DE870550C - Process and device for the decomposition of cobalt compounds contained in formylation products - Google Patents

Description

Method and device for the decomposition of cobalt compounds contained in formylation products The invention relates to the decomposition of cobalt compounds contained in formylation products. Formylation products are the products formed when a gas containing CO and H.sub.2 acts on carbon-containing compounds with an olefinic double bond at elevated pressure and temperature. By introducing a hydrogen atom and a aldehydes are obtained which can be converted into alcohols by reduction in a subsequent stage of the process. In the case of the formylation reaction, a cobalt-containing catalyst is preferred, which can be fixed in the reaction space or used in the starting material in the form of a suspension or solution. The formylation product emerging from the reaction chamber contains, in addition to smaller or larger amounts of dissolved gas and suspended catalyst, optionally soluble cobalt compounds, including compounds containing cobalt and carbon oxide, which have to be decomposed, while carbon monoxide has to be removed from the formylation product as far as possible. For this purpose, the aldehydic product emerging from the reaction chamber is first cooled with the reaction gas, then separated from the gas and, after complete or partial pressure relief and, if desired, renewed separation of the released gas, fed to an apparatus for the decomposition of the cobalt compounds and the removal of CO . For this purpose, the product containing cobalt must be heated to zoo to 25o °, preferably to r5o to r $ 0 °. However, this heating leads to the deposition of cobalt in the heating apparatus. The cobalt is mainly deposited in the hottest places, i.e. on the wall of the heating elements, so that blockages eventually arise.

It has now been found that this difficulty can be avoided when heating. is carried out in this way; that the decomposable cobalt compounds containing product to the temperature required for decomposition by mixing is brought with a formylation product which is above the decomposition temperature was heated, and in which the cobalt compounds have already been decomposed.

A product in which the cobalt compounds have been decomposed is im hereinafter referred to as the cobalt-free product. Before mixing the decomposable Product containing cobalt compounds with the formylation product heated to a higher temperature #Is it possible, if desired, to preheat the product to a temperature at which no disruptive decomposition of the cobalt compounds occurs.

In the case of such preheating of the product, the temperature can e.g. Be brought to 80 to foo °, if desired in the presence of carbon monoxide or a gas containing carbon monoxide, the partial pressure of the carbon monoxide z. B. to io at, after which .the preheated product overheated with a lot, of Kdbalt-freed product is mixed.

If the procedure is carried out in this way, it is shown that under certain conditions, especially when the throughput ratio is low has been kept,. in the preheater deposits are formed which, as is established, do not consist of a layer of metallic cobalt like: the normal one thermal deposition is the case, but from a paste-like mass, richer in cobalt than the catalyst used, e.g. B. up to 8o% metallic cobalt may contain.

When using a preheater it is, apart from the above-mentioned Disadvantage, possible a smaller amount of heated above the decomposition temperature Material to use. This has the advantage that the apparatus can be smaller and also the production cost can be reduced.

In the other mode of operation according to the invention, in which no preheater is used, there is the great advantage that the cobalt to be freed The product only needs to be kept at an elevated temperature for a short time. if an active catalyst is present in the formylation product, a temperature increase can occur lead to side reactions, e.g. B. to the formation of condensation products that making the process less effective and at the same time decomposing the cobalt compounds can adversely affect.

If the product to be freed from cobalt is not preheated, but is mixed directly with a product heated to a higher temperature A rapid release of cobalt is achieved, which prevents disruptive reactions will.

The metallic cobalt released during the decomposition can be from Carriers present in the vessel in which the cobalt is released be absorbed or it can be deposited on finely divided suspended carriers used in the formylation reaction and together with the formylation products were introduced into the vessel for the release of the cobalt.

