WO2017134139A1

WO2017134139A1 - A method of preparing glycolic acid (hoch2cooh)

Info

Publication number: WO2017134139A1
Application number: PCT/EP2017/052210
Authority: WO
Inventors: Jean Paul Andre Marie Joseph Ghislain LANGE; Jan Hermen Hendrik Meurs; Marcello Stefano Rigutto; Hans Arie Stil
Original assignee: Shell Internationale Research Maatschappij B.V.; Shell Oil Company
Priority date: 2016-02-04
Filing date: 2017-02-02
Publication date: 2017-08-10

Abstract

The present invention provides a method of preparing glycolic acid ( HOCH₂COOH ), the method at least comprising the steps of: (a) providing an aqueous oxalic acid (HOOCCOOH) containing stream having a molar ratio of water/oxalic acid of above 5.0; (b) subjecting the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) to hydrogenation in the presence of a hydrogenation metal catalyst and hydrogen, thereby obtaining a glycolic acid (HOCH₂COOH ) containing stream; and (c) optionally subjecting the glycolic acid containing stream obtained in step (b) to hydrogenation in the presence of a hydrogenation metal catalyst and hydrogen, thereby obtaining an ethylene glycol ( HOCH₂CH₂OH ) containing stream.

Description

A METHOD OF PREPARING GLYCOLIC ACID (HOCH₂COOH)

The present invention relates to a method of

preparing glycolic acid (HOCH2COOH) . In another aspect, the present invention relates to a method of preparing ethylene glycol (HOCH2CH2OH) . Various methods of

preparing ethylene glycol are known in the art .

One example of preparing ethylene glycol is disclosed in US4088682. According to US4088682, oxalic acid or alkali metal hydrogen oxalate containing less than 2 moles water of hydration is catalytically hydrogenated, optionally in the presence of ammonia at a temperature of from about 50 to about 500°C. According to US4088682 (whilst referring to Clark, Journal of Physical Chemistry 71(8), 2599-2601) the presence of water should be minimized as far as possible. US4088682 also refers to J.E. Carnahan et al . , JACS 77, 1955, 3766-8 as describing the preparation of ethylene glycol by hydrogenation of oxalic acid dihydrate (HOOCCOOH · 2H2O) without a solvent (and disclosing an ethylene glycol yield of 47%) .

An acknowledged problem of the above known methods of preparing ethylene glycol is that the presence of water needs to be kept as low as possible to obtain acceptable yields of ethylene glycol. US4088682 teaches that the presence of water favours the decomposition of oxalic acid, which is detrimental for the conversion of oxalic acid into glycolic acid and/or ethylene glycol.

It is an object of the present invention to overcome or minimize the above problem.

It is a further object of the present invention to provide an alternative method of preparing glycolic acid. It is an even further object of the present invention to provide an alternative method of preparing ethylene glycol .

One or more of the above or other objects can be achieved by providing a method of preparing glycolic acid

( HOCH2COOH ) , the method at least comprising the steps of:

(a) providing an aqueous oxalic acid (HOOCCOOH) containing stream having a molar ratio of water/oxalic acid of above 5.0;

(b) subjecting the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) to hydrogenation in the presence of a hydrogenation metal catalyst and hydrogen, thereby obtaining a glycolic acid ( HOCH2COOH ) containing stream; and

(c) optionally subjecting the glycolic acid

containing stream obtained in step (b) to hydrogenation in the presence of a hydrogenation metal catalyst and hydrogen, thereby obtaining an ethylene glycol

( HOCH2CH2OH ) containing stream.

It has surprisingly been found according to the present invention that glycolic acid and/or ethylene glycol can be prepared in the presence of a relatively large amount of water with a good yield in an effective manner .

A further advantage of the present invention is that the method can be performed at relatively low

temperatures, such as below 150°C.

An even further advantage of the present invention is that the method can be performed at relatively low pressures such as below 250 bar or even below 150 bar.

This, in contrast to 630-990 atmospheres (638-1003 bar) as mentioned for the preparation of ethylene glycol from oxalic acid (dihydrate) in Experiment 4 of Table I in the above-mentioned article by Carnahan et al.

The person skilled in the art will readily understand that the method according to the present invention can be performed in batch or continuous mode.

In step (a) , an aqueous oxalic acid (HOOCCOOH) containing stream having a molar ratio of water/oxalic acid of above 5.0 is provided. Preferably, the aqueous oxalic acid (HOOCCOOH) containing stream has a molar ratio of water/oxalic acid of above 7.0, more preferably above 10.0 and preferably below 500, more preferably below 250. For ease of comparison, the oxalic acid stream as used in the above-mentioned US4088682 contained less than 2 moles water of hydration and the oxalic acid as used in the above-mentioned Carnahan et al . at most 2.0 (i.e. crystal water).

