DE1184326B - Process for the production of cobalt molybdate catalysts - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Kl .: BOIj

German class:. 12 g -4/01

Number: 1184 326

File number: C 30274 IV a / 12 g

Filing date: June 25, 1963

Opening day: December 31, 1964

It is known that cobalt molybdate is suitable as a catalyst for gas phase oxidations. So can acrolein to acrylic acid, propylene to a mixture of acrolein and acrylic acid, butane to maleic anhydride and oxidize propylene with ammonia to acrylonitrile. The achievable yields depend on the The nature of the catalyst, in particular its stoichiometric composition. The relationship from cobalt to molybdenum should deviate as little as possible from 1: 1. Just a few percent raise Cobalt or more than 10% molybdenum in excess on the selectivity of the catalyst.

Cobalt molybdate can be produced in various ways. In each case serve as Starting materials cobalt salts of volatile acids and molybdenum salts of volatile bases, in general these salts dissolved separately in stoichiometric amounts, the solutions combined and from them with volatile bases or by heating the cobalt molybdate. Also can be accordingly Molybdenum trioxide dissolved in ammonia can be used as a molybdenum component.

From a purely chemical point of view, the course of the reaction is as follows: First there are cobalt, ammonium, Nitrate and polymolybdations side by side in dissolved form. By adding ammonia or Amine, the anion of the polymolybdic acid is broken down, and the solubility is reduced as the breakdown progresses of the cobalt molybdate drops and precipitation begins, but before the polyacid has completely dissolved monomeric acid is broken down or the salt of the polyacid precipitates in addition to the salt of the monomeric acid.

However, these processes lead to catalysts whose cobalt-molybdenum ratio fluctuates widely is subject to and is therefore not reproducible, d. H. to not defined connections, but to simple mixed oxides of non-uniform composition. However, the catalytic effectiveness requires a certain ratio of cobalt to molybdenum. Furthermore, there is one with regard to use usable hardness of the catalyst only at a ratio of 1.05 to 1.15 parts by weight of molybdenum to 1 part by weight of cobalt, while a catalyst with a different composition is too soft and therefore unusable is.

It has now been found that cobalt molybdate catalysts with an atomic ratio of cobalt can be used Molybdenum like 1: 1 for gas phase oxidation by converting aqueous solutions of cobalt salts Can produce volatile acids with aqueous solutions of molybdates of volatile bases more advantageously, Process for the production of cobalt molybdate catalysts

Applicant:

Chemical works Hüls Aktiengesellschaft,

Marl (district of Recklinghausen)

Named as inventor:
Dr. Rudolf Brockhaus,
Marl (district of Recklinghausen)

if the aqueous solution of stoichiometrically defined amine or ammonia salts of the monomeric molybdic acid H ₂ MoO _{4 is} reacted with the aqueous solution of cobalt salts and the salts precipitated are optionally applied to a support.

The amine or ammonia salts of the monomeric molybdic acid are obtained by depolymerization of amine or ammonia salts of the molybdenum polyacid H ₆ Mo ₇ O ₂₄ in the presence of stoichiometric amounts of ammonia or amine. It must be prevented that the salt of a polyacid is re-formed by the escape of ammonia or amine as a gas. Ammonia and amines which are volatile under the reaction conditions, ie amines which boil below 100 ° C., are therefore left in a closed system, e.g. B. in a closed vessel, from which no gas can escape, act on the solutions of salts of the polyacids. Non-volatile amines, ie amines boiling above 100 ° C. in the context of this application, can also be used in an open vessel. In any case, the bases added in the manner mentioned cause a breakdown of the polyacid, so that the salts of the monomeric acid H ₂ MoO ₄ and not the salts of a polyacid react during precipitation with cobalt salts.

