Process for the production of glycolic acid

Abstract

A process for the production of glycolic acid or derivatives thereof from formaldehyde comprising reacting formaldehyde with carbon monoxide and water in the presence of a silica catalyst, wherein from about 200 to about 5000 ppm of an alkyl silyl sulfonic acid is supplied to the reaction.

Claims

1. A process for the production of glycolic acid or derivatives thereof from formaldehyde comprising reacting formaldehyde with carbon monoxide and water in the presence of a silica catalyst, wherein from about 200 to about 5000 ppm of an alkyl silyl sulfonic acid is supplied to the reaction.

2. The process according to claim 1, wherein the silica is porous.

3. The process according to claim 1, wherein the silica has a surface area of from about 250 to about 500 m2 and a pore volume of from about 0.2 to 1 cc/g.

4. The process according to claim 1, wherein the silica is functionalised.

5. The process according to claim 4, wherein the functionalization is the presence of acid groups tethered to the silica support.

6. The process according to claim 5, wherein the acid groups are alkyl sulfonic acid groups.

7. The process according to claim 1, wherein the alkyl silyl sulfonic acid is trihydroxysilylalkyl sulfonic acid, such as trihydroxysilylpropyl sulfonic acid, or trihydroxysilylethyl sulfonic acid.

8. The process according to claim 1, wherein the alkyl silyl sulfonic acid is supplied in a recycle product stream.

9. The process according to claim 1, wherein the alkyl silyl sulfonic acid is added in an amount of from about 300 ppm to about 500 ppm.

10. The process according to claim 1, wherein the water is present in an amount from the stoichiometric requirement to a molar ratio of about 4:1 water:formaldehyde.

11. The process according to claim 1, wherein the reaction is carried out in the presence of a solvent.

12. The process according to claim 11, wherein the solvent is water, a carboxylic acid, or a sulphone.

13. The process according to claim 1, wherein the process is carried out at a temperature of from about 50 C. to about 400 C.

14. The process according to claim 1, wherein the process is carried out at a pressure of from about 1 to about 1000 bara.

15. The process according to claim 12, wherein the carboxylic acid is propionic acid and the sulphone is 2,3,4,5-tetrahydrothiophene-1, 1-dioxide.

16. The process according to claim 13 where the process is carried out at a temperature of from about 100 C. to about 250 C.

17. The process according to claim 14 where the process is carried out at a pressure of from about 10 to about 200 bara.

Description

(1) The present invention will now be described by way of example with reference to the following examples and figures in which:

(2) FIG. 1 is a graph illustrating the effect of concentration on activity from Example 1; and

(3) FIG. 2 is a graph illustrating the effect of sulphur in Example 1.

EXAMPLE 1

(4) In this example, the use of a liquid acid catalyst and a silica support for the hydrocarbonylation of formaldehyde to glycolic acid. The acid catalysts used at various times during the life of the catalyst were sulphuric acid, ethane sulfonic acid and trihydroxylsilylpropane sulfonic acid in varying quantities. The reaction was carried out at a temperature of 160 C. and a pressure of 170 bar(g). The feed flow of formaldehyde was 150 mL/h and the gas flow of carbon dioxide was 50 L/h. A graph illustrating how activity is affected by changing homogeneous acid concentration is illustrated in FIG. 2.

(5) It can be seen that the homogeneous acid trihydroxylacids interact closely with the silica support. From FIG. 2 it can be seen that the glycolic acid make increases after the feed acid is increased at 100 hours but this takes 20 hours to reach a steady activity. The effect of turning off the homogeneous silyl sulfonic acid in the feed is illustrated in FIG. 2 between 60 and 95 hours and again there is an extended time lag between the removal of acid from the feed and the reduction of the activity to a steady state.

(6) FIG. 1 illustrates the chromatographic effect is that the liquid feed/product have a residence time of under 1 hour (48 minutes) whereas the sulphur release over 24 hours later in the test run.

EXAMPLE 2

(7) The liquid feed for this example comprised 10% formaldehyde, 12% water and 78% glycolic acid. The feed then had sulfuric acid added to make up the desired sulfuric acid concentration.

