DE2654028A1 - COBALT CATALYST - Google Patents

Description

The invention relates to a cobalt catalyst and its production and its use for the hydrogenation of adipic acid dinitrile to hexamethylenediamine.

Catalysts containing cobalt have long been used to a significant extent for the industrial hydrogenation of adipic acid dinitrile to hexamethylenediamine. For this purpose, among others, the chromium or manganese as activator and a pyro or polyacid radical containing cobalt catalysts described in German patents 10 72 972 and 12 59 or the SiO _{2 or TiO 3} mentioned in US Pat. No. 2,776,315 as Supported cobalt catalysts have been proposed.

Cobalt catalysts with a low carrier content, in particular those known from the US Pat Activity that occurs at loads of approximately 0.1 kg adipic acid dinitrile / 1 Catalyst / h enable a 100 # conversion, but their mechanical properties are not sufficient, in order to achieve reasonable operating times.

The object was therefore to develop a catalyst which, with the same activity, had more favorable mechanical properties having.

It has been found that this is the case with cobalt catalysts which have a carrier content of 0.5 to 5.0 percent by weight, based on the reduced catalyst, and a pore volume of 0.05 ^{with a vBET surface area of 5 to 30 m 2 / g} up to 1.0 cnrVg have a maximum e in the range from 100 8 to 3OOO 8 . taiW ^^ / Cta ™ ..

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It has been shown that catalysts with. Surprisingly, such a pore distribution also results in very pure products, d. H. show better selectivity than state-of-the-art catalysts the technology. -

The oxides of the alkaline earths, namely magnesium oxide, calcium oxide, strontium oxide and barium oxide, have proven to be suitable as oxides which are difficult to reduce and which act both as carrier material and as activators themselves. Of the alkaline earth oxides mentioned, calcium oxide is particularly preferred. The proportion of the support material is such that the alkaline earth oxides are present in an amount of 0.5 to 5% by weight, but in particular from 1 to 2% by weight , based on the reduced contact, after the reduction of the catalyst. The catalyst may also have 1-5 weight% of a lubricant, such as graphite contained. Balance cobalt (98.5-9 ° wt. ^).

The preparation of the catalyst starts from aqueous solutions which contain the salts of cobalt and alkaline earths. In this case nitrate solutions are preferably used, "comprise% cobalt and a correspondingly lower proportion of alkaline earth metal" a content of 5 to 15 weight This solution of the nitrates of cobalt and the alkaline earths bei.Temperaturen between 0 and 100 ⁰ C, in particular between 20 and 80 C in a solution of carbonates, bicarbonates or hydroxides of the alkali metals, including the ΝΗΪ introduced with stirring. After the addition of the nitrate solution has ended, the precipitate which has separated out is stirred, then filtered and washed. When using alkali metal carbonate as a precipitating agent, the aim is to remove the alkali content down to a value of less than 2 wt / g, based on the finished contact. The filter cake is pressed into strands and first calcined at a higher temperature, then reduced and then largely stabilized so that the contact is no longer pyrophoric and ground to a grain size of less than 0.5 mm and after adding graphite as a lubricant compressed into tablets.

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During the production of the catalyst, the conditions are to be matched to one another in such a way that internal surfaces of 5 to

2 2

30 m / g, but in particular those of 10 to 20 m / g.

The inner surface is determined by the BET method (cf. J. Am. Chem. Soc. 60 (1938) S ₀ 309 ff) by absorption of nitrogen. It relates to the total catalyst, ie active metal including support component in the state after the reduction, ie to the finished catalyst. The Invent s £ \ proper catalyst has a pore volume in the range of 0.05 ./^y ₄ K yHDis 1 cnr / g, and has a distribution of pores in the range \ <\\ <γ of 100 to 3ooo A, wherein Maximum of pores? is in the range from O ^ 200 to 2000 8. A proportion of pores below 100 S is not desirable, since such small pores impair the selectivity of the catalyst. Pores above 2000 8 result in a low surface area; as a result, there is no longer sufficient hydrogenation activity "

If the limits of 0.5 to 5% by weight specified for the carrier substances are adhered to and the catalyst is tabletted, it can be used the pore size, surface and distribution of the pores, which are essential to the invention, can be achieved »

The catalyst is used in particular for the hydrogenation of adiponitrile (ADN) to hexamethylenediamine (HMD). There are two alternatives for the hydrogenation of ADN: 1. The The reaction can be carried out in the presence of the reaction product, namely hexamethylenediamine, which is recycled "In this case it is customary to add ammonia and use relatively high pressures. The reaction can but also in alcoholic, ethereal or hydrocarbon solutions be performed. In particular when using alcohols, even relatively low pressures of 30 to are sufficient 50 at out to get close to $ 100 in sales. Even it is not necessary in this case to carry out the hydrogenation in the presence of ammonia. The parameters below Include parameters for both solvent hydrogenation and hydrogenation in HMD and are therefore derived from these Reasons a little wider.

