JPS5829930B2 - Manufacturing method of ethylene glycol - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing ethylene glycol from formaldehyde and (1) synthesis gas containing carbon oxide and hydrogen.

More particularly, the present invention provides a multi-step process for producing ethylene glycol.

The main steps are (1) producing glycolic and diglycolic acids and simultaneously removing carbon monoxide and hydrogen in the syngas, (2) esterifying the acid product, and (3)
) includes reducing the ester.

In addition to the integrated reaction stage, this process utilizes a special recycle stage to increase the efficiency of the esterification and hydrogenation reactions.

U.S. Patent No. 391, granted on October 7, 1975.
No. 1003 describes an improved process for producing glycolic and diglycolic acids from formaldehyde and carbon monoxide using a hydrogen fluoride catalyst.

According to this description, when glycolic acid is to be used as feedback in the production of ethylene glycol, the acid is esterified with methanol and then catalytically hydrogenated to produce ethylene glycol.

Although this operation is chemically satisfactory, the economics of the process pose problems for large scale commercial production.

The substantial cost of esterification and hydrogenation with methanol is not completely offset by the improved yields and reaction rates achieved using hydrogen fluoride.

It remains therefore desirable to provide an effective process for producing ethylene glycol from formaldehyde and synthesis gas containing carbon monoxide and hydrogen.

According to the present invention, (1) in the presence of hydrogen fluoride, under conditions effective to reduce the carbon monoxide content in the synthesis gas and simultaneously produce glycolic acid and diglycolic acid;
contacting formaldehyde with a synthesis gas containing carbon monoxide and hydrogen: (2) the acid product of step (1);
(3) the carbon monoxide of step (1); (4) the glycolate and diglycolate products of step (2) under conditions effective to produce ethylene glycol or diethylene glycol; and (5) recycling a portion of the glycol product of step (4) to step (2). It was discovered that the production of ethylene glycol in high yields can be achieved economically.

Some features of the invention will become apparent from the following description with reference to the drawings.

FIG. 1 shows a flow sheet of an advantageous embodiment of the method according to the invention.

FIG. 2 shows an advantageous distillation scheme for the product.

The present invention provides an economical circular process for producing high yields of ethylene glycol with improved production rates.

The process attempts to achieve economic production rates and yields using a carefully selected series of reactions and recycling using specific reactants and reaction conditions.

As a first step, formaldehyde, (1) a gas containing carbon oxide and hydrogen, and hydrogen fluoride are introduced into the reaction zone.

The reaction zone is maintained at conditions effective to produce diglycolic acid and glycolic acid.

Note that these are otherwise known as oxydiacetic acid and hydroxyacetic acid, respectively.

Suitable reaction conditions for the production of glycolic acid include temperatures between about 0 degrees C and about 100 degrees C, preferably between about 0 degrees C and about 80 degrees C, and between about 10 psig and about 4000 psig.
It includes the syngas partial pressure between .

Narube (ha, the reaction is water, such as formaldehyde,
It is carried out in the presence of up to about 25 weight percent of water based on the total weight of water and hydrogen fluoride.

The presence of water increases the production of glycolic acid and decreases the production of diglycolic acid.

In a particularly advantageous embodiment of the process of the invention, the temperature in the reaction zone is maintained between 20 and 60 degrees C;
Syngas partial pressure is maintained between 10 and 3000 psig.

Typically, the total pressure will not significantly exceed the partial pressure of carbon oxide and hydrogen.

This is because carbon monoxide and hydrogen are the most volatile of the reactants and products.

Typically, the total pressure will be about 1 to 10 percent higher than the combined partial pressures of carbon monoxide and hydrogen.

Among other factors, the economic success of the process is due to the use of a catalyst containing hydrogen fluoride to promote the reaction of formaldehyde and carbon monoxide at mild temperatures and pressures. This can be attributed to the resulting high yield of glycolic acid.

One of the important features of the present invention is that by using a catalyst containing HF, raw gas having a molar ratio of hydrogen to carbon monoxide of approximately 2:1 is pressurized to a level sufficient to permit practical use. is low (Shiurokoto).

Although hydrogen fluoride itself is of course a satisfactory catalyst, other catalysts containing hydrogen fluoride can also be used with satisfactory results.

For example, U.S. Pat. No. 4,016,208 (197
April 29, 2015 Application U, S, Patent Application Series A, 5727
80) contains hydrogen fluoride and other non-interfering components, e.g.
Suitable catalysts containing copper oxide, silver oxide, nickel oxide and rogonic acids such as HBr, HCI and HI are described.

