rubber and fluorosilicone oil, and the basic raw material for synthesizing high value-added organic compounds such as trifluoropropylene oxide, 2-bromotrifluoropropane, fluorosilicone rubber, fluorosilicone oil, fluorosilicone coatings, and pharmaceutical intermediates. Among them, fluorosilicone rubber and fluorosilicone oil have excellent fuel resistance, solution resistance and cold resistance, so developed countries are accelerating the research and development of a series of fluorosilicone material products. Under the general environment of national energy conservation and emission reduction and the rapid growth of automobile and aerospace demand, the demand for 3,3,3-trifluoropropene has increased year by year, and at the same time, new requirements have been put forward for the green and environmental protection of the preparation technology.

[0003] In the prior art HFO-1243zf synthesis method, the one-step gas phase fluorination synthesis method using 1,1,1,3-tetrachloropropane and anhydrous hydrogen fluoride as raw materials has attracted much attention and has been widely studied due to its characteristics of cheap and readily available raw materials, short route, simple operation, high time and space yield, and easy to scale up. The core technology is the corresponding fluorination catalyst. For example, U.S. Patent No. 4,465,786 discloses a method for synthesizing HFO-1243zf by gas phase fluorination using chromium oxyfluoride as a catalyst. Japanese Patent Publication No. 59-080332 discloses a method for fluorinating halogenated hydrocarbons in the presence of a chromium oxyfluoride catalyst in the gas phase to produce 3,3,3-trifluoropropylene. Chinese Patent CN102001912A discloses a method for realizing the above-mentioned gas phase fluorination reaction using fluorides or fluorides of chromium, aluminum, zinc, cobalt, magnesium, and indium as catalysts. Chinese patent CN102388006B discloses a method of synthesizing HFO-1243zf by gas-phase fluorination in the presence of a zinc / chromium oxide catalyst. Chinese patent CN100500626C discloses the use of a chromium-based high-performance catalyst to synthesize HFO-1243zf by gas-phase fluorination. The above-mentioned catalysts for gas-phase fluorination reactions all use chromium as the core component. However, as a heavy metal element, large amounts of chromium can cause serious pollution to the ecological environment; in particular, hexavalent chromium is a highly toxic substance that poses a great threat to animal and human health.

[0004] The preparation method of 3,3,3-trifluoropropene using a chromium-free catalyst can meet the requirements of green environmental protection, but there are problems such as high production cost, complex production process, high reaction risk factor, rapid catalyst carbonization, and many tetrachloropropene polymers and product olefin impurities.

[0005] For example, Chinese patent CN102762523A discloses a method for producing 3,3,3-trifluoropropene by hydrogenating 1-chloro-3,3,3-trifluoropropene with hydrogen (H2) in the presence of "(A) a catalyst or an oxide of the transition metal selected from rhodium, nickel, germanium, iridium, iron, oxaline and cobalt loaded on a carrier", "(B) an oxide of copper and manganese" or "(C) a catalyst selected from bismuth, zinc, copper, silver, iridium, lead, zirconium, niobium, lead, magnesium, tin and arsenic loaded on a carrier". US Patent US20160145176 A1 discloses a method for synthesizing fluorinated olefins, the first step of which is to dehydrofluorinate 1,1,1,3,3-pentafluoropropane (CF3CH2CHF2; HFC-245fa) to produce 1,3,3,3-tetrafluoropropene (CF3CH=CHF) (HFC-1234ze). In the second step, 3,3,3-tetrafluoropropene (CF3CH=CHF) and hydrogen are reduced to 1,3,3,3-tetrafluoropropane (CF3CH2CH2F) under catalytic conditions and at a suitable reaction temperature. Finally, 1,3,3,3-tetrafluoropropane (CF3CH2CH2F) is dehydrofluorinated to obtain 3,3,3-trifluoropropene. This method has multiple dehydrohalogenation steps, the production process is complicated, and these steps produce a large amount of waste. Hydrogen is used in the reaction process of the above two patents, and the reaction risk factor is relatively high.

[0006] PG Kevin et al. (Organometallic Compounds, Vol. 19, pp. 944-946) reported a method for producing 3,3,3-trifluoropropylene (CF3CH=CH2) by thermal conversion of trifluoromethyl oxirane. The yield of this method was low, only 32%. At the same time, the prices of trifluoromethyl oxirane as a starting material and the catalyst as a catalyst were very expensive, which was not conducive to industrial production.

