Reactor for carrying out a reaction between two non-miscible fluids of different densities

Abstract

A reactor for performing a reaction between two immiscible fluids of different density, comprising an interior formed by a cylindrical, vertically oriented elongate shell, a bottom and a cap, wherein the interior is divided by internals into a backmixed zone, a zone of limited backmixing preferably arranged below the backmixed zone and a plug-flow zone which are at least consecutively traversable by one of the fluids, wherein the backmixed zone comprises at least one inlet and the plug-flow zone comprises an outlet and the backmixed zone comprises at least one mixing apparatus selected from a stirrer, a jet nozzle and means for injecting the fluid of lower density, a first cylindrical internal element which in the interior extends in the longitudinal direction of the reactor, which delimits the zone of limited backmixing from the plug-flow zone and which comprises a first passage to the backmixed zone and a second passage to the plug-flow zone, a second internal element which delimits the backmixed zone from the plug-flow zone such that there is no direct fluid connection between the backmixed zone and the plug-flow zone, and backmixing-preventing third internal elements in the form of random packings, structured packings or liquid-permeable trays arranged in the zone of limited backmixing. The reactor allows an optimal residence time distribution in the reaction of the two immiscible fluids of different density. The invention further relates to a process for performing a continuous reaction in the reactor.

Claims

1. A reactor for performing a reaction between two immiscible fluids of different density, comprising: an interior formed by a cylindrical, vertically oriented elongate shell, a bottom and a cap, wherein the interior is divided by internals into a backmixed zone, a zone of limited backmixing arranged below the backmixed zone and a plug-flow zone which are at least consecutively traversable by one of the fluids, wherein the backmixed zone comprises at least one inlet and the plug-flow zone comprises an outlet and the backmixed zone comprises at least one mixing apparatus selected from a stirrer, a jet nozzle and means for injecting the fluid of lower density; a first cylindrical internal element which in the interior extends in the longitudinal direction of the reactor, which delimits the zone of limited backmixing from the plug-flow zone and which comprises a first passage to the backmixed zone and a second passage to the plug-flow zone, wherein the first internal element is arranged concentrically to the shell so that the plug-flow zone has an annular horizontal cross section, and wherein the lower edge of the first internal element is arranged at a distance from the bottom of the reactor, a second internal element which delimits the backmixed zone from the plug-flow zone such that there is no direct fluid connection between the backmixed zone and the plug-flow zone, wherein the second internal element extends from the upper edge of the first internal element to the shell, and wherein the second internal element is a horizontally oriented annular plate, and backmixing-preventing third internal elements in the form of random packings, structured packings or liquid-permeable trays arranged in the zone of limited backmixing.

2. The reactor according to claim 1, wherein the plug-flow zone is arranged such that the flow through it is turbulent.

3. The reactor according to claim 1, wherein the second internal element divides the interior in the vertical direction into an upper half and a lower half in the ratio of 4:1 to 1:1.

4. The reactor according to claim 1, wherein the mixing apparatus is a jet nozzle.

5. A process for performing a continuous reaction, wherein a first fluid of higher density and a second fluid of lower density are introduced into the backmixed zone of the reactor according to claim 1 so that at least the first fluid consecutively traverses the backmixed zone, the zone of limited backmixing and the plug-flow zone, and the first fluid comprising a reaction product is withdrawn at the reaction product outlet of the plug-flow zone.

6. The process according to claim 5, wherein unconverted second fluid is at least partially discharged from the backmixed zone via an outlet.

7. The process according to claim 5, wherein the first fluid is a liquid and the second fluid is a gas.

8. The process according to claim 7 for performing a high-pressure reaction.

9. The process according to claim 7, wherein the gas is dispersed in the liquid in the backmixed zone, the liquid consecutively traverses the zone of limited backmixing and the plug-flow zone, wherein the volume ratio of dispersed gas to the liquid decreases in the flow direction from the zone of limited backmixing to the plug-flow zone so that the plug-flow zone is traversed by the substantially single-phase liquid.

10. The process according to claim 7 for producing an optically active carbonyl compound by asymmetric hydrogenation of a prochiral α,β-unsaturated carbonyl compound with hydrogen in the presence of a homogeneous rhodium catalyst comprising at least one chiral ligand.

11. The process according to claim 10, wherein the process is performed in the presence of a compound of formula (II) ##STR00008## wherein Z in formula (II) represents a CHR.sup.3R.sup.4 group and wherein the variables R.sup.1, R.sup.2, R.sup.3, R.sup.4 independently of one another and especially jointly are as follows: R.sup.1, R.sup.2: are identical or different and represent phenyl which is unsubstituted or bears 1, 2 or 3 substituents selected from methyl and methoxy; R.sup.3 represents C.sub.1- to C.sub.4-alkyl; R.sup.4 represents C.sub.1- to C.sub.4-alkyl bearing a P(═O)R.sup.4aR.sup.4b group; wherein R.sup.4a, R.sup.4b: are identical or different and represent phenyl which is unsubstituted or bears 1, 2 or 3 substituents selected from methyl and methoxy.

12. A process for producing optically active menthol in which optically active citronellal of formula (III) ##STR00009## wherein * denotes the asymmetric center; is produced by the process according to claim 10 by asymmetric hydrogenation of geranial of formula (Ia-1) or of neral of formula (Ib-1) ##STR00010## or of a mixture comprising neral and geranial, the optically active citronellal of formula (III) is subjected to a cyclization to afford optically active isopulegol and the optically active isopulegol is hydrogenated to afford optically active menthol.

13. The process according to claim 5, wherein the first fluid is a water-immiscible organic liquid and the second fluid is an aqueous liquid.

14. The process according to claim 13 for producing a β-hydroxy ketone, wherein the first fluid comprises a dialkyl ketone and the second fluid comprises a formaldehyde source.

15. The process according to claim 10, wherein the at least one chiral ligand is chiraphos.

16. The process according to claim 11, wherein R.sup.1 and R.sup.2 each represent unsubstituted phenyl.

17. The process according to claim 11, wherein R.sup.3 represents methyl.

18. The process according to claim 11, wherein R.sup.4 represents a CH.sub.2—P(═O)R.sup.4aR.sup.4b or CH(CH.sub.3)—P(═O)R.sup.4aR.sup.4b group.

19. The process according to claim 11, wherein R.sup.4a and R.sup.4b each represent unsubstituted phenyl.

20. The process according to claim 16, wherein R.sup.3 represents methyl, R.sup.4 represents a CH.sub.2—P(═O)R.sup.4aR.sup.4b or CH(CH.sub.3)—P(═O)R.sup.4aR.sup.4b group and R.sup.4a and R.sup.4b each represent unsubstituted phenyl.

Description

(1) The invention is more particularly elucidated by the accompanying FIGURE.

(2) FIG. 1 is a schematic diagram of a reactor according to the invention for performing a process according to the invention.

(3) According to FIG. 1 a reactor according to the invention is divided by internals into a backmixed zone 101, a zone of limited backmixing 102 and a plug-flow zone 103. The reactor comprises a stirrer 104. A first fluid of higher density, for example a liquid, is supplied to the reactor via conduit 105. A second fluid of lower density, for example a gas, is supplied to the reactor via conduit 106. The reactor is configured such that the reaction mixture consecutively traverses the backmixed zone 101, the zone of limited backmixing 102 and the plug-flow zone 103. Any offgas generated during the reaction is discharged from the reactor at a fluid outlet via conduit 107. The reaction product is withdrawn via conduit 108 at a reaction product outlet.