USE OF AN EPOXIDE IN ORDER TO REDUCE THE FORMATION OF HEAVY ENDS IN A HYDROFORMYLATION PROCESS

Abstract

The present invention refers to the use of an epoxide in order to reduce the formation of heavy ends in a continuous hydroformylation process, where an olefin or olefin mixture is reacted with carbon monoxide and hydrogen in the presence of a rhodium complex catalyst, comprising at least one organobisphosphite ligand, in order to produce an aldehyde. Said epoxide is added to the reaction mixture in an amount of 0.01-1.5 wt %, reducing the formation of heavy ends by 10-80%.

Claims

17. A method for reducing the formation of heavy ends in a continuous hydroformylation process comprising: adding 0.01 to 1.5 wt. % of an epoxide to a reaction mixture comprising an olefin or mixture of olefins, wherein the weight percent is based on the total weight of the reaction mixture; and reacting the olefin or mixture of olefins with carbon monoxide and hydrogen in the presence of a rhodium complex catalyst comprising at least one organobisphosphite ligand to produce an aldehyde, wherein the formation of heavy ends is reduced by 10 to 80% compared to an identical method without addition of the epoxide.

18. The method of claim 17, wherein the epoxide is added in an amount of 0.1 to 1 wt. %, based on the total weight of the reaction mixture.

19. The method of claim 17, wherein the epoxide is added in an amount of 0.2 to 0.5 wt. %, based on the total weight of the reaction mixture.

20. The method of claim 17, wherein the epoxide is a cycloaliphatic epoxide.

21. The method of claim 17, wherein the epoxide is chosen from cyclohexene oxide, 2,3-epoxynorbornane, 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-epoxydodecane, 2,3-epoxybutane and 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, and combinations thereof.

22. The method of claim 17, wherein the epoxide is 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate.

23. The method of claim 17, wherein the olefin or mixture of olefins is/are chosen from C2-C6 olefins.

24. The method of claim 17, wherein the olefin or mixture of olefins is/are 1-butene and/or cis- or trans-2-butene.

25. The method of claim 17, wherein the ligand is an organobisphosphite ligand of Formula (I) ##STR00005## wherein —R.sup.1, —R.sup.2, —R.sup.3, —R.sup.4, R.sup.5, R.sup.6, R.sup.7 and R.sup.8 are independently hydrogen or a linear or branched alkyl group and —Ar is a substituted or unsubstituted aryl group.

26. The method of claim 25, wherein the aryl group is represented by Formula (II) or Formula (III) ##STR00006##

27. The method of claim 26, wherein —Ar is a group of Formula (II) and —R.sup.1, —R.sup.3, —R.sup.6 and —R.sup.8 are independently n-butyl, iso-butyl, or tert-butyl, and R.sup.4 and R.sup.5 are methyl.

28. The method of claim 27, wherein —R.sup.1, —R.sup.3, —R.sup.6 and —R.sup.8 are tert-butyl.

29. The method of claim 25, wherein the ligand has the structure of formula (IV): ##STR00007##

30. The method of claim 17, wherein the ligand is in an amount of 0.5 to 15 wt. %, based on the total weight of the reaction mixture.

31. The method of claim 17, wherein the ligand is in an amount of 1 to 5 wt. %, based on the total weight of the reaction mixture.

32. The method of claim 17, wherein the formation of heavy ends is reduced by at least 50% compared to an identical method without addition of the epoxide.

33. The method of claim 17, wherein the rhodium is in an amount of 20-1000 ppm, based on the total weight of the reaction mixture.

34. The method of claim 17, wherein the rhodium is in an amount of 50 to 550 ppm, based on the total weight of the reaction mixture.

35. The method of claim 17, further comprising adding an antioxidant to the reaction mixture in an amount of 0.01 to 5 wt. %, based on the total weight of the reaction mixture.

36. The method of claim 35, wherein the antioxidant is a tertiary phosphine.

Description

EXAMPLES

[0029] Example 1 illustrates a reduction in heavy ends formation, when the use of the present invention is applied to a hydroformylation reaction mixture in an industrial production plant.

[0030] Example 2 illustrates an increase in purity of the aldehyde product, when the use of the present invention is applied to a hydroformylation reaction mixture in an industrial production plant.

[0031] Example 3 illustrates the effect of the use of the present invention in a pilot scale, evidencing a reduction in the rate of heavy ends formation.

[0032] Example 4 is a comparative lab experiment that illustrates the effect of different amounts of epoxide addition to a hydroformylation reaction mixture, evidencing a reduction in heavy ends formation rate and a reduction in ligand hydrolysis.

[0033] The added epoxide in all of the examples is 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate:

##STR00004##

Example 1

[0034] The amount of heavy ends removed, along with the aldehyde product, from an industrial hydroformylation process of the present invention was measured during a period of 8 months. During the first 5 months the amount of daily removed heavy ends gradually increased from about 2 tons to 5 tons. After 5 months an epoxide (3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate) was added to the reactor in an amount of 1 wt % of the reaction mixture. The epoxide was thereafter periodically added to the reactor in order to keep a concentration of about 0.5 wt % epoxide in the reaction mixture.

[0035] The amount of heavy ends leaving with the product decreased drastically during the following month to a daily production level of 1 ton heavy ends, a 80% decrease in heavy ends formation. The result, evidencing a substantial reduction in heavy ends formation upon epoxide addition, is given in attached FIG. 1.

Example 2

[0036] The amount of aldehyde in the product stream from an industrial hydroformylation process of the present invention was measured during a period of 11 weeks. During the first 7 weeks the amount of valeraldehyde was below or about 98.5% of the content of the product stream. After 7 weeks the above-described epoxide was added to the reactor in an amount of 1 wt % of the reaction mixture. The epoxide was thereafter periodically added to the reactor in order to keep a concentration of about 0.5 wt % epoxide in the reaction mixture.

[0037] The valeraldehyde content of the product stream steadily increased during the following 4 weeks to almost 99.5%, a 1% increase in purity, due to a dramatic decrease in more low-boiling heavy ends. The result, evidencing an increase in purity of the aldehyde product upon epoxide addition, is given in attached FIG. 2.

Example 3

[0038] Hydroformylation reactions were conducted for a period of 35 days in a continuous pilot scale process with two stirred tank reactors in series and a liquid recycle. An aged catalyst solution was taken from an industrial process and divided in two. One with an addition of roughly 1 wt % epoxide and the other one without any added epoxide. Samples of the reaction mixture were taken regularly and analyzed with gas chromatography (GC) and high pressure liquid chromatography (HPLC). The result of the analyses are given in attached FIG. 3, evidencing a clear decline in the rate of heavy ends formation. A reduction in the rate of heavy ends formation of up to 65%.

Example 4

[0039] Three parallel experiments in lab scale were carried out to illustrate the present invention. An aged catalyst solution was taken from an industrial process and divided in three parts. The reactors were loaded with equal amounts of the reactor solution. In two of the reactors, epoxide was added to the reactor solution in amounts of 0.5 wt % and 1 wt %, respectively. The reactors were heated to 90° C. and pressurized with nitrogen to 14 bar and left for 5 weeks under stirring. Samples of the reaction mixture were taken at regular intervals and concentration of the compounds in the reaction mixture were determined from analysis of GC and HPLC. Obtained result is given in attached FIGS. 4 and 5, illustrating that the addition of an epoxide reduces the rate of heavy ends formation and reduces the ligand hydrolysis reaction, by scavenging the acidic ligand decomposition products. In closed systems with an aged catalyst solution, the addition of the epoxide decreases the heavy ends formation by 50% and the positive effect on the ligand stability is clearly visible.