DE1568200A1 - Process for the production of acrylic acid - Google Patents

Description

BADISOHE ANILIlT- & SODA-FABRIK AG

Our reference: O.Z. 24 558 Bk / Hi Luäwigshafen am Rhein, October 24, 1966

Process for the production of acrylic acid

(The subject matter of the invention is a process for the production of Acrylic acid by the oxidation of propylene with gases containing oxygen.

It is known from the English patent 903 034 that acrylic acid by oxidation of propylene in the presence of Catalysts that contain iron and tungsten in addition to molybdenum and oxygen. According to another method that is used in the published documents of the Dutch patent application 6 501 294 is used for oxidation from propylene to acrylic acid catalysts that contain antimony, vanadium and oxygen, molybdenum and tungsten. The procedure have the disadvantage that acrylic acid is only obtained in yields of up to about 15? S, based on the propylene used. It is also known from French patent specification 1 425 871 that that when using catalysts containing tungsten, tin, molybdenum, tellurium and oxygen, in the oxidation of Propylene to acrylic acid gives good yields of acrylic acid. In order to obtain good yields, however, temperatures of 400

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and more can be applied. At such high temperatures, however partly volatile under the reaction conditions Oßllur dioxide and molybdenum trioxide, which increases the activity of the catalyst significantly impaired. Furthermore, in the Belgian patent 641 143 described that propylene can be used in the presence of catalysts which, in addition to oxygen, iron and antimony, are used as activators Oxides of at least one of the metals bismuth, copper, tin, germanium, tellurium, cobalt, manganese, lead, molybdenum, thallium, Contain barium or arsenic, can oxidize. As' process products however, essentially acrolein is obtained.

It has now been found that acrylic acid by oxidation of propylene with oxygen-containing gases in the gas phase in Presence of steam and catalysts at elevated temperature is advantageous when using catalysts which in addition to oxygen, molybdenum, tungsten and tellurium, iron and / or nickel and / or copper and / or manganese.

The new process has the advantage that acrylic acid is obtained in high yields. It also remains in the catalytic converters prolonged use of the tellurium content almost constant, which means that they retain their high activity for a long time.

In addition to propylene, the propylene used generally contains small amounts of other hydrocarbons, such as ethane, propane, butane or butylene. The propylene content is advantageously more than 85% by volume, preferably more than 98% by volume. Oxygen-containing gases generally have an oxygen content of 10

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up to 30 vol. #. It is advantageous to use gases that are 15 to 25 vol.

Contain oxygen, especially air. In addition to oxygen, the gases contain inert components such as nitrogen, carbon dioxide or argon. More than 1.5 parts by volume of oxygen, in particular 2 to 3 parts by volume of oxygen, is expediently used for one volume of gaseous propylene. The volume ratio of gaseous propylene to water vapor is generally 1 * 1.0 to 10, preferably 1 % 3 to 8.

The reaction is conveniently carried out at temperatures of 300 to 400 ⁰ O. Particularly good results are obtained when operating at temperatures of 320 to 35O ⁰ G. The oxidation is carried out in the gas phase, care being taken advantageously that the residence time of the starting materials on the catalyst is between 1 and 20 seconds, preferably between 6 and 15 seconds.

Preferred catalysts contain, in addition to oxygen, molybdenum, tungsten and tellurium, iron and / or nickel and / or copper and / or manganese in an atomic ratio of molybdenum: tungsten: tellurium: iron / nickel / copper / manganese such as 1 to 20: 0.01 to 20: 0.001 up to 1: 1, in particular such as 2 to 10: 0.1 to 4 s 0.01 to 0.6 : 1. The metals mentioned can be present in the catalyst as a mixture of oxides or as compounds with one another. The catalysts is made hot, for example, by placing in an aqueous Solution of ammonium paramolybdate, ammonium paratungstate and Telluric acid, iron and / or nickel and / or copper and / or manganese chlorides or sulfates dissolved in water can run. ',

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The precipitation is advantageously carried out in the presence of ammonium. salt or nitrogen bases. In this case, a precipitate is deposited which, after washing with water, for. B. 10 to 15 hours at 110 to 130 ö dried and then advantageously from 3 to 20 hours in air flow at 300 to 7OD, preferably 350, heated to 45O ⁰ O. It is also possible to add tellurium to the catalyst as telluric acid, tellurium dioxide or salts of telluric acid after drying the precipitate containing the remaining metals, e.g. B. by kneading to incorporate. Another way of working is to prepare the catalysts by mixing easily decomposable salts of metals, such as acetates, pormates, oxalates, chlorides and nitrates, and then decomposing them with heating. In this case too, teJ-luric acid, tellurium dioxide or salts of telluric acid can be subsequently introduced into the catalyst mass.

The process according to the invention is carried out, for example, by using a catalyst of the composition described Fixed in a reaction tube and a mixture of propylene and at the specified temperatures and residence times Oxygen-containing gases and water vapor passes over the catalyst layer in the specified ratio. Dig 'obtained hot reaction gases are z. B. rapidly cooled with water and washed, the acrylic acid formed in Water dissolves. If some aorolein is formed, it can again after the separation and separation from the acrylic acid Reaction can be fed or separated in a second stage are oxidized to acrylic acid. It is also possible to use the acrylic

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Hot gases containing acid and acrolein without cooling them -and to wash, optionally with repeated addition of oxygen-containing gases, a second oxidation stage add »in which acrolein is oxidized to acrylic acid. Appropriate one leads the washing water in the circuit, so that the Acrylic acid accumulates in water. The enriched aqueous solution is then converted into acrylic acid, advantageously with organic ones Solvents such as ethyl acetate extracted. After separating the aqueous phase »0. B * by decanting, the acrylic acid isolated from the extract by fractional distillation.

