DD248113A1 - PROCESS FOR PREPARING BUTANDIOL-1,4 - Google Patents

Abstract

For the production of 1,4-butanediol by hydrogenation of 1,4-butanediol serves a two-stage process in which in the 1st stage a nickel catalyst with a defined distribution of nickel in different bonding states on SiO2 and levels of molybdenum in the ratio SiO2: Mo of 1: 0.1 to 0.5 and copper in the ratio SiO2: Cu of 1: 0.05 to 0.3 is used and wherein in the 1st process stage in the continuously operating stirred reactor butynediol conversion of at least 95% and a butanediol-1 , 4 formation of greater than zero can be set. In the 2nd stage, the complete hydrogenation takes place in the fixed bed reactor. It is achieved a significantly improved butanediol yield.

Description

Attempts have therefore been made to combine the medium-pressure hydrogenation with Raney-Nickei in the stirred reactor with the high-pressure hydrogenation. In the two-stage process, in the 1st stage in the stirred reactor, the butynediol is partially hydrogenated under medium pressure. Subsequently, in the 2nd stage under high pressure in the trickle reactor, the hydrogenation is completed and formed aldehydes and acetals are largely eliminated (US-PS 3499445). Although these processes allow an increase in the yield to about 90% and a significantly better quality of the hydrogenation products. The main disadvantage of this procedure, however, is that the first stage of the hydrogenation with Raney nickel must be carried out batchwise.

Recently, it has been proposed to carry out the first stage of this process continuously in the stirred autoclave (DD-PS 219184). The thus possible continuous continuous operation of the two-stage process represents a significant advance. The main disadvantage of the process is the required use of a nickel-supported catalyst, which is relatively unselective. In the first stage of the process, considerable byproducts are formed. To minimize by-product formation, it is required that the hydrogenation of butenediol to butanediol be minimized, i. H. the first hydrogenation step is only up to a butynediol conversion of max. 98% (preferably 95%) operated. At higher Butindiolumsätzen and the significant formation of butanediol acetals are formed in this process, which hinder the hydrogenation in the high pressure stage.

To comply with the prescribed Butindiolumsatzes a complex and complicated control is required, which must take into account such barely calculable sizes as the catalyst deactivation and the activity fluctuations within and between different production batches of the catalyst exactly. In this method, the yield and the quality of the butanediol can not be improved.

Object of the invention

The aim of the invention is to develop an improved process for the hydrogenation of butynediol, which provides high purity butanediol high purity.

Explanation of the essence of the invention

The invention has for its object to develop a two-stage process for the preparation of butanediol by hydrogenation of butynediol, in which the 1st stage is carried out in a continuously operated stirred reactor with suspended catalyst and the 2nd stage in a fixed bed reactor.

This object is achieved in that an aqueous Butindiollösung with a content of butynediol from 20 to 50 wt .-% in the stirred reactor at a rate of not more than 30 kg butynediol per kg of catalyst and hour, based on the amount of catalyst in the stirred reactor metered using a catalyst prepared by addition of nickel salt solution, e.g. B. Niekeinitratlösung, to a maintained at about 60 ° C aqueous solution of waterglass and sodium carbonate in such amounts until from the precipitate formed with excess ammonium bicarbonate solution at about 9O ⁰ C within 10 minutes 70 to 75% of the precipitate contained Extract the nickel and the precipitate after washing and drying has a carbonate content, calculated as carbon dioxide, of 7.0 to 8.5%, the dried precipitate before or after treatment at higher temperatures in the hydrogen stream, to more than 75% of the im In the catalyst, an SiGv Mo mass ratio of 1: 0.1 to 0.5, and a SiO ₂ : Cu mass ratio of 1: 0.05, are treated in the catalyst with an amount of a copper salt and molybdenum salt-containing aqueous solution is present at 0.3, the butynediol at temperatures of 50 to 150 ° C, pressures of 0.5 to 5 MPa and a pH v is hydrogenated on 7 to 10 in a stirred reactor, wherein a conversion to butanediol of greater than zero and a conversion of butynediol of at least 95% by continuous metering of fresh catalyst in the reaction system and removal of catalyst from the reaction system is maintained and in the from Catalyst present in the stirred reactor removed from the hydrogenation product is continuously recycled to the stirring and the hydrogenation product is then passed through a supported nickel catalyst in a trickle bed reactor at temperatures of 50 to 150 ° C and pressures of 2 to 25 MPa. It is favorable if the catalyst used in the 1st stage is doped before its reduction with the components molybdenum and copper. Essential for the process is that is provided by intensive mixing in the I.Stufe for good material and heat transfer. In particular, the use of a hollow stirrer is important, so that the hydrogen can be sucked from the gas space above the liquid phase and distributed well in the reaction mixture. The stirrer must allow a speed of at least 200 rpm, preferably greater than 350 rpm.

