Method of fluorination in the gaseous phase

Abstract

The present invention concerns a method of producing at least one compound of formula (II): CF.sub.3—CX(Z)n-CHX(Z)n in which X represents, independently, a hydrogen, fluorine or chlorine atom, Z represents, independently, a hydrogen or fluorine atom, and n=0 or 1, from at least one compound of formula (I): CX(Y)2-CX(Y)m-CHmXY in which X and Y represent, independently, a hydrogen, fluorine or chlorine atom and m=0 or 1. The method comprises at least one step during which at least one compound of formula (I) reacts with HF in the gaseous phase in the presence of a fluorination catalyst in order to give at least one compound of formula (II), characterized in that the catalyst is made from chromium oxyfluoride containing at least nickel as the co-metal and at least one rare earth metal.

Claims

1. A process for manufacturing at least one compound of formula (II): CF.sub.3—CX(Z).sub.n—CHX(Z).sub.n in which X independently represents a hydrogen, fluorine or chlorine atom, Z independently represents a hydrogen or fluorine atom and n=0 or 1, comprising at least one step during which at least one compound of formula (I): CX(Y).sub.2—CX(Y).sub.m—CH.sub.mXY in which X and Y independently represent a hydrogen, fluorine or chlorine atom and m=0 or 1, reacts with HF in the gaseous phase in the presence of a fluorination catalyst, characterized in that the catalyst is based on chromium oxyfluoride containing at least nickel as co-metal and at least one rare-earth metal.

2. The process as claimed in claim 1, characterized in that the compounds of formula (II) are chosen from 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, 1-chloro-3,3,3-trifluoro-1-propene, and 2-chloro-3,3,3-trifluoro-1-propene.

3. The process as claimed in claim 1, characterized in that the compounds of formula (I) are chosen from 1,1,2,3-tetrachloropropene, 2,3,3,3-tetrachloropropene, 1,1,3,3-tetrachloropropene, 1,3,3,3-tetrachloropropene, 1,1,1,2,3-pentachloropropane, 1,1,1,3,3-pentachloropropane, 1,1,2,2,3-pentachloropropane, 1,2-dichloro-3,3,3-trifluoropropane, 2-chloro-2,3,3,3-tetrafluoropropane, 1,1,1,2,2-pentafluoropropane, 1-chloro-1,3,3,3-tetrafluoropropane and 1,1,1,3,3-pentafluoropropane.

4. The process as claimed in claim 1, characterized in that 2,3,3,3-tetrafluoropropene is manufactured from halopropanes of formulae CX.sub.3CHClCH.sub.2X and CX.sub.3CFXCH.sub.3, halopropenes of formulae CX.sub.3CCl═CH.sub.2, CClX.sub.2CCl═CH.sub.2 and CX.sub.2═CClCH.sub.2X, with X independently representing a fluorine or chlorine atom.

5. The process as claimed in claim 1, characterized in that 2,3,3,3-tetrafluoropropene is manufactured from 1,1,1,2,3-pentachloropropane, 1,1,2,3-tetrachloropropene, 1,1,1,2,2-pentafluoropropane and/or 2-chloro-3,3,3-trifluoro-1-propene.

6. The process as claimed in claim 2, characterized in that 1,3,3,3-tetrafluoropropene is manufactured from 1,1,1,3,3-pentachloropropane, 1,1,3,3-tetrachloropropene, 1,1,1,3,3-pentafluoropropane and/or 1-chloro-3,3,3-trifluoro-1-propene.

7. The process as claimed in claim 2, characterized in that 1-chloro-3,3,3-trifluoro-1-propene is manufactured from 1,1,1,3,3-pentachloropropane and/or 1,1,3,3-tetrachloropropene.

8. The process as claimed in claim 1, characterized in that the rare-earth metal(s) are chosen from cerium, lanthanum and praseodymium.

9. The process as claimed in claim 1, characterized in that the atomic ratio of rare-earth metal(s)/chromium in the catalyst is between 0.001-0.1, preferably between 0.001-0.02.

10. The process as claimed in claim 1, characterized in that the nickel co-metal/chromium atomic ratio in the catalyst is between 0.5 and 5 and preferably between 0.7 and 2.

11. The process as claimed in claim 1, characterized in that the catalyst is supported.

12. The process as claimed in claim 11, characterized in that the support is chosen from charcoal, magnesium derivatives, alumina or aluminum derivatives.

13. The process as claimed in claim 1, characterized in that the mole ratio of HF relative to the compounds of formula (I) to be reacted is between 5 and 40, preferably between 10 and 25.

14. The process as claimed in claim 1, characterized in that the fluorination temperature is between 180 and 420° C., preferably between 280 and 420° C.

15. The process as claimed in claim 1, characterized in that the catalyst is subjected to at least one activation step using a stream comprising HF.

