DD297399A5 - PROCESS FOR THE PREPARATION OF N, N-DIMETHYLCYCLOHEXYLAMINE IN THE LIQUID PHASE AND CATALYST FOR CARRYING OUT THE PROCESS - Google Patents

Abstract

The invention relates to a process for the preparation of N, N-dimethylcyclohexylamine in the liquid phase and a catalyst which is used in carrying out the process. The N, N-dimethylcyclohexylamine is used in the chemical industry as a catalyst for polyurethane systems and used in increasing Masz as an intermediate for syntheses of various chemicals and pharmaceutical agents. Characterized in that the catalytic hydrogenation in the liquid phase in the presence of an inert solvent at pressures between 15 and 99 bar and temperatures between 165C and 185C and by passing the liquid N, N-dimethylaniline and hydrogen over a fixed catalyst is carried out from top to bottom, and the N, N-dimethylaniline is reacted at rates of 0.1 to 0.2 kg 1 h 1 and for carrying out the process a catalyst is used which consists of palladium on g aluminum oxide carrier with basic proportions and palladium in amounts between 0, 1 and 5 * based on the total mass of the catalyst, basic proportions as oxides and / or carbonates of alkaline earth metals, especially of calcium, in amounts of 0.1 to 6 * calculated as calcium oxide, and the alkali metals in amounts of 0.1 to 3 * Calculated as sodium carbonate, it is achieved that with a low, technical and economic expenditure by a continuous kat Alytische nuclear hydrogenation of liquid N, N-dimethylaniline with complete conversion of N, N-dimethylcyclohexylamine can be prepared with a minimal amount of by-products, using a readily prepared, with a long service life, without any pre-activation, serviceable catalyst. {Production; N, N-dimethylcyclohexylamine; N, N-dimethylaniline; Fluessigphase; Medium pressure; elevated temperatures; Catalyst palladium on g alumina carrier with basic proportions}

Description

-2- 297 399 Explanation of the nature of the invention

The invention is to achieve the object of the object to produce colorless N, N-dimethylcyclohexylamine in the liquid phase by catalytic hydrogenation of Ν, Ν-dimethylaniline and in the medium pressure range with a minimum amount of by-products according to a suitable method, wherein the catalyst used a high Use has and is usable without preactivation.

According to the invention the object is achieved in that the catalytic hydrogenation in the liquid phase at pressures between 15 and 99 bar, preferably 20 to 95bar, and at temperatures between 165 ° C and 185 ° C, preferably 170 ° C to 180 ^c C, and by passing of the liquid N, N-dimethylaniline, optionally in the presence of an indifferent solvent, preferably N, N-dimethylcyclohexylamine, and hydrogen is passed through a fixed catalyst from top to bottom and the Ν, Ν-dimethylaniline at rates between 0.1 and 0.2 kg γ is reacted for ¹ h ^'1. the catalyst employed for carrying out the method is according to the invention of palladium on γ-alumina support with basic units and palladium in amounts of between 0.1 and 5 wt .-%, preferably 0.2 to 1 weight %, based on the total mass of the catalyst, basic proportions as oxides and / or carbonates of alkaline earth metals, especially of calcium, in amounts of 0.1 to 6% by weight, preferably 0.5 to 4% by weight, calculated as calcium oxide and that of the alkali metals, in particular of sodium, in amounts of 0.1 to 3% by weight, preferably 0.2 to 1.5% by weight. -%, calculated as sodium carbonate.

It was completely surprising that catalysts of palladium on γ-alumina, which is provided with basic additives, are suitable in an unexpectedly good manner with particular advantage in the medium-pressure range for a trickle-phase hydrogenation with fixed-current hydrogen, the conversion of DMANL too DMCHA completely and highly selectively catalyze the specified temperature range.

In contrast, in the medium pressure range in the specified temperature range, these catalysts of palladium on γ-alumina with basic additives for a trickle phase hydrogenation of DMANL with countercurrent hydrogen or a Sumpfphasenhydrierung the DMANL each in a fixed form or for hydrogenation in an autoclave in a suspended form is not or far less well suited.

