Separation processes

Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing

Reexamination Certificate

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Details

C568S451000, C568S453000, C560S177000, C558S085000, C556S013000, C556S025000

Reexamination Certificate

active

06307110

ABSTRACT:

BRIEF SUMMARY OF THE INVENTION
1. Technical Field
This invention relates to improved metal-organophosphorus ligand complex catalyzed processes. More particularly this invention relates to metal-organophosphorus ligand complex catalyzed processes in which the desired product, along with any organophosphorus ligand degradation products and reaction byproducts, can be selectively extracted and separated from the reaction product fluid by phase separation.
2. Background of the Invention
It is known in the art that various products may be produced by reacting one or more reactants in the presence of an metal-organophosphorus ligand complex catalyst. However, stabilization of the catalyst and organophosphorus ligand remains a primary concern of the art. Obviously catalyst stability is a key issue in the employment of any catalyst. Loss of catalyst or catalytic activity due to undesirable reactions of the highly expensive metal catalysts can be detrimental to the production of the desired product. Moreover, production costs of the product obviously increase when productivity of the catalyst decreases.
For instance, a cause of organophosphorus ligand degradation and catalyst deactivation of metal-organophosphorus ligand complex catalyzed hydroformylation processes is due in part to vaporizer conditions present during, for example, in the vaporization employed in the separation and recovery of the aldehyde product from the reaction product mixture. When using a vaporizer to facilitate separation of the aldehyde product of the process, a harsh environment of a high temperature and a low carbon monoxide partial pressure than employed during hydroformylation is created, and it has been found that when a organophosphorus promoted rhodium catalyst is placed under such vaporizer conditions, it will deactivate at an accelerated pace with time. It is further believed that this deactivation is likely caused by the formation of an inactive or less active rhodium species. Such is especially evident when the carbon monoxide partial pressure is very low or absent. It has also been observed that the rhodium becomes susceptible to precipitation under prolonged exposure to such vaporizer conditions.
For instance, it is theorized that under harsh conditions such as exist in a vaporizer, the active catalyst, which under hydroformylation conditions is believed to comprise a complex of rhodium, organophosphorus ligand, carbon monoxide and hydrogen, loses at least some of its coordinated carbon monoxide, thereby providing a route for the formation of such a catalytically inactive or less active rhodium. Accordingly, a successful method for preventing and/or lessening such degradation of the organophosphorus ligand and deactivation of the catalyst as occur under harsh separation conditions in a vaporizer would be highly desirable to the art.
Organophosphorus ligand degradation and catalyst deactivation of metal-organophosphorus ligand complex catalyzed hydroformylation processes can occur under process conditions other than vaporizer conditions. The buildup of organophosphorus ligand degradation products as well as reaction byproducts in the reaction product fluid can have a detrimental effect on the process, e.g., decreases catalyst efficiency, raw material conversion and product selectivity. Accordingly, a successful method for preventing and/or lessening such buildup of organophosphorus ligand degradation products and reaction byproducts in the reaction product fluid would be highly desirable in the art.
DISCLOSURE OF THE INVENTION
It has now been discovered that in metal-organophosphorus ligand complex catalyzed processes, the desired product, along with any organophosphorus ligand degradation products and reaction byproducts, can be selectively extracted and separated from the reaction product fluid by phase separation. By the practice of this invention, it is now possible to separate the desired product, along with any organophosphorus ligand degradation products and reaction byproducts, from the reaction product fluid without the need to use vaporization separation and the harsh conditions associated therewith. This invention provides a highly desirable separation method which prevents and/or lessens degradation of the organophosphorus ligand and deactivation of the catalyst as occur under harsh conditions with vaporization separation. This invention also provides a highly desirable separation method which prevents and/or lessens the buildup of organophosphorus ligand degradation products and reaction byproducts in the reaction product fluid.
This invention relates in part to a process for separating one or more organophosphorus ligand degradation products, one or more reaction byproducts and one or more products from a continuously generated reaction product fluid comprising one or more unreacted reactants, a metal-organophosphorus ligand complex catalyst, optionally free organophosphorus ligand, said one or more organophosphorus ligand degradation products, said one or more reaction byproducts, said one or more products, one or more nonpolar solvents and one or more polar solvents, wherein said process comprises (1) supplying said reaction product fluid from a reaction zone to a separation zone, (2) mixing said reaction product fluid in said separation zone to obtain by phase separation a nonpolar phase comprising said one or more unreacted reactants, said metal-organophosphorus ligand complex catalyst, said optionally free organophosphorus ligand and said one or more nonpolar solvents and a polar phase comprising said one or more organophosphorus ligand degradation products, said one or more reaction byproducts, said one or more products and said one or more polar solvents, (3) removing from said separation zone an amount of said one or more organophosphorus ligand degradation products, said one or more reaction byproducts and said one or more products essentially equal to their rate of formation in said reaction product fluid in said reaction zone whereby the amount of said one or more organophosphorus ligand degradation products, said one or more reaction byproducts and said one or more products in said reaction product fluid in said reaction zone is maintained at a predetermined level, (4) supplying from said separation zone to said reaction zone and/or said separation zone one or more recycle streams comprising said one or more unreacted reactants, said metal-organophosphorus ligand complex catalyst, said optionally free organophosphorus ligand and said one or more nonpolar solvents, (5) recovering said one or more organophosphorus ligand degradation products, said one or more reaction byproducts and said one or more products from said one or more polar solvents, and (6) supplying from said separation zone to said reaction zone and/or said separation zone one or more recycle streams comprising said one or more polar solvents; wherein (i) the selectivity of the nonpolar phase for the organophosphorus ligand with respect to the one or more products is expressed by the following partition coefficient ratio Ef1:
Ef1
=
Partition



coefficient



Kp1
of



organophosphorus



ligand
Partition



coefficient



Kp2
of



one



or



more



products
in which said partition coefficient Kp1 is the ratio of the concentration of organophosphorus ligand in the nonpolar phase after extraction to the concentration of organophosphorus ligand in the polar phase after extraction, said partition coefficient Kp2 is the ratio of the concentration of products in the nonpolar phase after extraction to the concentration of products in the polar phase after extraction, and said Ef1 is a value greater than about 2.5, (ii) the selectivity of the nonpolar phase for the organophosphorus ligand with respect to the one or more organophosphorus ligand degradation products is expressed by the following partition coefficient ratio Ef2:
Ef2
=
Partition



coefficient
&it

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