Method for separation and partial return of rhodium and catalytically effective complex compounds thereof from process streams
View Patent ↗The invention relates to a method for separating and partially returning transition metals and/or catalytically effective complex compounds thereof from a reaction mixture by combining one at least one-stage membrane separation and an adsorption, wherein a current comprising a catalyst, comprising a transition metal, is divided over at least one one-stage membrane separation step in a transition metal enriched retentate stream that resupplies the reaction mixture and a transition metal depleted permeate stream and the transition metal depleted permeate stream is further supplied to an adsorption step. The invention further relates to a method for producing tridecanals.
1. A process for separating off and partly recirculating at least one selected from the group consisting of a transition metal and a catalytically active complex of a transition metal, from a reaction mixture, the process comprising:
separating the reaction mixture, which comprises a catalyst-comprising stream that comprises the at least one transition metal and the catalytically active complex by applying the reaction mixture to at least a single-stage membrane,
to yield (i) a retentate stream enriched in transition metal, and (ii) a permeate stream depleted in transition metal but that comprises some transitional metal;
returning the retentate stream to the reaction mixture; and feeding the permeate stream to an absorbent material to absorb the transitional metal.
2. The process of claim 1 , wherein the transition metal is rhodium.
3. The process of claim 1 , wherein at least 60% by mass of the transitional metal remains in the retentate stream in the membrane separation.
4. The process of claim 2 , wherein at least 60% by mass of rhodium in the permeate stream after the membrane separation is separated off by adsorption.
5. The process of claim 1 , wherein the single stage membrane has a separation limit in a range from 200 to 2000 g/mol.
6. The process of claim 1 , wherein the separating is carried out at a temperature range from 40 to 150° C.
7. The process of claim 1 , wherein the separating is carried out at a transmembrane pressure range from 0.5 to 7 MPa.
8. The process of claim 1 , wherein the absorbent material is activated carbon.
9. The process of claim 1 , wherein the absorbent comprises a chemically modified silica material.
10. The process of claim 8 , wherein a liquid flows over the adsorbent as a bed.
11. The process of claim 10 , wherein an eluate from the adsorption of the transitional metal is recirculated to the adsorbent.
12. The process of claim 1 , wherein the adsorption of the transitional metal is carried out at a temperature range from 30 to 140° C.
13. The process of claim 1 , wherein the adsorption of the transitional metal is carried out at a space velocity in a range from 0.01 to 5 l/h.
14. The process of claim 1 , wherein the adsorption of the transitional metal is carried out in a fixed bed.
15. The process of claim 2 , wherein a product mixture comprising at least one compound selected from the group consisting of a tridecanal and a tridecanol is prepared, and
wherein removal of rhodium-comprising catalyst complex in the reaction mixture comprises:
a) thermally separating the product mixture from the reaction mixture from a hydroformylation, to obtain a first composition;
b) separating the first composition in an at least single-stage membrane separation which is carried out over at least one membrane so that at least 60% by mass of rhodium present remains in a retentate stream, to obtain a permeate stream;
c) introducing the permeate stream obtained into a subsequent adsorption so that at least 60% by mass of the rhodium present in the permeate stream is retained;
d) recirculating the retentate stream with a concentrated rhodium-comprising catalyst complex from step b) to the hydroformylation.
16. The process of claim 2 , wherein at least 60% by mass of rhodium remains in the retentate stream in the separating.
17. The process of claim 2 , wherein at least 60% by mass of rhodium in the permeate stream after the separating is separated by adsorption.
18. The process of claim 3 , wherein at least 60% by mass of rhodium in the permeate stream after the separating is separated off by adsorption.
19. The process of claim 2 , wherein the separating is carried out with a separation limit in a range from 200 to 2000 g/mol.
20. The process of claim 3 , wherein the separating is carried out with a separation limit in a range from 200 to 2000 g/mol.