[0007] Therefore, it is urgent to develop a green and environmentally friendly method for preparing 3,3,3-trifluoropropene, which has cheap and readily available initial raw materials, high catalytic efficiency, safe preparation process, high conversion rate in the entire reaction process, and few by-products. Summary of the invention

[0008] The invention aims to solve the problems of chromium-containing catalyst polluting the environment, high production cost, complex production process, high reaction risk factor, rapid catalyst carbonization, and many tetrachloropropylene polymer and product olefin impurities in the preparation of 3,3,3-trifluoropropene in the prior art. The invention provides a method for preparing 3,3,3-trifluoropropene by using cis-1-chloro-3,3,3-trifluoropropene as a starting raw material and hydrazine hydrate as a reducing agent under the action of a reaction solvent and a catalyst. The method has low raw material input cost, mild reaction conditions, high raw material conversion rate, high product selectivity, low over-hydrogenation by-products, palladium carbon, nickel and other catalysts can be recycled and reused, the green environmental protection catalysis cost is low, and using hydrazine hydrate as a raw material is relatively safer than using hydrogen.

[0009] The present invention provides a method for synthesizing 3,3,3-trifluoropropene, the principle of which is to use nickel-containing catalyst to disproportionately decompose hydrazine hydrate to generate a highly active reducing component -N2H2, and then use N2H2 as a hydrogen donor to catalyze dechlorination through Pd / C without destroying double bonds. To achieve the purpose of the invention, the technical solution adopted by the present invention is:

[0010] A method for preparing 3,3,3-trifluoropropene comprises the following steps: using cis-1-chloro-3,3,3-trifluoropropene as a raw material and hydrazine hydrate as a reducing agent, carrying out a dehalogenation reduction reaction under the action of a reaction solvent and a catalyst, and then purifying the product to obtain 3,3,3-trifluoropropene.

[0011] Its synthetic route is as follows:

[0012] .

[0013] Preferably, the dehalogenation reduction reaction temperature is -5 to 90° C., and the reaction time is 0.5 to 30 h.

[0014] Preferably, the molar ratio of cis-1-chloro-3,3,3-trifluoropropene to hydrazine hydrate is 1:3-20.

[0015] Preferably, the reaction solvent is any one of water, methanol, ethanol, isopropanol, acetic acid and ethyl acetate.

[0016] Preferably, the mass of the reaction solvent is 4 to 20 times the mass of cis-1-chloro-3,3,3-trifluoropropene.

[0017] Preferably, the catalyst is a mixture of aluminum-nickel-chromium alloy and palladium-carbon, wherein the mass ratio of the nickel-chromium alloy to cis-1-chloro-3,3,3-trifluoropropene is 1:45-55, and the mass ratio of the palladium-carbon to cis-1-chloro-3,3,3-trifluoropropene is 1:100-300.

[0018] Preferably, in the mixture catalyst of aluminum-nickel-chromium alloy and palladium-carbon, the mass percentage of palladium in palladium-carbon is 5-10%.

[0019] Preferably, the nickel-chromium alloy in the mixed catalyst of aluminum-nickel-chromium alloy and palladium-carbon is W-6 type Raney nickel.

[0020] Preferably, the purification treatment comprises distillation.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The method for preparing 3,3,3-trifluoropropene of the present invention uses cis-1-chloro-3,3,3-trifluoropropene as a starting material and hydrazine hydrate as a reducing agent to carry out a dehalogenation reduction reaction in the presence of a reaction solvent and a catalyst to prepare 3,3,3-trifluoropropene. The starting material cis-1-chloro-3,3,3-trifluoropropene is a by-product in the production process of trans-1-chloro-3,3,3-trifluoropropene, and the raw material input cost is low; the reaction conditions are mild, the raw material conversion rate is high, the product selectivity is high, and the over-hydrogenation by-products are low.

[0023] 2. The preparation method of 3,3,3-trifluoropropene of the present invention can recycle the palladium carbon, nickel and other catalysts used, and the catalytic cost is low; using hydrazine hydrate as a raw material is relatively safer than using hydrogen, the reaction conditions are mild, the process is simple and easy to control, and it is easy to implement industrialization. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the examples, which are used to illustrate the present invention but are not intended to limit the scope of protection of the present invention. The conditions in the examples can be further adjusted according to specific conditions, and simple improvements to the method of the present invention under the premise of the concept of the present invention all belong to the scope of protection claimed in the present invention.

[0025] Example 1

[0026] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 100.0g of 80% hydrazine hydrate solution, 300.0g of water, 0.2g of palladium carbon, and 0.5g of nickel, stir, keep the temperature at 30°C for 6h, stop heating, cool to 5°C, collect gas to obtain crude trifluoropropene, and distill the crude product to obtain 17.2g of finished product with a purity of 99.9% (GC) and a yield of 89.5%.