(8) A fixed bed reactor was loaded with 120 ml of 3 mm smooth glass balls. The reactor was then pressurised to 170 bar(g) with carbon monoxide and heated to 160 C. Once at reaction conditions the carbon monoxide flow to the reactor was set at 50 NL/h and the liquid feed containing 0% sulfuric acid was started at 150 mL/h. The reactor was set to pressure control at 170 bar(g) with any excess carbon monoxide being vented and the liquid product recovered. After 42 hours the feed was switched to 3 wt % sulfuric acid liquid feed. After 80 hours the feed was switched to 5 wt % sulphuric acid liquid feed. The results are set out in Table 1.

(9) This example shows that feeding a homogeneous acid over an inert, non-porous, material does not give the same enhanced activity observed when the homogeneous catalytic moiety reacts with the support as in Example 1.

EXAMPLE 3

(10) The liquid feed for the example was 10 wt % formaldehyde, 12 wt % water and 78 wt % glycolic acid. This feed then had silyl sulfonic acid added to make up to the desired sulfonic acid concentration.

(11) A fixed bed reactor was loaded with 205 mL of unfunctionalized silica chips with a surface area of 415 m2/g and a pore volume of 1.02 ml/g. The reactor was then pressurised to 170 bar(g) with carbon monoxide and heated to 160 C. Once at reaction conditions the carbon monoxide flow to the reactor was set at 50 NL/h and the liquid feed containing 0% acid was started at 150 ml/h. The reactor was set to pressure control at 170 bar(g) with any excess carbon monoxide being vented and the liquid product recovered. After 175 hours 500 ppm tri-hydroxysilyl propane sulfonic acid (silyl sulfonic acid) feed was started. After 248 hours the feed was switched to 1000 ppm silyl sulfonic acid liquid feed. After 282 hours the feed was switched to 500 ppm silyl sulfonic acid and 3 wt % sulfuric acid liquid feed. After 300 hours the feed was switched to 1 wt % silyl sulfonic acid liquid feed. The results are set out in Table 1 and show that the porous silica does not need to be functionalized prior to reaction to exhibit improved performance.

EXAMPLE 4

(12) The liquid feed for this example was 10 wt % formaldehyde, 12 wt % water and 78 wt % glycolic acid. The recycled product feed was the product from the start of the run containing 387 ppm silyl sulfonic acid groups which had been washed from the functionalised support. This product was dosed to contain 10 wt % formaldehyde so it could be passed back through the reactor.

(13) A fixed bed reactor was loaded with 120 ml of functionalised silica chips. The silica was functionalised with silyl sulfonic acid groups. The reactor was then pressurised to 170 bar(g) with carbon monoxide and heated to 160 C. Once at reaction conditions the carbon monoxide flow to the reactor was set at 50 NL/h and the liquid feed was started at 150 ml/h. The reactor was set to pressure control at 170 bar(g) with any excess carbon monoxide being vented and the liquid product recovered. At the start of the run a large proportion of the functional silyl sulfonic acid groups were washed from the support. This product was recovered for dosing with formaldehyde to be passed back through the reactor. A large boost in formaldehyde conversion was observed when this silyl sulfonic acid containing feed was brought online in comparison to feed which contained no sulfonic acid species. The results are set out in Table 1.

(14) The result shows that the active component can be recycled back to the reactor and activity can be recovered.

(15) TABLE-US-00001 TABLE 1 Inlet Reactor Solid Homogeneous Temp Pressure Formaldehyde Residence Example Component Component C. Bar (g) Conversion % Time h 4 Glass Balls None 160 170 0 0.27 3% wt 160 170 5.4 0.27 sulphuric acid 5% wt 160 170 12.6 0.27 sulphuric acid 5 Unfunctionalized None 160 170 0 0.52 Silica Chips 500 ppm (w) 160 170 39.6 0.52 Silyl Sulphonic Acid 1000 ppm (w) 160 170 40.5 0.52 Silyl Sulphonic Acid 1 wt % 160 170 45 0.52 Silyl Sulphonic Acid 500 ppm (w) 160 170 72.5 0.52 Silyl Sulphonic Acid + 3% wt sulphuric acid 6 Functionalised None 160 176 21.6 0.46 Silica Chips Recycled 160 176 39.9 0.46 Product (387 ppm (w)) Silyl Sulphonic Acid