Europâisches Patentamt à. European Patent Office (if) Publication number: O 015 379

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@ Dateof publication of patent spécification: 18.05.83 © Int. Cl.3: B 01 J 31/40, c 07 c 45/50, C 07 C 47/02 @^ ApplicationA ,• @ number:k 80100446.6oMnn„«* e (22) Date offiling: 29.01 .80

(54) Régénération of rhodium hydroformylation catalysts.

(§) Priority: 12.02.79 US 11604 @ Proprietor: EASTMAN KODAK COMPANY Patent Department 343 State Street Rochester, New York 1 4650 (US) (43) Date of publication of application: 17.09.80 Bulletin 80/19 @ Inventor: Dawes, John Leslie P.O. Box 7444 @ Publication of the grantof the patent: Longview Texas (US) 18.05.83 Bulletin 83/20 Inventor: Devon Jr., Thomas James P.O. Box 7444 Longview Texas (US) @ Designated Contracting States: DE FRGBNL (74) Représentative: Brandes, Jûrgen, Dipl.-Chem. Dr. et al, (56) Références cited: Thierschstrasse 8 EP - A - 0 000 685 D-8000 Munchen 22 (DE) FR - A - 2 258 357 US - A - 3 547 964

Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been a. paid. (Art. 99(1) European convention). IU patent Courier Press, Leamington Spa, England This invention relates to the Oxo process for effective method for catalyst reactivation the hydroformylation of an unsaturated com- without significant loss of the valuable rhodium. pound, such as an a-olefin, by the reaction Several methods of regeneration have been of the unsaturated compound with carbon suggested in the prior art. U.S. Patent monoxide and hydrogen in the presence of a 3,555,098 described the use of water or caustic catalyst. More specifically, this invention relates as a wash for the catalyst. This method removes to a method of regenerating a rhodium catalyst such poisons as acids but has not been effective useful in such a hydroformylation reaction. for regeneration of the rhodium catalyst. In a hydroformylation reaction, which is Japanese Patent 73/43799 describes reduc- called the Oxo process, an unsaturated com- tion with hydrogen as a suitable regeneration pound, such as an a-olefin, is reacted with syn- method. Japanese Patent 74/94385 describes thesis gas which contains carbon monoxide and the use of molecular oxygen for regeneration of hydrogen to form an aldehyde of the un- the catalyst. saturated compound. For example, propylene is European patent application 0 00685 reacted with carbon monoxide and hydrogen in describes the treatment of a rhodium triaryl the presence of a suitable catalyst to form iso- phosphite complex catalyst, which comprises an butyraldehyde and n-butyraldehyde. oxidation reaction at a temperature of from 0 to Cobalt catalysts are known to be efficient 85°C until the ligand is completely oxidized. and effective catalysts for the hydroformylation French patent 22 58 357 describes a reaction. However, the cobalt catalysts produce regeneration method according to which an undesirable quantities of by-products such as organic solution containing the complex of paraffins, alcohols, acetals, aldol type products rhodium in combination with triphenylphos- and other high boiling products. In contrast, phine is submitted to a treatment with an rhodium catalysts are known to be more selec- aldehyde such as formaldehyde or isobutyralde- tive in the hydroformylation process and to hyde in presence of an acid. produce yields of the desired aldehydes as high None of these methods restores fresh as 99% and substantially less of the undesired catalyst activity without significant loss of by-products. Also, the rhodium catalysts can be rhodium. used at much lower temperatures and pres- Numerous catalyst regeneration procedures sures than the cobalt catalysts and as a result have been tried. These procedures included significantly lower equipment and utilities treating the inactive catalyst with hydrogen, requirements are needed to build and oper- carbon monoxide, synthesis gas (the combina- ate a hydroformylation facility using rhodium tion of carbon monoxide and hydrogen used in catalysts. the Oxo reaction); washing the inactive catalyst The rhodium catalysts that are used in a with water or aqueous caustic; refluxing the hydroformylation reaction are complexes of inactive catalyst with aqueous caustic or an rhodium in combination with a ligand or func- acetic acid anhydride mixture; treating the tional group that activates rhodium into a inactive catalyst with hydrochloric acid followed hydroformylation catalyst under reaction con- by a sodium isobutyrate wash; treating the ditions. There are many known ligands that can inactive catalyst with reducing agents, e.g., be used in the rhodium catalyst complex. For sodium borohydride in methanol or hydrazine in example, triaryl, trialkyl or mixed aryl alkyl ethanol; and treating the inactive catalyst with amines, phosphines, arsines or stilbines can be air in the absence of aldehyde. None of these used. The complex of rhodium and ligand reacts procedures proved adequate as a catalyst with the carbon monoxide and hydrogen in the reactivation method. synthesis gas to become even more com- The process of this invention for regenerat- plicated. For example, when rhodium and tri- ing a deactivated rhodium