DE932606C - Process for the catalytic production of nitriles from primary aliphatic alcohols and ammonia - Google Patents

Description

Process for the catalytic production of nitriles from primary aliphatic alcohols and ammonia For the production of nitriles from primary alcohols and ammonia, catalytic processes are already known. In most cases aluminum oxide catalysts are used with suitable additives, e.g. B. with thorium oxide or molybdenum oxide, activated (see U.S. Patent 2,487 299). In the production of nitriles one has the alcohols to be reacted with ammonia or aldehydes already catalytically treated with zinc sulfide, which at 350 to 4750 was used (German patent 832 riss7). The yields are in these cases are not very satisfactory and in the best case reach 50 to 800/0 but mostly well below 50%. At. other processes are the alumina catalysts activated with silver or copper (see e.g. USA patents 2 337421 and 2 337 422). This results in significantly better yields, the catalysts but only have a short lifespan.

After usually a short time, these catalysts cover themselves with carbon, their activity decreases considerably. After only a few hours of reaction time must therefore these catalysts by treatment with gases and oxygen subsequent reduction can be regenerated with hydrogen-containing gases.

It has now been found that one leads to the catalytic conversion Obtains surprisingly good yields from primary aliphatic alcohols with ammonia, without periodic regeneration of the catalysts is required, if the alcohols to be converted together with excess ammonia in gaseous form Phase at 300 to 4700, preferably 360 to 4200, over catalysts which consist essentially of iron and / or iron oxides.

The catalysts can be carriers, for example kieselguhr, Containing bleaching earths, ceramic masses and the like.

The loading of the catalysts depends on the particular reaction temperatures used customized. In general, one works with a load of 25 to 501 per hour liquid alcohol per 100 liters of catalyst. The inventive method can but also run with a lower or higher load.

In general, the process of the invention is carried out at atmospheric pressure carried out. Depending on the circumstances, however, higher or lower pressures can also be used be used. An excess of ammonia is advantageous in all cases.

For example, three- - b5s five times the amount of theoretically required ammonia work.

The catalysts used according to the invention need during the Not to be regenerated during operation. They keep their catalytic effectiveness over very long operating times, for example several months.

For the production of the iron-containing catalysts used can you can use different procedures. The catalysts can both by precipitation from iron salt solutions as well as by melting or sintering the Components are manufactured. Between the effectiveness of the precipitation and the Melting or There is no essential difference between sintered catalysts. Enamel or sintered catalysts have a larger than the precipitation catalysts Hardness.

In general, those used according to the invention, iron and / or or iron oxide-containing catalysts are particularly effective when in the form of precipitation, melting or sintering catalysts without the use of carriers are made. However, the process does not rely on such supported free catalysts limited.

Also with iron and / or iron oxide containing catalysts, the suitable iron salt solutions on carriers, for example on kieselguhr, Pumice stone, aluminum oxide and similar substances that have been deposited can be removed achieve good yields.

Before they are used, the catalysts are expediently treated with hydrogen reduced. The extent of the reduction is of secondary importance here, since the catalysts are independent of the original one during the operating time Set the reduction value to a medium reduction value. After a long period of operation the iron is generally 15 to 25 ovo metallic within the catalyst In the form of 40 to 6o0 / o as FeO and 15 to 550/0 in the form of Fe2 Oo. The reduction of the catalysts can take place inside the reaction tube, whereby The starting materials for nitrile production can also be used as reducing agents can.

It is particularly useful if you use those according to the invention Iron catalysts activated with suitable additives. Additions from I to 5 ovo of an alkali oxide are advantageous. Certain amounts of copper are also available as additives useful for the catalysts. In general, the iron-iron oxide mixtures less than 10 ° / o copper was added. But you can also get copper contents of up to use up to 30 ° / o. Additions of silica have also proven to increase activity proven. The S.i O2 additions can be increased up to about 30 ovo. The installation of the Ski 02 can take place before or after the precipitation of the metal salts.

The alcohols used to produce nitrile are converted in the gaseous phase over fixed catalysts, which are best in vertical, externally tempered reaction tubes are attached. That at reaction temperature The preheated alcohol-ammonia mixture expediently flows from top to bottom through the catalyst layer. However, the process is not based on this type of reaction limited.

