DE1542030A1 - Process for the production of catalysts containing cobalt and molybdenum - Google Patents

Description

BADISOHE ANIIIN- & SODA-FABRIK AG

Our reference: O.Z .. 24 562 Bk / Hi Ludwigshafen am Rhein, October 27, 1966

Process for the production of catalysts containing cobalt and molybdenum

The invention relates to a process for the production of cobalt, molybdenum, oxygen and optionally tellurium containing Catalysts.

It is known from English patent specification 915 799 and German Auslegeschrift 1 184 326 that catalysts containing cobalt, molybdenum and oxygen are obtained if cobalt and molybdenum compounds are precipitated together from aqueous solutions in the presence of bases. For the good effectiveness of the catalysts, which can be used for the oxidation of acrolein with oxygen-containing gases to acrylic acid, it is essential to keep certain atomic ratios of cobalt to molybdenum very precisely. During the precipitation process, however, the Pjr value of the reaction solution changes continuously, and thus the ratio of cobalt to molybdenum, so that it is very difficult to produce larger amounts of catalyst with the same catalytic activity. The same applies analogously to cobalt-molybdenum catalysts which contain tellurium dioxide and which catalyze the oxidation of propylene to acrolein and / or to acrylic acid. "

- 2 009812/1545

516/66

- 2 - O.Z. 24 562

It has now been found that catalysts containing cobalt, molybdenum, oxygen and optionally tellurium are advantageously obtained if cobalt oxide and molybdenum oxy4 or slightly decomposed. Substantial compounds of cobalt and molybdenum, which are converted into the named oxides in the solid state when heated, the mixture ^{heated to 300 to 80O 0} C, optionally with the exclusion of oxygen, and optionally, in the cobalt and molybdenum-containing mass before or after heating, tellurium or its compounds are mixed in.

The new procedure then has the advantage that it is easy to use Catalysts are obtained that have a constant ratio of cobalt to molybdenum and thus constant activity. aside from that the catalysts can be easily produced in large quantities.

Cobalt oxide or cobalt compounds are used as starting materials, which turn into cobalt oxide when heated. Particularly suitable are cobalt nitrate and salts of cobalt with lower carboxylic acids, in particular cobalt formate, acetate, citrate or oxalate. Further starting materials are molybdenum trioxide * molybdic acid or its salts, which when heated easily convert to molybdenum trioxide pass over, .. like ammonium molybdate. Become the catalyst optionally tellurium or tellurium compounds mixed in. Preferred Tellurium compounds are, for example, tellurium dioxide, tellurides, tellurites and ortho or allotelluric acid.

It is advantageous to choose the mixing ratio of the cobalt and

- 3 ~ 009812/1545

- - 3 - O.Z. 24-562

Molybdenum compounds so that the atomic ratio of cobalt to molybdenum is about 1: 1. It is possible to use an excess of one or the other component of up to 20 atomic percent. the Cobalt and molybdenum compounds become beneficial in the solid state in finely divided form, preferably with a grain size of less than 300 / u, according to methods customary in the art mixed. Tellurium or tellurium compounds can also be added at this stage of the process.

The mixture of cobalt and molybdenum compounds, and optionally tellurium or tellurium is preferably heated to 300 to 800 ⁰ C, at 350 to 5P0 ° C. The heating can be done in the presence of oxygen. However, it has proven advantageous to work with the exclusion of oxygen; preferably it is heated in an inert gas atmosphere, e.g. B. under nitrogen, argon or carbon dioxide. In the mixture containing cobalt, molybdenum and oxygen produced by heating, if it was not carried out before heating, tellurium or its compounds, preferably with a grain size of less than 300 / u, z. B. by kneading or grinding, add. If the catalyst contains tellurium or its compounds, the teline content, determined analytically as tellurium dioxide, i.e. regardless of the actual binding state in which tellurium is actually present in the finished catalyst, is advantageously 0.1 to 15% by weight, preferably 0.5 to 5 wt.? S, based on the mass containing cobalt, molybdenum and oxygen.

The catalysts made by the process of the invention

009812/1545 " ⁴ "

- 4 - O.Z. 24 562

are suitable without a tellurium content for the oxidation of acrolein to acrylic acid or with a tellurium content for the oxidation of propylene to acrolein.