In the method of the invention, part of the from the vessel for the release of the cobalt discharged, cobalt-free product cooled ' and: then, if desired under pressure relief, fed to a separating vessel will; two separation of the liquid, together with the catalyst suspended in it, of the gas used and the gas released, whereupon the gas-free liquid either with or without a catalyst via a heater to the vessel for release is returned by cobalt. The cobalt-free product can be used on zoo Can be heated to 35o °. During this heating process, the benefit will be increased Hydrogen added to the heating product to prevent the formation of condensation products avoiding aldehydes and, in the case of using a suspended cobalt catalyst, to keep the cobalt in better condition for the hydrogenation phase. The hydrogen pressure should preferably be more than io at, e.g. B. 25 at, So at or more.

The product to be freed from cobalt is preferably placed in the reaction chamber, in which the cobalt is released, mixed with the circulated product. Care must be taken that the supply line for the cobalt The product to be liberated is not conducive to heat from the hotter parts of the apparatus becomes so hot that it causes cobalt to deposit. Therefore, the feed line for the cycle product above a sieve plate at some distance from the floor arranged and fed the product to be freed from cobalt below this plate will.

The ratio of the cobalt to be freed and that in the cycle conducted product heated above the decomposition temperature varies in general between r: r and z: 5.

The ratio in which the overheated product is recycled will depend on the used Temperatures. If a part of the product to be freed from cobalt at 20 ° is mixed with 2 parts superheated Product of 300 °, a mixture temperature of approximately -oo ° is obtained. the The same mixture temperature is obtained if i part of the cobalt is to be freed Product of 100 ° is mixed with 1 part of superheated product of 300 °.

When the decomposition of the cobalt compounds will be complete and that Cobalt is to be obtained in an active form for the hydrogenation step it is necessary to carry out the decomposition in the presence of hydrogen. Consequently Hydrogen can be used to heat the cycle product and even more Hydrogen can be added to the reaction vessel for the release of the cobalt. The gas leaving this reaction vessel together with the liquid can be separated off and fed to a gas container to heat the formylation reaction or for to be reused for other purposes.

The process can also be carried out in such a way that in the reaction vessel for the release of the cobalt itself, the cobalt-depleted product to the site is returned to which the preheated product to be freed from cobalt is fed will. When this product is placed in a vertical bottom reaction vessel, can remove the cobalt-free product from the top of this reaction vessel led to the floor through a space formed by a partition wall and in it be heated, after which it is mixed with the product to be freed from cobalt can. The mixture can then be sent up through the inner chamber.

It has already been stated above that the product freed from cobalt can be heated above the decomposition temperature of the cobalt compounds. That these high heating is possible is quite surprising as the formylation products easily prone to different reactions, e.g. B. condensation reactions, in particular in the presence of traces of formylation catalysts. The metallic one Cobalt, however, whether applied to a support or not, has no objectionable influence. It is also possible to use part of the hydrogenation as the end product or intermediate product to use the product obtained from the formylation product. This product consists to a greater or lesser extent from alcohols and can be easily adjusted to a temperature can be heated by 300 °. A high-boiling fraction that contains so-called thick 01, and is separated from the end product after the alcohols have been distilled off can also be used as a heating medium.

The invention can be illustrated by the following examples.

Example I In the formylation of C.- to C.- alkenes with a suspended catalyst consisting of 30% cobalt and 70% kieselguhr in one In an amount of 4%, based on the alkene starting material, a product was obtained which consisted of 65 percent by weight aldehydes and 7 percent by weight alcohol, while the dissolved cobalt content was 0.45 percent by weight.

To remove the dissolved cobalt from the product, it was with a temperature of 2o ° and in an amount of 2o 1 per hour together with hydrogen at a rate of 3 m3 per hour in the lower part of a tower 55o cm high and 8 cm in diameter.

At the same time, 4o 1 of a product freed from cobalt were combined with i m3 of hydrogen per hour at a temperature of 300 ° in the lower part of the tower to release cobalt was introduced. The pressure in that tower was So at.

