Production of Oxygenated Products

Abstract

A process for producing oxygenated products from a Fischer-Tropsch derived olefinic feedstock, includes reacting the feedstock, in a hydroformylation reaction stage, with carbon monoxide and hydrogen at an elevated reaction temperature and at a superatmospheric reaction pressure in the presence of a hydroformylation catalyst system. The catalyst system comprises a mixture, combination or complex of a transition metal, T, where T is selected from the transition metals of Group VIII of the Periodic Table of Elements; carbon monoxide, CO; hydrogen, H2; as a primary ligand, a monodentate phosphorus ligand; and as a secondary ligand, a bidentate phosphorus ligand which confers resistance on the catalyst system to poisoning arising from the presence of undesired components in the Fischer-Tropsch derived feedstock.

Description

EXAMPLE 1

Example 1a

Rh(acac)(CO)₂ (9.6×10⁻⁵ mol) and TPP (Rh:TPP=1:170) were dissolved in 50 ml toluene, which was then transferred to a 100 ml reactor. 1-Octene (10 ml) spiked with methyl vinyl ketone (100 mol eq. to Rh) was injected into the reactor once reaction temperature had been reached. The methyl vinyl ketone spiked 1-octene thus simulated a Fischer-Tropsch derived olefinic feedstock. The reaction was performed at 15 bar pressure and 100° C.

The time taken to reach 50% olefin conversion was 1 hr 45 min.

Example 1b

The same experimental procedure as described Comparative Example 1a was followed with the difference that 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (hereinafter referred to as xantphos) was added as a secondary ligand (Rh:TPP:Xantphos=1:170:5).

The time taken to reach 50% olefin conversion was 1 hr.

Example 1c

The same procedure as described for Example 1b was followed with the difference that the Rh:TPP:Xantphos ratio was changed to 1:170:3. The time taken to reach 50% olefin conversion was 1 hr.

Example 1d

The same procedure as described for Example 1b was followed with the difference that the Rh:TPP:Xantphos ratio was changed to 1:170:1. The time taken to reach 50% olefin conversion was 1 hr 3 min.

Example 1e

The same procedure as described for Example 1b was followed with the difference that the Rh:TPP:Xantphos ratio was changed to 1:90:5. The time taken to reach 50% olefin conversion was 35 min.

EXAMPLE 2

Example 2a

Rh(acac)(CO)₂ (9.6×10⁻⁵ mol) and TPP (Rh:TPP=1:170) were dissolved in 50 ml toluene, which was then transferred to a 100 ml reactor. 1-Octene (10 ml) spiked with isoprene (100 mol eq. to Rh) was injected into the reactor once reaction temperature had been reached. The isoprene spiked 1-octene thus simulated a Fischer-Tropsch derived olefinic feedstock. The reaction was performed at 15 bar pressure and 100° C.

The rate of hydroformylation, between 0-50% olefin conversion, was compared to a similar reaction where no isoprene was added and it was found that the diene had inhibited the reaction by 51%.

Example 2b

The same experimental procedure as described Comparative Example 2a was followed with the difference that xantphos was added as a secondary ligand (Rh:TPP:Xantphos=1:170:5).

At 0-50% olefin conversion no catalyst inhibition was recorded when compared to a similar reaction where no diene had been added.

Example 2c

The same experimental procedure as described in Example 2a was followed with the difference that (oxydi-2,1-phenylene)bis(diphenylphosphine) (hereinafter referred to as DPEphos) was added as a secondary ligand rather than xantphos (Rh:TPP:DPEphos=1:170:3).

At 0-50% olefin conversion 16% catalyst inhibition was recorded when compared to a similar reaction where no diene had been added.

EXAMPLE 3

In a series of experiments the influence of a pure feed (dodecene-paraffin solution; 1:1) and a complex Fischer-Tropsch derived olefinic feed (C11/12 fraction) on different rhodium hydroformylation catalysts were evaluated and compared. The dodecene was diluted with an inert C9-11 paraffin to give a solution with a similar reactable olefin content to that of the Fischer-Tropsch derived feed. The Fischer-Tropsch derived olefinic feed had the following composition (on a mass basis): 53% paraffins and olefins, including α-olefins, internal linear olefins, branched internal and terminal olefins, dienes, trienes, cyclic olefins and cyclic dienes; 24% aromatics; and 23% oxygenates, including ketones, aldehydes, esters and carboxylic acids. Rh(acac)(CO)₂ (6×10⁻⁵ mol) and TPP (Rh:TPP=1:90) were dissolved in 30 ml toluene together with a bidentate ligand (Rh:bidentate=1:5), selected from Formulae I-VI, in which Ph is C₆H₅ and ^tBu is C(CH3)₃, and the reactor prepared as described hereinbefore. The hydroformylation reaction was commenced by charging an olefin mixture consisting of hexene (10 ml) and either the dodecene-paraffin solution or Fischer-Tropsch feed (30 ml) into the reactor by means of synthesis gas overpressure on a sample vessel connected to the reactor. The reaction was carried out at 20 bar.

The productivity of the catalyst system under investigation was determined by sampling the reactor contents and determining the amount of hexene converted to aldehyde by GC-FID analysis of these samples. By comparing the difference in 1-hexene conversion after 0.5 hr, for the catalyst exposed to pure and Fischer-Tropsch derived feed, it is possible to obtain a measure by which the catalyst has been inhibited by undesired components in the latter feed. The results from these studies are collected in Table 1.

