DE2043349A1 - Geo2/sb catalyst for colourless polyesters - Google Patents

Abstract

The polyesters (I) are products of terephthalic acid (III)/glycol ester polymerisation containing at least 80% of (III). The atomic proportion of Sb to Ge is 0.1-2.0. Ge compounds give good whiteness and transparency. Sb metal gives freedom from ether links. The combination of these catalysts gives highly polymerised polyesters useful for fibres and films of high whiteness, transparency and good heat resistance combining the advantages of each catalyst. Germanium oxide (II) issued as a solution in ethylene glycol. Concentration of (II) is 0.005-0.5 wt.% of (I). The Sb metal particles are sized 1-100 microns. Polymerisation is performed at 220-320 degrees C and 0.1 10 mmHg pressure.

Description

Process for the preparation of 1,4-butanediol The present invention relates to a process for the production of 1,4-butanediol from γ-butyrolactone. 1,4-Butanediol lat a well-known compound, which can be used as a solvent or as Plasticizer suitable for epoxy resins. Furthermore, this compound is a raw material for Polyurethane fibers as well as an intermediate product for the production of tetrahydrofuran.

According to the invention, γ-butyrolactone, which is easier and cheaper Way by reducing maleic anhydride with hydrogen can be used as a starting material.

The purpose of the present invention is to provide an economical Process for the production of 1,4-butanediol in a high yield is available to provide, namely by selective reducing hydrogenation of γ-butyrolactone in the presence of a copper oxide / chromium oxide catalyst, the -3utyrolactone from Maleic anhydride can be produced by reduction with hydrogen.

The invention is based on the knowledge that in the absence of an L. solution or diluent, the reaction temperature is extremely high Selectivity with regard to the formation of 1,4-butanediol in the case of the one described above Affects reaction. It is very important to keep the reaction temperature between 180 and 2300C to selectively keep 1,4-rutanediol in economically high levels Achieve yields.

It was also found that a small amount of succinic acid and Succinic anhydride, these compounds as impurities in the # -butyrolactone and the water content in the reaction system has an adverse effect exercise on the yield of 1,4-butanediol. Hence, the acid and the anhydride must together are kept below 0.5% by weight, while the water content is up less than 1% by weight needs to be depressed.

It became the effect of the reaction temperature on the yield of 1,4-butanediol examined. For this purpose the copper oxide / chromium oxide catalyst was used in one Amount of 20% by weight, based on the γ-butyrolactone, pure XI g-butyrolactone added, which was followed by hydrogenation at different temperatures, namely at 150, 170, 190, 200, 210, 220, 230 and 25000. The hydrogenation time is 5 hours. A hydrogen pressure of 120kg / cm2 was used.

The results are summarized in FIG.

Even if the copper oxide / odorous oxide catalyst is a reductive hydrogenation caused by gr-butyrolactone at a temperature of more than 1500C, it will nevertheless 1,4-butanediol at a temperature below 1800C at too low a rate generated. For example, X is the 1,4-butanediol production rate at 17000 is only about 40% of the speed at 20000 and is less at 15000 as 1/10 of the first given value. Hence it is such a low temperature unsuitable for carrying out the process on a technical scale. on the other hand The catalytic activity decreases rapidly at a temperature of more than 2300C the activity of the reductive hydrogenation lost within a few hours goes. An analysis of the residue of the used at such a high temperature Catalyst shows that some metallic swab has been formed. Hence will at such high temperatures the yield is low. The catalyst can't can be used again without regeneration.

It is known that the used copper oxide / chromium oxide catalyst, who has lost his activity can be regenerated in such a way that he roasted in air. However, it is very costly and uneconomical to use the catalyst roasted after one or two cycles for regeneration. Such a thing The procedure is not suitable for carrying out the process on a technical scale. Furthermore, roasting in air cannot sufficiently restore activity will.

According to the invention, the reaction temperature is therefore 180-23000 limited. Within this temperature range, not only 1, 4-3itanediol in high yield can be obtained, but it can also reduce the activity of the copper oxide / chromium oxide catalyst can be practically avoided. The lifespan of the catalytic converter can be lengthened noticeably.

The copper oxide / odorous oxide catalyst is often used as a catalyst for Production of higher alcohols by reducing hydrogenation of higher fatty acid esters or used to carry out other reducing reactions. During execution this. reducing hydrogenation processes, it is usually recommended to use the Use catalyst at temperatures which are comparatively higher than 2300C. However, a rapid decrease in activity is hardly observed at these temperatures.

In the reducing hydrogenation of butyrolactone, however, the Activity abrupt at temperatures above 2300C in the above Way off. This abrupt decrease in activity is a peculiar phenomenon in the reduction of t-butyrolactone, which was first observed according to the invention is.

