DD213432A1 - METHOD FOR FORMING DEHYDRATIZING CATALYSTS - Google Patents

Abstract

The invention relates to a process for the formation of dehydrating catalysts containing active alumina and used in the preparation of methylamines by catalytic reaction of methanol and ammonia. The aim of the invention is the reduction of the effort in the preparation and commissioning of the catalysts and the improvement of their catalytic properties. This is accomplished by thermally forming the catalysts in two stages under synthetic conditions in the reactor. The catalysts are highly active and have a longer life.

Description

VEB Leuna-Werke Leuna, the

"Walter UIbgllcat"

LP 8293

Title of the invention

Process for the formation of de-hydrating catalysts:

Field of application of the invention

The present invention relates to a process for the formation of de-hydrate active catalysts containing active alumina and used in the production of methylamines by the catalytic reaction of methanol and ammonia.

Characteristic of the known technical solutions

The catalytic reaction of methanol with ammonia to give methylamines has been described many times in the literature (Issoire, J ·: Bull · Soc.-chim., France T96O, 2004; Gerber, G. Dissertation ETH Zurich, 1996). Thereafter, the catalytic reaction takes place predominantly in the vapor phase at temperatures of 480 to 770 K and at pressures of 1 to 20 MPa

on fixed catalysts. Suitable catalysts are the most diverse dehydratisieren acting variants. They often consist of natural aluminosilicates, synthetic aluminas or aluminosilicates or mixtures thereof (DE-PS 621 124, US-PS 1 935, 2 017 051, 4 082 805, DD-PS 108 275, 149 213) and may also contain additives (U.S. Patent 3,387,032). In industrial use, the catalyst used should have sufficient mechanical strength, a high catalytic activity and selectivity and the highest possible loading capacity and have a long service life, since these properties decisively determine the technical and economic level of a process for the preparation of methylamines ,

The preparation of these known catalysts usually results in the knowledge that the starting materials, together with water and other substances or additives, e.g. As mineral acids or certain deformation aids, to a:. kneaded plastic mass, then deformed and finally the catalyst moldings dried and at least 4 to 5 hours in a separate process stage from the reactor at 720 to 870 K by annealing formed. The catalyst moldings then have sufficient strength and activity for their technical use. From the general point of view of the further perfection of technical processes, the elaborate preparation of the catalysts and their commissioning require improvement in the context of the known processes for preparing methylamines.

Object of the invention

The aim of the invention is the effort in the production and. Commissioning of amination catalysts containing active alumina to reduce and at the same time to achieve improvements in their catalytic properties.

- 3 Presentation of the essence of the invention

It was therefore the object to produce the catalysts with reduced effort and zu.erzielen by an amended Formierungsverfahren a for-their technical use sufficient mechanical strength and to improve their catalytic properties, in particular their activity and service life.

The object is achieved by a process for the formation of dehydrating catalysts containing active alumina and used in the preparation of methylamines by catalytic reaction of methanol and ammonia ¬, according to the invention solved in that the formation of the uncalcined catalyst with a Glue residue of at least 75 pigs in the reactor in an atmosphere of ammonia and optionally methylamines at a temperature of 400 to 600 K and then with further addition of methanol at 600 to 730 K, wherein the temperature difference in the catalyst bed is not more than 30 K, and. finally usual synthesis conditions, advantageously a C / IT ratio of the reactants of greater than 0.8 and an hourly throughput

3 to be reacted methanol of more than 20 kmol / m catalyst can be adjusted.

It has proved to be particularly advantageous if the formation of the catalyst takes place under synthesis conditions in the second stage at 650 to 700 K for a time of at least 1 hour.

The erfindimgageaße process, the large-scale synthesis of methylamines is significantly improved. Compared with known processes or the preparation of the known catalysts, the above-mentioned energy-consuming step of activation and solidification of the catalysts by annealing is eliminated. The only predried and partially solidified catalyst moldings are rather in the reactor under synthesis conditions in the presence of the reactants and

thus activating with lower temperature reaction product gain. The success of this procedure could not be foreseen. In particular, it must be surprising that the new catalysts formed and activated in the process of the invention are superior in terms of their catalytic activity and lifetime to the known catalysts. These advantages are particularly evident when the synthesis of the methylamines is operated at a C / H ratio of reactants greater than 0.8 and an hourly methanol throughput of greater than 20 kmol / m catalyst. The combination of these known process conditions with the new two-stage catalyst formation and activation in the synthesis reactor is therefore an essential feature of the invention. The preparation of the catalyst mass is carried out in a known manner by, for example, intensively mixing pseudo-boehmite or other clay components together with kaolin or other hardening components in a kneading machine and kneading them to give a plastic mass after addition of a peptizing agent such as nitric acid and water · This plastic mass is deformed in a likewise known manner. Subsequently, the moldings are dried at a maximum of 430 K, the water is removed to a level of about 10 to 15 pigs. At the same time solidification of the moldings occurs, which is sufficient for installation in a technical reactor.