	TABLE 1
		Primary	Secondary	Difference in 1-hexene
	Entry	Ligand	Ligand	conversion/%
	1	TPP	none	17
	2	TPP	I	<1
	3	TPP	II	3
	4	TPP	III	<1
	5	TPP	IV	9
	6	TPP	V	<1
	7	TPP	VI	<1

The Applicant has thus unexpectedly found that by using either a catalyst system comprising a Group VIII transition metal together with a monodentate phosphorus ligand/bidentate phosphorus ligand combination as hereinbefore described, in a hydroformylation process, an olefinic feedstock comprising at least one α-olefin and at least one undesired compound can be accommodated in the process. Thus, such an olefinic feedstock can then be treated in the hydroformylation process without unacceptable deactivation and/or loss of activity of the catalyst occurring.

Claims

1. A process for producing oxygenated products from a Fischer-Tropsch derived olefinic feedstock, which process includes reacting the feedstock, in a hydroformylation reaction stage, with carbon monoxide and hydrogen at an elevated reaction temperature and at a superatmospheric reaction pressure in the presence of a hydroformylation catalyst system, which comprises a mixture, combination or complex of (i) Rh(acac)(CO)2 where ‘acac’ is acetylacetonate, Rh(acac)(CO)(TPP) where ‘acac’ is acetylacetonate and ‘TPP’ is triphenylphosphine, [Rh(OAc)2]2 where ‘OAc’ is acetate, Rh2O3, Rh4(CO)12, Rh6(CO)16, Rh(CO)2(dipivaloyl methanoate), or Rh(NO3)2;′(ii) carbon monoxide, CO;(iii) hydrogen, H2;(iv) as a primary ligand, a monodentate phosphorus ligand; and(v) as a secondary ligand, a bidentate phosphorus ligand which confers resistance on the catalyst system to poisoning arising from the presence of undesired components in the Fischer-Tropsch derived feedstock.

2. A process according to claim 1, wherein the hydroformylation reaction stage comprises a hydroformylation reactor, with the process including initially preparing the catalyst system by dissolving component (i), together with the ligands, in a solvent, to produce a catalyst solution, and heating the catalyst solution in the reactor in the presence of synthesis gas comprising CO and H2 to form an active hydroformylation catalyst system in which the rhodium concentration in the catalyst solution in the hydroformylation reactor is from 10 to 1000 ppm.

3. A process according to claim 1, wherein the monodentate phosphorus ligand is used in a molar excess, relative to the rhodium, of from 50:1 to 1000:1.

4. A process according to claim 1, wherein the bidentate phosphorus ligand is employed at a lower ligand to rhodium molar ratio than the monodentate phosphorus ligand, and wherein the bidentate phosphorus ligand to rhodium ratio is from 0.2:1 to 100:1.

5. A process according to claim 1, wherein the monodentate phosphorus ligand is P(Ra)(Ra)(Ra)   (L1a)

6. A process according to claim 5, wherein in the ligand of formula (L1a), each Ra is an aryl group and all Ra are the same.

7. A process according to claim 6 wherein, in the ligand of formula (L1a), each Ra is phenyl so that ligand (L1a) is triphenylphosphine.

8. A process according to claim 1, wherein the monodentate phosphorus ligand is P(ORa)(ORa)(ORa)   (L1b)

9. A process according to claim 8, wherein in the ligand of formula (L1b), each Ra is an aryl group and all Ra are the same.

10. A process according to claim 9, wherein in the ligand of formula (L1b), each Ra is a substituted phenyl ring.

11. A process according to claim 10, wherein the ligand (L1b) is tris(2,4-ditertiary butylphenyl) phosphite or tris(2-tertiary butylphenyl) phosphite.

12. A process according to claim 1, wherein the bidentate phosphorus ligand is

13. A process according to claim 1, wherein the bidentate phosphorus ligand is

14. A process according to claim 1, wherein the bidentate phosphorus ligand is

15. A process according to claim 12, wherein in the ligand (L2a), M+ is an ion of an alkali or alkali earth metal, or is ammonium or a quaternary ammonium ion.

16. A process according to claim 12, wherein in the ligand (L2a), X− is an organic acid, phosphate or sulphate group.

17. A process according to claim 12, wherein in the ligand (L2a), W1, W2, W3 and W4 are each an alkyl, aryl or aryloxy radical.

18. A process according to claim 17, wherein in the ligand (L2a), W1, W2, W3 and W4 are each an aryl or aryloxy radical in accordance with formula (1), with the proviso that the structure of formula (1) does not represent a bridging unit connecting Pa to Pb—for Pa, W1 and W2 represent radicals connected through their respective G linkers, and for Pb, W3 and W4 represent radicals connected through their respective G linkers

19. A process according to claim 18 wherein, in formula (1), n=0, in (E)n, so that the independent E bridge is absent; formula (1) will then have the structure of formula (2)

20. A process according to claim 18 wherein, in formula (1), n=0, in (D)n, so that the independent D bridging is absent; formula (1) will then have the structure of formula (3)

21. A process according to claim 18, wherein, in formula (1), n=0, in both (D)n and (E)n, so that both the independent bridges D and E are absent; formula (1) will then have the structure of formula (4)

22. A process according to claim 1, wherein the bidentate phosphorus ligand is (W1)(W2)Pa—(G)n—(A)—(G)n—Pb(W3)(W4)   L2d)

23. A process according to claim 1, wherein the reaction temperature is from 50° C. to 150° C.; the synthesis gas pressure under which the hydroformylation reaction is performed is from 1 to 100 bar; and the H2:CO ratio is from 1:10 to 100:1.