An essential advantage of the process is the use of a much more selective catalyst in the 1st stage. With the "

The process of the invention can be carried out in the first stage in a wide range of the conversion of butenediol to butanediol without high by-product formation occurs. This considerably simplifies the control of the process. The process according to the invention enables a substantial increase in the yield of butanediol and a reduction in by-product contents in crude butanediol.

embodiments

Example 1 (comparative example)

A continuously operated laboratory stirred reactor with suspended nickel catalyst (10 g) was charged with 650 ml / h of a 35% butynediol solution. At a temperature T = 8O ⁰ C and a pressure ρ = 1 MPa, a hydrogenation product was removed, the organic constituent of which had the following composition:

(GC analysis)

Butynediol 5.4Ma .-%

Butenediol 82.5Ma .-%

Butanediol 2.5Ma .-%

Hydroxybutyraldehyde 8.4Ma .-%

Acetals 1.2Ma .-%

This hydrogenation product was hydrogenated in a fixed bed reactor at a temperature T = 100 ⁰ C and a pressure of ρ = 24.5 MPa on a Nickeiträgerkatalysator. The organic content of the obtained crude butanol had the following composition;

Butanediol 92.7 Ma. % Hydroxybutyraldehyde 0.5Ma% acetals 0.5 mass% butanol 3.6Ma% light and high boiling components 2.7Ma%

Example 2 (comparative example)

To a continuously operated stirred laboratory reactor with suspended nickel catalyst (30 g) was added 800 ml / h of a 35% butynediol solution. At a temperature T = 85 ° C and a pressure ρ = 1 MPa, a hydrogenation product was taken off whose organic constituent had the following composition:

(GC analysis)

Butynediol 0Ma .-%

Butenediol 56.5Ma .-%

Butanediol 20.8Ma .-%

Hydroxybutyraldehyde 13.1% by mass

Acetals 9,6Ma .-%

This hydrogenation was performed in a fixed bed reactor at einerTemperaturT = 100 ⁰ C and hydrogenated at a pressure ρ = 24.5 MPa at a Nickeiträgerkatalysator. The organic part of the crude butanol obtained had the following composition:

Butenediol 0.1 mass% butanediol 91.5 mass% hydroxybutyraldehyde 0.7 mass% acetals 0.8 mass% butanol 4.1 mass% light and high boiling components 2.8 mass%

Example 3 Inventive Example Catalyst Preparation

7.81 of a Na 2 CO ₃ solution was mixed with 4.51 of a waterglass solution (SiGv content 200 g) heated to 60 ° C and nickel nitrate solution added slowly. The addition of nickel nitrate solution was continued for as long as until the precipitate formed had an extractable NH4HCO ₃ solution nickel amount of 70 to 75% of the total nickel content. To determine the extractable nickel content, the precipitation was interrupted in each case, and a sample of about 3 g of solid with 30 g NH ₄ HCO ₃ in about 150 ml of water for 10 minutes at 9O ⁰ C maintained. The solution was filtered and the content of nickel was determined in the filtrate and in the remaining precipitate. The precipitation was terminated at an extractable nickel content of 73.7% of the nickel in the precipitate. After washing and drying the precipitate, which had a carbonate content of 7.3% CO ₂ contained with a solution containing 70g of ammonium molybdate and 54g of copper acetate, impregnated, dried and reduced for 8 hours under a hydrogen stream at 40O ⁰ C was added. The finished catalyst had a SiO ₂ : Mo mass ratio of 1: 0.19 and a SiO ₂ : Cu mass ratio of 1: 0.08. 86% of the nickel present in the catalyst was in metallic form.

