Method for manufacturing perfluorovinylethers

Abstract

The invention pertains to a process for the manufacture of a perfluorovinylether by hydrodehalogenation of a halofluoroether (HFE) having general formula (I-A) or (I-B):
RfOCRfXCRfRfX(I-A)
wherein Rf represents a C1-C6 perfluoro(oxy)alkyl group; Rf, Rf and Rf, equal or different from each other, independently represent fluorine atoms or C1-C5 perfluoro(oxy)alkyl groups; X and X, equal or different from each other, are independently chosen among Cl, Br or I; ##STR00001##
wherein Rf* and Rf*, equal or different from each other, independently represent fluorine atoms or C1-C3 perfluoro(oxy)alkyl groups; Y1 and Y2, equal or different from each other, independently represent fluorine atoms or C1-C3 perfluoroalkyl groups; X and X are as above defined;
said process comprising contacting said halofluoroether (HFE) with hydrogen in the presence of a catalyst comprising palladium and at least one transition metal (M) selected from the group consisting of the metals of group VIIIB, other than palladium, and of group IB.

Claims

1. A process for the manufacture of a perfluorovinylether by hydrodehalogenation of a halofluoroether (HFE) having general formula (I-A) or (I-B):
R.sub.fOCR.sub.fXCR.sub.fR.sub.fX(I-A) wherein R.sub.f represents a C.sub.1-C.sub.6 perfluoro(oxy)alkyl group; R.sub.f, R.sub.f and R.sub.f, equal or different from each other, independently represent fluorine atoms or C.sub.1-C.sub.5 perfluoro(oxy)alkyl groups; X and X, equal to or different from each other, are independently selected from the group consisting of Cl, Br and I; ##STR00006## wherein R.sub.f* and R.sub.f*, equal to or different from each other, independently represent fluorine atoms or C.sub.1-C.sub.3 perfluoro(oxy)alkyl groups; Y.sub.1 and Y.sub.2, equal to or different from each other, independently represent fluorine atoms or C.sub.1-C.sub.3 perfluoroalkyl groups; X and X are as above defined; said process comprising the step of contacting said halofluoroether (HFE) with hydrogen in the presence of a catalyst, said catalyst comprising: palladium; at least one transition metal (M) selected from the group consisting of the metals of group VIIIB, other than palladium, and metals of group IB; and an inert carrier, wherein the molar ratio between palladium and the at least one transition metal (M) ranges from 2:1 to 1:5, and wherein the catalyst is prepared by a process where the inert carrier is impregnated with an aqueous solution comprising palladium and the at least one transition metal selected from ruthenium, copper and gold.

2. The process of claim 1, wherein the halofluoroether (HFE) is a chlorofluoroether (HFE-1) having general formula (I-A), wherein X and X, equal to or different from each other, are independently selected from the group consisting of Cl, Br and I, wherein that at least one of X and X in said formula (I-A) is a chlorine atom.

3. The process of claim 1, wherein the halofluoroether (HFE) is a chlorofluoroether (HFE-2) having general formula (II-A):
R.sub.fOCR.sub.fClCR.sub.fR.sub.fCl(II-A) wherein R.sub.f represents a C.sub.1-C.sub.6 perfluoro(oxy)alkyl group, R.sub.f, R.sub.f and R.sub.f, equal to or different from each other, independently represent fluorine atoms or C.sub.1-C.sub.5 perfluoro(oxy) alkyl groups.

4. The process of claim 1, wherein the inert carrier is carbon.

5. The process of claim 4, wherein the amount of palladium on the inert carrier ranges from 0.1 wt % to 2 wt %.

6. The process of claim 1, wherein the metal (M) is ruthenium.

7. The process of claim 1 wherein the metal is copper or gold.

8. The process of claim 1, said process being carried out at temperatures of at most 340 C.

9. The process of claim 1, said process being carried out at temperatures of at least 190 C.

10. The process of claim 1, wherein the hydrogen/halofluoroether (HFE) molar ratio is comprised between 0.8 and 4.

11. The process of claim 3, wherein R.sub.f represents a C.sub.1-C.sub.4 perfluoroalkyl group.

12. The process of claim 10, wherein the hydrogen/halofluoroether (HFE) molar ratio is comprised between 0.8 and 3.

13. The process of claim 12, wherein the hydrogen/halofluoroether (HFE) molar ratio is comprised between 0.8 and 2.

Description

EXAMPLES

General Hydrodehalogenation Procedure

(1) A continuous gas-phase catalytic process was carried out at atmospheric pressure in a plug-flow reactor. The overall reaction is illustrated by the following equation:
CF.sub.3OCFClCF.sub.2Cl+H.sub.2.fwdarw.CF.sub.3OCFCF.sub.2+2HCl

(2) An amount of each catalyst equal to 1.0 g in all of the runs was loaded in a stainless steel tubular reactor having a length of 520 mm and an internal diameter of 10 mm. The catalyst bed was placed in the middle section of the reactor whereas the upper and lower sections thereof were filled with granular quartz. The catalyst was dried at 300 C. in flowing helium (5 Nl/h) for 4 hours and then cooled down to room temperature. The catalyst was then pre-reduced under a flow of hydrogen diluted with helium at 300 C. for one hour. The temperature was lowered to 250 C. and CF.sub.3OCFClCF.sub.2Cl and a mixture of hydrogen and helium were continuously fed into the reactor.