The person skilled in the art will understand that the aqueous oxalic acid (HOOCCOOH) containing stream is - apart from the presence of water and oxalic acid - not particularly limited. Preferably, the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) comprises from 1.0 to 40 wt . % oxalic acid (HOOCCOOH), preferably above 3.0 wt.%, more preferably above 5.0 wt . % and preferably below 25 wt.%. Typically, the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) comprises from 1.0 to 125 g oxalic acid (HOOCCOOH) per 100 g water, preferably at least 2.0 g, more

preferably at least 4.0 g, preferably at most 100 g.

Typically, the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) comprises one or more other compounds selected from ethylene glycol, glycolic acid, sodium or potassium glycolate, sodium or potassium oxalate, sodium or potassium hydrogenoxalate, sodium or potassium carbonate and sodium or potassium formate. Preferably, the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) comprises less than 80 wt . % (in total) of such other compounds,

preferably less than 50 wt . % and more preferably less than 20 wt . % .

In step (b) , the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) is subjected to hydrogenation in the presence of a hydrogenation metal catalyst and hydrogen, thereby obtaining a glycolic acid containing stream.

The hydrogenation according to the present invention is not particularly limited. As the person skilled in the art is familiar with the process of hydrogenation, this is not discussed here in detail. As an example, the hydrogenation reaction has been described in the above- mentioned US4088682 and Carnahan et al .

Typically, the hydrogenation in step (b) is performed at a temperature of from 10 to 300°C. Preferably, the hydrogenation in step (b) is performed at a temperature of below 250°C, preferably below 200°C, more preferably below 150°C, even more preferably below 140°C.

Preferably, the hydrogenation in step (b) is performed at a temperature of above 20°C, preferably above 30°C, more preferably above 40°C.

Typically, the hydrogenation in step (b) is performed at an ¾ pressure of from 1.0 to 800 bar, preferably above 10 bar, more preferably above 30 bar and preferably below 400 bar, more preferably below 250 bar, even more preferably below 150 bar.

The hydrogenation metal catalyst to be used in step (b) according to the present invention is not

particularly limited and may be homogeneous or heterogeneous and supported or unsupported. As the person skilled in the art is familiar with suitable

hydrogenation metal catalysts, this is not discussed here in detail. Typically, the hydrogenation metal catalyst suitably comprises one or more metals selected from

Groups VIIB, VIII or IB of the Periodic Table of Elements such as platinum, palladium, copper, iron, ruthenium, rhodium, osmium, iridium, gold. It will be appreciated that metals (such as Group 7 metal rhenium) other than the aforementioned one or more metals selected from

Groups VIIB, VIII or IB may be present provided that they do not unduly inhibit the catalyst activity.

Preferably, the hydrogen metal catalyst comprises one or more metals selected from platinum, ruthenium, rhodium and iridium. According to especially preferred embodiment of the present invention, the hydrogenation metal catalyst comprises ruthenium (Ru) .

As mentioned above, the hydrogen metal catalyst may be supported or unsupported. If supported, the support may vary widely. Examples of suitable supports may be carbon, T1O2, ZrO∑ and oxides containing T1O2 and/or Zr02. If a supported hydrogen metal catalyst is used, the metal loading is typically from 0.1 to 90 wt.%, preferably above 0.3 wt.%, more preferably above 1.0 wt.%, even more preferably above 2.0 wt.% and preferably below 70 wt.%, more preferably below 50 wt.%, even more preferably below 30 wt.%, yet even more preferably below 20 wt.%.

In optional step (c) , the aqueous glycolic acid containing stream obtained in step (b) is subjected to hydrogenation in the presence of a hydrogenation metal catalyst and hydrogen, thereby obtaining an ethylene glycol containing stream. Again, as the person skilled in the art is familiar with the process of hydrogenation, this is not discussed here in detail (and reference is made to what has been described for step (b) above, including the description of the hydrogenation metal catalyst) . The person skilled in the art will readily understand, that hydrogenation steps (b) and step (c) , as well as further steps, can be performed in the same or different reactors. Also, the same or different catalysts can be used in steps (b) and (c) . Furthermore, the process conditions, as well as the adding of any

additives may be the same or different for the different steps .

Preferably the hydrogenation in step (c) is performed at a temperature of below 250°C, preferably below 200°C, more preferably below 150°C, even more preferably below 140°C. Further, it is preferred that the hydrogenation in step (c) is performed at an ¾ pressure of from 1.0 to 800 bar, preferably above 10 bar, more preferably above 30 bar and preferably below 400 bar, more preferably below 250 bar, even more preferably below 150 bar. Also, it is preferred that the hydrogenation metal catalyst comprises ruthenium (Ru) .

