METHOD

Abstract

A method for activating a chromia-based catalyst for fluorination and/or hydrofluorination comprises the steps of: a) optionally drying the catalyst at a temperature of from 100° C. to 400° C.; b) treating the catalyst with a composition comprising HF at a temperature of from 100° C. to about 500° C.; c) treating the catalyst with a composition comprising an oxidant and optionally HF at a temperature of from about 100° C. to about 500° C.

Claims

1. A method for activating a catalyst comprising the steps of: a) optionally drying the catalyst at a temperature of from 100° C. to 400° C.; b) treating the catalyst with a composition comprising HF at a temperature of from 100° C. to about 500° C.; c) treating the catalyst with a composition comprising an oxidant and optionally HF at a temperature of from about 100° C. to about 500° C.

2. The method according to claim 1, wherein the oxidant is selected from air, oxygen (O.sub.2), chlorine (Cl.sub.2), chlorine monofluoride (ClF), nitrogen trifluoride (NF.sub.3).

3. The method according to claim 1, wherein the molar ratio of HF to oxidant is from 1:20 to 20:1.

4. The method according to claim 3, wherein the molar ratio of HF to oxidant is from 15:1 to 1:3, more preferably from 11:1 to 1:1.

5. The method according to claim 1, wherein the catalyst is a chromia catalyst.

6. The method according to claim 5, wherein the catalyst is a chromia catalyst comprising zinc or a compound thereof, such as zinc oxide.

7. The method according to claim 6, wherein zinc oxide is present in the catalyst at a level of from 1% wt to 10% wt, more preferably from 2% wt to 8% wt, more preferably from 3% wt to 7% wt based on the total weight of the catalyst.

8. The method according to claim 1, wherein step (b) and/or (c) is carried out at a pressure of from 0.1 bara to 20 bara, preferably from 3 bara to 10 bara.

9. The method according to claim 1, wherein step (b) and/or (c) is carried out over an extended period of time.

10. The method according to claim 1, wherein step (b) and/or (c) is carried out at a temperature of from about 200° C. to about 500° C., preferably from about 250° C. to about 475° C.

11. The method according to claim 1, wherein step (b) and/or (c) is conducted at a temperature of from about 300° C. to 460° C., such as from about 310° C. to about 450° C.

12. A method for activating a catalyst comprising the steps of: (a) optionally drying the catalyst at a temperature of from 100° C. to 400° C.; (b) treating the catalyst with a composition comprising HF at a temperature of from 500° C. to about 700° C.

13. The method according to claim 12, wherein step (b) is carried out at a pressure of from 0.1 bara to 20 bara, preferably from 3 bara to 10 bara.

14. The method according to claim 12, wherein step (b) is carried out over an extended period of time.

15. The method according to claim 12, wherein step (b) is carried out at a temperature of from about 500° C. to about 600° C., preferably about 520° C.

16. A method for activating a catalyst, wherein the catalyst comprises a chromia catalyst, with zinc oxide present in the catalyst at a level of from 1% wt to 10% wt, wherein the catalyst has a total pore volume equal to or greater than 0.3 cm.sup.3/g and a mean pore diameter greater than or equal to 100 Å, wherein the pore volume is measured using N.sub.2 adsorption porosimetry and the mean pore diameter is measured using N.sub.2 BET adsorption porosimetry; comprising the steps of: (a) optionally drying the catalyst at a temperature of from 100° C. to 400° C.; (b) treating the catalyst with a composition comprising HF at a temperature of from 100° C. to about 500° C.; (c) treating the catalyst with a composition comprising an oxidant and optionally HF at a temperature of from about 100° C. to about 500° C.

17. The method according to claim 16, further comprising a catalyst preparation process comprising the steps of: preparing a metal salt solution and a hydroxide solution; combining the solutions at a pH of greater than 7.5 in order to precipitate the metal hydroxide(s); drying the precipitated metal hydroxides; calcining the metal hydroxide(s) to form the metal oxide(s).