Other hydrogenation catalysts, such as a mixture of cobalt oxide and Calciumcarbonai or palladium on a-alumina or palladium on γ-alumina carrier with increased basic content, for example 20Gew .-% calcium oxide are in the medium pressure range in festoidneter form for the implementation of DMANL according to the trickle phase principle with hydrogen carried in cocurrent in the specified temperature range is not or far less suitable.

Thus, exclusively and only with particular advantage in the intermediate pressure range between 15 and 99 bar, especially 20 and 95bar, fully and highly selectively hydrogenated when continuously liquid DMANL together with co-current hydrogen from top to bottom fixedly arranged catalysts of palladium on γ-alumina with basic additives at temperatures between 165 ⁰ C and 185 ⁰ C, in particular 17O ⁰ C and 18O ⁰ C, is passed.

The carrier used is alumina having a surface area greater than 10 μmVg, preferably greater than 150 m ² / g, as an intimate mixture with basic proportions.

The carriers are, after intimate mixing of γ-alumina with the basic additives in a known manner into strands, cylinders or spheres deformed, wherein the strand form is preferred. For the preparation of the complete hydrogenation catalysts, the palladium from acidic, in particular nitric acid solution is applied in a known manner by impregnating the moldings on this fine and uniform, and then dried at about 100 ⁰ C. The hydrogenation catalysts are usable without preactivation and have a useful life of at least 2000 hours.

When using only average pressures below 10000 bar, the process according to the invention permits the complete and almost by-product-free nuclear hydrogenation of the DMANL to give colorless DMCHA. This represents a significant enrichment of the state of the art, because it reduces the technical and economic effort is reduced. A further advantage is that the hydrogenation of available raw materials are easy to produce.

Also advantageous are the usability without pre-activation and the long service life of the catalysts.

The invention will be explained with the following embodiments.

Embodiment 1

About 2! of a fixed, extruded catalyst of 3 mm Ouichmesser containing 0.7 wt .-% palladium on γ-alumina with shares, in 3.5 gw .-% calcium oxide and 1.3 wt .-% as sodium carbonate and previously by uniform impregnation of the Carrier with palladium nitrate solution and subsequent drying at about 100 ° C, is passed per hour 340g liquid DMANL together ml. 220NL hydrogen continuously in cocurrent at 60bar un 174 ° C from top to bottom through. After cooling and venting, a colorless DMCHA with a purity of more than 98% is obtained, which, if necessary, can be further purified by distillation.

embodiment

Above 21 of a fixed catalyst of 3 mm diameter in the form of extrudates containing 0.5 wt% palladium on gamma alumina support with proportions of 2.5 wt% calcium oxide and 0.8 wt% as sodium carbonate and analogously Example 1 was prepared, passed per hour 260g liquid DMANL together with 180 NL hydrogen continuously in cocurrent at 27 bar and 176 ⁰ C from top to bottom through. It is a colorless DMCHA obtained with a purity of over 98%.

Comparative example

The procedure is as in Example 2, but the liquid DMANL together with hydrogen from bottom to top over or passed through the catalyst and then a dyed synthesis mixture with a maximum of 70 wt .-% DMCHA content.

Comparative example

The procedure is as in Example 2, but using a catalyst of 30 wt .-% Cobaitoxid and 70 wt .-% calcium carbonate in extruded form of 3mm diameter and then a dyed synthesis mixture with a maximum of 20 wt .-% DMCHA content.

Ausführungsbelsplel The procedure is analogous to Embodiment 2, but every hour a mixture of iJiOg DMANL and 100g DMCHA together

passed through with 200 NL of hydrogen. This gives a colorless DMCHA with a purity of about 99%.