HBF is a particularly advantageous component. In the presence of hydrogen fluoride, the reaction to produce glycolic acid is surprisingly fast.

Since the reaction rate is very fast, the reaction is completed in a relatively short time even at mild temperatures of 20 to 60 degrees Celsius.

The low reaction temperatures that can be used in the early stages of the process of the invention minimize corrosion of the reaction vessel, so a suitable stainless steel reaction vessel is sufficient.

At higher temperatures more expensive materials such as Mone 1, H
Asteroid alloy or titanium is required.

Preferably, the ratio of reactants to be condensed to catalyst is such that for every mole of formaldehyde there is a 0.5 mole excess of hydrogen fluoride.

Suitable molar ratios of hydrogen fluoride to formaldehyde range from about 1:2 to about 4:1, preferably 7:3.

The overall proportion of reactants on a weight basis is about 5 to about 6
Formaldehyde up to 5 percent, about 40 to about 9
up to 5% catalyst, and the partial pressure of carbon oxide is approximately 1
0 to about 4000 psig.

A more advantageous range is 5 to about 40 percent formaldehyde and 45 to about 85 percent catalyst.

The reaction rate is rapid with a high proportion of catalyst in the reaction mixture.

The flow of synthetic leather gas to the reaction zone may be in the same direction as the flow of formaldehyde or may be countercurrent.

In an advantageous embodiment, the synthetic leather gas is flowed in the same direction as the formaldehyde and the catalyst, and the carbon monoxide is reacted away upstream of the stream, resulting in a purified hydrogen-enriched stream with a low carbon monoxide content. Do it like this.

The recirculating nature of the process allows the carbon monoxide depleted stream to be used for subsequent hydrogenation, as will be described in more detail below.

Crude glycolic acid and diglycolic acid are collected from the first reaction zone.

The crude acid contains catalyst and is preferably removed prior to esterification and recycled to the first reaction zone.

The boiling point of hydrogen fluoride is 19.7 degrees Celsius at 1 atmosphere, which is much lower than the boiling points of diglycolic acid and glycolic acid.

The hydrogen fluoride catalyst can then be easily separated by distillation and recycled to the reaction zone.

According to the method of the invention, the purified acid product is esterified with ethylene glycol, diethylene glycol or a mixture of the two and hydrogenated to ethylene glycol and diethylene glycol.

June 9, 1942 Patent U, S, Patent 22 s 54
4s describes the esterification and hydrogenation of glycolic acid.

Before esterification, at 0.1 to 0.2 atm, about 120
It is desirable to dehydrate the glycolic acid by heating to a temperature between about 150 and about 180 degrees Celsius, preferably between about 150 and about 180 degrees Celsius.

Glycolic acid has the properties of both a carboxylic acid and an alcohol, so the reaction of the alcohol group of one molecule with the carboxyl group of another molecule forms a linear ester with simultaneous formation of water, which is eliminated. I can do it.

These esters may take the form of mono- or polyglycolides.

Most of the glycolides of glycolic acid are solid at room temperature and pressure.

However, they are soluble in hot ethylene glycol.

As used hereinafter, the term "glycolic anhydride" encompasses various dehydrated forms of the acid and in particular refers to mixtures of glycolic acid and polyglycolides.

After dehydration, the glycolic anhydride is contacted with ethylene glycol or diethylene glycol under conditions effective to form the glycolate ester.

Preferably, complete esterification is achieved by adding heated ethylene glycol or diethylene glycol and removing the water produced during esterification, so that substantially all of the carboxyl groups of the acid anhydride are esterified.

Suitable conditions for esterification include from about 150 to about 250 degrees Celsius, preferably from about 170 to about 220 degrees Celsius.
and a pressure of from about 0 to about 1100 psi, and preferably from about 0 to about 50 psig.

The glycol used during esterification may preferably be a recycled portion of the crude glycol product.

According to the reaction scheme shown below, theoretically, 1 mole of ethylene glycol combines with 1 mole of glycolic anhydride to yield 2 moles of ethylene glycol, a portion of which is recycled to the esterification step. The residue is collected as a product.

In practice, it is advantageous to recycle sufficient ethylene glycol to ensure that a molar excess of alcohol is present during the esterification.

The molar ratio of glycol to acid during esterification may suitably vary from about 1.5:1 to about 10:1, preferably from about 2:1 to about 6:1.

After producing the ester, the next step in the process is to hydrogenate the ester to produce the glycol, as also shown in the scheme above.

Liquid phase hydrogenation is carried out at a temperature of about 150 to about 300 degrees Celsius, preferably about 200 to about 250 degrees Celsius, and about 50 degrees Celsius.
From 0 psig to about 5000 psig, preferably about 1
The temperature of the hydrogenation can be made significantly higher through the use and selection of the hydrogenation catalyst, which can be carried out at pressures from 1,000 psig to about 2,000 psig.