18. The method according to claim 16, wherein the catalyst is amorphous, or from 0.1 to 50% by weight of the catalyst is in the form of one or more crystalline compounds of chromium and/or one or more crystalline compounds of zinc

19. The method according to claim 16, wherein the oxidant is selected from air, oxygen (O.sub.2), chlorine (Cl.sub.2), chlorine monofluoride (GIF), nitrogen trifluoride (NF.sub.3).

20. The method according to claim 16, wherein the molar ratio of HF to oxidant is from 1:20 to 20:1, more preferably from 15:1 to 1:3, more preferably from 11:1 to 1:1.

21. The method according to claim 16, wherein step (b) and/or (c) is carried out at a pressure of from 0.1 bara to 20 bara, preferably from 3 bara to 10 bara.

22. The method according to claim 16, wherein step (b) and/or (c) is carried out over an extended period of time

23. The method according to claim 16, wherein step (b) and/or (c) is carried out at a temperature of from about 200° C. to about 500° C., preferably from about 250° C. to about 475° C.

24. The method according to claim 23, wherein step (b) and/or (c) is conducted at a temperature of from about 300° C. to 460° C., such as from about 310° C. to about 450° C.

25. Use of a catalyst produced in accordance with the method according to claim 1 in fluorination and/or hydrofluorination.

26. Use according to claim 25, in fluorination and/or hydrofluorination of a halogenated hydrocarbon.

27. Use of the catalyst according to claim 26, wherein the halogenated hydrocarbon is a (hydro)haloalkene.

28. Use of the catalyst according to claim 27, wherein the (hydro)haloalkene is a C.sub.2-7(hydro)haloalkene.

29. Use of the catalyst according to claim 28, wherein the C.sub.2-7(hydro)haloalkene is a C.sub.2-7(hydro)chlorofluoroalkene.

30. Use of the catalyst according to claim 29, wherein the C.sub.2-7(hydro)chlorofluoroalkene is 2-chloro-3,3,3-trifluoropropene (1233xf).

31. A process for preparing a fluorinated hydrocarbon, which process comprises reacting an optionally halogenated hydrocarbon with hydrogen fluoride in the presence of the catalyst produced in accordance with the method of claim 1, wherein the process is carried out in vapour phase.

Description

EXAMPLES

Catalyst Activation Examples

[0063] 3 ml of chromia catalyst particles (size range from 0.5 mm to 1.0 mm) containing 3 wt % ZnO was dried by heating at 250° C. for 4 hours under a nitrogen atmosphere (60 ml/min) at 1 Bara.

[0064] The catalyst was subjected to a first activation step at 380° C. for 16 hours under a HF atmosphere (30 ml/min).

[0065] The catalyst was subjected to a second activation step under the conditions as outlined below.

TABLE-US-00001 Second Activation Step Example Temperature Duration Activants 1  380° C. 16 hours Air and HF (25 ml/min each) 2  380° C. 40 hours Air and HF (25 ml/min each) 3* 380° C. 16 hours Air and HF (25 ml/min each) 4* 380° C. 40 hours Air and HF (25 ml/minm each) *the chromia contained 6.5 wt % ZnO.

TABLE-US-00002 Comparative Second Activation Step Example Temperature Duration Activants A 380° C. 16 hours Nitrogen and HF (25 ml/min each) B 380° C. 16 hours Nitrogen and Air (25 ml/min each) C 380° C. 16 hours Nitrogen (50 ml/min) D 380° C. 40 hours Nitrogen and HF (2 ml/min each) E 380° C. 40 hours Nitrogen and Air (25 ml/min each) F 380° C. 40 hours Nitrogen (50 ml/min)  G* 380° C. 16 hours Nitrogen and HF (25 ml/min each)  H* 380° C. 16 hours Nitrogen and Air (25 ml/min each)  I* 380° C. 16 hours Nitrogen (50 ml/min)  J* 380° C. 40 hours Nitrogen and HF (25 ml/min each  K* 380° C. 40 hours Nitrogen and Air (25 ml/min each)  L* 380° C. 40 hours Nitrogen (50 ml/min) *the chromia contained 6.5 wt % ZnO.