The amine salts of monomeric molybdic acid are ammonium molybdate, mono-, di-trimethyl-

409 760-85

3 4

to produce amine molybdate, mono-, di- and triethylamine molybdenum-inducible, defined composition, dat, propylamine molybdate, hexylamine molybdate, cyclo- enthexylamine molybdate, which meets the requirements of gas phase oxidation, Piperidine molybdate, pyrrolidine- speaks.

molybdate, pyrroline molybdate, aniline molybdate, methyl- The process and the technical level that can be achieved with it

Aniline molybdate, pyridine molybdate and piccoline molybdate will be advanced with reference to the examples below

dat in question. explained in more detail.

The amine or ammonia salts of the monomeric _R. . ,.

Molybdic acid can also be obtained by reacting e ι s ρ ι

polymeric molybdenum trioxide with equivalent MeN 353 parts by weight Ammonmolybdat (NH ₄₎ Mo ₇ O _e · _M gene amines or ammonia, under the above-excluded io 4 H ₂ O in 400 parts by weight of water are dissolved and carried conditions can be obtained. A so manufactured at 30 ⁰ C with 178 parts by weight of ammonia water imputed contact is displaced after its completion blue- (d = 0.900). This solution is colored in geviolett, uniform hardness and surface closed vessel is heated to 6O ⁰ C and 2 hours in size (16 to 17 m ² / g) and can be broken well, and kept at this temperature. 586 parts by weight of ground, which for use in the fluidized bed 15 advance cobalt nitrate Co (NO _{3) 2} · 6H ₂ O in 600 Gesetzung. The ratio of cobalt to molybdenum in parts by weight of water dissolved and heated to 60 ° C is also optimal at 1: 1.07. Ammonium molybdate solution is stirred vigorously and at

Combined for carrying out the present method 6O ⁰ C with the cobalt nitrate solution. Commercially available ammonium molybdate (NH ₄ ) SMo ₇ is added in 1 minute. There is immediately a blue 4H ₂ O in the necessary amount of water dissolved, the 20 precipitate from the another hour at 6O ⁰ C gezur neutralization of monomeric molybdic acid is stirred and then filtered, washed three times with water H ₂ MoO ₄ calculated amount of ammonia or amine to-washed, dried and, where sets 16 hours at 520 ⁰ C, the tempered already proposed in the salt of the polyacid, crushed and (mesh size is 0.1 considered to handene amount of ammonia and 0.3 mm) sieved,
then pour the solution into a closed vessel on a 25

Temperature between 20 and 100 ° C, for example example 2
6O ⁰ C, heated.

Starting from molybdenum trioxide, 353 parts by weight of ammonium molybdate (NHI ₈ Mo ₇ O ₂₄ · the oxide in the stoichiometric amount of ammonium 4 H ₂ O is dissolved in 400 parts by weight of water, and niacin-water or amine-water. In both cases 30 at 30 ° C with 178 parts by weight of ammonia water is necessary to ensure that no ammonia or (d = 0.900) was added This solution is able to escape in a GE-amine;. because there always heated polyacid in the closed vessel at 6O ⁰ C and 2 hours equilibrium with monomeric acid is present, kept at this temperature 476 parts by weight of ammonia or amine is partially chemically un- Cobalt chloride CoCl ₂ · 6 H ₂ O are present in 500 units by weight and can optionally be dissolved and dissolved in water as a gas 6O ⁰ C is heated. in this soft. It is now an equimolar, concen- temperature is stirring the cobalt chloride solution vigorously getrierte aqueous cobalt salt solution at, for example, and within a minute with the Amm on-6O ⁰ C with stirring in the molybdate solution added molybdate solution, a blue or vice versa the molybdate solution immediately precipitates in the presented precipitate. Cobalt salt solution is added to the precipitate. Likewise, the Fäl- can stirred 40 I hour at 6O ⁰ C, then abzentrilung by continuously combining superiors fugal, washed with water, dried for 16 hours are taken. The precipitation occurs shortly after supply at 520 ⁰ C annealed, ground and sieved (Maschensammengeben of the two solutions, where strong wide 0.1 to 0.3 mm),
must be stirred to prevent the

to prevent precipitated catalyst. Given 45 EXAMPLE 3
if the precipitation is carried out in the presence of carriers. Silica, aluminum oxide, kieselguhr, carborundum or pumice stone in a catalyst produced according to Examples 1 and 2 are used as supports. The catalyst is shaped, if necessary, and fluidized bed apparatus made of quartz glass in a heated salt bath is dried and tempered. For use in the fluidized bed 50 with a diameter of 4.5 cm and a height of 40 cm, the catalyst is optionally crushed and sieved with a diameter of 4.5 cm and a height of 40 cm. puts. At 340 ° C., 25 liters of acrolein vapor and 125 liters of air

