DD212193A1 - METHOD FOR PROCESSING MOLYBDA-CONTAINING CATALYSTS - Google Patents

Abstract

The invention relates to a wet-chemical processing of no longer utilizable bismuth, molybdenum and Sio deep 2 containing catalysts. The goal is to recover all components. The task of recycling the bismuth, molybdenum and SiO 2 in a one-step process so that the catalyst components are separated and produced in an immediately further processable form is achieved by dissolving the spent catalyst for 2 to 6 hours with a 15 to 30 % sodium hydroxide solution treated at temperatures of 353 to 373K, wherein the ratio Na / Mo and Si is 2 to 4, the suspension thus obtained filtered off and the residue optionally grows. The digestion components obtained according to the invention can be used again for catalyst preparation.

Description

VEB Leuna-Werke Merseburg,

ȴ old Ulbricht"

LP 8290

Title of the invention

Process for the treatment of molybdenum-containing catalysts

Field of application of the invention

The invention relates to a process for the wet-chemical processing of bismuth, molybdenum and SiO-containing catalysts which can no longer be used, it being possible for the decomposition components obtained to be used again for catalyst preparation.

Characteristic of the known technical solutions

The processing of spent catalysts is gaining valuable from the point of view of .Recovery:

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Constituents increasingly important «

This also applies to the large group of selective oxidation catalysts, whose demand is constantly increasing, and hence also the accumulation of spent catalysts. Most of these catalysts contain molybdenum, and many also contain bismuth and support constituents, such as SiO 2

Known, the state of Tachnik corresponding methods are based either on the recovery of only one component, such as. B. MoO from hydrorefining catalysts according to DE-OS 2 JOk 3kO by soda digestion and connect] triummolybdate ·

and subsequent leaching of the MoO in the form of Na

Another method involves the treatment of catalysts containing MoO and Al O with sodium hydroxide solution under pressure (DE-OS 2,631,089). This also makes it possible to obtain Al 0 in the form of sodium aluniinate «

A transfer of the first method to bismuth, molybdenum and SiO-containing catalysts is associated with excessive work-up losses and also energetically very expensive.

The second method also has the disadvantage of high energy costs and also involves the risk of dissolving all catalyst components.

Object of the invention

The object of the invention is a process for the recovery of allsr components of bismuth, molybdenum and SiO containing catalysts, which is further characterized by

distinguishing favorable economic parameters,

Explanation of the essence of the invention

It is an object of the present invention to treat ssfismuth, molybdenum, and SiO 2 -containing catalysts in a one-step process, if possible, in such a way that the catalyst components are separated and obtained in an immediately further processable form.

This object is achieved according to the invention by treating spent bismuth, molybdenum and SiO 2 -containing catalysts with a 15 to 30% strength sodium hydroxide solution at temperatures of 353 to 373 K for 2 to 6 hours, the molar ratio Na / Mo and Si being 2 to k , The resulting suspension is then filtered off and optionally washed with water. It is advantageous if the mass ratio of filtrate; Residue Zk is up to 32.

Conveniently, 12 to 10 l of washing water are passed through per kg of residue.

Preferably, the filter cake after washing a Na O content of less than 0.2% on "The filtrate preferably comprises a MoO content of 20 to 35 g / l and a content of SiO kOe to 80 g / l. The filter cake, which is an oxidic form of bismuth, is fed to the preparation of new bismuth-containing catalysts. The filtrate - an aqueous sodium molybdate-sodium silicate solution - is used for the preparation of hydrogenation or hydrocracking catalysts or for their carriers.

The observance of the mentioned parameters is not only important for a complete digestion, but also for its economy, ie. Energy consumption, sodium hydroxide consumption and filtrate. The latter is especially for

the recovery of an immediately usable sodium silicate-NatriummolybdatlÖsung with complete leaching of the sodium from the bismuth-containing filter cake of importance.

Exemplary embodiments Example 1 (comparison)

100 g of a catalyst containing 50 % SiO 2, 22 % MoO and 28 $ Bi_0 are intimately mixed with a slurry of kO s of Na CO in 30 ml HpO, dried and then calcined at Ю73 K for k h »The annealed product is ground and k h cooked in 1 1 H_0. Thereafter, it is filtered, washed with 300 ml H β and the filter cake at 873 K annealed · The annealed insoluble residue containing 3 _f k g MoO. Thus, about 15 % of the MoO is lost by this prior art method.

Example 2 (comparison)

100 g of the catalyst already used in Example 1 are stirred together with k $ 0 ml of 20% NaOH for 3 h at 323 K. The precipitate is then filtered off, washed with 200 ml of H 2 O, dried and calcined at 873 K for 1 h. This residue still contains k g MoO and 6.2 g SiO, so that no complete digestion is achieved *

Example 3 (comparison)

It is, as in Example 2, only with the difference that the treatment of the catalyst 30 tain · takes place at 353 K.

The annealed, insoluble residue contains, in addition to 21.1 g of SiO ₂ and 8.7 g of MoO ·

Example 4 (according to the invention)

The procedure is as in Example 3> only with the difference that the treatment time is increased to k h "The residue contains Bi 0 only 0.23 S MoO, 0.21 g of SiO ₂ and 0.09 S Na ₃ O.

 The filtrate contains 35.7 g MoOVl and 81.5

Example 5 (according to the invention)

The procedure is as in Example 3, but with the difference that the filtered insoluble residue was washed with 5OO ml of H 2 O

After annealing, this residue contains, in addition to Bi 0, 0.11 g of MoO, 0.13 g of SiO ₂ and 0.058 g of Na ₂ O. The filtrate contains 2 x 3 g of MoO / l and 55.3 g of SiO 2 / l.

The digestion components obtained by the process according to the invention are thus further processable without further purification steps for catalyst preparation.

The examples show that bismuth, molybdenum and SiO-containing catalysts can be easily and completely worked up by the process according to the invention.

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can be done so that the workup products can be fed immediately to further processing, preferably catalyst preparation.

Claims (4)

- 7 Inventory 1 · Process for the treatment of molybdenum-containing catalysts, gekmelznet by reacting the
consumed 2 to 6 hours with a catalyst
15 to 30% caustic soda at temperatures of
Treated 353 to 373 K, wherein the molar ratio of Na / Mo and Si is 2 to h , the suspension thus obtained filtered off and the residue optionally
washes · Method according to item 1, characterized in that the mass ratio is filtrate; Residue is 2k to 32, 3 · Process according to items 1 and 2, characterized in that 12 to 16 l of washing water are passed through per kg of residue « 4. The method according to item 1, characterized in that the filter cake after washing a Na _p 0 content of less than 0.2 fo and the filtrate has a MoO content of 20 to 35 g / l or a SiO ₂ content of ^ O up to 80 g / l »