According to an especially preferred embodiment according to the present invention, at least a part of the ethylene glycol (HOCH2CH2OH) containing stream obtained in step (c) is used as the aqueous oxalic acid

(HOOCCOOH) containing stream provided in step (a) .

Herewith, any or all of the ethylene glycol and/or glycolic acid in the ethylene glycol (HOCH2CH2OH)

containing stream obtained in step (c) can be reused (dependent on what end product is desired) .

Hereinafter the invention will be further illustrated by the following non-limiting examples . Examples

Example 1 - Glycolic acid

An aqueous oxalic acid containing solution was prepared by mixing 5.61 g oxalic acid dihydrate (99+%, obtainable from Acros Organics (Geel, Belgium) ) in 50 ml demineralized water. Consequentially, the aqueous oxalic acid containing solution contained 44.53 mmol oxalic acid.

A hydrogenation metal catalyst was activated by bringing 0.4527 g of a 2.6% Ru catalyst (supported on an extruded T1O2 support (P25, obtainable from Evonik

Industries AG (Essen, Germany) ) into the glass insert of a 250 ml autoclave reactor containing a magnetic stirring bar and provided with a heating mantle. The catalyst was prepared by incipient wetness impregnation using

ruthenium nitrosyl nitrate, starting from a ruthenium nitrosyl nitrate solution containing 10.7% Ru (obtainable from Heraeus Holding GmbH (Hanau, Germany) , drying at 140°C and subsequently calcining at 225°C.

The reactor was closed, rinsed 3 times with 30 bar hydrogen to remove air and then pressurized to 100 bar. Subsequently, the temperature of the heating mantle of the reactor was raised with 2°C per minute from ambient temperature to 200°C. The temperature of the reactor contents was then about 170°C. After 6 hours the reactor was cooled to ambient temperature and the pressure was reduced to 70 bar.

Then, the aqueous oxalic acid containing solution as prepared above was introduced into the reactor by means of an HPLC pump. Stirring was started and the pressure was increased to 100 bar. The temperature of the heating mantle was raised with 2°C per minute to 110°C. The temperature of the reactor contents was then about 100°C. After 4 hours the reactor was cooled to ambient

temperature .

A sample was taken from the gascap of the reactor and analysed with GC; the gascap analysis result was 0.2% CO2, 2% methane and 0.3% ethane. Next, the reactor was depressurized and its contents were filtered using a 0.6 μπι polypropylene filter (ANO 604700, obtainable from Merck Millipore Ltd. (Cork, Ireland) ) to remove the catalyst . The clear filtrate was analysed with LC/UV (oxalate) and ¹H NMR (other non-gaseous components) in d4 methanol using dimethylsulfoxide as internal standard. Oxalic acid conversion was found to be 80% and glycolic acid yield 76%.

Table 1 below lists some of the hydrogenation conditions and the composition of the filtrate, as determined using LC/UV and ¹H NMR.

Example 2 - Ethylene glycol

An aqueous oxalic acid containing solution was prepared by mixing 5.59 g oxalic acid dihydrate (99+%, obtainable from Acros Organics (Geel, Belgium) ) in 50 ml demineralized water.

A hydrogenation metal catalyst was activated by bringing 0.9012 g of a 2.6% Ru catalyst (supported on an extruded T1O2 support (P25, obtainable from Evonik

ruthenium nitrosyl nitrate, starting from a ruthenium nitrosyl nitrate solution containing 10.7% Ru (obtainable from Heraeus Holding GmbH (Hanau, Germany) , drying at 140°C and subsequently calcining at 225°C. The reactor was closed, rinsed 3 times with 30 bar hydrogen to remove air and then pressurized to 90 bar. Subsequently, the temperature of the heating mantle of the reactor was raised with 2°C per minute from ambient temperature to 200°C. The temperature of the reactor contents was then about 170°C. After 6 hours the reactor was cooled to ambient temperature and the pressure was reduced to 70 bar.

Then, the aqueous oxalic acid containing solution as prepared above was introduced into the reactor by means of an HPLC pump. Stirring was started and the pressure was increased to 100 bar. The temperature of the heating mantle was raised with 2°C per minute to 150°C. The temperature of the reactor contents was then about 135°C. After 4 hours the reactor was cooled to ambient

temperature .

A sample was taken from the gascap of the reactor and analysed with GC; the gascap analysis result was 0.1% CO2, 7% methane and 6% ethane. Next, the reactor was depressurized and its contents were filtered using a 0.6 μπι polypropylene filter (ANO 604700) to remove the catalyst . The clear filtrate was analysed with LC/UV (oxalate) and ¹H NMR (other non-gaseous components) in d4 methanol using dimethylsulfoxide as internal standard. Oxalic acid conversion was found to be 98% and ethylene glycol yield 64%.