I.Stufe

In a stirred reactor, 18 kg of butynediol per kg of catalyst per hour in the reactor were metered in continuously. The catalyst described above was used. During the hydrogenation, the following conditions were observed:

The volume of the metered 35% butynediol solution was equal to the volume of the hydrogenation solution removed from the reactor

- hydrogen pressure 1 MPa

- temperature 8O ⁰ C

PH of the reaction solution 7 to 8

Throughout the duration of the hydrogenation experiment, the catalyst contained in the hydrogenation solution removed from the reactor was continuously separated and returned to the reactor. By metering fresh catalyst into the reactor and removing catalyst from the reactor, a butynediol conversion of about 97% and a butanediol content in the removed hydrogenation product of about 5% were constantly maintained. The organic constituent of the hydrogenation product had the following composition:

(GC analysis)

Butynediol 3.1% by mass

Butenediol 91.2Ma .-%

Butanediol 5.2% by mass

Hydroxybutyraldehyde 0.3Ma .-%

Acetals 0.2Ma .-%

2nd stage

The hydrogenation product of the 1st stage was hydrogenated in a fixed bed reactor at a temperature of T = 100 ⁰ C and a pressure of ρ = 24.5 MPa on a supported nickel catalyst. The organic content of the obtained crude butanol had the following composition:

Butanediol 94.3% by mass Hydroxybutyraldehyde 0.1% by mass Acetals 0.1% by mass Butanol 2.8% by weight Light and high-boiling constituents 2.7% by mass

Example 4 (Inventive Example)

catalyst Preparation

The preparation of the catalyst for Example 4 was carried out analogously to that of Example 3. However, the doping with molybdenum and copper was carried out only after the reduction of the catalyst.

I.Stufe

The hydrogenation in the 1st stage was carried out analogously to that of Example 3. However, the following conditions have changed:

- Temperature: 85 ° C

Metered amount of butynediol per kg of catalyst per hour in the reactor: 10 kg / kg.h

By metering fresh catalyst into the reactor and withdrawing equal amounts of catalyst from the reactor, a butynediol conversion of 100% and a butanediol content in the recovered hydrogenation product of about 25% were constantly maintained. The organic constituent of the hydrogenation product had the following composition:

(GC analysis)

Butenediol 69.6% by mass

Butanediol 25.7Ma .-% ^ Hydroxybutyraldehyde 3.3Ma .-% '

Acetals 1.4Ma .-%

2nd stage

The hydrogenation product of the first stage was hydrogenated in a fixed bed reactor at a temperature of T = 100 ° C and a pressure of ρ = 24.5 MPa on a supported nickel catalyst. The organic content of the obtained crude butanol had the following composition:

Butanediol 93.8% by mass Hydroxybutyraldehyde 0.3% by mass Acetals 0.2% by mass Butanol 3.0% by mass Light and high-boiling constituents 2.7% by mass

A comparison of the examples shows that in the process according to the invention a significantly better butanediol yield is present. As Example 4 shows in comparison to Example 2, despite the high butanediol contents in the hydrogenation product of the first stage, no strong contamination of the crude butanol by aldehyde and acetals occurs in the process according to the invention, the yield of butanediol is comparatively high. The catalyst in the 1st stage of the process according to the invention works much more selectively under the given conditions than undoped catalysts. The control range with respect to butynediol and butenediol conversion is much greater.