Metals and metal oxides are preferred catalysts.

Typical metal oxide catalysts include, for example, copper oxide, chromium oxide or oxides of magnesium, barium, sodium, nickel, silver, lithium, potassium, cesium, zinc, cobalt in combination with and the like and mixtures thereof. There is copper oxide.

A preferred catalyst is cobalt metal in combination with zinc oxide and copper oxide.

As mentioned above, the carbon monoxide depleted and hydrogen enriched stream from the first reaction zone is directed to the ester hydrogenation reaction.

The hydrogen pressure is easily usable.

However, carbon monoxide is poisonous in the ester hydrogenation reaction.

Carbon monoxide may be removed by any known method.

The usual method is to react some of the hydrogen with carbon monoxide to form methane.

Known commercial catalysts are used, usually nickel on an inert oxide or nickel on a diatomaceous earth support.

Hydrogen can be purified by cyclic adsorption impurity adsorption processes or by cryogenic separation methods.

The stream reduced in carbon monoxide content is therefore preferably passed through a hydrogenation vessel to convert the remaining carbon monoxide to methane.

Any conventional hydrogenation catalyst can be used for this purpose.

U.S. Pat.

The carbon monoxide-depleted stream from the first reaction zone further contains a hydrogen fluoride catalyst.

This catalyst can be removed by known methods. For example, if the catalyst is N
It is adsorbed onto aF particles to form a composite, from which the catalyst can be recovered and reused.

After hydrogenation, the ethylene glycol product is purified, for example by distillation, to provide purified commercial ethylene glycol.

Next, the implementation of the present invention will be further explained with reference to Examples.

This example is not intended to limit the scope of the invention;
Various modifications and alterations of the principles of the invention will be readily apparent to those skilled in the art.

This example shows a material balance for producing 20 billion pounds of ethylene glycol per year in accordance with an advantageous embodiment of the cyclic process of the present invention.

In FIG. 1, a line 2 is connected to a carbonylation reaction vessel 1.
12,960 lb/hr formaldehyde, 3,884 lb/hr water, and 570 lb/hr hydrogen fluoride through line 3 and 14,056 lb/hr through line 3.
hour of carbon monoxide and 3092 pounds/hour of hydrogen.

Reaction vessel 1 is about 1500p at a temperature of about 40 to 70 degrees C.
Operate at sig pressure.

Crude glycolic acid and hydrogen fluoride catalyst enter hydrogen fluoride stripper 5 from reaction vessel 1 through line 4 .

Similarly, a reduced carbon oxide content gas containing 570 lb/hr HF, 3092 lb/hr H2 and 1960 lb/hr CO is transferred from reactor vessel 1 to line 6.
The remaining H is passed through the scrubber 24 through
Remove F.

Purified gas is sent to methanator 7.

28,940 pounds/hour of purified glycolic acid and polyglycolide are conducted from stripper 5 to deno iderator 10 via line 9 where line 1
1940 lb/hour of water is removed through 1.

27,000 lb/hour of glycolic acid polymer in line 1
2 to esterification vessel 13, to which vessel is simultaneously added recycled ethylene glycol through line 14 at a rate of 53,570 pounds/hour.

The esterification is carried out at a temperature of about 225 degrees Celsius and a pressure of about 50 psig.

1890 lb/hr of water is distilled off via line 23.

The ethylene glycol ester is led via line 15 to an ester hydrogenation vessel 16 (.

Hydrogenation vessel 16 receives 2,672 pounds/hour of hydrogen and 1,180 pounds/hour of methane from vessel 7 through line 17.
Leading via 3 to a temperature of about 225 degrees C and about 150
Hydrogenate at 0 psig pressure.

Unutilized excess hydrogen, together with methane, forms a bleed (b
lead) is discharged from the hydrogenation vessel via line 25 as a gas stream.

Crude ethylene glycol is led from the hydrogenation container 16 to a distillation column 19 via a line 18.

A portion of the product from line 18 is transferred to line 14 (first
(indicated by a dotted line in the figure) is returned to the esterification container 13.

The remainder is then purified to produce ethylene glycol product.

776 lb/hr water, methanol and ethanol mixture and 690 lb/hr bottoms product to distillation column 19
Then, they are taken out from lines 20 and 21, respectively.

25,345 pounds/hour of ethylene glycol product is collected in line 22.

FIG. 2 shows an advantageous variant of the process described in the example above.