The invention is characterized in that # -butyrolactone with hydrogen at temperatures between 180 and 2300C in the presence of a copper oxide / chromium oxide catalyst is reduced. In this way, 1,4-butanediol can be selectively in high yield as well can be produced in an economical manner.

To observe the effects of the mentioned impurities, i.e. the effects of serious acid, succinic anhydride and water in the starting The following tests were carried out on t-butyrolactone: γ-butyrolactone with various amounts of these impurities is in the presence of a copper oxide / chromium oxide catalyst (20% by weight based on the weight of the γ-butyrolactone) at one temperature of 200 ° C under a hydrogen pressure of 120 kg / cm² for a period of Hydrogenated for 5 hours. The results obtained are compared with the results, obtained when using pure g-butyrolactov. Figure 2 shows the relationship between the content of acids and the yield of 1,4-butanediol, while Figure 3 shows the relationship between the water content and the yield.

As can be seen from the two drawings, all acids with the exception of ButtersOure, have a significant adverse effect. The presence of water in an amount greater than 1 ffi remarkably sets the yield of g-butyrolactone decreases. Therefore, the water content must be below 1% by weight being held. Maleic anhydride has a significant adverse effect, however, γ-butyrolactone contains, which is derived from maleic anhydride by hydrogen reduction No appreciable amounts of maleic anhydride have been produced, so that this compound cannot cause any adverse effects.

It is known that the copper chromite catalyst is disadvantageous Way is influenced by various acids, It has been found that butyric acid, which is a monocarboxylic acid and has the same number of carbon atoms as Succinic acid and succinic anhydride, has no effect in an amount of .5%, as can be seen from FIG. In contrast, succinic acid and succinic anhydride show which inevitably occurs during the formation of g-butyrolactone from maleic anhydride formed by hydrogen reduction have an extremely adverse effect the reduction of s -butyrolactone, even if the amount of these Impurities is below 0.5%. This fact was invented for recognized for the first time.

As mentioned above, succinic acid interrupts succinic anhydride and water to an extreme extent the reaction, even if it is present in a very small amount. You need succinic acid, succinic anhydride, and water be removed as much as possible from the t - butyrolactone starting material, the from maleic anhydride by hydrogen reduction.

Water in the butyrolactone can be obtained by simply rectifying or can be removed by dewatering with anhydrous calcium chloride or sodium sulfate. Succinic acid and its anhydride can be easily rectified as well as through Esterification with alcohol in the presence of an acidic catalyst can be eliminated. These Dibasic acid esters can be used in the system without adverse effects. are present.

It has been found that for the production of pure 1,4-butanediol in using high yields by catalytic hydrogenation of t-butyrolactone of a catalyst made of copper oxide and chromium oxide, the reaction temperature is important to be kept between 180 and 230 ° C, with the content of succinic acid and succinic anhydride in which 3tityrolactone must not be more than 0.5%. The water content of the γ-butyrolactone must be below 1.0%.

D'er copper oxide / chromium oxide catalyst, which is used to carry out the inventive Method used can be prepared by the method of Adkins et al (see "Journal of the American Chemical Society", Vol. 54, 1092 (1931)). As this procedure has been modified many times, one can choose one appropriate procedure to achieve better results.

The reduction of # -butyrolactone with hydrogen in the presence of a Copper oxide / chromium oxide catalyst according to the inventive method is under a hydrogen pressure of 50-300 kg / cm² and preferably under a pressure of 100 - 250 kg / cm2 carried out. It is preferable to use the copper oxide / chromium oxide analyzer to be used in an amount of more than 15%, based on the ç-butyrolactone. the The reaction time is expediently generally between 3 and 10 hours. However, the reaction time may vary depending on the catalyst as well as the reaction conditions vary.

Probably lies in that according to the method according to the invention 1,4-Btitanediol produced a very small amount of high-boiling materials before, in addition to not converted 2-butyrolactone. However, no monocarboxylic acids were such as propionic acid, butyric acid etc. and no monoalcohols, such as for example propanol and butanol.

Therefore, a 1,4-butanediol with a very high purity can be used in easily separate from the crude product by simple distillation.

Example 1 Production of the Catalyst 252 g of ammonium dichromate are used dissolved in 1 liter of water to which concentrated liquid ammonia is added, until the color of the solution has changed from orange to yellow. This solution will cooled to room temperature, whereupon a solution of 483 g of copper nitrate trihydrate, in 600 ml of water is added with stirring. The reddish-brown precipitates formed ' are filtered with suction and at about 10,000 for a period of time dried for 24 hours. The product is pulverized and at around 3500C Roasted to obtain 250 g of a copper oxide / chromium oxide catalyst.