Claims (1)

- 1 - Z4Ö 1 I ό claim for invention: Process for the preparation of 1,4-butanediol in two stages, in which the first stage in a continuously operated stirred reactor with suspended catalyst and the second stage are carried out in a fixed bed reactor, characterized in that an aqueous Butindiollösung containing Butindiol of 20 to 50 wt .-% in the stirred reactor at a rate of not more than 30 kg butynediol per kg of catalyst and hour, based on the catalyst in the stirred reactor, metered, using a catalyst which is prepared by adding a nickel salt solution , z. B. nickel nitrate solution, to a maintained at about 6O ⁰ C aqueous solution of waterglass and sodium carbonate in such amounts until extracted from the precipitate formed with excess ammonium bicarbonate at about 9O ⁰ C within 10 minutes 70 to 75% of the nickel contained in the precipitate and the precipitate after washing and drying has a carbonate content, calculated as carbon dioxide, from 7.0 to 8.5, the dried precipitate before or after treatment at higher temperatures in the hydrogen stream, to more than 75% of the nickel present in the precipitate are treated in the metallic form, treated with such amounts of copper salts and molybdenum salts containing aqueous solution, that in the catalyst SiO ₂ : Mo mass ratio of 1: 0.1 to 0.5 and a SiO ₂ : Cu mass ratio of 1: 0.05 to 0.3, the butynediol at temperatures of 5O ⁰ C to 150 ⁰ C, pressures of 0.5 to 5 MPa and a pH of 7 to 10 is hydrogenated in the stirred reactor, wherein a conversion to butanediol of greater than zero and a conversion of butynediol of at least 95% by continuous metering of fresh catalyst into the reaction system and removal of catalyst from the reaction system is maintained and the in the hydrogenation product removed from the stirred reactor catalyst is continuously recycled to the stirred reactor and the hydrogenation product is then passed through a nickel carrier catalyst in a trickle bed reactor at temperatures of 50 to 200 ⁰ C and pressures of 2 to 25 MPa. Field of application of the invention The invention relates to an improved process for the production of 1,4-butanediol by hydrogenation of 1,4-butynediol. Characteristic of the known technical solutions The hydrogenation of butyn-2-diol-1,4 (butynediol for short) to butanediol-1,4 (butanediol for short) is a technically large-scale reaction for the production of butanediol. Numerous procedures for practicing hydrogenation are known. For example, in continuous high-pressure processes with fixed-bed catalysts, butynediol can be hydrogenated in one step to give butanediol (German Pat. No. 890,944). The main shortcoming of these single-stage high-pressure process is the unfavorable heat removal, which is indeed improved by partial recycling of the hydrogenation product for dilution of the aqueous Butindiollösung, but still leads to strong by-product formation (butanol, acetals and high-boiling residues). These processes therefore provide relatively impure products at low yields (about 85%). By-product formation also occurs in the hydrogenation processes which are conducted at medium pressure in the slurry reactor with suspended catalyst. The catalyst used in these processes is Raney nickel, which has been modified with doping in some processes. These methods also allow only comparatively low yields of about 88%. However, the heat removal during the hydrogenation is much better than in the high pressure process. However, a significant disadvantage of the medium-pressure method with suspended catalyst is that these processes must be carried out batchwise. The effectiveness of these batch processes is correspondingly low. In order to reduce the content of by-products to an acceptable level, each hydrogenation mixture must be carried out in two stages at different temperatures (DE-PS 858094). The received. Nevertheless, hydrogenation products are of comparatively low quality. The cause of the high by-product content is that in the hydrogenation of butynediol under the conditions of the known processes always considerable amounts of aldehyde and acetals are formed, which can be partially converted to butanediol only at relatively high temperatures and in particular pressures. With the use of ruthenium / palladium catalysts in medium pressure batch hydrogenation, attempts have been made to hydrogenate the by-products by high levels of ruthenium in the catalyst, even at medium pressure (U.S. Patent 4,438,285). The quality of the products obtained is indeed very good. The discontinuous procedure of this method and the high cost of the catalyst (catalyst use 5%, content of precious metal 5%) represent fundamental disadvantages that preclude a technical use.