hydroformylation methylphosphine are reacted with carbon catalyst which has been removed from the monoxide and hydrogen, a complex material hydroformylation reaction, overcomes the whose structure is unknown is formed. problems of the prior art. The method of this During hydroformylation reactions, rhodium invention is characterized by catalysts become deactivated to a point where a) adding aldehyde to the deactivated they have insufficient activity to support an catalyst so that at least one mole of aldehyde is economical reaction. Normally a fully active present for each mole of rhodium and each rhodium catalyst complex is straw colored while mole of ligand, an inactive complex is black. Monitoring this b) oxidizing the aldehyde-containing catalyst color change is one practical method of deter- with an oxygen-containing gas at a tempera- mining if a catalyst is active or inactive. ture below the boiling point of the aldehyde The principal disadvantages of rhodium until substantially all the ligand is oxidized, catalysts for a hydroformylation reaction are the c) removing solid oxidized ligand formed extremely high capital investment needed for during the oxidation, and the initial catalyst charge and the lack of an d) adjusting the ligand to rhodium ratio of the regenerated catalyst for use in a hydroformyla- thereof. Air is then blown through the solution tion reaction. at a slow rate so the temperature of the mix- Optionally, it may be desirable to remove ture does not rise rapidly. As catalyst reactiva- some ligand from the catalyst prior to the tion proceeds the solution changes from a black adjustment of the aldehyde content. This will color to a straw color. From a few minutes (30 serve to reduce the amount of ligand lost during or less) to 48 hours or more are needed for the oxidation and to reduce the amount of alde- reactivation. Excess aldehyde and any acids hyde which must be added to achieve the formed during oxidation are then removed. The correct aldehyde/rhodium/ligand balance. In amount of aldehyde and air used in the oxida- addition, following oxidation, it may be desirable tion are controlled to minimize the formation of to treat the catalyst so as to remove any acid acid in the regeneration process. The solution is produced during the oxidation step. This then filtered to remove any solids, for example method results in a virtually complete reactiva- triphenylphosphine oxide, and returned to the tion of catalyst with minimal rhodium loss and it catalyst recycle stream with added phosphine. can be used repeatedly on the same catalyst Progress of the catalyst regeneration can be charge without the build-up of undesirable by- monitored by the change in color from the dark products. Surprisingly it has been found that deactivated form to the straw yellow of the this method is also effective in reactivating active form.. Regeneration is not complete until rhodium oxo catalysts which have been all the phosphine, etc., is oxidized to the poisoned by sulfur. phosphine oxide. When excess phosphine is The reactivation of the deactivated rhodium employed in the reaction it should be removed catalyst is carried out under mild reaction con- from the stream prior to regeneration and then ditions. Consequently, the reactivation of the replaced after the regeneration. catalyst can be accomplished in inexpensive In the following example triphenylphosphine equipment using ambient or atmospheric con- is represented by the symbol P03. ditions. An oxygen-containing gas, such as air, is used for the oxidation and the oxidation reac- Example tion is carried out at a temperature below the A sample of an oxo catalyst containing 1 boiling point of the aldehyde that is added to the mole of rhodium and 19 moles of triphenyl deactivated catalyst. Preferably, the oxidation phosphine, deactivated in propylene hydro- reaction is carried out at room temperature. formylation at 100°C. and 6792 kPa, was The aldehyde that is added to the deactivated removed from the reactor, stripped in vacuo and catalyst is preferably an aldehyde that is formed divided into four portions. The first portion was in the hydroformylation reaction. When an @- diluted with isobutyraldehyde to 55 ppm (parts olefin is being reacted in the hydroformylation per million) rhodium and tested for propylene process, a saturated aliphatic aldehyde such as hydroformylation at 100°C. and 6792 kPa. acetaldehyde, propionaldehyde, n-butyralde- Butyraldehydes were produced at a rate of 11 hyde, isobutyraldehyde or higher boiling alde- pounds per cubic foot (176 g/liter) per hour and hydes can be used. When propylene is being the deactivated catalyst had only 22 percent of hydroformylated to form butyraldehydes, either the activity of the fresh catalyst. the iso or normal butyraldehyde can be used in The second portion of catalyst was diluted the catalyst reactivation. The amount of alde- with isobutyraldehyde to 55 ppm rhodium, 19 g hyde that is used is at least equivalent on a moles of P03 were added per g-atom of rhodium mole basis to the amount of rhodium and ligand and tested for propylene hydroformylation at that is present in the catalyst. Thus, a mole of 100°C. and 6792 