Example 3 - Ethylene glycol

Example 2 was repeated, except for that the

hydrogenation took place at 2 different temperatures. After introducing the aqueous oxalic acid containing solution into the reactor by means of an HPLC pump, stirring was started and the pressure was increased to 100 bar. The temperature of the heating mantle was then raised with 2°C per minute to 100°C (instead of 150°C as in Example 2) and kept at this first temperature for 6 hours. The temperature of the reactor contents was then about 90 °C.

Then, the temperature of the heating mantle was raised with 2°C per minute to 130°C and kept at this second temperature for 12 hours. The temperature of the reactor contents was then about 120°C. Subsequently, the reactor was cooled to ambient temperature.

Oxalic acid conversion was found to be 99% and ethylene glycol yield 70%. Table 1 below lists some of the hydrogenation conditions and the composition of the filtrate for Example 2.

Comparative Example 1 - Ethylene glycol

Example 2 was repeated, except for that instead of preparing an aqueous oxalic acid containing solution, a solution of oxalic acid in THF was prepared. This to mimic a low molar ratio of water/oxalic acid (NB . the value 2.0 in Table 1 originates from the oxalic acid dihydrate [crystal water]) . To this end, 5.59 g oxalic acid dihydrate (3.99 g oxalic acid, 44.37 mmol) was dissolved in 50 ml THF (SeccoSolv®, containing max.

0.005% water; obtainable from Merck (Darmstadt,

Germany) ) .

Oxalic acid conversion was found to be 100% and ethylene glycol yield only 23%. Table 1 below lists some of the hydrogenation conditions and the composition of the filtrate for Comparative Example 1. Table 1

*Remainder contained i.a. acetic acid, ethanol, methane, ethane and traces of CO and CO2 Discussion

As can be seen from the Examples, the present invention surprisingly provides a method for preparing glycolic acid (Example 1) and/or ethylene glycol

(Examples 2-3) from an oxalic acid containing stream in the presence of water, with desirable yields and

conversion .

On the preparation of ethylene glycol: whilst

Carnahan et al . reported an ethylene glycol yield

(starting from oxalic acid-2H20) of 47%, the present invention resulted in higher yields (64% for Example 2 and 70% for Example 3) at lower temperatures and much lower pressure (110-120 bar for Examples 1-3, versus 630- 990 atmospheres (638-1003 bar) as mentioned for the preparation of ethylene glycol from oxalic acid

(dihydrate) in Experiment 4 of Table I in the above- mentioned article by Carnahan et al.) . Please note in this respect that Comparative Example 1 (mimicking a low molar ratio of water/oxalic acid resulted in an ethylene glycol yield (starting from oxalic acid-2H20) of only 23% .

Noteworthy is also the increase in yield when performing the hydrogenation in 2 separate steps (cf. Examples 2 and 3), even though the hydrogenation steps in Example 3 were performed under 150°C.

The person skilled in the art will readily understand that many modifications may be made without departing from the scope of the invention.

Claims

C L A I M S

1. A method of preparing glycolic acid ( HOCH2COOH ) , the method at least comprising the steps of:

(c) optionally subjecting the glycolic acid

( HOCH2CH2OH ) containing stream.

2. The method according to claim 1, wherein the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) comprises from 1.0 to 40 wt . % oxalic acid (HOOCCOOH).

3. The method according to claim 1 or 2, wherein the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) comprises from 1.0 to 125 g oxalic acid (HOOCCOOH) per 100 g water, preferably at least 2.0 g, more preferably at least 4.0 g, and preferably at most 100 g.

4. The method according to any one of the preceding claims, wherein the hydrogenation in step (b) is

performed at a temperature of below 250°C, preferably below 200°C, more preferably below 150°C, even more preferably below 140°C.

5. The method according to any one of the preceding claims, wherein the hydrogenation in step (b) is

performed at an ¾ pressure of from 1.0 to 800 bar, preferably above 10 bar, more preferably above 30 bar and preferably below 400 bar, more preferably below 250 bar, even more preferably below 150 bar.

6. The method according to any one of the preceding claims, wherein the hydrogenation metal catalyst

comprises ruthenium (Ru) .

7. The method according to any one of the preceding claims, wherein the hydrogenation in step (c) is

8. The method according to any one of the preceding claims, wherein the hydrogenation in step (c) is

9. The method according to any one of the preceding claims, wherein the hydrogenation metal catalyst

comprises ruthenium (Ru) .

10. The method according to any one of the preceding claims, wherein at least a part of the ethylene glycol

(HOCH2CH2OH) containing stream obtained in step (c) is used as the aqueous oxalic acid (HOOCCOOH) containing stream provided in step (a) .