The parts given in the following examples are parts by weight.

example 1

624 parts of cobalt acetate · 4 water of crystallization are dry-ground with 405 parts of technical-grade molybdic acid (molybdenum trioxide content: 89 »2% by weight) in a ball mill for 2 1/2 hours and thoroughly mixed. The grain size of the ground material is 95 7 ° smaller than 300 / u. The dry mixture is dehydrated for 3 hours at 140 ⁰ C and 5 hours at 160-180 ⁰ C and carefully decomposed for 7 hours at 26O-3OO ° C. The mass is then heated for 16 hours at 400 ° C. and the resulting violet mass (542 g), which X-ray consists exclusively of cobalt molybdate, is mixed with 5.5 parts of tellurium dioxide powder (75% by weight less than 100 / u) after cooling Addition of 135 room parts dist. V / ater kneaded intensively for 2 1/2 hours. The solidified composition is dried for 15 hours at 120 ⁰ C, nachkalziniert 3 hours at 400 ⁰ C and comminuted after cooling and sieved (mesh size 1.5-3 mm).

Example 2

As in Example 1, there are 748 parts of cobalt acetate x 4 water of crystallization mixed with 405 parts of technical molybdic acid (89.2 -) and heated dry and then that

009812/1645 - 5 -

- 5 - O.Z. 24 562

The product formed was kneaded with 5.5 parts of tellurium dioxide. The atomic ratio of the catalyst obtained (sieve fraction 1.5-3 mm) was cobalt: molybdenum = 1.2: 1.

Example 3

As in Example 1, 624 parts of cobalt acetate * 4 become knallwasser mixed intimately dry with 360 parts of molybdenum trioxide and reacted (Atomic ratio cobalt: molybdenum = 1: 1) and then 1 wt. $ Tellurium dioxide, based on the cobalt, molybdenum and Oxygen-containing mass, kneaded.

Example 4

As in Example 1, 624 parts of cobalt acetate x 4 water of crystallization are ground with 405 parts of technical molybdic acid (89.2 wt. MoO,) and mixed intimately (atomic ratio of cobalt: molybdenum = 1: 1). The mixture is first, as described in Example 1, dehydrated in a normal atmosphere and then in a vertically arranged quartz tube while passing through 60 l / h. Nitrogen calcined, the temperature being increased gradually to 310 G ⁰ within 4 hours. The mass is kept at this temperature for 1 hour and then the temperature is increased ^{to 400 ° C. over the course of 2 hours.} Subsequently, the mass is tempered under constant nitrogen stream for 16 hours at 400 ⁰ O and allowed to cool under nitrogen. The addition of 1% by weight of tellurium dioxide and the subsequent comminution of the contact are carried out as in Example 1.

009812/1545 " ⁶ "

- 6 - O.Z. 24 562

Example 5

457 parts of technical cobalt oxalate (cobalt content: 32.2% by weight) are dry-ground with 425 parts of technical molybdic acid (οΟ, content: 89.2% by weight) in a ball mill for 2 hours. The intimate mixture (atomic ratio of cobalt: molybdenum = 1: 1.05) is dehydrated for 5 hours at 150-170 ⁰ C and decomposes it, within 4 hours at 250 to 300 C. The mass is heated for 16 hours at 400 ⁰ C. The fine, gray-blue powder obtained after cooling is intensively mixed with 5.7 parts of tellurium dioxide powder (corresponding to 1% by weight of tellurium dioxide) for 30 minutes and then kneaded for 1 hour with the addition of 150 parts by volume of distilled water. The solidified composition is dried nachkalziniert 15 hours at 120 ⁰ C and 3 hours at 400 ⁰ C and crushed after cooling.

- 7 -009812/1545

Claims (1)

- 7 - O.Z. 24 562 Claim Process for the production of catalysts containing cobalt, molybdenum, oxygen and optionally tellurium, characterized in that cobalt oxide and molybdenum oxide or easily decomposable cobalt and molybdenum compounds which convert into the oxides mentioned on heating are mixed in the solid state 300 to 800 ^° C., optionally heated with exclusion of oxygen and optionally mixed with tellurium or its compounds into the cobalt and molybdenum-containing mass before or after heating. BADISCHE ANILIN- & SODA-FABRIK AG 009812/1545