The formation of the catalyst to achieve the necessary for the amination of methanol activity is carried out in the technical reactor initially during a heating phase in an atmosphere of ammonia and optionally methylamines to reach a temperature in KataIysatorschüttung of about 600 K, the heating rate largely dependent on technical conditions can be adjusted, but should not be significantly more than · 40 K per hour. After reaching the temperature of about 600 K, the formation of the catalyst

under conditions of synthesis, by passing ethanol over the catalyst except ArjBcniak and optionally methylamines. In this case, the amount of methanol passed over the catalyst per hour should be such that the temperature difference in the catalyst charge, caused by the heat of reaction, is not more than 30 K. The maximum temperature in the catalyst bed is advantageously not higher than 700 K. After only one or a few hours, customary synthesis conditions are finally set, that is, the throughput of thethanol is increased and is preferably more than 20 kraol / m ² catalyst at a C / i Ratio of reactants - greater than 0.3.

The reaction pressure may range between 2 and 20 MPa, the lower limit being suitably adapted to the subsequent bIethylamine / ammonia / 7 mixture separation technology.

In the exemplary embodiment, a typical procedure for the inventive process including the unclaimed Katalysatorherateilung is given. * With catalysts of other composition, which also contain active alumina according to the invention, similar results are obtained.

Exemplary embodiment Preparation of the catalyst

In a kneading machine, 10 kg of pseudo-boehmite which is accessible in a known manner (for example, according to the exemplary embodiment of DD-PS 149 213) are intensively mixed with 5 kg of kaolin. ] After adding 1 l of 5% nitric acid and 6 l of distilled water, knead the mixture to a plastic mass, adjusting the desired plasticity by adding aqueous ammonium hydroxide solution. The plastic mass is then by means of a

Single-screw extruder, which is preceded by a Hotistenranglochloch plate at the product outlet, processed into hollow strand moldings. The moldings have an outer diameter of 8 mm and an inner diameter of 3.2 mm. Finally, the hollow strand blanks are dried at 395K.

The catalyst moldings produced in this way have the following properties:

Bulk density 0.750 kg / 1 abrasion 5.7 %

Abrasion resistance 93.7 %

Residual residue 84.0 ^С , Ь

Formation of the catalyst

2.5 l of the dried and solidified catalyst moldings are introduced into a full-space reactor. The reactor is purged with nitrogen and heated to 400K. The further heating takes place at a rate of about 25 K per hour up to a temperature of 585 K, with ammonia being passed over the catalyst. When the temperature of 585 K is reached, 1.5 kg of ammonia and 0.5 kg of methanol are passed over the catalyst every hour, and the temperature is further increased to 670 K. After 2.5 hours, the formation of the catalyst is completed. The pressure in the reactor during this phase is 8.5 MPa.

Preparation of methylamines

7.6 kg of a mixture of the following composition are passed through the catalyst at an inlet temperature of 583 K per hour:

29.70 mass of methanol 31.70 "ammonia

8.45 parts of ethylomethylamine 0.07 "of diethylamine 30.05" of prime-chylamine

This Liethanoldurchsats corresponds to about 23 mol / 1 catalyst. The C / JJ ratio is calculated to be 1.03. The reaction pressure is 13.5 IvIPa. The maximum temperature in the reactor is 675K. 3s, a reaction mixture of the following composition is obtained:

23.96 mass? * Ammonia,

9.24 "blonomethylamine,

17.76 »dimethylamine,

32.26 ^{l of} triethylamine,

0.06 "methanol,

16.72 "v. Asser.

With an operating time of 17 months, the catalyst still has barely diminished activity. Its carbon content is about 1 mass%, which suggests an extremely low ETebenproduktbildung. If the alike prepared and deformed catalyst mass is activated by incorporation in the prior art reactor at 873K prior to incorporation into the prior art reactor, the methanol conversion will decrease to about 97.5 % after 17 months despite a higher reaction temperature of 683K. The carbon content in the catalyst is on average 1.9% by weight.

Claims (2)

- 8 claim for invention A process for the formation of dehydrogenating catalysts containing active alumina and used in the production of methylamines by the catalytic reaction of methanol and ammonia, characterized in that the formation of the uncalcined catalyst having a residue of at least 75 pigs in the reactor in an atmosphere of ammonia .. and optionally methylamines at a temperature of 400 to 600 K and then with further addition of methanol at 600 to 730 K, wherein the temperature difference in the catalyst bed is not more than 30 K, and finally usual synthesis conditions, advantageous a C / IT ratio of the reactants of greater than 0.8 and an hourly throughput of methanol to be reacted of more than 20 kmol / m catalyst. 2. The method according to item 1, characterized in that the formation of the catalyst under. Synthesis conditions in the second stage at 650 to 700 K for a period of at least one hour takes place.