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The hydrogenation can be carried out without pressure or under pressure. Prints between 30 and 350 at can be applied. Solvent hydrogenation generally uses lower pressures and the hydrogenation starts noticeably at one Pressure of about 30 atmospheres »In the case of hydrogenation in recycled Hydrogenation product as a solvent are expediently used: pressures in the range from 200 to 300 atmospheres. the Ydrification takes place in the liquid phase, the catalyst is expediently arranged in a fixed bed or acted upon in swamp mode. The inventive Catalyst allows loads from 0.01 to over 0.3 kg ADN / 1 Catalyst and hour; in particular, loads of 0.05 to 0.3 and preferably those of 0.1 to 0.2 are used.

Hydrogen with a degree of purity of at least 99.0 % can be used as the hydrogenation gas »The hydrogen may contain small amounts of nitrogen or methane, but should be free of carbon oxides» A range of 20 to 150 ° C is suitable as a reaction temperature »At higher temperatures However, if the hydrogenation becomes unselective, hexamethyleneimine is formed alongside more highly condensed products. The reaction is carried out adiabatically; An adiabatic maximum temperature between 90 and 115 ° C is preferred »

In the event that ammonia is used and HMD as the solvent, the volume ratios of ammonia e-aw. Amine too Nitrile from 1 to 0.1 to 1 to 10 and preferably volume ratios from 2 to 1 to 7 to 1 applied.

The raw material, the adiponitrile, is required when applying the erfii Corresponding catalysts do not require any further cleaning. Füi the further processing of the hexamethylenediamine e.g. in a Polymerization reaction, the purification customary for this according to the prior art is necessary.

The invention is explained in more detail in the following examples. In Example 1, a preferred production method is the

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(d

Catalyst described, Example 2 contains a comparison test of the catalyst according to the invention versus a catalyst from the prior art, as described in US Pat. No. 2,776. Example 3 contains experiments for the hydrogenation of ADN using various carrier materials. Example ^L \ contains a series of hydrogenations in selected solvents. In all examples, the tablet shape with the size 3 × 3 or 3 × 5 mm was chosen as the catalyst shape, since this had proven to be particularly advantageous.

example 1 Preparation of the catalyst according to the invention

Solution I 19.17 kg of Co nitrate solution (12 % Co) 0.17 kg of Ca nitrate 4 H ₃ O

Solution II 6 kg soda in 60 1 K "0 (or 6.5 kg (NH ^) ₂ CO ₃ ⁰ H ₂ O)

Solution II is introduced into a precipitation vessel and heated to 6O ⁰ C. The mixture of Co and Ca nitrate solution (II) is allowed to run in while stirring. After the precipitation has ended, the mixture is stirred for a further hour and the precipitate is pumped onto a filter press, on which it is washed with water until alkali-free (when using (NK ^) ₂ CO., ⁰ H ₃ O as the precipitating agent, washing does not need to be carried out).

The filter cake is mixed with water and dried by spraying in a spray tower. The dry product is then calcined in an externally heated rotary kiln for 2 hours at 38O ⁰ C and then compressed into 10 mm extrudates.

The product obtained in this way is poured into a reduction furnace and treated as follows:

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2 % H ₂ -containing nitrogen is used to heat up to 320 ° C. (approx. 30 ° C./h), then the H 2 concentration is slowly increased until pure hydrogen passes through the furnace. The reduction temperature is then raised to 360 ° C. and reduced for a further 10 hours at this temperature, after which the reduction is complete.

It is allowed to cool to room temperature and begins with the Stabilization.

For this purpose, a gas stream (mixture of 1 % - air with pure nitrogen) is passed through the furnace in such an amount that there is no temperature increase to over 50 ° C anywhere in the contact layer »

One observes the migration of a temperature profile through the .Contact layer ο After this exothermic reaction has ended, you can. Increase the proportion of ventilation in N "slowly until finally only pure air goes through the oven.

The contact is then expanded, ground to a grain size <1 mm and pressed together with 2% graphite to form 3x3 or 5x3 mm tablets, which should have a hardness of 200 kp / cm, which is as uniform as possible «. A contact produced in this way has a debris weight of 1.8 kg / l, a surface area of

2
19.9 m ~ / g and had a forum maximum in the range from 100 to 3,000 Å with an average pore radius of 63Ο S. 90 % of the pores are in this area, 10 % of the total pores are still below or above the stated area.

Example 2.

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In accordance with Example 1 of US Pat. No. 2,776,315, a catalyst was prepared which contained 1 % SiO 2, based on CoO. The finished catalyst had a surface area of 38 m / g, a pore volume of 0.32 cnr / g and a mean pore radius

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of 89 8, This catalyst was with the invention Contact compared in terms of activity and selectivity.