Example I In a vertically arranged glass tube with a diameter of 23 mm 280 cm3 of a melt catalyst made up of 100 parts by weight were filled in Iron and 1.5 parts of potassium oxide. This catalyst was previously at increased Temperature has been reduced with hydrogen. ufer the catalyst heated to 4000 were hourly 100 cm0 hexanol mixed with 100 1 ammonia from top to bottom directed. The gaseous reaction products emerging at the lower end of the catalyst tube were condensed in a brine-cooled receiver. With a single pass through the catalyst layer was here 800/0 of the theoretically expected yield obtained on C6 nitrile (capronitrile).

Example 2 The apparatus used in Example 1 was 280 cm3 a catalyst prepared by precipitation filled, which consists of 100 parts of iron, 5 parts copper and 2 parts potassium oxide and reduced with hydrogen. This catalyst was heated to 400 ° inside the reaction tube. At a The passage of 100 cm 3 of hexanol per hour mixed with 100 1 of ammonia was obtained the C6-nitrile in 82% yield.

Example 3 In the apparatus used according to Example 1, 280 cm3 of a catalyst produced by precipitation, containing 100 parts of iron, Contained 5 parts of copper, 5 parts of potassium oxide and 100 parts of kieselguhr. The catalyst had previously been reduced in the usual way with hydrogen.

100 cm3 per hour were passed over the catalyst heated to 4000 Hexanol passed in a mixture with ion 1 ammonia. At the lower end of the reaction tube C6-nitrile could be taken off in 83% of the above yield.

Example 4 Using the apparatus used in Example 1 280 cm3 of a melt catalyst were used, consisting of 100 parts of iron, 25 parts Copper, 2.5 parts of potassium oxide and Io, 5 parts of silica. The one before with Hydrogen reduced catalyst was heated to 4000.

100 cm³ of hexanol and ion 1 ammonia were then passed over every hour and the C6-nitrile was obtained in 87% above yield.

Example 5 Over 280 cm3 of a previously reduced with hydrogen Catalyst, which consists of 100 parts of iron, 5 parts of copper, 5 parts of potassium oxide and 25 parts of silica consisted of and was made by precipitation, were at 4000 100 cm3 of hexanol and ion 1 ammonia are passed every hour. The reaction product was obtained the C6-nitrile in 88% above yield.

Example 6 The apparatus used in Example 1 was 280 cm3 a catalyst obtained by precipitation and previously reduced with hydrogen filled, which consists of 100 parts of iron, 5 parts of copper, 5 parts of potassium oxide and 25 parts Silicic acid existed. At 4000 cm3 of butanol were poured over this catalyst every hour passed in mixture with ion 1 ammonia. The end product was found in a yield of 80/0 Butyronitrile.

Example 7 Over 280 cm3 of the catalyst used in Example 6 70 liters of ammonia and 80 cm³ of a CXo alcohol were passed every hour at 3800, which is produced by the so-called "oxo" synthesis with subsequent hydrogenation had been. The end product was obtained with about% of the theoretical yield CtO nitrile (capric acid nitrile).

Example 8 In the apparatus used in Example 1, 280 cm3 of a non-reduced catalyst with the same composition as possessed by the catalyst used in Example 5. At 3800 were over this catalyst 80 cm³ of a C1 alcohol mixed with 70 liters of ammonia I passed every hour. To With a start-up time of 5 hours, the same results were achieved as in the Example 7 achieved using the previously reduced catalyst.

Claims (7)

PATENT CLAIMS: I. Process for the catalytic production of nitriles from primary aliphatic alcohols and ammonia, characterized in that the alcohols to be converted together with excess ammonia in the gaseous phase at 300 to 4700, preferably at 360 to 4200, are passed over catalysts, which essentially consist of iron and / or iron oxides. 2. The method according to claim 1, characterized in that the iron and / or catalysts containing iron oxide by precipitation from iron salt solutions were manufactured. 3. The method according to claim 1, characterized in that the iron and / or catalysts containing iron oxide by melting or sintering processes were manufactured. 4. The method according to claim I Ibis 3, characterized in that the iron and / or iron oxide-containing catalysts are carriers, preferably Contains diatomite, pumice stone, aluminum oxide, bleaching earth, ceramic masses. 5. The method according to claim I to 4, characterized in that the iron-iron oxide mixtures with small amounts of alkali oxides used as catalysts, are preferably activated with 1 to 5 to the alkali metal oxide. 6. The method according to claim I to 5, characterized in that the Mixtures of iron and / or iron oxide 10 bis used as catalysts Contains 30% copper. 7. The method according to claim I to 6, characterized in that the Iron-iron oxide mixtures used as a catalyst contain up to 30 ovo of silica. Referenced publications: German patent specification No. 832 147.