According to the present procedure it is extremely and 1501 water vapor in 2 hours through the appa-

simple way possible, a catalyst repro- ratur passed. Acrolein conversion and acrylic acid yield

, ",. ,. (g acrolein used - g acrolein recovered) 100

(% Acrolein conversion = ----

g acrolein used

n, _A ι - λ- mol acrylic acid · 100

% Acrylic acid yield =

Moles of converted acrolein

using known (0) as well as the above procedures (example 1 = I and example 2 = II) The catalysts produced are compiled in the table below.

Tabel

1 2 3 4th 5 Catalytic properties Atomic ratio Sales acrolein Yield acrylic acid catalyst Flow properties (at constant (at constant Co / Mo = l / x Reaction Reaction X conditions) conditions) 1. 0/1 1.42 bad (channeling) 78 33 2. 0/1 1.22 bad (channeling) 68 44 3. 0/1 1.67 very bad (cakes) 80 22nd 4. 0/1 1.49 very bad (cakes) 75 27 5. 0/1 1.53 very bad (cakes) 76 25th 6. 0/1 1.05 Well 72 71 7. 0/2 2.3 unusable (cakes) - - 8. 0/2 1.9 unusable (cakes) - - 9. 0/3 1.61 very bad (cakes) 81 25th 10. 0/3 1.03 very good 74 75.1 11.0/3 1.47 bad (channeling) 81 27 12. 0/3 1.36 bad (channeling) 75 35 13. 0/3 1.14 mediocre (flows irregularly) 70 65 14. I. 1.08 Well 72 75.5 15. I. 1.07 Well 74 76.2 16. II 1.06 very good 72 79.5 17. II 1.06 very good 73 80.0

The known catalysts were manufactured by

0/1 addition of a solution of cobalt nitrate and ammonium molybdate

[(NH ^ ₆ Mo ₇ O ₂₄ ]

with ammonia and work-up of the precipitated cobalt molybdate;

0/2 heating a solution of cobalt nitrate and ammonium molybdate

[(NHa) ₆ Mo ₇ O ₂₄ ]

to 100 ⁰ C and working up of the failed Kobaltmolybdats;

0/3 by dissolving molybdenum trioxide in a stoichiometric amount of ammonia water at 100 ⁰ C in a beaker and adding aqueous solutions of cobalt nitrate in a stoichiometric amount. The precipitation took place at 100 ^° C.

The table shows that conversion and yield depend on the atomic ratio. Just one contact with a uniform fine structure and the atomic ratio Co / Mo sl: l is suitable for this specific reaction procedure. It should also be noted that the flow properties are also optimum in terms of the atomic ratio 1: 1.

Claims (1)

Claim: Process for the production of cobalt molybdate catalysts with an atomic ratio of cobalt to molybdenum such as 1: 1 for gas phase oxidation by reacting aqueous solutions of cobalt salts of volatile acids with aqueous solutions of molybdate of volatile bases, characterized in that the aqueous solution of stoichiometrically defined amine or Ammonia salts of the monomeric _{molybdic acid H 2} MoO _{4 are} reacted with the aqueous solution of cobalt salts and the salts precipitated in the process are optionally applied to a carrier. Considered publications:
German Auslegeschriften Nos. 1 051 818, 1 057 073; Ref. Chemisches Zentralblatt, 1963, p. 753. 409 760/385 12.6 * © Bundesdruckerei Berlin