Description

EXPERIMENTAL SECTION

(1) The apparatus used comprises a tubular reactor made of Inconel® 600 with an inside diameter of 19 mm, heated by a tubular oven. The reactor is equipped with pressure and temperature regulators. The reagents are preheated and mixed, by means of a static mixer, and then introduced in the gaseous phase into the upper part of the reactor.

(2) On exiting the reactor, a sample of the reaction products is taken and is analyzed online by gas chromatography. The analysis is performed using a CP Sil 8CB column, of dimensions 50 m×0.32 mm×5 μm, and a 1% SP1000/Carbopack B, 60/80 mesh packed column 5 m long. The oven temperature programs are as follows: 40° C. for 10 min then ramp of 10° C./min upto 250° C. and 40° C. for 20 min then ramp of 10° C./min to 180° C.

(3) The contact time is defined as the ratio of the volume of the catalytic bed to the total volume flow rate under the temperature and pressure experimental conditions. The HF mole ratio is defined as the ratio between the molar flow rate of HF and the molar flow rate of HCFO-1233xf. The reaction is performed in the presence of air. The oxygen mole ratio is defined as the ratio between the molar flow rate of oxygen and the molar flow rate of HCFO-1233xf.

Example 1: Fluorination of HCFO-1233xf

(4) The catalyst used is an Ni—Cr/AlF.sub.3 catalyst prepared as follows.

(5) 343 g of a support obtained in a preceding step by fluorination of GRACE HSA alumina in a fixed bed at about 280° C. using air and hydrofluoric acid (volume concentration of 5% to 10% of this acid in the air) are placed in a rotary evaporator. The starting GRACE HSA alumina has the following physicochemical characteristics: beads 0.5-2 mm in diameter with a BET surface area=220 m.sup.2/g, pore volume=1.3 cm.sup.3/g.

(6) Two separate aqueous solutions are moreover prepared:

(7) (a) chromic solution supplemented with nickel chloride containing: chromium trioxide CrO.sub.3=55 g nickel chloride hexahydrate NiCl.sub.2.6H.sub.2O=130 g water=63 g

(8) (b) methanolic solution containing: methanol=81 g water=8 g

(9) These two solutions are introduced simultaneously at a temperature of 40° C. at atmospheric pressure and over about 2 hours, onto the support with stirring. After a step of maturation under nitrogen, the catalyst is dried under nitrogen, and then under vacuum at 65° C. and then at about 90° C. for 6 hours.

(10) The fluorination of HCFO-1233xf is performed in the reactor described above by introducing 73 cm.sup.3 of Ni—Cr catalyst supported on AlF.sub.3.

(11) After the introduction, the solid is treated at a temperature of between 320° C. and 390° C. in the presence of a mixture of hydrofluoric acid and nitrogen (volume concentration of 5% to 10% of this acid in the nitrogen).

(12) The activation process then comprises 5 cycles of:

(13) fluorination of the catalyst by performing the fluorination reaction for 6 to 30 hours under the conditions stated below,

(14) treatment in air at 370° C. and 1.5 L/h for 64 hours.

(15) The reaction is performed by continuously feeding in 3.4 g/h of anhydrous HF and 1.0 g/h of HCFO-1233xf at atmospheric pressure and at a temperature of 350° C. Thus, the contact time is 29 s, the HF mole ratio is 22. The amount of oxygen is 8 mol % relative to the amount of HCFO-1233xf.

(16) The results are presented in the table below.

Comparative Example 2: Fluorination of HCFO-1233xf

(17) The catalyst used is an Ni—Cr—La/AlF.sub.3 catalyst prepared as previously, the chromic solution supplemented with nickel chloride and lanthanum chloride containing: chromium trioxide CrO.sub.3=55 g nickel chloride hexahydrate NiCl.sub.2.6H.sub.2O=130 g lanthanum chloride hexahydrate LaCl.sub.3.6H.sub.2O=2 g water=63 g

(18) The fluorination of HCFO-1233xf is performed in the reactor described above by introducing 73 cm.sup.3 of Ni—Cr—La catalyst supported on AlF.sub.3.

(19) The activation process is identical and the reaction is also performed by continuously feeding in 3.4 g/h of anhydrous HF and 1.0 g/h of HCFO-1233xf at atmospheric pressure and at a temperature of 350° C. The amount of oxygen is 8 mol % relative to the amount of HCFO-1233xf.

(20) The full results are presented in the table below.

(21) TABLE-US-00001 Conver- Selectivity Selectivity Selectivity Reaction sion toward HFO- toward HFC- toward time (%) 1234yf 245cb others Example 1  7 h 69.7% 65.7% 32.8% 1.5% 33 h 54.7% 64.6% 32.3% 3.1% Example 2  8 h 70.2% 66.4% 32.4% 1.2% 41 h 63.8% 65.1% 32.6% 2.3%