(3) The gaseous reactor mixture coming from the reaction was sampled and analyzed by GC and GC-MS for the determination of selectivity and conversion.

(4) General Procedure for the Preparation of Pd-M Catalyst

(5) 50 g of extruded activated carbon NORIX RX3 EXTRA (Norit Nederland B.V.) having BET area of 1400 m.sup.2/g and 0.8 cm.sup.3/g pore volume, were crushed and sieved to obtain 20-40 mesh granules. Sieved carbon was dried under vacuum at 200 C. and then impregnated with incipient wetness method with an aqueous hydrochloridric solution of PdCl.sub.2 and CuCl.sub.2.2H.sub.2O in order to obtain three different catalysts (A, B and C) having different Pd:Cu molar ratios.

(6) Each catalyst was dried at 120 C. for 6 h under a nitrogen flow and then reduced under H.sub.2 at 300 C. for 1 h.

(7) Following the same procedure sieved carbon was impregnated with an aqueous hydrochloridric solution of PdCl.sub.2 and HAuCl.sub.4.3H.sub.2O (catalyst D); an aqueous solution of PdCl.sub.2 and AgNO.sub.3 (catalyst E) or an aqueous hydrochloridric solution of PdCl.sub.2 and RuCl.sub.3.3H.sub.2O (catalyst F). Catalysts compositions are shown in Table 1.

(8) TABLE-US-00001 TABLE 1 Catalyst M Pd (wt %) Pd:M (molar ratio) A Cu 0.97 1:1 B Cu 1.1 1:2 C Cu 0.97 1:4 D Au 0.96 1:2 E Ag 0.97 1:1.1 F Ru 1.04 1:4.1

Example 1

(9) A sample of 1.0 g of each catalyst was loaded in the reactor and tested according to the general hydrodehalogenation procedure.

(10) Before starting the reaction the catalyst was dried at 300 C. for 4 h and reactivated with H.sub.2 at 300 C. for 1 h.

(11) CF.sub.3OCFClCF.sub.2Cl space velocity was 1.4 g/h CF.sub.3CFClCF.sub.2Cl*g.sub.cat.sup.1 and residence time was 10 sec, the molar ratio between H.sub.2 and CF.sub.3OCFClCF.sub.2Cl was 1:1. Process temperature was 250 C. Conversion and selectivity were calculated via GC with internal standard method. Results are reported in Table 2.

(12) TABLE-US-00002 TABLE 2 Run Catalyst Time on stream Conversion % Selectivity % # (M) (h) CF.sub.3OCFClCF.sub.2Cl CF.sub.3OCFCF.sub.2 1 A (Cu) 50 75 84 2 B (Cu) 9 83 90 3 B (Cu) 51 89 93 4 B (Cu) 106 88 94 5 C (Cu) 50 88 96 6 D (Au) 50 83 94 7 D (Au) 79 81 95 8 E (Ag) 50 48 76 9 F (Ru) 9 78 76 10 F (Ru) 50 68 87 11 F (Ru) 80 67 90

Comparative Example 1

(13) The same dried sieved carbon used in the preparation of catalysts A to F was used to prepare samples of catalyst comprising one transition metal of group VIIIB. The sieved carbon was impregnated with incipient wetness method with an aqueous hydrochloridric solution of RuCl.sub.3.3H.sub.2O (catalyst G) or PdCl.sub.2 (catalyst H) as shown in Table 3.

(14) Each catalyst was dried at 120 C. for 6 h under a nitrogen flow and then reduced under H.sub.2 at 300 C. for 1 h.

(15) TABLE-US-00003 TABLE 3 Catalyst M wt % G Ru 1.1 H Pd 1.0

(16) A sample of 1.0 g of catalyst (G or H) was tested according to the general hydrodehalogenation procedure. CF.sub.3OCFClCF.sub.2Cl space velocity was 1.4 g/h CF.sub.3CFClCF.sub.2Cl*g.sub.cat.sup.1, residence time was 10 sec and temperature was 250 C. Molar ratio between H.sub.2 and CF.sub.3OCFClCF.sub.2Cl was 1:1. Results in are reported in Table 4.

(17) TABLE-US-00004 TABLE 4 Run Catalyst Time on stream Conversion % Selectivity % # (M) (h) CF.sub.3OCFClCF.sub.2Cl CF.sub.3OCFCF.sub.2 12 G (Ru) 10 40 70 13 G (Ru) 47 20 95 14 G (Ru) 70 10 97 15 H (Pd) 4 69 50

(18) Comparing the results of Tables 2 (runs 9-11) with those of Table 4 runs 12-14), it can be appreciated that catalysts according to the invention, comprising Pd and Ru, maintain their catalytic activity (conversion and selectivity) unchanged up to 80 hours on stream whereas catalysts comprising Ru only supported on carbon show a visible reduction in conversion already after 50 hours on stream and an even greater decrease at longer times.

(19) On the other hand catalysts comprising Pd alone supported on carbon have very low selectivity in the desired end product already at the beginning of the catalytic activity.