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1. WO2021006795 - A METHOD FOR REDUCING HEAVY END FORMATION AND CATALYST LOSS IN A HYDROFORMYLATION PROCESS

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[ EN ]

CLAIMS

1. A method for reducing heavy end formation and catalyst loss in a continuous

hydroformylation process, where an olefin or olefin mixture is reacted with carbon monoxide and hydrogen in a reactor assembly (1) in the presence of a rhodium complex catalyst, comprising at least one organobisphosphite ligand, in order to produce an aldehyde, characterized in that said method comprises the following steps:

a) adding 0.01-1.5 wt% of an epoxide to the reaction mixture,

b) separating the obtained aldehyde from a mixture of aldehyde, catalyst, ligand and early heavy ends in a distillation unit (2),

c) separating early heavy ends by feeding a part of a catalyst and ligand return flow, comprising a mixture of catalyst, ligand, early heavy ends and rest aldehyde from a lower outlet (23) of a final stage (2b) of the distillation unit (2), into a short residence time evaporator unit (3) having at least a first rest aldehyde stripper stage (3 a) and at least one last early heavy ends stripper stage (3b), said evaporator units (3) being of a falling film and/or wiped film type, the rest of the catalyst and ligand return flow being fed back to the reactor assembly (1),

d) entering the catalyst and ligand mixture from a lower end (3b 1) of the at least one last early heavy ends stripping stage (3b) into a cooling unit (4) immediately after stripping of early heavy ends.

2. The method according to Claim 1, characterized in that said epoxide is added in an

amount of 0.1-lwt% of the reaction mixture.

3. The method according to Claim 1, characterized in that said epoxide is added in an

amount of 0.2-0.5 wt% of the reaction mixture.

4. The method according to Claim 1, characterized in that said epoxide is a cycloaliphatic epoxide.

5. The method according to Claim 1, characterized in that said epoxide is selected from the group consisting of cyclohexene oxide, 2,3-epoxynorbomane, 1,2-octene oxide, 1,2- dodecene oxide, 1,2-cyclododecene oxide, 1,2-decene oxide, 1,2-hexadecene oxide, 1,2- octadecene oxide, 1,2-cyclododecene oxide, 1, 2-epoxy dodecane, 2,3-epoxybutane and 3,4- epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, or combinations thereof.

6. The method according to Claim 1, characterized in that said epoxide is 3,4- epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate.

7. The method according to Claim 1, characterized in that said distillation unit (2) have at least a first and a final stage (2a and 2b respectively) where all stages (2a and 2b respectively) have an upper outlet (21a and 21b respectively) for aldehyde, a central inlet (25a and 25b respectively) for the mixture of aldehyde, catalyst, ligand and early heavy ends and lower outlets (22 and 23 respectively) for the mixture of rest aldehyde, catalyst, ligand and early heavy ends.

8. The method according to Claim 1, characterized in that said step c) separating early heavy ends is performed discontinuously at regular intervals through means of analysis of heavy ends presence in the catalyst and ligand return flow.

9. The method according to Claim 1, characterized in that said step c) separating early heavy ends is performed continuously.

10. The method according to Claim 9, characterized in that said continuous separation of early heavy ends is guided through means of statistical process guiding, where analysis of heavy end presence in the catalyst and ligand return flow is regulating the flow through the evaporator unit (3) as well as at least the temperature in the early heavy ends stripper stage (3b).

11. The method according to Claim 1, characterized in that 1-10% of the catalyst and ligand return flow is being fed into the evaporator unit (3) in step c) to separate early heavy ends.

12. The method according to Claim 1, characterized in that said at least one last early heavy ends stripping stage (3b) have a short path and is operated in the range 0.1 - 3 mbar and at a temperature in the range 130 - 170°C.

13. The method according to Claim 1, characterized in that said cooling unit (4) have an outlet (41) through which the recovered, through the process purified, catalyst and ligand mixture is fed back to the reactor assembly (1).

14. The method according to Claim 13, characterized in that said recovered catalyst and ligand mixture from the outlet (41) of the cooling unit (4) is fed back to the reactor assembly (1) via a return inlet (26) of the final stage (2b) of the distillation unit (2).

15. The method according to Claim 1, characterized in that said olefin is a C2-C6 olefin.

16. The method according to Claim 1, characterized in that said olefin is 1 -butene and/or cis- or trans- 2-butene.

17. The method according to Claim 1, characterized in that said ligand is an

organobisphosphite ligand of Formula (I)

wherein -R , -R2, -R3, -R4, R5, R6, 7 and R8 individually is hydrogen or a linear or branched alkyl group and -Ar is a substituted or unsubstituted aryl group, such as a group of Formula (II) or (III).


18. The method according to Claim 17, characterized in that -Ar is a group of Formula (II) and that -R1, -R3, -R6 and -R8 are n-butyl, iso-butyl or preferably tert-bu and that R4 and

R5 are methyl.

19. The method according to Claim 17, characterized in that said ligand has the structure of formula (IV):

20. The method according to Claim 1, characterized in that said ligand is present in an amount of 0.5-15, such as 1-10 or 1-5 wt% of the reaction mixture.

21. The method according to Claim 1, characterized in that the formation of heavy ends is reduced by 10-80 %.

22. The method according to Claim 1, characterized in that the formation of heavy ends is reduced by at least 50 %.

23. The method according to Claim 1, characterized in that rhodium is present in an amount of 20-1000, such as 50-550, ppm by weight of the reaction mixture.

24. The method according to Claim 1, characterized in that an anti-oxidant is additionally added to the reaction mixture.

25. The method according to Claim 16, characterized in that said anti-oxidant is added in an amount of 0.01-5, such as 0.05-2 wt% of the reaction mixture.

26. The method according to Claim 24 or 25, characterized in that said anti-oxidant is a tertiary phosphine, such as triarylphosphine, dicycloalkylarylphosphine and/or cycloalky ldiary lpho sphine .

27. Use of an epoxide in the method according to any of the preceding Claims, in order to reduce the amount of heavy ends formation and accumulation in a continuous hydroformylation process.