Catalytic Examples

[0066] The activated catalyst was contacted with 2-chloro-3,3,3-trifluoropropene (1233xf) (1 ml/min) and hydrogen fluoride (25 ml/min) in a reactor. The cycle time was between about 21 hours and about 28 hours. The pressure was 1 bara.

[0067] The data generated was in the form of reactor off-gas (ROG) compositions for the feed (1233xf) and main reaction products 2,3,3,3-tetrafluoropropene (1234yf) and 1,1,1,2,2-pentafluoropropane (245cb).

[0068] Results

TABLE-US-00003 Cycle time 1233xf 1234yf 245cb Catalyst (hrs) (mol %) (mol %) (mol %) k′.sub.xf 1  0.5 23.63 59.29 17.08 1.12 2.06 28.71 56.03 15.26 0.94 3.38 30.96 54.29 14.76 0.94 4.7 31.10 54.30 14.60 0.93 21.1 36.07 50.37 13.56 0.83 2  0.83 29.14 55.15 15.71 1.01 3.12 31.35 53.63 15.01 0.95 4.86 31.64 53.50 14.85 0.99 21.38 34.74 51.14 14.11 0.81 27 36.24 49.98 13.77 0.76 3* 1.13 28.74 53.59 17.67 1.03 3.65 31.79 51.38 16.82 0.97 5.3 32.88 50.62 16.50 0.90 22.13 47.94 39.63 12.43 0.47 24.43 50.55 37.71 11.74 0.43 4* 0.76 29.13 54.26 16.61 0.94 2.86 33.55 51.43 15.01 0.81 23.65 43.10 44.36 12.54 0.60

TABLE-US-00004 Treatment Cycle time 1233xf 1234yf 245cb Catalyst time (hrs) (hrs) (mol %) (mol %) (mol %) k′.sub.xf A 16 0.82 31.83 52.99 15.18 0.82 16 2.23 34.14 51.25 14.60 0.72 16 3.56 36.42 49.65 13.93 0.71 16 4.88 37.60 48.72 13.68 0.69 16 21.35 44.83 43.05 12.11 0.54 B 16 1.06 27.82 55.37 16.81 0.89 16 2.48 33.60 50.98 15.43 0.73 16 3.82 39.54 46.55 13.91 0.60 16 5.12 45.62 41.95 12.44 0.48 16 21.52 78.37 16.83 4.78 0.13 C 16 1.25 57.58 32.09 10.33 0.30 16 2.65 68.17 24.40 7.42 0.20 16 3.98 72.70 21.06 6.25 0.16 16 5.32 74.48 19.71 5.81 0.16 16 21.75 77.31 17.62 5.07 0.14 D 40 0.5 36.04 49.97 13.99 0.71 40 2.92 37.61 48.63 13.75 0.76 40 4.7 38.02 48.42 13.56 0.73 40 21.1 41.74 45.50 12.76 0.62 40 26.78 42.29 45.11 12.59 0.62 E 40 1.38 34.67 49.35 15.98 0.77 40 3.48 47.01 40.08 12.89 0.48 40 5.32 63.56 27.69 8.75 0.25 40 21.78 79.24 16.12 4.63 0.12 40 27.45 79.36 16.05 4.59 0.12 F 40 1.22 52.51 36.37 11.12 0.38 40 3.26 62.89 28.61 8.49 0.25 40 5.12 66.87 25.64 7.49 0.22 40 21.56 73.37 20.69 5.94 0.17 40 27.26 73.61 20.47 5.92 0.17 G 16 0.92 27.64 54.83 17.51 1.04 16 3.47 31.48 52.23 16.29 0.96 16 5.02 32.32 51.65 16.03 0.89 16 21.92 46.46 41.07 12.47 0.49 16 24.23 48.78 39.37 11.84 0.44 H 16 0.6 30.80 52.49 16.71 0.87 16 3.22 43.99 43.03 12.97 0.54 16 4.83 55.67 34.23 10.09 0.35 16 21.73 80.14 15.57 4.29 0.12 16 24.03 80.04 15.65 4.30 0.12 I 16 0.5 30.20 53.80 15.99 0.91 16 3.05 36.33 49.99 13.67 0.79 16 4.62 41.97 45.55 12.48 0.62 16 21.55 72.69 21.51 5.79 0.19 16 23.88 72.60 21.57 5.82 0.18 J 40 1 27.66 56.52 15.81 0.98 40 3.15 31.29 53.94 14.76 0.85 40 23.85 39.72 47.36 12.91 0.68 K 40 0.62 34.20 51.44 14.36 0.76 40 2.65 48.32 40.50 11.18 0.46 40 23.45 81.76 14.43 3.81 0.12 L 40 1.2 32.34 52.62 15.03 0.89 40 3.35 39.99 46.74 13.26 0.67 40 24.16 74.73 19.82 5.45 0.16