[0027] Example 2

[0028] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 160.0g of 50% hydrazine hydrate solution, 200.0g of ethanol, 0.2g of palladium carbon, and 0.5g of nickel. Stir and maintain the temperature at 5°C for 10 hours. Collect the gas to obtain a crude trifluoropropene product. Distill the crude product to obtain 17.9g of a finished product with a purity of 99.9% (GC) and a yield of 93.1%.

[0029] Example 3

[0030] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 160.0g of 50% hydrazine hydrate solution, 200.0g of ethyl acetate, 0.2g of palladium carbon, and 0.5g of nickel. Stir and keep the temperature at -5°C for 30h. Collect the gas to obtain a crude trifluoropropene product. Distill the crude product to obtain 16.8g of a finished product with a purity of 99.9% (GC) and a yield of 87.4%.

[0031] Example 4

[0032] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 160.0g of 50% hydrazine hydrate solution, 100.0g of acetic acid, 200.0g of water, 0.2g of palladium carbon, and 0.5g of nickel. Stir and maintain the temperature at 90°C for 15h. Collect the gas to obtain a crude trifluoropropene product. Distill the crude product to obtain 10.4g of a finished product with a purity of 99.9% (GC) and a yield of 54.1%.

[0033] Example 5

[0034] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 60.0g of 50% hydrazine hydrate solution, 400.0g of ethanol, 0.2g of palladium carbon, and 0.5g of nickel. Stir and maintain the temperature at 50°C for 12h. Collect the gas to obtain a crude trifluoropropene product. Distill the crude product to obtain 12.2g of a finished product with a purity of 99.9% (GC) and a yield of 63.4%.

[0035] Example 6

[0036] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 400.0g of 50% hydrazine hydrate solution, 0.2g of palladium carbon, and 0.5g of nickel. Stir and keep the temperature at -5°C for 10 hours. Collect the gas to obtain a crude trifluoropropene product. The crude product is distilled to obtain 13.7g of a finished product with a purity of 99.9% (GC) and a yield of 71.2%.

[0037] Example 7

[0038] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 300.0g of 50% hydrazine hydrate solution, 100.0g of isopropanol, 0.2g of palladium carbon, and 0.5g of nickel. Stir and keep the temperature at 0°C for 20h. Collect the gas to obtain a crude trifluoropropene product. Distill the crude product to obtain 14.8g of a finished product with a purity of 99.9% (GC) and a yield of 77.0%.

[0039] Example 8

[0040] In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 200.0g of 50% hydrazine hydrate solution, 100.0g of ethanol, 0.2g of palladium carbon, and 0.5g of nickel. Stir and maintain the temperature at 60°C for 20h. Collect the gas to obtain a crude trifluoropropene product. Distill the crude product to obtain 13.2g of a finished product with a purity of 99.9% (GC) and a yield of 68.6%.

[0041] The specific embodiments listed above are illustrations of the present invention. It should be pointed out that the above embodiments are only used to further illustrate the present invention and do not represent the scope of protection of the present invention. Non-essential modifications and adjustments made by others based on the suggestions of the present invention still fall within the scope of protection of the present invention.

Claims

1. A method for preparing 3,3,3-trifluoropropene, characterized in that: In a reaction kettle equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 160.0g of 50% hydrazine hydrate solution, 200.0g of ethanol, 0.2g of palladium carbon, and 0.5g of nickel. Stir and maintain the temperature at 5°C for 10 hours. Collect the gas to obtain crude trifluoropropene. Distill the crude product to obtain 17.9g of finished 3,3,3-trifluoropropene.

2. A method for preparing 3,3,3-trifluoropropene, characterized in that: In a reactor equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 100.0g of 80% hydrazine hydrate solution, 300.0g of water, 0.2g of palladium carbon, and 0.5g of nickel, stir, maintain the temperature at 30°C for 6h, stop heating, cool to 5°C, collect gas to obtain crude trifluoropropene, and distill the crude product to obtain 17.2g of finished product.

3. A method for preparing 3,3,3-trifluoropropene, characterized in that: In a reaction kettle equipped with condensation reflux, stirring and temperature control devices, add 26.1g of cis-1-chloro-3,3,3-trifluoropropene, 160.0g of 50% hydrazine hydrate solution, 200.0g of ethyl acetate, 0.2g of palladium carbon, and 0.5g of nickel. Stir and maintain the temperature at -5°C for 30h. Collect the gas to obtain crude trifluoropropene, and distill the crude product to obtain 16.8g of the finished product.