kPa. Butyraldehyde was rhodium and a mole of ligand would require produced at the same rate as the previous run about 2.05 moles of aldehyde. When a catalyst showing that addition of P03 did not enhance is formed from 1 mole of rhodium and as much the activity of the deactivated catalyst. as 19 moles of ligand, such a triphenylphos- The two remaining portions of deactivated phine, it is preferred to remove some of the tri- catalyst were combined, diluted with isobutyr- phenylphosphine from the deactivated catalyst aldehyde and treated at room temperature with before aldehyde is added for the oxidation a slow stream of air for 48 hours. The solution reaction. Thus, less aldehyde is required for the changed from black to a straw yellow and all the oxidation reaction and less triphenylphosphine triphenylphosphine was oxidized to triphenyl- is converted to the corresponding oxide during phosphine oxide. The solvent was stripped in the oxidation reaction. vacuo at 100°C. to remove the isobutyric acid In a more specific illustration, a rhodium produced in the oxidation. The residue was catalyst utilized in a process such as that diluted with isobutyraldehyde to 55 ppm described in U.S. Patent 3,527,809 can be rhodium and divided into two parts. The first removed as a slip or side stream from the part was tested for propylene hydroformylation process. For each mole of rhodium and ligand at 100°C. and 6792 kPa and produced present in the side stream an equal molar butyraldehydes at a rate of 224 g/liter per hour amount of aldehyde plus a slight excess of showing that oxidized catalyst without added aldehyde is added. The aldehydes are preferably PØ3 was only 27 percent as active as fresh iso- or normal butyraldehydes or mixtures catalyst. The second part of the combined catalyst pratiquement tout le coordinat soit oxydé (c) on was treated with 19 equivalents of triphenyl- élimine les produits solides, résultant de phosphine per equivalent of rhodium and tested l'oxydation du coordinat, formés pendant in a similar manner. This catalyst produced l'oxydation et (d) on ajuste le rapport du butyraldehydes at 51 pounds per cubic foot coordinat au rhodium du catalyseur régénéré (816,5 g/liter) per hour which was equivalent to pour son utilisation dans une réaction d'hydro- the fresh catalyst under identical conditions. formylation. 2. Procédé conforme à la revendication 1, dans lequel le coordinat est la triphènyl- phosphine. 1. A method for regenerating a rhodium- 3. Procédé conforme à la revendication 1, ligand catalyst, that has been deactivated in a dans lequel l'aldéhyde est l'isobutyraldéhyde. hydroformylation reaction, characterized by 4. Procédé conforme à la revendication 1, a) adding aldehyde to the deactivated dans lequel le catalyseur qui contient de catalyst so that at least one mole of aldehyde is l'aldéhyde est oxydé par l'air à la température present for each mole of rhodium and each ambiante. mole of ligand, b) oxidizing the aldehyde-containing catalyst with an oxygen-containing gas at a tempera- ture below the boiling point of the aldehyde 1. Ein Verfahren zum Regenerieren eines Li- until substantially all the ligand is oxidized, ganden aufweisenden Rhodium-Katalysators, c) removing solid oxidized ligand formed der durch Verwendung in einer Hydroformylie- during the oxidation, and rungsreaktion deaktiviert wurde, gekennzeich- d) adjusting the ligand to rhodium ratio of the net durch: regenerated catalyst for use in a hydro- a) Zusatz von Aldehyd zu dem deaktivierten' formylation reaction. Katalysator, so daß mindestens ein Mol Aldehyd 2. The method according to Claim 1 wherein für jedes Mol Rhodium und jedes Mol Liganden the ligand is triphenylphosphine. vorliegt; 3. The method according to Claim 1 wherein b) Oxidieren des Aldehyd enthaltenden the aldehyde is isobutyraldehyde. Katalysators mit einem Sauerstoff enthaltenden 4. The method according to Claim 1 wherein Gas bei einer Temperatur unterhalb der Siede- the aldehyde-containing catalyst is oxidized temperatur des Aldehydes bis praktisch sämt- with air at room temperature. licher Ligand oxidiert ist; c) Entfernung des während der Oxidation ge- bildeten festen oxidierten Liganden und d) Einstellung des Verhältnisses von Li- ganden zu Rhbdium des regenerierten Kataly- 1. Procédé pour la régénération d'un sators für die Verwendung in einer Hydro- catalyseur, contenant un complexe d'un formylierungsreaktion. coordinat et de rhodium, qui a été désactivé 2. Verfahren nach Anspruch 1, dadurch dans une réaction d'hydroformylation, carac- gekennzeichnet, daß der Ligand Triphenyl- térisé en ce que (a) on ajoute un aldéhyde au phosphin ist. catalyseur désactivé de manière qu'au moins 3. Verfahren nach Anspruch 1, dadurch une mole d'aldéhyde soit présente pour chaque gekennzeichnet, daß der Aldehyd Isobutyralde- mole de rhodium et chaque mole de coordinat, hyd ist. (b) on oxyde le catalyseur qui contient de 4. Verfahren nach Anspruch 1, dadurch l'aldéhyde avec un gaz contenant de l'oxygène à gekennzeichnet, daß der Aldehyd enthaltende une température inférieure à la température Katalysator bei Raumtemperatur mit Luft oxi- d'ébullition de l'aldéhyde jusqu'à ce que diert wird.