Manufacture of 9-butyrolactone according to the method described above The catalyst produced is pelletized and placed in a reactor with a Volume of 30 ml filled. The reactor is heated to 3000C, followed by a stream of hydrogen is sent through to reduce the catalyst. Then maleic anhydride becomes in an amount of 10 g / hour, hydrogen is sent in an amount of 12 1 / hour (under standard conditions). The implementation takes place in each case for a period of 50 hours. In this way, maleic anhydride becomes reduced to γ-butyrolactone in the gas phase. 455 g of the product obtained are distilled to collect all of the t-butyrolactone in the reaction product. The fraction is collected that is between 120 and 130 ° C under a pressure of 110 mm Hg boils. 320 g of a crude 5-butyrolactone are obtained. This crude $ -butyrolactone contains 1.5% water and 1.3% dibasic acids, such as succinic anhydride, Succinic acid and the like. This crude γ-butyrolactone is rectified, using a column consisting of 50 trays and in compliance a reflux ratio of 5: 1. This gives 120 g of 2 utyrolactone with a Boiling point of 960C under a pressure of 20 mm EgO The water content of this γ-butyrolactone is 0.1%, while the content of the sum of succinic anhydride, succinic acid or compare is below 0.1%.

Production of 1,4-butanediol In a 300 ml autoclave, which is equipped with equipped with an electromagnetic stirrer, 80 g of the purified γ- Butyrolactone and 12 g of the above-described copper oxide / chromium yd catalyst introduced, whereupon the autoclave is quickly heated to 200 ° C. Immediately after after heating, hydrogen is introduced under a pressure of 120 kg / cm 2 with stirring. The reaction is allowed to proceed for a period of 8 hours, hydrogen is continuously introduced. After cooling down, the contents taken out of the autoclave, whereupon the catalyst from the reaction mixture is filtered off. The filter cake is washed with ethanol. The previously obtained The filtrate and the washing solution are combined. The 1,4-butanediol in the mixed Solution is being analyzed. The 1,4-butanediol yield is correspondingly 54 g 86 ff. Of the theoretical yield.

The filtered catalyst is washed and 4 more times in one used in a similar manner as previously described.

The yields of 1,4-butanediol are 85-89%. One noticeable No decrease in the catalytic activity can be determined.

Example 2 80 g of the crude 3-butyrolactone prepared in a similar manner as has been obtained in Example 1, with 12 g of methanol in the presence of 4 g of a cation exchange resin esterified.

The esterification takes place at a temperature of 800C during a Time span of 5 hours. The ester obtained in this way is used for removal rectified by methanol and water. The purified.-T-BuYrolactone obtained is reduced with hydrogen in the manner described in Example 1.

This gives 74 g of 1,4-butanediol. This yield corresponds to 89 % of theory.

Comparative experiment 1 In a 300 ml autoclave, which is equipped with an electromagnetic Stirrer is provided, 80 g of the same purified f-butyrolactone and 16 g of the same copper oxide / chromium oxide catalyst according to Example 1 were introduced. Of the The autoclave is quickly heated to 250 ° C. Immediately after heating it becomes hydrogen introduced under a pressure of 120 kg / cm². The response will last for a period allowed to progress for 8 hours. It is found that about 2 hours after When the reaction begins, the absorption of hydrogen begins to abruptly decrease. 4th Hours later, the absorption of hydrogen is practically complete. After cooling down the contents of the autoclave are removed, whereupon the catalyst is filtered off will. The filter cake is washed with ethanol.

The filtrate obtained previously and the washing solution are taken together mixed. The 1,4-butanediol in the mixed solution is determined. The yield of 1,4-butanediol is correspondingly 30.7 g 36 of theory.

The filtered catalyst has a reddish color after washing Appearance in contrast to the black color of the fresh catalyst. The presence some metallic copper is determined by X-ray analysis.

The recovered catalyst is used repeatedly in a way ' which is similar to that described above. However, it is not an absorption, of Detect hydrogen. The catalytic activity has been practically lost.

Comparative experiment 2 80 g of the crude # -butyrolactone, according to the example 1 are obtained with hydrogen in the same manner as in Example 1 reduced. This produces only 18 g of 1,4-butanediol. This yield corresponds to 21% of theory.

Claims (1)

Claim Process for the preparation of 1,4-butanediol by hydrogenation of t-butyrolactone in the presence of a catalyst made of copper oxide and chromium oxide under superatmospheric pressure in the liquid phase, characterized in that the hydrogenation takes place at a temperature is carried out between 180 and 250 ° C, the amount of succinic anhydride and succinic acid in the # -butyrolactone below 0.5% by weight and the water content of the # -butyrolactone are kept below 1% by weight.