Process for recovering homogeneous metal hydride catalysts
View Patent ↗The present invention relates to a process for recovery of homogeneous metal hydride catalyst from a reactor stream as catalyst suitable for recycle to a reactor comprising the steps of: removing a stream from a reactor, said stream comprising the homogeneous metal hydride catalyst; contacting the stream with a solid acidic absorbent under process conditions which allow at least some of the metal to become bound to the absorbent; subjecting the metal bound to the absorbent, under process conditions which allow desorption of the metal, to a fluid stripping medium comprising hydrogen and solvent; and recovering the active metal hydride catalyst.
1. A process for recovery of homogeneous Group VIII noble metal hydride catalyst from a reactor stream as catalyst suitable for recycle to a reactor comprising the steps of:
(a) removing a stream from a reactor, said stream comprising deactivated homogeneous Group VIII noble metal hydride catalyst;
(b) contacting the stream with a solid acidic absorbent under process conditions which allow at least some of the metal to become bound to the absorbent;
(c) subjecting the metal bound to the absorbent to a fluid stripping medium comprising hydrogen and a solvent, under process conditions which allow the metal to be desorbed from the absorbent and rehydrided at a pressure above 200 kPa to form an active Group VIII noble metal hydride catalyst; and
(d) recovering the homogeneous active Group VIII noble metal hydride catalyst.
2. A process according to claim 1 wherein the fluid stripping medium is a single fluid phase.
3. A process according to claim 1 wherein the fluid stripping medium comprises two fluid phases.
4. A process according claim 1 wherein the Group VIII noble metal hydride catalyst is a platinum, palladium, iridium or rhodium hydride catalyst.
5. A process according to claim 4 wherein the catalyst is HRh(CO)(PPh 3 ) 3 .
6. A process according to claim 1 wherein the reactor stream is from a hydroformylation reactor.
7. A process according to claim 6 wherein the reactor stream contains non-volatile by-products of the reaction.
8. A process according to claim 1 wherein the reactor stream having been contacted with the solid acidic absorbent is removed.
9. A process according to claim 1 wherein the acidic absorbent is an ion-exchange resin.
10. A process according to claim 1 wherein the acidic absorbent is a styrene divinyl copolymer containing sulphonic acid groups or carboxylic acid groups.
11. A process according to claim 1 wherein the acidic absorbent has a silica-containing backbone and an acidic functional group attached to the silica.
12. A process according to claim 11 wherein the acidic functional group is an aromatic carboxylic acid, an aliphatic carboxylic acid, an aromatic sulphonic acid or an aliphatic sulphonic acid.
13. A process according to claim 1 wherein the acidic absorbent is a sulphonic acid in protonated form.
14. A process according to claim 1 wherein step (b) is carried out at a temperature of from about 20° C. to about 100° C.
15. A process according to claim 14 wherein the temperature is in the region of about 50° C. to about 95° C.
16. A process according to claim 1 wherein the reactor stream is concentrated prior to contact with the acidic absorbent.
17. A process according to claim 1 wherein the reactor stream is diluted with a solvent compatible with the absorbent before it is contacted with the absorbent.
18. A process according to claim 1 wherein the reactor stream is subjected to oxidation to break clustered catalyst prior to being contacted with the acidic absorbent.
19. A process according to claim 18 wherein the stream having been subjected to oxidation is treated to hydrocarbonylation.