To this end 1 1 of the catalysts in question were charged in a reaction tube of 42 mm internal diameter and reduced with hydrogen at 33O ⁰ C, respectively. Passivation was not carried out.

over the catalyst from top to bottom (trickle mode) at 300 bar hydrogen pressure per hour in experiment A 0.1 kg, at Experiment B 0.2 kg of adipic dinitrile, 0.3 l or 0.6 l of ammonia and 1 l or 2 l of recirculation (Kydrieraustrag consisting of crude hexamethylene amine and liquid ammonia). At the same time, 1 Nnr or 2 Ιμπτ hydrogen in the circle was used to dissipate heat guided.

In the tables below is the activity and selectivity

ν the respective catalytic converters listed at different loads. (VgI ₀ abbreviations HMI, ACM and residue under example 3, page ß).

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Contact

React temp. HMD, ADN radical ^Q C., ..%%

HMI

: Experiment A: Bel. 0.1 kg ADN / l'h

Cat. According to Ex. 1 U.S. Patent 2,776,315

success.
catalyst

90

90

Experiment B: At. 0.2 kg ADN / l ^Q h

110

Cat. According to Ex. 1 U.S. Patent 2,776,315

according to
catalyst

110

98.7

99.93

96.8

99.85

, 0.12, 0.03-, 0.02

0.9 '0.2

0.05

Residue

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0.5 0.2

LO

0.95

0.3 _c

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Example 3

A)

Further catalysts were prepared analogously to the procedure of Example 1, but the corresponding ones instead of Ca oxide Contain amounts of strontium, barium and magnesium oxide as a carrier component. The physical parameters of these contacts can be found in the table.

Contact Surface Pore volume average Pores proportion of the carrier m ² / g cirrVg radius 8 Pores from 100 to 3 000 8 CaO 19.9 0.23 630 90 % SrO 12.4 0.1 510 3d % BaO 3.7 0.14 560 88 % MgO 23.5 0.18 430 87 %

The contacts produced in this way were subjected to the following comparative test »

In a reaction tube with a clear width of 42 mm, which was surrounded by an aluminum block heater as a protective heater, and in which there was a 6 mm thermal sleeve, 400 ml of the respective contact were poured in and treated with pure H at 330.degree reduced.

The mixture was then cooled to 50 ⁰ C and then a mixture of 10% ADN in ethanol at forth below (upflow mode) passed through the contact bed. The reaction was carried out at 50 ata H "pressure. The load was, based on ADN, 0.1 kg / l * h.

A temperature profile was formed along the catalyst layer through which the flow occurred. As a comparative activity variable the conversion and the selectivity were measured. The results are shown in the table below.

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HMD .% "» ■ HMI 33 0..Z • 2654028 4th 99 68 ADN ACN
0 / Qt
fa P 16 32 303 2 98 75 0.32 sp. O, 12th Residue 0 Approx 99 10 0.52 0.40 O, 1, 9 Sr 99 22nd 0.42 0.32 O, 2, Ba 0.38 0.36 2, Mg Adipic acid dinitrile 1, ADN: £ -aminocapronitrile ACN: Setback: Hexamethyleneimine higher condensed products HMI: HMD: Hexamethylenediamine 4th example

In the reaction tube described in Example 2, 400 ml of a contact were installed which had been produced according to the procedure of Example 1 by precipitation with (NH _1. ) "CO -," HpO. After reduction with pure H at 33O ⁰ C ADN different solvent mixtures were hydrogenated in upflow mode at 50 bar K "pressure. The results are shown in the table below.

solvent HMD
% Remainder ADN
% ACN
% HMI
% Residue
% Ethanol 99.1 0.3 . . 1.38 Propanol 98.0 1.57 0.44 Sp ₀ 3.6 iso-propanol 95.27 2.31 0.59 1.81 1.8 Methanol 96.32 0.18 0.1 3.41 1.4 toluene 92.15 2.70 2.22 2.93 1.3 THF 77.21 15.43 5.66 1.71 - Ethanol / 97.77 0.47 0.09 1.66 4.1 Triethanol diamine

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Claims (3)

Claims 1 _f cobalt and 0.5 to 5 wt. $ of a difficult to reducible oxide as a carrier containing catalyst, which has a pore volume in the range from 0.05 to 1 cmVg a maximum of the pores in the range from 100 to 3OOO 8 and a BET surface area of 5 to 30 m / g, based on the reduced Catalyst. 2. A method for producing a cobalt catalyst, according to claim 1, by precipitation of the catalyst components, drying, calcining and reducing and optionally stabilizing the precipitation, characterized in that the cobalt together with the support material, an oxide of the alkaline earth metals, with carbonates, bicarbonates or Hydroxides of the alkali metals including NHj, co-precipitate, optionally stabilized after the reduction, ground and, after the addition of a lubricant, compressed to tablets. 3. Use of the catalysts according to claims 1 and 2 for hydrogenation from adipic dinitrile to hexamethylenediamine. BASF Aktiengesellschaft 809822/0357 ORIGINAL INSPECTED