Claims (3)

1. A process for the preparation of NN-dimethylcyclohexylamine in the liquid phase by catalytic HyHrierung of Ν, Ν-dimethylaniline, characterized in that the catalytic hydrogenation in the liquid phase at pressures between 15 and 99bar, preferably 20 to 95bar, and at temperatures between 165 ° C and 185 ° C, preferably 17O ⁰ C to 18O ⁰ C, and by passing the liquid Ν, Ν-dimethylaniline, optionally in the presence of an inert solvent, and hydrogen over a fixed catalyst is carried from top to bottom and the Ν, Ν Dimethylaniline is reacted at rates between 0.1 and 0.2 kg Γ ¹ h ~ ¹ . 2. Catalyst for carrying out the process, characterized in that the catalyst consisting of palladium on γ-alumina carrier with basic proportions, palladium in amounts of between 0.1 and 5 wt .-%, preferably 0.2 to 1 wt .-% , based on the total mass of the catalyst, basic proportions as oxides and / or carbonates of alkaline earth metals, in particular calcium, in amounts of 0.1 to 6 wt .-%, preferably 0.5 to 4Gew .-%, calculated as calcium oxide and the the alkali metals, in particular of sodium, in amounts of from 0.1 to 3 wt .-%, preferably 0.2 to 1.5Gew .-%, calculated as sodium carbonate. Field of application of the invention The invention relates to a process for the preparation of N, N-dimethylcyclohexylamine in the liquid phase and to a catalyst which is used in carrying out the process. The Ν, Ν-dimethylcyclohexylamine (DMCHA) is used in the chemical industry as a catalyst for polyurethane systems and increasingly needed as an intermediate for syntheses of various chemicals and pharmaceutical agents. Characteristic of the known state of the art There has been no lack of attempts to develop DMCHA production processes on different raw material basis. In this case, the reaction reactions should proceed as completely and selectively as possible with rational use of raw materials in order to facilitate or facilitate the subsequent isolation of high purity DMCHA. Thus, the DMCHA production by various substitution of cyclohexane derivatives and phenol-based (DE-OS 2118283; DE-AS 2524797; DE-OS 2324855; DE-OS 1518496) in terms of raw material use, the degree of reaction or by-product formation and the workability of the synthesis mixture more or less material and costly. For example, due to the process, the synthesis mixtures always contain water which must be removed beforehand by complex azeotropic distillation or extraction in order to be able to recover pure DMCHA. By contrast, only two raw materials are required if the synthesis route of the high-pressure nuclear hydrogenation of DMANL "is carried out by means of hydrogen in the presence of hydrogenation catalysts. χ = Ν, Ν-dimethylaniline Thus, according to DE-PS 851189 a water-clear DMCHA with less than 1% starting material by trickle phase hydrogenation of DMANL on the nickel contact at about 180 to 200bar and increased cycle gas with a conversion rate of 0.075kg Γ ¹ h " ¹ , based on DMANL won. After a recent process DMCHA is obtained by passing liquid DMANL and hydrogen over a catalyst of 0.5% palladium on magnesium-aluminum spinel carrier at 250 bar with a yield of 98% of theory (DE-OS 3240286). A disadvantage of the DMANL core hydrogenation process is the high-pressure procedure, which requires a technically complex design of the reaction apparatus, including increased safety technology. Further cost-increasing factors are the increased cycle gas quantity and low conversion speed (DE-PS 851189) and the production of the magnesium aluminum spinel carrier at temperatures above 1000 ⁰ C (DE-OS 3240286). Zekannt is also a discontinuous 10 & 5YM5erstellungsverfahrenL after which in the Oitteldruckbereich »CJJN AJJJ psig ύ, about 20 to 70 bar) with nickel catalysts is used (US-PS 3376341). This conversion levels of only a maximum of 79%, combined with increased Aufarboiiungsaufwand achieved. Object of the invention The aim of the invention is to produce mit, Ν-dimethylcyclohexylamine (DMCHA) with complete conversion Ν-dimethylcyclohexylamine (DMCHA) with a low technical and economic expenditure by a continuous catalytic core hydrogenation of liquid Ν, Ν-dimethylaniline (DMANL). The required catalyst should be easy to produce.