The parts given in the following examples are parts by weight. They relate to parts of the tree like kilograms

In 1800 parts of boiling water, one carries a mixture of 55 Parts by weight of ammonium paratungstate »445 parts by weight of ammonium paramolybdate, 34 parts by weight telluric acid and 113 parts by weight Ammoniumehlosdd in portions. Then one leaves while stirring into the boiling solution within 20 minutes • a solution of 133 parts of iron (III) chloride in 150 parts of water run up. During this operation a precipitate separates out.The aqueous suspension is cooled with stirring, the precipitate is filtered off and by three times slurrying in 10 OÖQ parts of water from. adhering impurities freed. The precipitate thus obtained is then at 12 hours

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12O ⁰ O dried, then heated ^{to 400 0} G in a stream of air for 4 hours. The catalyst mass obtained is comminuted and sieved, the sieve fraction of 2 to 5 mm being used further. The finished catalyst contains molybdenum, tungsten, tellurium and iron in an atomic ratio of 5.1 a 0.42 ι 0.5 t 1 «

1 tree part of the catalyst described above, which has a grain size of 2 to 5 mm, is firmly arranged in a reaction tube. Through the reaction tube 30 parts by volume passes aan hour at 34O ⁰ C propylene, 400 parts of trees air, 280 parts of trees water vapor The reaction gases obtained are mixed with gasohromatographisohen methods analyzed »BAQ propylene used is about 43 i> in acrylic acid to 3.9 £ in acrolein and converted to 42.4 i> i & other products. 10.7 pounds of the propylene are returned as solohes.

Indians the atomic ratio in the above-described catalyst and performs oxidation ton propylene in the manner described by, the Auebeuten listed in the following table sow receives at one acrylic acid ·

Atomic ratio of the catalyst Molybdenum t tungsten ι tellurium t Bieen

i> yield

■ "■ ■... ■ ■; - ■

Acrylic acid acrolein

; 5.1 I. 0.42 S. 0.15 I. 1 5.1 : 0.42 : 0.30 I. 1 i 5.1 I. 0.42 I. 0.50 I. 1 I. ^: 3.9. : 1.7 I. 0.5 S. 1 '. 4.7 Z 0.83 ι 0.5 I. 1 5.1 I. 0.42 I. 0.5 I. 1

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' Example 2

The catalyst is prepared as described in Example 1, with the exception that the telluric acid is not precipitated with it, but is incorporated after the precipitate has dried. 8.5 parts of telluric acid dissolved in 50 parts of water are kneaded into 110 parts of dried precipitate for 2 hours. The catalyst mass is then ^{heated to 40O 0} O for 4 hours in a stream of air.

A half hour of 15 parts of propylene, 150 parts of air and 110 parts of water vapor is passed every hour over 1 tree part of the catalyst described above, which is arranged in a reaction tube, a temperature of 35O ⁰ O being maintained. According to gas chromatographic analysis, the yield of acrylic acid is 50.8 mol. ^. Acrolein and other compounds are only formed in traces. 5 % of the propylene used is not converted.

Example 3

A mixture of 55 parts is made in 1800 parts of boiling water Ammonium paratungstate x 3 crystal waters, 445 parts ammonium paramolybdate x 4 crystal waters and 113 parts ammonium chloride entered in portions. A solution of is then allowed to stir in the boiling solution within 20 minutes 93 parts of manganese (II) chloride »1 water of crystallization in 150 parts Running water. A precipitate separates out that

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After cooling, the aqueous suspension is filtered off and freed from adhering impurities by three suspensions in 10,000 parts of water. The precipitate is ^{dried at 120 °} C. for 12 hours. 114 parts of the dried precipitate are suspended in 100 parts of water. The suspension is combined with a solution of 17.2 parts of tellurium in 120 parts of a mixture of equal parts of concentrated nitric acid and water and evaporated to dryness. The resulting mass is pressed mm then dried for 12 hours at 12O ⁰ C and with the addition of 2 wt. £ graphite into pills 3 x 3. The pills are then heated ^{to 400 °} C. in a stream of air for 4 hours.

Part of the space of the catalyst described above is filled into a reaction tube and conducts 15 parts by volume of propylene, 150 parts by volume of air, 110 parts by volume of water vapor over the catalyst every hour, a temperature of 340 C is maintained. 24 Mol.fi of the propylene used are in acrylic acid, 40 converted into acrolein and 26 mol. # into carbon monoxide and carbon dioxide.

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Claims (1)

- 9 - O.Z. 24 558 Claim Process for the preparation of acrylic acid by oxidation of propylene with oxygen-containing gases in the gas phase in the presence of steam and catalysts at elevated temperature, characterized in that catalysts are used which, in addition to oxygen, molybdenum, tungsten and tellurium, iron and / or nickel and / or contain copper and / or manganese. BADISCHE ANILIN- & SODA-FABRIK AG 909886/1602