This variant provides another product for recycling to the esterification vessel.

With reference to FIG. 2, the crude glycol product from the hydrogenation vessel is sent through line 18 to dehydration distiller 26.

Water and ethanol are removed from distiller 26 via line 27.

The dehydrated crude product is removed from the distiller via line 28.

In this regard, various products may be selected for recycling,
Typical cases will be explained using three examples.

In the first case, if the hydrogenation is carried out under conditions where the conversion of the glycolate in the hydrogenation reaction vessel is relatively high,
The crude product in line 18 contains wet ethylene glycol and a small proportion of unconverted glycolate.

A portion of the dehydrated product in line 28 may be recycled to the esterification reaction vessel via line 29.

The remainder is purified to remove unconverted glycolate, if present.

Alternatively, the dehydrated product in line 28 may be introduced via line 30 to glycol distillation unit 31.

Distillation unit 31 separates the ethylene glycol with dehydrated glycol as the top product.

This passes through line 32.

The bottom product passes through line 33. A portion of the purified ethylene glycol in line 32 may be recycled to the esterification reaction vessel via line 34, and the remainder is collected via line 35 as purified ethylene glycol product.

Of course, the rate of recirculation using lines 29 and 32 can be adjusted accordingly.

In a second case, when hydrogenation is carried out at conditions where the conversion of the glycolate in the hydrogenation vessel is relatively low, line 18
The crude product in will contain wet ethylene glycol and unconverted glycolate.

A portion of the dehydrated product recovered via diyne 28 may be recycled into the esterification reaction vessel.

The remaining amount is then led to the glycol distiller 31 via line 20.

The latter is fractionated in still 31, purified ethylene glycol is taken off via line 32 and the bottom residue containing unconverted glycolate and heavy products is taken off in line 33.
Collect via.

The bottom residue is then divided into a small bleed stream 31 and a large fraction, the latter being recycled via line 36 to the esterification reaction vessel.

Of course, additional ethylene glycol can be recycled via line 34 to replenish line 29 if desired.

In the third case, if diethylene glycol is the desired product for recycling, no recycling of the dehydrated product in line 28 occurs because ethylene glycol will accumulate in the esterification reaction vessel.

The dehydrated product is conducted via line 30 to distiller 31 where the diethylene glycol as bottom product is recycled via line 36.

Further variations of the above exemplary process are also possible according to the invention according to the claims.

[Brief explanation of the drawing]

FIG. 1 shows a circular process for the production of ethylene glycol. Figure 2 shows the distillation and recycling of the crude product.

Claims (1)

Claims: 1. formaldehyde in the presence of hydrogen fluoride under conditions effective to reduce the carbon monoxide content in the synthesis gas and to produce glycolic acid and diglycolic acid;
(2) contacting the acid product of step (1) with ethylene glycol, diethylene glycol, or a mixture thereof with a synthesis gas containing carbon monoxide and hydrogen; (3) removing residual carbon monoxide and hydrogen fluoride from the carbon monoxide-depleted synthesis gas of step (1) to produce hydrogen; (4) step (2)
) with the hydrogen-rich gas of step (3) under conditions effective to produce ethylene glycol; and (5) contacting the glycolate product of step (3) with the hydrogen-rich gas of step (3); A process for producing ethylene glycol comprising the step of directing a sufficient amount of glycol product from the product of step (4) to the esterification reaction zone of step (2). 2. The hydrogen in hydrogenation stage (4) originates from the hydrogen stream of stage (1) with a reduced content of carbon monoxide, which has been hydrogenated to give a mixture of hydrogen and methane. the method of. at temperatures between 30 and about 100 degrees C and partial pressures of carbon monoxide between 10 and 4000 psig,
The method according to item 1 above, wherein formaldehyde and synthesis gas are brought into contact. At temperatures between 420 and about 60 degrees C and partial pressures of carbon monoxide between 10 and 3000 psig,
The method according to item 1 above, wherein formaldehyde and synthesis gas are brought into contact. 5. The method according to item 1 above, wherein step (1) is carried out in the presence of water. 6. Prior to step (2), the acid product of step (1) is dehydrated to produce various forms of glycolic acid.
The method described in section. 7. The method of paragraph 1, wherein the glycolic acid and ethylene glycol or diethylene glycol are contacted at a temperature between about 150 and about 250 degrees Celsius and a pressure between about 0 and about 100 psig. 8 With the presence of a hydrogenation catalyst, the temperature ranges from about 150 to about 300 degrees Celsius.
temperatures between and about 500 to about 5000 ps
2. The method of claim 1, wherein the glycolate product is contacted with hydrogen at a pressure of up to ig.