[0069] For each data point the equilibrium position of the reaction was calculated and then the instantaneous net rate constant for 1233xf conversion, k′.sub.xd was calculated In this way for each experiment it was possible to quantify catalyst effectiveness vs time and so derive useful catalyst performance characteristics relating to activity and stability.

[0070] For each experiment a plot of k′.sub.xf vs time was produced and fitted using the equation:

k′.sub.xf=b+(a−b)exp.sup.−k″t

Where:

[0071] a=initial activity [0072] b=final activity [0073] k″=catalyst activity decay rate
and where the initial rate of catalyst activity decay at t=0 hrs=

[00001]$-\frac{k^{″}\left(a-b\right)}{{\exp }^{k″t}}$

This is exemplified in the table below

TABLE-US-00005 Initial Final Rate constant k′.sub.xf Initial rate Activity Activity decay rate (24 hr) of k′.sub.xf Catalyst (s.sup.−1) (s.sup.−1) (hr.sup.−1) (s.sup.−1) decay 1  1.1608 0.8447 0.3949 0.8447 −0.1248 2  1.0115 0 0.0105 0.7862 −0.0106 3* 1.0941 0 0.0378 0.4416 −0.0414 4* 1.0122 0.6018 0.2356 0.6032 −0.0967 A 0.8377 0.5329 0.1523 0.5408 −0.0464 B 1.0617 0.1095 0.1775 0.1229 −0.1690 C 0.5585 0.1432 0.7607 0.1432 −0.3159 D 0.7468 0 0.0074 0.6253 −0.0055 E 1.1896 0.1195 0.3471 0.1198 −0.3714 F 0.5057 0.1693 0.3983 0.1693 −0.1340 G 1.0769 0 0.0356 0.4583 −0.0383 H 0.9966 0.1174 0.2508 0.1195 −0.2205 I 0.9646 0.0713 0.0922 0.1690 −0.0824 J 1.0678 0.6747 0.2538 0.6756 −0.0998 K 0.8959 0.1143 0.3037 0.1148 −0.2374 L 1.044 0.146 0.1619 0.1644 −0.1454

[0074] The catalytic example was repeated under the same conditions as above with the exception that the pressure was increased to 6 bara. The kinetic data obtained is shown in the table below.

TABLE-US-00006 Rate Initial Final constant activity activity decay rate Catalyst (s.sup.−1) (s.sup.−1) (hr.sup.−1) C 0.0143 0.0000 0.0131 1 0.3696 0.0000 0.0233

[0075] The catalysts activated according to the method of the invention not only show high initial activity but also show a lower decrease in said activity when compared to catalysts activated in a comparative method.

[0076] Pore Size Measurements

[0077] Pore sizes of the catalyst were measured according to the BET Ads (4V/A) method. The results are shown in the table below.

TABLE-US-00007 Average pore diameter BET Ads (4V/A) Catalyst (Å) 1  142.5 2  151.6 3* 146.6 4* 146.7 A 130.4 B 175.2 C 133.6 D 139.6 E 184.4 F 142.7 G 150.3 H 170.5 I 144.6 J 150.5 K 170.7 L 144.8

[0078] Thus, it has been demonstrated how catalyst activation treatments according to the teaching of this patent result in working catalysts with increased porosity and enhanced activity and stability.