Carbonylation process and catalyst system therefor

Abstract

A catalyst system for a liquid phase carbonylation reaction comprising a homogeneous acid catalyst component and a porous solid component, in particular for use in the formation of glycolic acid by carbonylation of formaldehyde. The homogeneous acid catalyst component is, for instance, sulphuric acid while the solid component can be unfunctionalized silica. A process for the carbonylation of an aldehyde to form a carboxylic acid or derivative thereof is also described. The process comprises the steps of contacting the catalyst with carbon monoxide, water and the aldehyde.

Claims

1. A catalyst system for a liquid phase carbonylation reaction comprising: a homogeneous acid catalyst selected from sulphuric acid, triflic acid, sulfonic acids, alkyl phosphonic acids, phosphoric acid, and formic acid; and, a porous solid component.

2. The catalyst system according to claim 1, wherein the homogeneous acid catalyst is a sulfonic acid that is selected from methylsulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, perfluorooctanesulfonic acid, trihydroxysilylpropane sulfonic acid, and trihydroxysilylethylsulfonic acid.

3. The catalyst system according to claim 1, wherein the solid component has alkyl sulfonic acid groups, hydroxyl groups, or both alkyl sulfonic acid groups and hydroxyl groups on a surface of the solid component, in pores of the solid component, or on both a surface and in pores of the solid component.

4. The catalyst system according to claim 3, wherein the solid component is a porous silica material.

5. The catalyst system according to claim 1, wherein the solid component has a surface area of from about 250 to about 900 m.sup.2/g and a pore volume of from about 0.2 to 1 cc/g.

6. The catalyst system according to claim 1, wherein the amount of homogeneous acid catalyst component present in the catalyst system is from: about 10 ppm to about 25 wt %; from about 50 ppm to about 20 wt %; from about 1 wt % to about 15 wt %; or from about 2 wt % to about 10 wt %.

7. A process for the carbonylation of an aldehyde to form a carboxylic acid or derivative thereof comprising the steps of contacting the catalyst system of claim 1 with carbon monoxide, water, and the aldehyde.

8. The process according to claim 7 for the production of glycolic acid by the reaction of carbon monoxide, water, and formaldehyde.

9. The process according to claim 8, wherein the water is present in an amount from the stoichiometric requirement to a molar ratio of about 4:1 water:formaldehyde.

10. The process according to claim 8, wherein the reaction is carried out in the presence of a solvent.

11. The process according to claim 10, wherein the solvent is, water, a carboxylic acid, or a sulfone.

12. The process according to claim 10, wherein the solvent is glycolic acid or polyglycolide.

13. The process according to claim 8, wherein the process is carried out at a temperature of from about 50 C. to about 400 C.

14. The process according to claim 8, wherein the process is carried out a pressure of from about 1 to about 1000 bara.

15. The process according to claim 8, wherein the amount of homogeneous acid catalyst component present in the catalyst system may be varied during the process.

16. The process according to claim 8, wherein the process is carried out in a continuous flow configuration or batch-wise.

17. The process according to claim 8, wherein the process is carried out at a temperature of from about 100 C. to about 250 C.

18. The process according to claim 8, wherein the process is carried out a pressure of from about 10 to 200 bara.

Description

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

(2) FIG. 1 is a graph illustrating the results of Comparative Example 1;

(3) FIG. 2 is a graph illustrating the results of Comparative Example 2; and

(4) FIG. 3 is a graph illustrating the results of Example 1.

COMPARATIVE EXAMPLE 1

(5) An aqueous solution of formaldehyde was passed to a fixed bed reactor charged with a silica catalyst functionalised with trihydroxysilylethylsulfonic acid where it was contacted with carbon monoxide. The reactor was operated at a temperature of 160 C., a pressure of 170 barg, a formaldehyde flow rate of 150 mL/h and a gas flow of 50 L/h.

(6) Initially reaction occurred and glycolic acid was produced. The initial catalyst activity was calculated to be in the region of 0.3 to about 0.35, as illustrated in FIG. 1, the catalyst deactivated. Without wishing to be bound by any theory it is postulated that the functionalization is removed as the reaction continues such that after about 1000 hours there is effectively only silica present although practically there may be some of the silica that still is functionalised albeit with low effective catalytic activity.

(7) The catalyst activity number is an assessment of the activity of the catalyst taking a variety of factors into consideration including conversion and yield. The same method of assessing catalyst activity was utilised for all examples and therefore the values can be considered as empirical values allowing a direct comparison of results.

COMPARATIVE EXAMPLE 2

(8) Comparative Example 1 was repeated. However, the silica catalyst was replaced with sulfuric acid as catalyst. The reaction was carried out over a bed of glass balls which it will be understood are a non-porous support.

(9) As illustrated in FIG. 2, the amount of sulfuric acid was varied with time. When the amount of sulfuric acid is above about 5 wt %, the catalyst activity was adequate for reaction but the catalyst activity was only around 0.1.

EXAMPLE 1

(10) Comparative Example 1 was repeated except that the catalyst was replaced with a catalyst system comprising an unfunctionalised porous silica support and a sulfuric acid catalyst. Typical physical properties of the material include 0.98 cm.sup.3/g pore volume, 2.1 to 2.7 nm pore size and a surface area of 500 to 1000 m.sup.2/g (BET). As illustrated in FIG. 3, whilst the catalyst activity did vary with the sulfuric acid concentration, the combination of the porous support and the liquid catalyst resulted in a catalyst activity significantly higher than was achieved in either Comparative Examples 1 or 2.

(11) It is therefore clear that the interaction between the porous support and the liquid acid provides an improvement which is not observed when a non-porous support such as glass balls is used.