It occurred over a period of 500 hours and at 99- bis 100% decomposition of the 'dissolved cobalt no difficulties, such as undesirable Cobalt deposits, a. Example II Fig. I. The. Drawing shows an apparatus for releasing cobalt from a decomposable cobalt compound containing Product. This product is fed through line i to the preheater2, in which it is preheated to ioo °. The preheated product is placed in the vessel for release introduced by cobalt 3, where it mixes with the product supplied through line 4 will. This product was heated to a temperature of 2oo ° and is in a in such an amount that a temperature of 180 ° results after mixing. The hydrogen is fed in through line 5. Decompose in the reaction vessel 3 the volatile and dissolved cobalt compounds, while cobalt at the same time is separated.

The product freed from cobalt leaves the reaction space together with the gas 3 through the line 6, which leads to the cooling apparatus 7, whereupon 8 gas in the separation vessel is separated from the liquid product, some of which is transferred to the reaction vessel 3 , the preheater 9 is fed back, while the remaining part via the line io is fed to an apparatus for converting aldehydes into alcohols. Example III Fig. 2 shows an apparatus for. The release of cobalt from a Aldehydic product containing decomposable cobalt compounds. This product is through a line i i via a preheater 12 to the inner vessel 13 of a Reaction vessel 14 supplied. Hydrogen can via .ein line 15 of the line i i was added at a point just before the confluence in the reaction vessel 14 will. The inner vessel 13 is formed by a cylinder 16 with a conical bottom part 17 educated. The product to be freed from cobalt and hydrogen is added to the cylinder at the top , of the cone, which points downwards, added. Overheated, The cycle product freed from cobalt is added at the same point because at the upper part of the reaction vessel 14, part of the cobalt-free flows Product over the edge of the cylinder 16 down into, the from, the cylinder 16 and the Wall of the reaction vessel 14 formed space and is there by the in the of the wall of the reaction vessel 14 and the conical bottom of the inner vessel Formed space provided heating device 18 heated. Some hydrogen will go through line 20 into the heating zone. The cycle can be accomplished because the feed line for the preheated gas containing the gas in the reaction vessel 13 product to be freed from cobalt is arranged in such a way that these products Take the product to be returned with you.

Claims (1)

PATENT CLAIMS: i. Process for the decomposition of formylation products contained cobalt compounds, characterized in that the ze, resolvable, cobalt compounds containing product by mixing with heated to above decomposition temperature Formylation product in which the cobalt compounds have already decomposed is advantageous in the presence of hydrogen, brought to the temperature necessary for decomposition will. Ä. Method according to claim i, characterized in that: the decomposable, Product containing cobalt compounds by mixing with a recycled one Part of the product obtained during the actual decomposition to that for the decomposition necessary temperature is brought. Method according to claims 1 and 2, characterized characterized in that: the in one with the aid of a suspended cobalt catalyst cobalt compounds contained on a carrier formylation product are decomposed and a part: of the product freed from cobalt either with or without the suspended catalyst to the reaction vessel for the release of the Cobalt is recycled. 4. The method according to .den claims 1 to 3, characterized in that that the product, in which the cobalt compounds are already decomposed, is in the presence heated by hydrogen under pressure. 5. The method according to claims i to 4, characterized in that the decomposable product containing cobalt compounds preheated to a temperature not exceeding 100 °, and: by mixing with the freed from cobalt and optionally further hydrogenated product which is brought to a temperature heated to a temperature between 180 and 200 ° will. 6. Device for performing the method according to claims i to 5, consisting from a vertical shaft (14) with supply line (i i) for the to be treated Well below and discharge line (ig) for the treated material above, characterized in that that the shaft contains a top not tightly closing insert (16), the runs down into a cone (17), but is open at the cone tip, and that the Feed line (i i) protrudes into the open cone tip and on the outside the cone heating elements (18) are arranged. Printed publications: Fiat-Final. Report no. Iooo; Berl, Chemical Engineering, Vol. 3, p. 362 (I935) Badger 1VI c C abe, Elements of Chemical Engineering Technology, 1932, pp. 131 and 146.